Update metadata.txt

Opravy chyb a optimalizace napříč pluginem

Souhrn revize celého kódu pluginu:

- Opravy pádů: chybějící locale při startu QGIS; životní cyklus
  úlohy aktualizace heslářů (GC reference, zákaz souběhu, message
  boxy nad hlavním oknem).
- Datová korektnost: transformace fallback geometrií WGS-84 do
  S-JTSK, oprava nevalidních polygonů přes makeValid(), normalizace
  hodnot pian_presnost/pian_typ, heslář přístupnosti bez záznamů
  s kódem None, ošetření null hodnot u komponent.
- Přihlašování a stahování: ověření údajů před uložením do správce
  autentizace, zřetelné hlášení síťových chyb a neúplných výsledků,
  jedno parsování JSON odpovědí, úspornější stránkování, guard proti
  souběžným stahováním, logování do QgsMessageLog.
- Metadata a CI: oprava ikony pluginu, akce ve workflow povýšeny na
  aktuální verze a připnuty na commit hash, poznámka o závislosti
  na requests v README.

Otestováno ručně v QGIS dle checklistu v PR (včetně hraničních
případů: výpadek sítě, expirovaná session, špatné heslo, zrušení
úlohy, prázdné výsledky, limit záznamů).

.github/workflows/release_plugin.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
       # 1. Stáhne kód z repozitáře
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
 
       # 2. Vytvoří ZIP (předpokládá, že kód je ve složce 'amcr_viewer')
       - name: Zip Plugin
@@ -22,7 +22,7 @@ jobs:
 
       # 3. Nahraje ZIP k Releasu
       - name: Upload Release Asset
-        uses: softprops/action-gh-release@v1
+        uses: softprops/action-gh-release@b4309332981a82ec1c5618f44dd2e27cc8bfbfda # v3.0.0
         if: startsWith(github.ref, 'refs/tags/')
         with:
           files: amcr_viewer.zip

.gitignore

@@ -211,3 +211,4 @@ __marimo__/
 README_files/
 README.html
 amcr_viewer.zip
+pyrefly.toml

CITATION.cff

@@ -20,11 +20,10 @@ identifiers:
     value: 10.5281/zenodo.18609813
 repository-code: 'https://github.com/ARUP-CAS/aiscr-qgis-amcr-viewer'
 abstract: >-
-  This QGIS plugin is intended for downloading the data
-  (Fieldwork events data only, at the time) from the
-  Digiarchive of the Archaeological Map of the Czech
-  Republic (AMCR). As of now, only publicly accessible data
-  can be downloaded.
+  This plugin is intended for downloading the data
+  (Fieldwork events, Sites, and their Components) from
+  the Digital archive of the Archaeological Map of the
+  Czech Republic (https://digiarchiv.aiscr.cz/).
 license: GPL-3.0
-version: '1.0.1'
-date-released: '2026-02-11'
+version: '2.0.0'
+date-released: '2026-06-05'

README.md

@@ -2,7 +2,7 @@
 
 [![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](https://www.gnu.org/licenses/gpl-3.0)
 
-**Platform:** QGIS 3.4.0–4.99.0
+**Platform:** QGIS 3.44.0–4.99.0
 
 **Module Type:** Data Acquisition & Visualization
 
@@ -12,8 +12,7 @@
 
 ## 1. Overview
 
-**AMCR Viewer** is a QGIS plugin designed to facilitate direct access to the Digital Archive of the Archaeological Map of the Czech Republic (AMČR). It allows researchers to **query, retrieve, and visualize *Fieldwork events* and *Sites* data (metadata and geometry) directly within the GIS environment**, eliminating the need to manually export data from the web interface. Both *Fieldwork events* and *Sites* layers may be accompanied by a *Components* layer with additional information. **Only publicly accessible data are supported at the time** (accessibility = anonymous).
-
+**AMCR Viewer** is a QGIS plugin designed to facilitate direct access to the Digital Archive of the Archaeological Map of the Czech Republic (AMČR). It allows researchers to **query, retrieve, and visualize *Fieldwork events* and *Sites* data (metadata and geometry) directly within the GIS environment**, eliminating the need to manually export data from the web interface. Both *Fieldwork events* and *Sites* layers may optionally include component-level data (period and activity area) embedded directly in the attribute table. The plugin supports both **anonymous (public) access** and **authenticated access** for users with an AMČR account.
 
 ### Key Features
 
@@ -21,150 +20,163 @@
 * **Advanced Attribute Filtering:** Supports multi-criteria filtering using controlled vocabularies.
 * **Dynamic Geometry Retrieval:** Automatically downloads and categorizes spatial data into Point, Line, and Polygon layers.
 * **Semantic Interoperability:** Automatically translates internal system codes into human-readable labels using the AIS CR API.
+* **Authenticated Access:** Users with an AMČR account can log in to access non-public records.
 
 ## 2. Installation Guide
 
-**Install the plugin from QGIS plugin repository.**  
+**Install the latest version of the plugin from the QGIS plugin repository.**
 
-**OR**  
+**OR** (*in case you need older version*)
 
-*1. Obtain the [plugin distribution package](https://github.com/ARUP-CAS/aiscr-qgis-amcr-viewer/releases) (ZIP archive containing the `amcr_viewer` directory).*  
-*2. Launch QGIS.*  
-*3. Navigate to Plugins → Manage and Install Plugins...*  
-*4. Select the Install from ZIP tab.*  
-*5. Locate the source ZIP file and click Install Plugin.*  
-*6. Upon successful installation, the AMCR download button (load AMCR data) will appear in the interface.*  
+1. *Obtain the [plugin distribution package](https://github.com/ARUP-CAS/aiscr-qgis-amcr-viewer/releases) (ZIP archive containing the `amcr_viewer` directory).*
+2. *Launch QGIS.*
+3. *Navigate to Plugins → Manage and Install Plugins...*
+4. *Select the Install from ZIP tab.*
+5. *Locate the source ZIP file and click Install Plugin.*
+6. *Upon successful installation, the AMCR Viewer button will appear in the toolbar.*
 
 ## 3. User Manual
 
-### 3.1 Data Retrieval
+### 3.1 Authentication (Optional)
 
-To initiate a search query, click either the **Stáhnout data akcí** or the **Stáhnout data lokalit** icon from the dropdown menu. The filter dialog provides the following options. Shown options vary based on the choosed tool.
+By default, the plugin accesses only publicly available records (accessibility = anonymous). To access non-public data, log in using your AMČR account:
 
-* **Spatial Filter:** *Checkbox "Limit search to current map extent":* If checked, the query is restricted to the geographical area currently visible in the QGIS canvas. If unchecked, the query searches the entire database (use with caution regarding data volume).
-* It is possible to view only those Fieldwork events with positive outcome, if "Positive findings only" is checked. Only *PIANs* marked as (or rather *PIANs* belonging to Documentation units marked as) "Type of evidence" = "positive" are rendered.
+* Click the dropdown arrow on the AMCR Viewer toolbar button and select **Přihlásit se**.
+* Enter your e-mail and password. Credentials are encrypted and stored securely in the **QGIS Authentication Manager** (DPAPI on Windows, Keychain on macOS, encrypted SQLite on Linux).
+* Stored credentials are reused automatically across sessions. To update or remove them, open the login dialog again.
 
+### 3.2 Data Retrieval
+
+To initiate a search query, click either the **Stáhnout data akcí** or the **Stáhnout data lokalit** option from the dropdown menu. The filter dialog provides the following options. Shown options vary based on the chosen tool.
+
+* **Spatial Filter:** *Checkbox "Omezit vyhledávání rozsahem okna":* If checked, the query is restricted to the geographical area currently visible in the QGIS canvas. If unchecked, the query searches the entire database (use with caution regarding data volume).
+* **Positive findings only:** If checked, only *PIANs* belonging to Documentation units marked as "Type of evidence" = "positive" are included. *(Fieldwork events only.)*
 
 * **Attribute Filters:**
-  * The dialog utilizes "Picker" widgets for controlled vocabularies (common: Region, District, Cadastral area, Period, Activity Area, *PIAN* accuracy; *events* related: Organisation, Researcher, Event type; *sites* related: Site type and class, Level of confidence, State of preservation).
-  * Click **Select...** to open a searchable selection window. Multiple values can be selected simultaneously (Logic: OR).
+  * The dialog uses "Picker" widgets for controlled vocabularies (common: Region, District, Cadastral area, Period, Activity Area, *PIAN* accuracy, Accessibility; *events* related: Organisation, Researcher, Event type; *sites* related: Site type and class, Level of confidence, State of preservation).
+  * Click **Vybrat...** to open a searchable selection window. Multiple values can be selected simultaneously (Logic: OR).
 
+* **Codelists (Hesláře):**
+  * Controlled vocabularies are downloaded from the AMČR OAI-PMH API and cached locally in `codelists/heslar.csv`.
+  * To refresh all codelists, click the **Aktualizovat hesláře 🔄** button in the filter dialog. This runs as a background task and may take a few minutes.
 
-* **Fieldwork Manager (Dynamic List):**
-  * Due to the dynamic nature of the persons database, the list of Fieldwork Managers is retrieved from the AIS CR servers and needs to be updated the first time (and subsequently, if there is need).
-  * To refresh the list from the server, click the **Refresh (🔄)** button next to the selection field. This downloads the latest list of researchers from the API.
+* **Components:** Check **Načíst komponenty** to include period and activity area data directly in the output layers.
+  > ⚠ When components are loaded, spatial features are duplicated — each feature corresponds to one component. Spatial analyses (areas, counts) may be inaccurate.
 
-* **Components:** The *components* data are downloaded as well upon checking the corresponding check box. This enriches the main (*Events* and *Sites*) layers with additional information (period and activity area).
-
-* If no filter is used, all accessible Fieldwork events/PIANs are returned (although the number of Fieldwork events to be loaded is capped at 20000 records; it is advisable to set at least one filter).  
+* If no filter is used, all accessible Fieldwork events/PIANs are returned (the number of records is capped at 20 000; it is advisable to set at least one filter).
 
 For a more in-depth tutorial refer to the [AMČR Documentation](https://amcr-help.aiscr.cz/digiarchiv/qgis-viewer.html) (only in Czech).
 
-### 3.2 Layer Structure & Attributes
+### 3.3 Layer Structure & Attributes
 
-Upon successful retrieval, the plugin generates four temporary memory layers:
+Upon successful retrieval, the plugin generates up to three temporary memory layers:
 
-1. **AMCR Plochy (Polygons)**
-2. **AMČR Linie (Lines)**
-3. **AMČR Body (Points)**
-4. **AMČR Komponenty (*Components*/no geometry)**
+1. **AMCR\_[Akce|Lokalita]\_Polygony**
+2. **AMCR\_[Akce|Lokalita]\_Linie**
+3. **AMCR\_[Akce|Lokalita]\_Body**
 
-The Attribute Table includes standardized fields with important metadata. The components layer has no geometry on its own and depend solely on a relation with the other three layers.
+Layers are only created if the query returns features of the corresponding geometry type. All layers share the same attribute schema.
 
-#### 3.2.1 Fields of the layers with geometry
+#### 3.3.1 Common fields
 
 | Field | Description |
 | --- | --- |
-| PIAN | PIAN (spatial identifier) ID |
-| Přesnost | spatial deviation [in units/tens/hundreds of meters/defined by cadastre] |
-| PIAN – typ | [point/line/polygon] |
-| Dokumentační jednotka | Documentation unit ID |
-| Typ dokumentační jednotky | [trench/event part/whole event/cadastral territory] |
-| Definiční bod(y) (WGS-84) | feature centroid in WGS-84 coordinate system |
-| Akce/Lokalita | Event/Site ID |
-| Odkaz do Digitálního archivu AMČR | link to the Event/Site record in the Digital Archive |
-| Okres | district |
-| Katastr | main cadastre |
-| Další katastr | other cadastres, if the event extends beyond the main cadastre |
-| Přístupnost | record accessibility [A/B/C/D] |  
+| pian | PIAN (spatial identifier) ID |
+| presnost | Spatial deviation \[units/tens/hundreds of meters/defined by cadastre\] |
+| pian\_typ | \[point/line/polygon\] |
+| dj | Documentation unit ID |
+| typ\_dj | \[trench/event part/whole event/cadastral territory\] |
+| definicni\_body | Feature centroid in WGS-84 coordinate system |
+| akce / lokalita | Fieldwork event / Site ID |
+| odkaz\_do\_digiarchivu | Link to the record in the Digital Archive |
+| okres | District |
+| katastr | Main cadastral area |
+| dalsi\_katastry | Other cadastral areas, if the event extends beyond the main cadastre |
+| Přístupnost | Record accessibility \[A/B/C/D\] |
 
-> Common fields
+#### 3.3.2 Fields related to *Fieldwork events*
 
 | Field | Description |
 | --- | --- |
-| Vedoucí akce | main fieldwork manager |
-| Organizace | organization conducting the research |
-| Specifikace data | [exact date/exact years/sometime in years] |
-| Datum zahájení | Event start date |
-| Datum ukončení | Event end date |
-| Hlavní typ | primary research method [total excavation/pit trench/surface collection survey/…] |
-| Vedlejší typ | secondary research method [same options as in Hlavní typ] |
-| Zjištění | did the research reveal archaeological contexts? [positive/negative] |
-| Akce – lokalizace | verbal description of the event location |
-| Akce – nahrazuje NZ | replaces a fieldwork report? [yes/no] |  
+| akce\_lokalizace | Verbal description of the event location |
+| vedouci | Main fieldwork manager |
+| organizace | Organisation conducting the research |
+| specifikace\_data | \[exact date/exact years/sometime in years\] |
+| zahajeni | Event start date |
+| ukonceni | Event end date |
+| hlavni\_typ | Primary research method |
+| vedlejsi\_typ | Secondary research method |
+| zjisteni | Did the research reveal archaeological contexts? \[positive/negative\] |
+| nahrazuje\_NZ | Replaces a fieldwork report? \[yes/no\] |
 
-> Fields related to *Fieldwork events*  
+#### 3.3.3 Fields related to *Sites*
 
 | Field | Description |
 | --- | --- |
-| nazev_lokality | site name |
-| popis_lokality | site description |
-| typ_lokality | site classification by definition method [survey polygon/heritage site/landscape] |
-| druh_lokality | site classification by the nature of identified field relics [aerial survey polygon/landscape/remains of settlement/…] |
-| zachovalost | site preservation state [buried site/ruin/aboveground remains/…] |
+| nazev\_lokality | Site name |
+| popis\_lokality | Site description |
+| typ\_lokality | Site classification by definition method |
+| druh\_lokality | Site classification by the nature of identified field relics |
+| zachovalost | Site preservation state |
 
-> Fields related to *Sites*
-
-#### 3.2.2 Fields of the *Components* layer
+#### 3.3.4 Component fields (only when *Načíst komponenty* is checked)
 
 | Field | Description |
 | --- | --- |
 | komponenta | Component ID |
-| dj_id | parent Documentation unit ID |
-| komponenta_areal | Activity area [settlement/burial area/field/…] |
-| komponenta_obdobi | Period [Neolithic/High Middle Ages–Modern Period/Middle La Tène (LtB–C1)/…] |
-| vrstva | system value linking to a specific geometry table with the corresponding documentation unit |
+| komponenta\_areal | Activity area \[settlement/burial area/field/…\] |
+| komponenta\_obdobi | Period \[Neolithic/High Middle Ages–Modern Period/…\] |
 
 ## 4. Technical Architecture
 
 The plugin is developed in **Python 3** using the **PyQt6** framework for the GUI and the **Requests** library for HTTP communication.
 
+> **Note:** The `requests` library is bundled with the QGIS installers for Windows and macOS. On Linux (distribution packages), it may need to be installed separately (e.g. `python3-requests`).
+
 ### 4.1 File Structure
 
-* `amcr_viewer.py`: Entry point; handles GUI integration and initialization.
-* `amcr_dialog.py`: Manages the UI logic, including the custom `FilterableSelectionDialog` for handling large vocabularies.
-* `amcr_tools.py`: Core logic module. Handles API requests, pagination, data parsing, and vector layer generation.
-* `amcr_codelists.py`: Manages local caching of controlled vocabularies (`codelists/*.csv`).
+* `amcr_viewer.py`: Entry point; handles GUI integration, toolbar/menu setup, and login flow.
+* `amcr_dialog.py`: Manages the UI logic, including `AmcrFilterDialog`, `FilterableSelectionDialog`, and `LoginDialog`.
+* `amcr_tools.py`: Core logic module. Handles authentication, API requests, pagination, data parsing, and vector layer generation.
+* `amcr_codelists.py`: Manages local caching of controlled vocabularies (`codelists/heslar.csv`) downloaded via OAI-PMH.
 
 ### 4.2 Data Flow & API Integration
 
-The plugin interacts with three primary endpoints of the AIS CR infrastructure:
+The plugin interacts with the following endpoints:
 
-1. **Search API (Solr):**
-* Endpoint: `https://digiarchiv.aiscr.cz/api/search/query`
-* Method: `GET`
-* Parameters: `entity=akce`, `rows/page` (pagination).
-* Logic: The plugin implements a `while True` loop to handle pagination, processing data in batches of 500 records to ensure stability.
+1. **Login API:**
+   * Endpoint: `https://digiarchiv.aiscr.cz/api/user/login`
+   * Method: `POST`
+   * Returns a session cookie used for subsequent authenticated requests.
+   * Credentials are stored in the QGIS Authentication Manager; the session is restored automatically if it expires mid-download.
 
-2. **Translation API:**
-* Endpoint: `https://digiarchiv.aiscr.cz/api/assets/i18n/cs.json`
-* Function: Retrieves the mapping between system codes (e.g., `HES-xxxx`) and Czech labels. This dictionary is cached in memory during the session.
+2. **Search API (Solr):**
+   * Endpoint: `https://digiarchiv.aiscr.cz/api/search/query`
+   * Method: `GET`
+   * Parameters: `entity=akce|lokalita|pian`, `rows/page` (pagination), `mapa=true`.
+   * Logic: Paginated in batches of 500 records (metadata) and 200 records (geometries). A safety cap of 20 000 records is enforced.
+
+3. **Translation API:**
+   * Endpoint: `https://digiarchiv.aiscr.cz/api/assets/i18n/cs.json`
+   * Function: Retrieves the mapping between system codes (e.g. `HES-xxxx`) and Czech labels. Cached in memory for the session.
+
+4. **Codelists API (OAI-PMH):**
+   * Endpoint: `https://api.aiscr.cz/2.2/oai`
+   * Used for downloading controlled vocabularies (periods, regions, organisations, etc.) on demand.
 
 ### 4.3 Data Persistence
 
-* **Vocabularies:** Static vocabularies (e.g., Periods, Regions) are stored in `codelists/heslar.csv`.
-* **Dynamic Data:** The list of researchers is downloaded on-demand and cached in `codelists/vedouci.csv`.
+* **Vocabularies:** Stored in `codelists/heslar.csv`; updated on user request via the background task.
 * **Layers:** Output layers are created as `memory` layers. They are non-persistent and will be lost if QGIS is closed without saving.
 
 ### 4.4 Constraints
 
-* **Record Limit:** A safety cap of 20,000 records is enforced.
-* **Batch Processing:** Geometry fetching is batched (50 IDs per request) to comply with URL length limitations and server load balancing.
-
-### 4.5 Relational Data Linking
-The plugin automatically utilizes advanced QGIS features for data relationship management, specifically Polymorphic Relations. The *Components* layer is dynamically linked within the project to the spatial layers of events and sites via the documentation unit identifier (dj_id). This allows users to immediately see all *components* belonging to a given geometry (point, line, or polygon) directly in the attribute form or the identify features tool, without the need to manually filter or join the data.
+* **Record Limit:** A safety cap of 20 000 records is enforced.
+* **Batch Processing:** Geometry fetching is batched (200 IDs per request) to comply with URL length limitations and server load balancing.
+* **Component duplication:** When components are loaded, each output feature corresponds to one component rather than one documentation unit. A single PIAN may therefore appear multiple times in the layer.
 
 ## 5. Links and resources
 
 * [AMCR/Digiarchive Documentation](https://amcr-help.aiscr.cz/) (only in Czech).
 * [AMCR Viewer tutorial](https://amcr-help.aiscr.cz/digiarchiv/qgis-viewer.html) (only in Czech).
+* [Import/Export. Pluginy propojující QGIS s AMČR \[poster\]](https://zenodo.org/records/20504909) (only in Czech; valid for v1.3.2).

amcr_viewer/amcr_codelists.py

@@ -2,7 +2,7 @@
 import os
 import csv
 import requests
-import xml.etree.ElementTree as ET  # nosec B314
+import xml.etree.ElementTree as ET  # nosec
 import time
 from qgis.core import QgsMessageLog, Qgis
 
@@ -13,20 +13,20 @@ BASE_URL = "https://api.aiscr.cz/2.2/oai"
 OUTPUT_FILE = os.path.join(CODELISTS_DIR, 'heslar.csv')
 
 slovnicek = {
-    'obdobi' : 'heslo:obdobi',
-    'typ_akce' : 'heslo:akce_typ',
-    'areal' : 'heslo:areal',    
-    'kraj' : 'ruian_kraj',
-    'organizace' : 'organizace',
-    'okres' : 'ruian_okres',
-    'katastr' : 'ruian_katastr',
-    'vedouci' : 'osoba',
-    'pian_presnost' : 'heslo:pian_presnost',
-    'typ_lokality' : 'heslo:lokalita_typ',
-    'druh_lokality' : 'heslo:lokalita_druh',
-    'jistota' : 'heslo:jistota_urceni',
-    'lokalita_zachovalost' : 'heslo:stav_dochovani',
-    'pristupnost' : 'heslo:pristupnost'
+    'obdobi': 'heslo:obdobi',
+    'typ_akce': 'heslo:akce_typ',
+    'areal': 'heslo:areal',
+    'kraj': 'ruian_kraj',
+    'organizace': 'organizace',
+    'okres': 'ruian_okres',
+    'katastr': 'ruian_katastr',
+    'vedouci': 'osoba',
+    'pian_presnost': 'heslo:pian_presnost',
+    'typ_lokality': 'heslo:lokalita_typ',
+    'druh_lokality': 'heslo:lokalita_druh',
+    'jistota': 'heslo:jistota_urceni',
+    'lokalita_zachovalost': 'heslo:stav_dochovani',
+    'pristupnost': 'heslo:pristupnost'
 }
 
 NS = {
@@ -35,30 +35,35 @@ NS = {
     'oai_dc': 'http://www.openarchives.org/OAI/2.0/oai_dc/'
 }
 
+
 def ensure_codelists_dir():
     """Creates the codelists directory if it does not exist."""
     if not os.path.exists(CODELISTS_DIR):
         os.makedirs(CODELISTS_DIR)
 
+
 def parse_codelist_file(filename, target_dict=None):
-    """Reads a CSV codelist file and populates the target dictionary grouped by categories."""
+    """
+    Reads a CSV codelist file and populates
+    the target dictionary grouped by categories.
+    """
     if target_dict is None:
         target_dict = {}
-        
+
     path = os.path.join(CODELISTS_DIR, filename)
-    
+
     # Return early if the file doesn't exist to avoid missing file errors
-    if not os.path.exists(path): 
+    if not os.path.exists(path):
         return target_dict
-        
+
     try:
         # Open the file using standard UTF-8 encoding
         with open(path, 'r', encoding='utf-8') as f:
             reader = csv.reader(f, delimiter=';')
-            
+
             # Skip the CSV header row
-            next(reader, None) 
-            
+            next(reader, None)
+
             # Iterate through rows and extract label, code, and category
             for row in reader:
                 if len(row) >= 3:
@@ -66,18 +71,24 @@ def parse_codelist_file(filename, target_dict=None):
                     code = row[1].strip()
                     cat = row[2].strip()
                     clean = code if code else None
-                    
-                    # Initialize a new dictionary for a category if encountered for the first time
+
+                    # Initialize a new dictionary for a category if encountered
+                    # for the first time
                     if cat not in target_dict:
                         target_dict[cat] = {}
-                        
-                    # Assign the extracted code to the corresponding label within the category
+
+                    # Assign the extracted code to the corresponding label
+                    # within the category
                     target_dict[cat][label] = clean
+
     except Exception as e:
-        QgsMessageLog.logMessage(f"AMČR Codelist Read Error for {filename}: {e}", "AMČR", Qgis.Critical)
-        
+        QgsMessageLog.logMessage(
+            f"AMČR Codelist Read Error for {filename}: {e}",
+            "AMČR", Qgis.Critical)
+
     return target_dict
 
+
 def load_all_data():
     """Loads the codelist during plugin startup."""
     ensure_codelists_dir()
@@ -85,6 +96,7 @@ def load_all_data():
     parse_codelist_file('heslar.csv', categorized_data)
     return categorized_data
 
+
 def fetch_set(internal_name, api_set, task=None):
     dataset = []
     params = {
@@ -92,42 +104,65 @@ def fetch_set(internal_name, api_set, task=None):
         "metadataPrefix": "oai_dc",
         "set": api_set
     }
-    
+
     while True:
-        # Kontrola zrušení v každém kroku
+        # Check for cancellation at each iteration
         if task and task.isCanceled():
             return None
 
         try:
             response = requests.get(BASE_URL, params=params, timeout=30)
             response.raise_for_status()
-            root = ET.fromstring(response.content)
-            
+            root = ET.fromstring(response.content)  # nosec
+
             records = root.findall('.//oai:record', NS)
             for rec in records:
                 metadata = rec.find('.//oai_dc:dc', NS)
                 if metadata is not None:
-                    # Kód (identifier)
-                    kod = metadata.find('dc:identifier', NS).text if metadata.find('dc:identifier', NS) is not None else ""
-                    
-                    # Název (title) - filtrujeme systémové popisky "AMČR - ..."
+                    # Code (identifier)
+                    identifier_el = metadata.find('dc:identifier', NS)
+                    kod = (
+                        identifier_el.text
+                        if identifier_el is not None
+                        else ""
+                    )
+
+                    # Title – filter out system labels "AMČR - ..."
                     titles = metadata.findall('dc:title', NS)
                     nazev = ""
                     for t in titles:
-                        if t.text and not t.text.startswith("AMČR -") and not t.text.startswith(" AMČR -"):
+                        if (
+                            t.text
+                            and not t.text.startswith("AMČR -")
+                            and not t.text.startswith(" AMČR -")
+                        ):
                             nazev = t.text
                             break
-                    # Pokud by náhodou žádný title neprošel filtrem, vezmeme první dostupný
+                    # If no title passed the filter, fall back
+                    # to the first available one
                     if not nazev and titles:
                         nazev = titles[0].text
-                    
+
                     specialni_pripady = ['okres', 'katastr']
 
                     if internal_name in specialni_pripady:
                         kod = nazev
 
                     if internal_name == 'pristupnost':
-                        kod = next((t.text for t in titles if t.text and len(t.text) == 1 and t.text.isalpha()), None)
+                        kod = next(
+                            (
+                                t.text for t in titles
+                                if t.text
+                                and len(t.text) == 1
+                                and t.text.isalpha()
+                            ),
+                            None
+                        )
+                        # Skip records without a valid one-letter code –
+                        # a None code would end up in the CSV and later
+                        # in the API filter as the string "None"
+                        if not kod:
+                            continue
 
                     dataset.append({
                         'Název': nazev,
@@ -135,7 +170,7 @@ def fetch_set(internal_name, api_set, task=None):
                         'Kategorie': internal_name
                     })
 
-            # Stránkování
+            # Pagination
             token = root.find('.//oai:resumptionToken', NS)
             if token is not None and token.text:
                 params = {
@@ -145,40 +180,45 @@ def fetch_set(internal_name, api_set, task=None):
                 time.sleep(0.5)
             else:
                 break
-                
+
         except Exception as e:
-            QgsMessageLog.logMessage(f"Chyba u setu {api_set}: {e}", "AMČR", Qgis.Warning)
+            QgsMessageLog.logMessage(
+                f"Chyba u setu {api_set}: {e}",
+                "AMČR", Qgis.Warning)
             break
-            
+
     return dataset
 
+
 def download_heslare(task=None):
     """Fetches the codelists from the AMČR API and saves it to a CSV file."""
     ensure_codelists_dir()
     all_data = []
     total_sets = len(slovnicek)
-    
+
     for index, (interni, api_nazev) in enumerate(slovnicek.items()):
-        # Pokud uživatel task zrušil v liště QGISu
+        # Check if the user cancelled the task via the QGIS taskbar
         if task and task.isCanceled():
             return False
 
-        QgsMessageLog.logMessage(f"Zpracovávám kategorii: {interni}...", "AMČR", Qgis.Info)
-        
-        # Nyní předáváme task správně do upravené funkce
+        QgsMessageLog.logMessage(
+            f"Zpracovávám kategorii: {interni}...",
+            "AMČR", Qgis.Info)
+
+        # Pass the task correctly to the updated fetch function
         data = fetch_set(interni, api_nazev, task=task)
-        
+
         if data is None:
-            return False # Bylo zrušeno uprostřed stahování
+            return False  # Cancelled mid-download
 
         all_data.extend(data)
 
-        # Reportování postupu (0-100)
+        # Report progress (0-100)
         if task:
             progress = (index + 1) / total_sets * 100
             task.setProgress(progress)
 
-    # Uložení do CSV
+    # Save to CSV
     with open(OUTPUT_FILE, 'w', newline='', encoding='utf-8-sig') as f:
         fieldnames = ['Název', 'Kód', 'Kategorie']
         writer = csv.DictWriter(f, fieldnames=fieldnames, delimiter=';')
@@ -187,13 +227,11 @@ def download_heslare(task=None):
 
     return True
 
+
 def refresh_globals():
-    """Znovu načte data ze souborů do globálních proměnných."""
-    global OBDOBI, TYP_AKCE, AREAL, KRAJE, ORGANIZACE, OKRESY, KATASTRY
-    global VEDOUCI, PIAN_PRESNOST, TYP_LOKALITY, DRUH_LOKALITY, JISTOTA, LOKALITA_ZACHOVALOST, PRISTUPNOST
-    
+    """Reloads data from files into the global variables."""
     data = load_all_data()
-    
+
     OBDOBI.clear()
     OBDOBI.update(data.get('obdobi', {}))
     TYP_AKCE.clear()
@@ -224,7 +262,7 @@ def refresh_globals():
     PRISTUPNOST.update(data.get('pristupnost', {}))
 
 
-# Inicializace prázdných diktů, které se naplní hned pod tím
+# Initialize empty dicts that will be populated immediately below
 OBDOBI = {}
 TYP_AKCE = {}
 AREAL = {}
@@ -240,4 +278,4 @@ JISTOTA = {}
 LOKALITA_ZACHOVALOST = {}
 PRISTUPNOST = {}
 
-refresh_globals()
+refresh_globals()

amcr_viewer/amcr_dialog.py

@@ -1,16 +1,26 @@
 # -*- coding: utf-8 -*-
-from qgis.PyQt.QtWidgets import (QDialog, QVBoxLayout, 
-                                 QLineEdit, QDialogButtonBox, 
+from qgis.PyQt.QtWidgets import (QDialog, QVBoxLayout,
+                                 QLineEdit, QDialogButtonBox,
                                  QCheckBox, QGroupBox, QPushButton,
                                  QListWidget, QListWidgetItem, QHBoxLayout,
                                  QMessageBox, QLabel, QFormLayout)
 from qgis.PyQt.QtCore import Qt, QSettings
-from qgis.core import QgsTask, QgsApplication, QgsMessageLog, Qgis, QgsAuthMethodConfig
-from .amcr_codelists import (OBDOBI, TYP_AKCE, KRAJE, AREAL, ORGANIZACE, 
-                             OKRESY, KATASTRY, VEDOUCI, PIAN_PRESNOST, TYP_LOKALITY,
-                             DRUH_LOKALITY, JISTOTA, LOKALITA_ZACHOVALOST, PRISTUPNOST,
+from qgis.core import (QgsTask, QgsApplication,
+                       QgsMessageLog, Qgis, QgsAuthMethodConfig)
+from qgis.utils import iface
+from .amcr_codelists import (OBDOBI, TYP_AKCE, KRAJE, AREAL, ORGANIZACE,
+                             OKRESY, KATASTRY, VEDOUCI, PIAN_PRESNOST,
+                             TYP_LOKALITY, DRUH_LOKALITY, JISTOTA,
+                             LOKALITA_ZACHOVALOST, PRISTUPNOST,
                              download_heslare, refresh_globals)
 
+
+# Keep Python references to running tasks. QgsTaskManager only holds the
+# C++ object; without a Python-side reference the wrapper can be garbage
+# collected before the task finishes, which crashes QGIS.
+_ACTIVE_TASKS = []
+
+
 class UpdateCodelistsTask(QgsTask):
     def __init__(self, description):
         super().__init__(description, QgsTask.CanCancel)
@@ -18,9 +28,9 @@ class UpdateCodelistsTask(QgsTask):
         self.exception = None
 
     def run(self):
-        """Tato část běží ve vedlejším vlákně."""
+        """Runs in a background thread."""
         try:
-            # Voláme upravenou funkci
+            # Call the download function with the task reference
             self.success = download_heslare(task=self)
             return self.success
         except Exception as e:
@@ -28,52 +38,61 @@ class UpdateCodelistsTask(QgsTask):
             return False
 
     def finished(self, result):
-        """Tato část běží v hlavním vlákně po skončení run()."""
+        """Runs in the main thread after run() completes."""
         if result:
-            # Teď bezpečně aktualizujeme globální proměnné v hlavním vlákně
+            # Safely update the global variables in the main thread
             refresh_globals()
-            QgsMessageLog.logMessage("Hesláře AMČR byly úspěšně aktualizovány.", "AMČR", Qgis.Info)
+            QgsMessageLog.logMessage(
+                "Hesláře AMČR byly úspěšně aktualizovány.",
+                "AMČR", Qgis.Info)
         else:
             if self.isCanceled():
-                QgsMessageLog.logMessage("Aktualizace heslářů byla zrušena.", "AMČR", Qgis.Warning)
+                QgsMessageLog.logMessage(
+                    "Aktualizace heslářů byla zrušena.",
+                    "AMČR", Qgis.Warning)
             else:
-                QgsMessageLog.logMessage(f"Chyba aktualizace: {self.exception}", "AMČR", Qgis.Critical)
+                QgsMessageLog.logMessage(
+                    f"Chyba aktualizace: {self.exception}",
+                    "AMČR", Qgis.Critical)
+
 
 class FilterableSelectionDialog(QDialog):
     """
-    A custom dialog for selecting multiple items from a list with a search filter.
+    A custom dialog for selecting multiple items from
+    a list with a search filter.
     Updated for PyQt6/Qt6 compatibility.
     """
     def __init__(self, title, data_dict, preselected_codes, parent=None):
         super().__init__(parent)
         self.setWindowTitle(f"Výběr: {title}")
         self.resize(400, 500)
-        
+
         # Store the source data and previously selected items
         self.data_dict = data_dict
         self.preselected = preselected_codes if preselected_codes else []
-        
+
         layout = QVBoxLayout()
-        
+
         # Setup search input for filtering items
         self.search_bar = QLineEdit()
         self.search_bar.setPlaceholderText("Hledat v seznamu...")
         self.search_bar.textChanged.connect(self.filter_list)
         layout.addWidget(self.search_bar)
-        
+
         # Main list widget for displaying selectable items
         self.list_widget = QListWidget()
         self.populate_list()
         layout.addWidget(self.list_widget)
-        
+
         # Standard OK/Cancel dialog buttons
         buttons = QDialogButtonBox(
-            QDialogButtonBox.StandardButton.Ok | QDialogButtonBox.StandardButton.Cancel
+            QDialogButtonBox.StandardButton.Ok
+            | QDialogButtonBox.StandardButton.Cancel
         )
         buttons.accepted.connect(self.accept)
         buttons.rejected.connect(self.reject)
         layout.addWidget(buttons)
-        
+
         self.setLayout(layout)
 
     def populate_list(self):
@@ -82,19 +101,19 @@ class FilterableSelectionDialog(QDialog):
         for name in sorted_names:
             code = self.data_dict[name]
             item = QListWidgetItem(name)
-            
+
             # Store the actual code (ID) hidden in the UserRole
             item.setData(Qt.ItemDataRole.UserRole, code)
-            
+
             # Make the item checkable (adds a checkbox)
             item.setFlags(item.flags() | Qt.ItemFlag.ItemIsUserCheckable)
-            
+
             # Restore previous selection state
             if code in self.preselected:
                 item.setCheckState(Qt.CheckState.Checked)
             else:
                 item.setCheckState(Qt.CheckState.Unchecked)
-                
+
             self.list_widget.addItem(item)
 
     def filter_list(self, text):
@@ -125,20 +144,21 @@ class AmcrFilterDialog(QDialog):
         super().__init__(parent)
         self.setWindowTitle("Filtr AMČR")
         self.resize(500, 750)
-        
-        # Determines if we are fetching 'akce' (projects) or 'lokalita' (locations)
+
+        # Determines if we are fetching 'akce' (events)
+        # or 'lokalita' (sites)
         self.typ_dat = typ_dat
-        
-       
+
         # Cache dictionary to store selected codes for each category
         self.selection_cache = {
-            'organizace': [], 'kraj': [], 'obdobi': [], 'areal': [], 
-            'typ_akce': [], 'okres': [], 'katastr': [], 'vedouci': [], 'pian_presnost': [], 'pristupnost': [],
-            'typ_lokality': [], 'druh_lokality': [], 'jistota': [], 'lokalita_zachovalost': []
+            'organizace': [], 'kraj': [], 'obdobi': [], 'areal': [],
+            'typ_akce': [], 'okres': [], 'katastr': [], 'vedouci': [],
+            'pian_presnost': [], 'pristupnost': [], 'typ_lokality': [],
+            'druh_lokality': [], 'jistota': [], 'lokalita_zachovalost': []
         }
-        
+
         layout = QVBoxLayout()
-        
+
         # Filter by current map canvas extent
         self.chk_bbox = QCheckBox("Omezit vyhledávání rozsahem okna")
         self.chk_bbox.setChecked(True)
@@ -149,9 +169,9 @@ class AmcrFilterDialog(QDialog):
         if self.typ_dat == "akce":
             self.chk_posevidence = QCheckBox("Pouze pozitivní zjištění")
             layout.addWidget(self.chk_posevidence)
-        
+
         layout.addSpacing(10)
-        
+
         # Spatial information – valid for all
 
         self.picker_kraj = self.setup_picker("Kraj", 'kraj', KRAJE)
@@ -160,156 +180,259 @@ class AmcrFilterDialog(QDialog):
         self.picker_okres = self.setup_picker("Okres", 'okres', OKRESY)
         layout.addWidget(self.picker_okres)
 
-        self.picker_katastr = self.setup_picker("Katastr", 'katastr', KATASTRY)
+        self.picker_katastr = self.setup_picker(
+            "Katastr",
+            'katastr',
+            KATASTRY
+        )
         layout.addWidget(self.picker_katastr)
 
-        self.picker_presnost = self.setup_picker("PIAN – přesnost", 'pian_presnost', PIAN_PRESNOST)
+        self.picker_presnost = self.setup_picker(
+            "PIAN – přesnost",
+            'pian_presnost',
+            PIAN_PRESNOST
+        )
         layout.addWidget(self.picker_presnost)
-        
-        self.picker_pristupnost = self.setup_picker("Přístupnost", 'pristupnost', PRISTUPNOST)
+
+        self.picker_pristupnost = self.setup_picker(
+            "Přístupnost",
+            'pristupnost',
+            PRISTUPNOST
+        )
         layout.addWidget(self.picker_pristupnost)
 
         # Filters valid for Akce
 
         if self.typ_dat == "akce":
-            self.picker_org = self.setup_picker("Organizace", 'organizace', ORGANIZACE)
+            self.picker_org = self.setup_picker(
+                "Organizace",
+                'organizace',
+                ORGANIZACE
+            )
             layout.addWidget(self.picker_org)
-        
-            self.picker_vedouci = self.setup_picker("Vedoucí výzkumu", 'vedouci', VEDOUCI)
+
+            self.picker_vedouci = self.setup_picker(
+                "Vedoucí výzkumu",
+                'vedouci',
+                VEDOUCI
+            )
             layout.addWidget(self.picker_vedouci)
 
             # Type of event
 
-            self.picker_typ = self.setup_picker("Typ výzkumu", 'typ_akce', TYP_AKCE)
+            self.picker_typ = self.setup_picker(
+                "Typ výzkumu",
+                'typ_akce',
+                TYP_AKCE
+            )
             layout.addWidget(self.picker_typ)
 
         # Filters valid for Lokality
 
         if self.typ_dat == "lokalita":
-            self.picker_typ_lokality = self.setup_picker("Lokalita – typ", 'typ_lokality', TYP_LOKALITY)
+            self.picker_typ_lokality = self.setup_picker(
+                "Lokalita – typ",
+                'typ_lokality',
+                TYP_LOKALITY
+            )
             layout.addWidget(self.picker_typ_lokality)
 
-            self.picker_druh_lokality = self.setup_picker("Lokalita – druh", 'druh_lokality', DRUH_LOKALITY)
+            self.picker_druh_lokality = self.setup_picker(
+                "Lokalita – druh",
+                'druh_lokality',
+                DRUH_LOKALITY
+            )
             layout.addWidget(self.picker_druh_lokality)
 
-            self.picker_jistota = self.setup_picker("Lokalita – jistota určení", 'jistota', JISTOTA)
+            self.picker_jistota = self.setup_picker(
+                "Lokalita – jistota určení",
+                'jistota',
+                JISTOTA
+            )
             layout.addWidget(self.picker_jistota)
-            
-            self.picker_lokalita_zachovalost = self.setup_picker("Lokalita - stav dochování", 'lokalita_zachovalost', LOKALITA_ZACHOVALOST)
+
+            self.picker_lokalita_zachovalost = self.setup_picker(
+                "Lokalita - stav dochování",
+                'lokalita_zachovalost',
+                LOKALITA_ZACHOVALOST
+            )
             layout.addWidget(self.picker_lokalita_zachovalost)
 
         # Contextual information
 
         self.picker_obdobi = self.setup_picker("Období", 'obdobi', OBDOBI)
         layout.addWidget(self.picker_obdobi)
-        
+
         self.picker_areal = self.setup_picker("Areál", 'areal', AREAL)
         layout.addWidget(self.picker_areal)
 
         # Option to download related components table
         self.chk_komponenty = QCheckBox("Načíst komponenty")
         layout.addWidget(self.chk_komponenty)
-        
+
+        # Warning label
+        self.lbl_komponenty_warning = QLabel(
+            "⚠ Při načtení komponent jsou prostorové prvky duplikovány — "
+            "každý prvek odpovídá jedné komponentě. "
+            "Prostorové analýzy (plochy, počty) mohou být zkreslené."
+        )
+        self.lbl_komponenty_warning.setWordWrap(True)
+        self.lbl_komponenty_warning.setStyleSheet(
+            "color: #8a6d00; background-color: #fff8e1; "
+            "border: 1px solid #ffe082; border-radius: 4px; padding: 6px;"
+        )
+        self.lbl_komponenty_warning.setVisible(False)
+        layout.addWidget(self.lbl_komponenty_warning)
+
+        self.chk_komponenty.toggled.connect(
+            self.lbl_komponenty_warning.setVisible
+        )
+
         # Pushes everything above to the top
         layout.addStretch(1)
 
         # Main dialog OK/Cancel/Update buttons
-        
+
         buttons = QDialogButtonBox()
 
         self.btn_update = QPushButton("Aktualizovat hesláře 🔄")
-        self.btn_update.setToolTip("Provede kompletní aktualizaci heslářů AMČR. Toto bude trvat pár minut.")
+        self.btn_update.setToolTip(
+            "Provede kompletní aktualizaci heslářů AMČR. "
+            "Toto bude trvat pár minut."
+        )
         self.btn_update.clicked.connect(self.action_update_heslare)
 
-        buttons.addButton(self.btn_update, QDialogButtonBox.ButtonRole.ActionRole)
+        buttons.addButton(
+            self.btn_update,
+            QDialogButtonBox.ButtonRole.ActionRole
+        )
         buttons.addButton(QDialogButtonBox.StandardButton.Ok)
         buttons.addButton(QDialogButtonBox.StandardButton.Cancel)
 
         buttons.accepted.connect(self.accept)
         buttons.rejected.connect(self.reject)
         layout.addWidget(buttons)
-        
+
         self.setLayout(layout)
 
     def setup_picker(self, label_text, cache_key, data_source, extra_btn=None):
         """
-        Creates a reusable UI component consisting of a label, a read-only 
-        text field showing selected items, and a button to open the selection dialog.
+        Creates a reusable UI component consisting of a label, a read-only
+        text field showing selected items, and a button to open
+        the selection dialog.
         """
-        row_widget = QGroupBox(label_text) 
+        row_widget = QGroupBox(label_text)
         row_layout = QHBoxLayout()
         row_layout.setContentsMargins(5, 5, 5, 5)
-        
+
         # Read-only field displaying the names of selected items
         display_field = QLineEdit()
         display_field.setReadOnly(True)
         display_field.setPlaceholderText("Nic nevybráno (vše)")
         display_field.setStyleSheet("background-color: #f0f0f0; color: #333;")
-        
+
         btn = QPushButton("Vybrat...")
         btn.setFixedWidth(80)
-        
-        # Nested function that handles opening the dialog and saving results
+
+        # Nested handler: opens the selection dialog and saves the result
         def open_dialog():
-            dlg = FilterableSelectionDialog(label_text, data_source, self.selection_cache[cache_key], self)
+            dlg = FilterableSelectionDialog(
+                label_text,
+                data_source,
+                self.selection_cache[cache_key],
+                self
+            )
             if dlg.exec() == QDialog.DialogCode.Accepted:
                 codes, labels = dlg.get_selected_codes()
-                # Update local cache with selected IDs
+                # Update the local cache with selected IDs
                 self.selection_cache[cache_key] = codes
-                # Update the UI text field with selected names
+                # Update the display field with the selected item names
                 if labels:
                     display_field.setText(", ".join(labels))
                 else:
                     display_field.clear()
-        
-        # Special case: Pre-fill specific accuracy levels by default
+
+        # Special case: pre-select default PIAN accuracy levels
         if cache_key == 'pian_presnost':
-            display_field.setText("odchylka jednotky metrů, odchylka desítky metrů, odchylka stovky metrů")
-            self.selection_cache[cache_key] = ['HES-000861', 'HES-000862', 'HES-000863']
+            display_field.setText(
+                "odchylka jednotky metrů, odchylka desítky metrů, "
+                "odchylka stovky metrů"
+            )
+            self.selection_cache[cache_key] = [
+                'HES-000861',
+                'HES-000862',
+                'HES-000863'
+            ]
 
         btn.clicked.connect(open_dialog)
-        
+
         row_layout.addWidget(display_field)
         row_layout.addWidget(btn)
-        
-        # Add an optional extra button (e.g., the refresh button for leaders)
+
+        # Optionally append an extra button (e.g. a refresh button)
         if extra_btn:
             row_layout.addWidget(extra_btn)
-            
+
         row_widget.setLayout(row_layout)
         return row_widget
 
     def action_update_heslare(self):
-        # Vytvoření instance tasku
+        # Create the task instance and keep a reference so the Python
+        # wrapper survives until the task finishes
         task = UpdateCodelistsTask("Aktualizace heslářů AMČR")
-        
-        # Povolíme tlačítko zpět bez ohledu na výsledek
-        task.taskCompleted.connect(lambda: self.btn_update.setEnabled(True))
-        task.taskTerminated.connect(lambda: self.btn_update.setEnabled(True))
-        
-        task.taskCompleted.connect(lambda: QMessageBox.information(self, "Hotovo", "Hesláře byly úspěšně aktualizovány."))
-        
-        # Ošetření, aby se přesně ukázala případná chyba
+        _ACTIVE_TASKS.append(task)
+
+        # Prevent parallel downloads overwriting heslar.csv
+        self.btn_update.setEnabled(False)
+
+        # Message boxes are parented to the main window, not to this dialog –
+        # the dialog may already be closed (and its C++ object deleted)
+        # by the time the minute-long task finishes.
+        parent_win = iface.mainWindow() if iface else None
+
+        def _cleanup():
+            if task in _ACTIVE_TASKS:
+                _ACTIVE_TASKS.remove(task)
+            try:
+                self.btn_update.setEnabled(True)
+            except RuntimeError:
+                pass  # dialog already closed
+
+        def on_completed():
+            _cleanup()
+            QMessageBox.information(
+                parent_win,
+                "Hotovo",
+                "Hesláře byly úspěšně aktualizovány."
+            )
+
+        # Show the exact error if the task fails
         def on_error():
+            _cleanup()
             if task.exception:
-                # Tohle ti přesně řekne, na čem to teď padá (např. PermissionError)
-                msg = f"Aktualizace selhala z důvodu chyby:\n{str(task.exception)}"
+                # This will show exactly what went wrong (e.g. PermissionError)
+                msg = (
+                    "Aktualizace selhala z důvodu chyby:\n"
+                    f"{str(task.exception)}"
+                )
             else:
                 msg = "Aktualizace byla zrušena uživatelem."
-            QMessageBox.warning(self, "Chyba / Zrušeno", msg)
-            
+            QMessageBox.warning(parent_win, "Chyba / Zrušeno", msg)
+
+        task.taskCompleted.connect(on_completed)
         task.taskTerminated.connect(on_error)
-        
+
         QgsApplication.taskManager().addTask(task)
 
     def get_bbox(self):
         return "true" if self.chk_bbox.isChecked() else "false"
-        
+
     def get_komponenty(self):
         return "true" if self.chk_komponenty.isChecked() else "false"
-        
+
     def get_filters(self):
-        """Compiles the user selections from the cache into API-ready filter parameters."""
+        """Compiles the user selections from the cache into
+        API-ready filter parameters."""
         filters = {}
 
         if self.selection_cache['kraj']:
@@ -323,10 +446,10 @@ class AmcrFilterDialog(QDialog):
         if self.selection_cache['areal']:
             filters['f_areal'] = self.selection_cache['areal']
         if self.selection_cache['pian_presnost']:
-            filters['f_pian_presnost'] = self.selection_cache['pian_presnost']  
+            filters['f_pian_presnost'] = self.selection_cache['pian_presnost']
         if self.selection_cache['pristupnost']:
-            filters['pristupnost'] = self.selection_cache['pristupnost'] 
-            
+            filters['pristupnost'] = self.selection_cache['pristupnost']
+
         if self.typ_dat == "akce":
             if self.chk_posevidence.isChecked():
                 filters['posevidence'] = 'true'
@@ -346,12 +469,14 @@ class AmcrFilterDialog(QDialog):
                 filters['f_jistota'] = self.selection_cache['jistota']
             if self.selection_cache['lokalita_zachovalost']:
                 filters['f_lokalita_zachovalost'] = self.selection_cache['lokalita_zachovalost']
-        
+
         return filters
 
+
 class LoginDialog(QDialog):
     """
-    Dialog for saving AMČR login credentials securely in the QGIS Authentication Manager.
+    Dialog for saving AMČR login credentials securely in the
+    QGIS Authentication Manager.
 
     Credentials are encrypted by the platform's native secret storage
     (DPAPI on Windows, Keychain on macOS, encrypted SQLite on Linux).
@@ -365,10 +490,13 @@ class LoginDialog(QDialog):
     - storeAuthenticationConfig() and loadAuthenticationConfig() both have
       SIP_INOUT on their config parameter, so Python bindings return a tuple
       (bool, QgsAuthMethodConfig) rather than just bool. Always unpack both.
+    - loadAuthenticationConfig() with full=False loads only metadata (name, method,
+      id) but NOT the config() values like username/password. Use full=True to
+      access those.
     """
 
     SETTINGS_KEY = "amcr_viewer/auth_config_id"
-    CONFIG_NAME  = "AMČR Viewer"
+    CONFIG_NAME = "AMČR Viewer"
 
     def __init__(self, parent=None):
         super().__init__(parent)
@@ -379,17 +507,29 @@ class LoginDialog(QDialog):
 
         # Check whether a config ID is already stored from a previous session.
         # We attempt a lightweight load (full=False) to confirm it is readable,
-        # since hasConfigId() may return False even for valid configs (cache lag).
+        # since hasConfigId() may return False even for valid configs
+        # (cache lag).
+        # The Auth Manager must be unlocked before we attempt to read from it;
+        # otherwise loadAuthenticationConfig() returns ok=False even for valid
+        # configs, causing _has_saved to be incorrectly set to False.
         existing_id = QSettings().value(self.SETTINGS_KEY, "")
-        self._has_saved = bool(existing_id) and bool(self._load_username_from_config(existing_id))
+        if existing_id:
+            QgsApplication.authManager().setMasterPassword(True)
+        username = self._load_username_from_config(existing_id)
+        self._has_saved = bool(existing_id) and bool(username)
 
         if self._has_saved:
-            info = QLabel("✔ Přihlašovací údaje jsou bezpečně uloženy ve správci autentizace QGIS.\n"
-                          "Vyplňte pole níže pouze pokud je chcete změnit.")
+            info = QLabel(
+                "✔ Přihlašovací údaje jsou bezpečně uloženy "
+                "ve správci autentizace QGIS.\n"
+                "Vyplňte pole níže pouze pokud je chcete změnit."
+            )
             info.setStyleSheet("color: green; font-style: italic;")
         else:
-            info = QLabel("Zadejte přihlašovací údaje k Digitálnímu archivu AMČR.\n"
-                          "Budou zašifrovaně uloženy ve správci autentizace QGIS.")
+            info = QLabel(
+                "Zadejte přihlašovací údaje k Digitálnímu archivu AMČR.\n"
+                "Budou zašifrovaně uloženy ve správci autentizace QGIS."
+            )
         info.setWordWrap(True)
         layout.addWidget(info)
         layout.addSpacing(8)
@@ -406,7 +546,9 @@ class LoginDialog(QDialog):
         self.txt_pass = QLineEdit()
         self.txt_pass.setEchoMode(QLineEdit.EchoMode.Password)
         self.txt_pass.setPlaceholderText(
-            "ponechte prázdné pro zachování stávajícího hesla" if self._has_saved else "heslo"
+            "ponechte prázdné pro zachování stávajícího hesla"
+            if self._has_saved
+            else "heslo"
         )
         form.addRow("Heslo:", self.txt_pass)
 
@@ -422,7 +564,8 @@ class LoginDialog(QDialog):
         layout.addStretch(1)
 
         buttons = QDialogButtonBox(
-            QDialogButtonBox.StandardButton.Ok | QDialogButtonBox.StandardButton.Cancel
+            QDialogButtonBox.StandardButton.Ok
+            | QDialogButtonBox.StandardButton.Cancel
         )
         buttons.accepted.connect(self._save_and_accept)
         buttons.rejected.connect(self.reject)
@@ -438,7 +581,8 @@ class LoginDialog(QDialog):
     def _load_config(config_id: str, full: bool = False):
         """
         Attempt to load a QgsAuthMethodConfig by ID.
-        Returns (ok, cfg). Never raises; returns (False, empty cfg) on any error.
+        Returns (ok, cfg). Never raises; returns (False, empty cfg)
+        on any error.
         full=True decrypts and includes the password.
         """
         try:
@@ -453,8 +597,10 @@ class LoginDialog(QDialog):
             return False, QgsAuthMethodConfig()
 
     def _load_username_from_config(self, config_id: str) -> str:
-        """Load just the username from a stored config (no password decryption)."""
-        ok, cfg = self._load_config(config_id, full=False)
+        """Load the username from a stored config.
+        Requires full=True since config() values are only populated
+        when the config is fully decrypted."""
+        ok, cfg = self._load_config(config_id, full=True)
         return cfg.config("username", "") if ok else ""
 
     def _ensure_master_password(self) -> bool:
@@ -469,16 +615,51 @@ class LoginDialog(QDialog):
             QMessageBox.critical(
                 self, "Správce autentizace nedostupný",
                 "Správce autentizace QGIS je zakázán nebo poškozený.\n"
-                "Zkuste obnovit databázi: Nastavení → Možnosti → Autentizace → Pomůcky."
+                "Zkuste obnovit databázi: "
+                "Nastavení → Možnosti → Autentizace → Pomůcky."
             )
             return False
 
-        # setMasterPassword(True) shows the QGIS master password dialog if needed
+        # setMasterPassword(True) shows the QGIS
+        # master password dialog if needed
         if not auth_mgr.setMasterPassword(True):
             return False  # User cancelled the master password dialog
 
         return True
 
+    def _verify_credentials(self, username: str, password: str) -> bool:
+        """
+        Verify the credentials against the API before saving them.
+        Returns True if they should be stored: either the login succeeded,
+        or the server was unreachable and the user chose to keep them
+        unverified. Wrong credentials are never stored.
+        """
+        # Lazy import to avoid an import cycle
+        # (amcr_tools imports LoginDialog lazily as well)
+        from . import amcr_tools
+
+        if amcr_tools.login_to_api(username, password):
+            return True
+
+        if amcr_tools.LAST_LOGIN_ERROR == 'network':
+            answer = QMessageBox.question(
+                self,
+                "Server nedostupný",
+                "Přihlašovací údaje se nepodařilo ověřit – server AMČR "
+                "je nedostupný.\nChcete je přesto uložit (neověřené)?",
+                QMessageBox.StandardButton.Yes
+                | QMessageBox.StandardButton.No
+            )
+            return answer == QMessageBox.StandardButton.Yes
+
+        QMessageBox.warning(
+            self,
+            "Neplatné přihlašovací údaje",
+            "Přihlášení se nezdařilo – zkontrolujte e-mail a heslo.\n"
+            "Údaje nebyly uloženy."
+        )
+        return False
+
     # ------------------------------------------------------------------
     # Button actions
     # ------------------------------------------------------------------
@@ -488,7 +669,11 @@ class LoginDialog(QDialog):
         password = self.txt_pass.text()
 
         if not username:
-            QMessageBox.warning(self, "Chybí údaje", "Vyplňte prosím e-mailovou adresu.")
+            QMessageBox.warning(
+                self,
+                "Chybí údaje",
+                "Vyplňte prosím e-mailovou adresu."
+            )
             return
 
         existing_id = QSettings().value(self.SETTINGS_KEY, "")
@@ -501,6 +686,11 @@ class LoginDialog(QDialog):
             if ok:
                 if not self._ensure_master_password():
                     return
+                # Verify the new username against the stored password
+                if not self._verify_credentials(
+                    username, cfg.config("password", "")
+                ):
+                    return
                 cfg.setConfig("username", username)
                 auth_mgr.updateAuthenticationConfig(cfg)
                 self.accept()
@@ -510,6 +700,11 @@ class LoginDialog(QDialog):
             QMessageBox.warning(self, "Chybí údaje", "Vyplňte prosím heslo.")
             return
 
+        # Verify before prompting for the master password – wrong
+        # credentials must never reach the Authentication Manager
+        if not self._verify_credentials(username, password):
+            return
+
         if not self._ensure_master_password():
             return
 
@@ -521,13 +716,19 @@ class LoginDialog(QDialog):
 
         settings = QSettings()
 
-        # Try to update an existing config first; fall back to creating a new one.
-        # We skip hasConfigId() as it may return False despite the config existing
+        # Try to update an existing config first;
+        # fall back to creating a new one.
+        # We skip hasConfigId() as it may return False
+        # despite the config existing
         # (in-memory cache may not be populated yet in QGIS 4).
-        ok_load, existing_cfg = self._load_config(existing_id, full=False) if existing_id else (False, None)
+        ok_load, existing_cfg = (
+            self._load_config(existing_id, full=False)
+            if existing_id
+            else (False, None)
+        )
         if ok_load:
             cfg.setId(existing_id)
-            ok, cfg = auth_mgr.updateAuthenticationConfig(cfg)
+            ok = auth_mgr.updateAuthenticationConfig(cfg)
         else:
             ok, cfg = auth_mgr.storeAuthenticationConfig(cfg)
 
@@ -536,7 +737,8 @@ class LoginDialog(QDialog):
         if not ok or not config_id:
             QMessageBox.critical(
                 self, "Chyba uložení",
-                "Přihlašovací údaje se nepodařilo uložit do správce autentizace QGIS.\n"
+                "Přihlašovací údaje se nepodařilo "
+                "uložit do správce autentizace QGIS.\n"
                 "Zkuste restartovat QGIS a přihlásit se znovu."
             )
             return
@@ -550,7 +752,11 @@ class LoginDialog(QDialog):
         if existing_id:
             QgsApplication.authManager().removeAuthenticationConfig(existing_id)
             settings.remove(self.SETTINGS_KEY)
-        QMessageBox.information(self, "Hotovo", "Uložené přihlašovací údaje byly odebrány.")
+        QMessageBox.information(
+            self,
+            "Hotovo",
+            "Uložené přihlašovací údaje byly odebrány."
+        )
         self.reject()
 
     # ------------------------------------------------------------------
@@ -565,8 +771,9 @@ class LoginDialog(QDialog):
 
         Note: hasConfigId() is intentionally skipped here – it checks an
         in-memory cache that may lag behind the actual database contents,
-        causing false negatives (see class docstring). loadAuthenticationConfig()
-        is called directly and its return value is used as the authoritative result.
+        causing false negatives (see class docstring).
+        loadAuthenticationConfig() is called directly and its return value is
+        used as the authoritative result.
         """
         settings = QSettings()
         config_id = settings.value(LoginDialog.SETTINGS_KEY, "")
@@ -578,4 +785,4 @@ class LoginDialog(QDialog):
         if not ok:
             return "", ""
 
-        return cfg.config("username", ""), cfg.config("password", "")  # nosec B106
+        return cfg.config("username", ""), cfg.config("password", "")  # nosec B106

amcr_viewer/amcr_viewer.py

@@ -1,37 +1,39 @@
 # -*- coding: utf-8 -*-
-from qgis.PyQt.QtCore import QSettings, QTranslator, QCoreApplication
-from qgis.PyQt.QtGui import QIcon
+from qgis.PyQt.QtCore import QSettings, QTranslator, QCoreApplication, QUrl
+from qgis.PyQt.QtGui import QIcon, QDesktopServices
 from qgis.PyQt.QtWidgets import QMenu, QAction, QToolButton, QDialog
 from qgis.core import Qgis
-from qgis.utils import iface
 
 from .amcr_tools import load_amcr_data, login_to_api
 from .amcr_dialog import AmcrFilterDialog, LoginDialog
-from .resources import *
 import os.path
 
+
 class AmcrViewer:
     """
-    Main plugin class that manages the GUI elements, menu entries, 
+    Main plugin class that manages the GUI elements, menu entries,
     and coordinates the flow between user input and data processing.
     """
-    
+
     def __init__(self, iface):
         """
-        Constructor initializes the connection to QGIS interface and sets up 
+        Constructor initializes the connection to QGIS interface and sets up
         internationalization (i18n).
         """
         self.iface = iface
         self.plugin_dir = os.path.dirname(__file__)
-        
-        # Determine the user's locale to load appropriate translation files
-        locale = QSettings().value('locale/userLocale')[0:2]
+
+        # Determine the user's locale to load appropriate translation files.
+        # The setting may be missing (None) on a fresh QGIS install.
+        locale = str(QSettings().value('locale/userLocale') or 'en')[0:2]
         locale_path = os.path.join(
             self.plugin_dir,
             'i18n',
-            'AmcrViewer_{}.qm'.format(locale))
+            'AmcrViewer_{}.qm'.format(locale)
+        )
 
-        # Install the translator if a translation file for the current locale exists
+        # Install the translator if a translation file
+        # for the current locale exists
         if os.path.exists(locale_path):
             self.translator = QTranslator()
             self.translator.load(locale_path)
@@ -43,14 +45,17 @@ class AmcrViewer:
         self.first_start = None
 
     def tr(self, message):
-        """Helper method for translating strings within the AmcrViewer context."""
+        """
+        Helper method for translating strings within
+        the AmcrViewer context.
+        """
         return QCoreApplication.translate('AmcrViewer', message)
 
     def add_action(self, icon_path, text, callback, enabled_flag=True,
                    add_to_menu=True, add_to_toolbar=True, status_tip=None,
                    whats_this=None, parent=None):
         """
-        Helper method to create QActions and automatically register them 
+        Helper method to create QActions and automatically register them
         into the QGIS Menu and Toolbar.
         """
         icon = QIcon(icon_path)
@@ -71,26 +76,29 @@ class AmcrViewer:
         if add_to_menu:
             self.iface.addPluginToMenu(self.menu, action)
 
-        # Store only actions that are directly attached to the QGIS UI for later cleanup
+        # Store only actions that are directly attached
+        # to the QGIS UI for later cleanup
         if add_to_toolbar or add_to_menu:
             self.actions.append(action)
-            
+
         return action
 
     def initGui(self):
         """
-        Called when the plugin is loaded. Creates the menu structure, 
+        Called when the plugin is loaded. Creates the menu structure,
         sub-actions, and the dropdown tool button in the toolbar.
         """
         # Define paths for action-specific icons
         icon_akce_path = os.path.join(self.plugin_dir, 'akce.png')
         icon_lokality_path = os.path.join(self.plugin_dir, 'lokality.png')
+        icon_amcr_help_path = os.path.join(self.plugin_dir, 'amcr-help.png')
 
         # 1. Create a container menu for the plugin
         self.plugin_menu = QMenu()
 
         # 2. Create sub-actions (Download Projects / Download Sites)
-        # add_to_menu/toolbar is False because these go into our custom dropdown menu
+        # add_to_menu/toolbar is False because these go into our
+        # custom dropdown menu
         self.action_download_akce = self.add_action(
             icon_path=icon_akce_path,
             text=self.tr(u'Stáhnout data akcí | AMČR Viewer'),
@@ -104,7 +112,7 @@ class AmcrViewer:
         self.action_download_lokality = self.add_action(
             icon_path=icon_lokality_path,
             text=self.tr(u'Stáhnout data lokalit | AMČR Viewer'),
-            callback=lambda checked=False: self.run_download('lokalita'), 
+            callback=lambda checked=False: self.run_download('lokalita'),
             parent=self.iface.mainWindow(),
             add_to_menu=False,
             add_to_toolbar=False
@@ -114,16 +122,30 @@ class AmcrViewer:
         self.action_login_dialog = self.add_action(
             icon_path=icon_akce_path,
             text=self.tr(u'Přihlásit se | AMČR Viewer'),
-            callback=lambda checked=False: self.login(), 
+            callback=lambda checked=False: self.login(),
             parent=self.iface.mainWindow(),
             add_to_menu=False,
             add_to_toolbar=False
         )
         self.plugin_menu.addAction(self.action_login_dialog)
 
+        self.action_amcr_help = self.add_action(
+            icon_path=icon_amcr_help_path,
+            text=self.tr(u'Nápověda AMČR Help | AMČR Viewer'),
+            callback=lambda checked=False: self.open_help(),
+            parent=self.iface.mainWindow(),
+            add_to_menu=False,
+            add_to_toolbar=False
+        )
+        self.plugin_menu.addAction(self.action_amcr_help)
+
         # 3. Create the main project action and attach the menu to it
         main_icon = QIcon(icon_akce_path)
-        self.main_action = QAction(main_icon, 'AMČR Viewer', self.iface.mainWindow())
+        self.main_action = QAction(
+            main_icon,
+            'AMČR Viewer',
+            self.iface.mainWindow()
+        )
         self.main_action.setMenu(self.plugin_menu)
         self.iface.addPluginToMenu(self.menu, self.main_action)
 
@@ -132,16 +154,19 @@ class AmcrViewer:
         self.tool_button = QToolButton()
         self.tool_button.setMenu(self.plugin_menu)
         self.tool_button.setDefaultAction(self.action_download_akce)
-        self.tool_button.setPopupMode(QToolButton.ToolButtonPopupMode.MenuButtonPopup)
-        
-        # Add the widget directly to the toolbar and store the reference for cleanup
+        self.tool_button.setPopupMode(
+            QToolButton.ToolButtonPopupMode.MenuButtonPopup
+        )
+
+        # Add the widget directly to the toolbar
+        # and store the reference for cleanup
         self.toolbar_action = self.iface.addToolBarWidget(self.tool_button)
-        
+
         self.first_start = True
 
     def unload(self):
         """
-        Called when the plugin is disabled or removed. 
+        Called when the plugin is disabled or removed.
         Ensures all GUI elements are removed from QGIS to avoid ghost icons.
         """
         # 1. Remove the custom entry from the main 'Plugins' menu
@@ -157,7 +182,7 @@ class AmcrViewer:
             self.iface.removePluginMenu(self.menu, action)
             self.iface.removeToolBarIcon(action)
         self.actions.clear()
-        
+
         # 4. Reset map tools if currently active
         if hasattr(self, 'tool'):
             self.iface.mapCanvas().unsetMapTool(self.tool)
@@ -165,20 +190,22 @@ class AmcrViewer:
     # --- Data downloading ---
     def run_download(self, typ_dat):
         """
-        Triggered by menu/toolbar actions. Opens the filter dialog and 
+        Triggered by menu/toolbar actions. Opens the filter dialog and
         hands off the parameters to the data loader.
         """
         # Open the specific filter dialog (Projects vs Sites)
         dlg = AmcrFilterDialog(typ_dat)
         result = dlg.exec()
-        
-        # If user confirmed the dialog (OK button), gather filters and load data
+
+        # If user confirmed the dialog (OK button),
+        # gather filters and load data
         if result == QDialog.DialogCode.Accepted:
             filters = dlg.get_filters()
             bbox = dlg.get_bbox()
             komponenty = dlg.get_komponenty()
-            
-            # Access the map canvas and start the fetch/render process from amcr_tools
+
+            # Access the map canvas and start
+            # the fetch/render process from amcr_tools
             canvas = self.iface.mapCanvas()
             load_amcr_data(canvas, bbox, filters, typ_dat, komponenty)
 
@@ -190,9 +217,18 @@ class AmcrViewer:
             session = login_to_api(username, password)
             if session:
                 self.iface.messageBar().pushMessage(
-                    "AMČR", "Přihlášení proběhlo úspěšně.", level=Qgis.MessageLevel.Success
+                    "AMČR",
+                    "Přihlášení proběhlo úspěšně.",
+                    level=Qgis.MessageLevel.Success
                 )
             else:
                 self.iface.messageBar().pushMessage(
-                    "AMČR", "Přihlášení se nezdařilo – viz záložka AMČR login v panelu Zprávy.", level=Qgis.MessageLevel.Critical
-                )
+                    "AMČR",
+                    "Přihlášení se nezdařilo – viz záložka AMČR login "
+                    "v panelu Zprávy.",
+                    level=Qgis.MessageLevel.Critical
+                )
+
+    def open_help(self):
+        help_url = "https://amcr-help.aiscr.cz/digiarchiv/qgis-viewer.html"
+        QDesktopServices.openUrl(QUrl(help_url))

amcr_viewer/metadata.txt

@@ -5,10 +5,10 @@
 
 [general]
 name=AMČR Viewer
-qgisMinimumVersion=3.4.0
+qgisMinimumVersion=3.44.0
 qgisMaximumVersion=4.99.0
 description=Viewing and downloading the AMČR data.
-version=2.0.0-alpha.2
+version=2.0.2
 author=David Spáčil
 email=spacil@arub.cz
 
@@ -22,16 +22,36 @@ repository=https://github.com/ARUP-CAS/aiscr-qgis-amcr-viewer
 
 hasProcessingProvider=no
 # Uncomment the following line and add your changelog:
-# changelog=
+changelog=
+  Aktualizace na verzi 2.0.0 výrazně mění chování pluginu. Před updatem je doporučeno přečíst si seznam změn níže.
+  Version 2.0.0 changes the plugin behavior dramatically. It is advised to check the changelog below.
+  Plný seznam změn v češtině je dostupný zde: https://github.com/ARUP-CAS/aiscr-qgis-amcr-viewer/releases/tag/v2.0.0
+  v2.0.2 (2026-06-13)
+   * Plugin-wide fixes and optimalizations (details https://github.com/ARUP-CAS/aiscr-qgis-amcr-viewer/pull/49)
+  v2.0.1 (2026-06-10)
+   * Fixed QGIS minimum version
+  v2.0.0 (2026-06-05)
+   * Added warning regarding the feature duplication when loading components to the dialog 
+   * Added Help button to the plugin menu
+   * Code clean-up
+  v2.0.0-alpha.4 (2026-06-03)
+   * Backend filtering of the results based on the component-related filters improvement (plugin not only loads the results from API, it filters them further)
+  v2.0.0-alpha.2–3 (2026-05-19)
+   * Security vulnerabilities fix
+  v2.0.0-alpha.1 (2026-05-19):
+   * Attribute fields renamed to be ASCII compliant
+   * Codelist update; codelist can be recompiled from AMČR API
+   * Base element changed from Documentation Unit to Component if user asks for components to simplify result filtering
+   * Plugin now supports logging with an AMČR account and enables the downloading of Events and Sites available to the roles Researcher and higher 
 
 # Tags are comma separated with spaces allowed
-tags=python,AMCR,AIS CR,archaeology,PIAN,AMČR
+tags=python,AMCR,AIS CR,archaeology,PIAN,AMČR,archeologie
 
 homepage=https://amcr-help.aiscr.cz/digiarchiv/qgis-viewer.html
 category=Vector
-icon=download.png
+icon=akce.png
 # experimental flag
-experimental=True
+experimental=False
 
 # deprecated flag (applies to the whole plugin, not just a single version)
 deprecated=False