"""
sn_basis/functions/qgiscore_wrapper.py – zentrale QGIS-Core-Abstraktion
"""

from typing import Type, Any, Optional
from sn_basis.functions.qt_wrapper import (
    QUrl,
    QEventLoop,
    QNetworkRequest,
)

# ---------------------------------------------------------
# QGIS-Symbole (werden dynamisch gesetzt)
# ---------------------------------------------------------

QgsProject: Type[Any]
QgsVectorLayer: Type[Any]
QgsRasterLayer: Type[Any]
QgsNetworkAccessManager: Type[Any]
Qgis: Type[Any]
QgsMapLayerProxyModel: Type[Any]
QgsVectorFileWriter: Type[Any]  # neu: Schreib-API
QgsFeature: Type[Any]
QgsField: Type[Any]
QgsGeometry: Type[Any]
QgsFeatureRequest: Type[Any]
QgsCoordinateTransform: Type[Any]
QgsCoordinateReferenceSystem: Type[Any]
QgsPrintLayout: Type[Any]
QgsLayoutItemMap: Type[Any]
QgsLayoutItemLabel: Type[Any]
QgsLayoutPoint: Type[Any]
QgsLayoutSize: Type[Any]
QgsUnitTypes: Type[Any]
QgsLayoutItem: Type[Any]

QGIS_AVAILABLE = False

# ---------------------------------------------------------
# Versuch: QGIS-Core importieren
# ---------------------------------------------------------

try:
    from qgis.core import (
        QgsProject as _QgsProject,
        QgsVectorLayer as _QgsVectorLayer,
        QgsRasterLayer as _QgsRasterLayer,
        QgsNetworkAccessManager as _QgsNetworkAccessManager,
        Qgis as _Qgis,
        QgsMapLayerProxyModel as _QgsMaplLayerProxyModel,
        QgsVectorFileWriter as _QgsVectorFileWriter,
        QgsFeature as _QgsFeature,
        QgsField as _QgsField,
        QgsGeometry as _QgsGeometry,
        QgsFeatureRequest as _QgsFeatureRequest,
        QgsCoordinateTransform as _QgsCoordinateTransform,
        QgsCoordinateReferenceSystem as _QgsCoordinateReferenceSystem,
        QgsPrintLayout as _QgsPrintLayout,
        QgsLayoutItemMap as _QgsLayoutItemMap,
        QgsLayoutItemLabel as _QgsLayoutItemLabel,
        QgsLayoutPoint as _QgsLayoutPoint,
        QgsLayoutSize as _QgsLayoutSize,
        QgsUnitTypes as _QgsUnitTypes,
        QgsLayoutItem as _QgsLayoutItem,
    )

    QgsProject = _QgsProject
    QgsVectorLayer = _QgsVectorLayer
    QgsRasterLayer = _QgsRasterLayer
    QgsNetworkAccessManager = _QgsNetworkAccessManager
    Qgis = _Qgis
    QgsMapLayerProxyModel = _QgsMaplLayerProxyModel
    QgsVectorFileWriter = _QgsVectorFileWriter
    QgsFeature = _QgsFeature
    QgsField = _QgsField
    QgsGeometry = _QgsGeometry
    QgsFeatureRequest = _QgsFeatureRequest
    QgsCoordinateTransform = _QgsCoordinateTransform
    QgsCoordinateReferenceSystem = _QgsCoordinateReferenceSystem
    QgsPrintLayout = _QgsPrintLayout
    QgsLayoutItemMap = _QgsLayoutItemMap
    QgsLayoutItemLabel = _QgsLayoutItemLabel
    QgsLayoutPoint = _QgsLayoutPoint
    QgsLayoutSize = _QgsLayoutSize
    QgsUnitTypes = _QgsUnitTypes
    QgsLayoutItem = _QgsLayoutItem

    QGIS_AVAILABLE = True

# ---------------------------------------------------------
# Mock-Modus
# ---------------------------------------------------------

except Exception:
    QGIS_AVAILABLE = False

    class _MockLayoutManager:
        def layoutByName(self, name: str):
            return None

        def addLayout(self, layout: Any) -> bool:
            return True

    class _MockQgsProject:
        def __init__(self):
            self._variables = {}
            self._layout_manager = _MockLayoutManager()

        @staticmethod
        def instance() -> "_MockQgsProject":
            return _MockQgsProject()

        def read(self) -> bool:
            return True

        def layoutManager(self):
            return self._layout_manager

    QgsProject = _MockQgsProject

    class _MockQgsVectorLayer:
        def __init__(self, *args, **kwargs):
            self._valid = True

        def isValid(self) -> bool:
            return self._valid

        def loadNamedStyle(self, path: str):
            return True, ""

        def triggerRepaint(self) -> None:
            pass

        def dataProvider(self):
            return None

    QgsVectorLayer = _MockQgsVectorLayer

    class _MockQgsNetworkAccessManager:
        @staticmethod
        def instance():
            return _MockQgsNetworkAccessManager()

        def head(self, request: Any):
            return None

    class _MockQgsRasterLayer:
        """
        Minimaler Mock für QgsRasterLayer, ausreichend für Tests und
        um im Datenabruf ein Raster-Layer-Objekt im pruef_ergebnis kontext mitzugeben.
        """
        def __init__(self, source: str, name: str = "Raster", provider: str = "wms"):
            self.source = source
            self._name = name
            self.provider = provider
            self._valid = True

        def isValid(self) -> bool:
            return self._valid

        def name(self) -> str:
            return self._name

        def dataProvider(self):
            return None

    QgsRasterLayer = _MockQgsRasterLayer

    class _MockQgsPrintLayout:
        def __init__(self, project: Any):
            self.project = project
            self._name = ""
            self._page = _MockQgsLayoutPage()

        def initializeDefaults(self) -> None:
            pass

        def setName(self, name: str) -> None:
            self._name = name

        def pageCollection(self):
            return self

        def page(self, index: int):
            return self._page

        def addLayoutItem(self, item: Any) -> None:
            pass

    class _MockQgsLayoutPage:
        def setPageSize(self, size: Any) -> None:
            self.size = size

    class _MockQgsLayoutItem:
        class ReferencePoint:
            LowerLeft = 0

    class _MockQgsLayoutItemMap:
        def __init__(self, layout: Any):
            self.layout = layout

        def setId(self, item_id: str) -> None:
            pass

        def setExtent(self, extent: Any) -> None:
            pass

        def setScale(self, scale: float) -> None:
            pass

        def attemptMove(self, point: Any) -> None:
            pass

        def attemptResize(self, size: Any) -> None:
            pass

        def setFollowVisibilityPreset(self, active: bool) -> None:
            pass

        def setFollowVisibilityPresetName(self, name: str) -> None:
            pass

    class _MockQgsLayoutItemLabel:
        ModeHtml = 1

        def __init__(self, layout: Any):
            self.layout = layout

        def setId(self, item_id: str) -> None:
            pass

        def setText(self, text: str) -> None:
            pass

        def setMode(self, mode: Any) -> None:
            pass

        def setFont(self, font: Any) -> None:
            pass

        def setReferencePoint(self, point: Any) -> None:
            pass

        def attemptMove(self, point: Any) -> None:
            pass

        def attemptResize(self, size: Any) -> None:
            pass

    class _MockQgsLayoutPoint:
        def __init__(self, x: float, y: float, unit: Any):
            self.x = x
            self.y = y
            self.unit = unit

    class _MockQgsLayoutSize:
        def __init__(self, width: float, height: float, unit: Any):
            self.width = width
            self.height = height
            self.unit = unit

    class _MockQgsUnitTypes:
        LayoutMillimeters = 0

    QgsPrintLayout = _MockQgsPrintLayout
    QgsLayoutItemMap = _MockQgsLayoutItemMap
    QgsLayoutItemLabel = _MockQgsLayoutItemLabel
    QgsLayoutPoint = _MockQgsLayoutPoint
    QgsLayoutSize = _MockQgsLayoutSize
    QgsUnitTypes = _MockQgsUnitTypes
    QgsLayoutItem = _MockQgsLayoutItem

    class _MockQgsFeatureRequest:
        def __init__(self):
            self._filter_rect = None

        def setFilterRect(self, rect):
            self._filter_rect = rect
            return self

    QgsFeatureRequest = _MockQgsFeatureRequest

    class _MockQgsCoordinateTransform:
        def __init__(self, *args, **kwargs):
            pass

        def transformBoundingBox(self, rect):
            return rect

    class _MockQgsCoordinateReferenceSystem:
        def __init__(self, *args, **kwargs):
            pass

    QgsCoordinateTransform = _MockQgsCoordinateTransform
    QgsCoordinateReferenceSystem = _MockQgsCoordinateReferenceSystem

    QgsNetworkAccessManager = _MockQgsNetworkAccessManager

    class _MockQgis:
        class MessageLevel:
            Success = 0
            Info = 1
            Warning = 2
            Critical = 3

    Qgis = _MockQgis

    class _MockQgsMapLayerProxyModel:
        # Layer-Typen (entsprechen QGIS-Konstanten)
        NoLayer = 0
        VectorLayer = 1
        RasterLayer = 2
        PluginLayer = 3
        MeshLayer = 4
        VectorTileLayer = 5
        PointCloudLayer = 6

        def __init__(self, *args, **kwargs):
            pass

    QgsMapLayerProxyModel = _MockQgsMapLayerProxyModel

    # ---------------------------------------------------------
    # Mock für QgsVectorFileWriter
    # ---------------------------------------------------------

    class _MockSaveVectorOptions:
        """
        Minimaler Ersatz für QgsVectorFileWriter.SaveVectorOptions.
        Felder werden als einfache Attribute bereitgestellt.
        """
        def __init__(self):
            self.driverName: str = "GPKG"
            self.layerName: Optional[str] = None
            self.fileEncoding: str = "UTF-8"
            # Action-Konstanten werden symbolisch verwendet
            self.actionOnExistingFile: Optional[int] = None

    class _MockQgsVectorFileWriter:
        """
        Minimaler Mock für QgsVectorFileWriter mit der benötigten API:
        - SaveVectorOptions (als Klasse)
        - writeAsVectorFormatV3(layer, path, transformContext, options) -> error_code
        - NoError (Konstante)
        - CreateOrOverwriteFile / CreateOrOverwriteLayer (Konstanten)
        """

        # Fehlerkonstanten (0 = NoError)
        NoError = 0

        # Action-Konstanten (Werte nur symbolisch)
        CreateOrOverwriteFile = 1
        CreateOrOverwriteLayer = 2

        # SaveVectorOptions-Klasse
        SaveVectorOptions = _MockSaveVectorOptions

        @staticmethod
        def writeAsVectorFormatV3(layer: Any, path: str, transform_context: Any, options: Any) -> int:
            """
            Mock-Schreibfunktion.

            Verhalten im Mock:
            - Wenn 'layer' None oder options.layerName fehlt, geben wir NoError zurück,
              aber schreiben nichts (Tests erwarten nur Rückgabecode).
            - Diese Implementierung versucht nicht, echte Dateien zu schreiben.
            - Rückgabewert: 0 (NoError) bei Erfolg, sonst eine positive Fehlernummer.
            """
            try:
                # Sehr einfache Validierung: wenn path leer -> Fehler
                if not path:
                    return 999
                # Simuliere Erfolg
                return _MockQgsVectorFileWriter.NoError
            except Exception:
                return 999  # generischer Fehlercode

    QgsVectorFileWriter = _MockQgsVectorFileWriter

# ---------------------------------------------------------
# Netzwerk
# ---------------------------------------------------------

class NetworkReply:
    """
    Minimaler Wrapper für Netzwerkantworten.
    """
    def __init__(self, error: int):
        self.error = error


def network_head(url: str) -> NetworkReply | None:
    """
    Führt einen HTTP-HEAD-Request aus.

    Rückgabe:
    - NetworkReply(error=0) → erreichbar
    - NetworkReply(error!=0) → nicht erreichbar
    - None → Netzwerk nicht verfügbar / Fehler beim Request
    """

    if not QGIS_AVAILABLE:
        return None

    if QUrl is None or QNetworkRequest is None:
        return None

    try:
        manager = QgsNetworkAccessManager.instance()
        request = QNetworkRequest(QUrl(url))
        reply = manager.head(request)

        # synchron warten (kurz)
        if QEventLoop is not None:
            loop = QEventLoop()
            reply.finished.connect(loop.quit)
            loop.exec()

        return NetworkReply(error=reply.error())
    except Exception:
        return None

# ---------------------------------------------------------
# Layer-Geometrie / Extent
# ---------------------------------------------------------

def get_layer_extent(layer: Any) -> Any:
    """
    Gibt die Ausdehnung (Extent) eines Layers zurück.

    Diese Funktion kapselt den Zugriff auf ``layer.extent()`` und dient als
    zentrale Abstraktion für alle Stellen, die die Bounding Box eines Layers
    benötigen (z.B. für räumliche Filter im Datenabruf).

    Verhalten
    ---------
    - Wenn QGIS verfügbar ist und der Layer eine ``extent()``-Methode besitzt,
      wird deren Rückgabewert zurückgegeben.
    - Wenn QGIS nicht verfügbar ist oder der Layer keine ``extent()``-Methode
      hat, wird ``None`` zurückgegeben.
    """
    if not QGIS_AVAILABLE or layer is None:
        return None

    extent_func = getattr(layer, "extent", None)
    if callable(extent_func):
        try:
            return extent_func()
        except Exception:
            return None

    return None

# ---------------------------------------------------------
# Buffer-Layer erzeugen
# ---------------------------------------------------------

def create_buffer_layer(
    source_layer: Any,
    distance_m: float,
    layer_name: str = "BufferLayer"
) -> Optional[Any]:
    """
    Erzeugt einen Pufferlayer um alle Features eines Quelllayers.

    Diese Funktion dient als zentrale Abstraktion für die Erzeugung eines
    Pufferlayers in QGIS. Sie wird z.B. im Datenabruf verwendet, wenn der
    Raumfilter ``"Pufferlayer"`` aktiv ist.

    Verhalten
    ---------
    - Wenn QGIS verfügbar ist und der ``source_layer`` gültig ist, wird ein
      temporärer Vektorlayer erzeugt, der die gepufferten Geometrien enthält.
    - Der Puffer wird in Metern angegeben.
    - Der zurückgegebene Layer ist **nicht gespeichert**, sondern ein
      temporärer Speicherlayer, der anschließend über den UI‑Wrapper ins
      Projekt geladen werden kann.
    - Wenn QGIS nicht verfügbar ist oder ein Fehler auftritt, wird ``None``
      zurückgegeben.
    """
    if not QGIS_AVAILABLE:
        return None

    if source_layer is None or not hasattr(source_layer, "getFeatures"):
        return None

    try:
        # Geometrien puffern
        buffered_geoms = []
        for feat in source_layer.getFeatures():
            geom = feat.geometry()
            if geom is None:
                continue
            buf = geom.buffer(distance_m, 8)
            if buf is not None:
                buffered_geoms.append(buf)

        if not buffered_geoms:
            return None

        # Neuen Memory-Layer erzeugen
        crs = source_layer.crs().authid() if hasattr(source_layer, "crs") else "EPSG:4326"
        mem_layer = QgsVectorLayer(f"Polygon?crs={crs}", layer_name, "memory")

        prov = mem_layer.dataProvider()
        prov.addAttributes([])
        mem_layer.updateFields()

        # Features hinzufügen
        from qgis.core import QgsFeature
        for geom in buffered_geoms:
            f = QgsFeature()
            f.setGeometry(geom)
            prov.addFeature(f)

        mem_layer.updateExtents()
        return mem_layer

    except Exception:
        return None
    
#Hilfsfunktion, keine qgiscore-Entsprechung    

def layer_exists_in_gpkg(gpkg_path: str, layer_name: str) -> bool:
    """
    Prüft, ob ein Layer mit dem Namen `layer_name` in `gpkg_path` existiert.
    - bevorzugt: SQLite-Abfrage auf gpkg_contents
    - fallback: kurzer Versuch, mit QgsVectorLayer zu laden (wenn QGIS verfügbar)
    """
    import os, sqlite3
    if not gpkg_path or not layer_name or not os.path.exists(gpkg_path):
        return False

    # 1) SQLite-Check (schnell)
    try:
        conn = sqlite3.connect(gpkg_path)
        cur = conn.cursor()
        cur.execute("SELECT COUNT(1) FROM gpkg_contents WHERE table_name = ?", (layer_name,))
        row = cur.fetchone()
        conn.close()
        if row and row[0] > 0:
            return True
    except Exception:
        # falls sqlite fehlschlägt, weiter zum QGIS-Fallback
        pass

    # 2) QGIS-Fallback: versuche kurz, den Layer zu laden
    try:
        if getattr(QgsVectorLayer, "__call__", None) and QGIS_AVAILABLE:
            uri = f"{gpkg_path}|layername={layer_name}"
            layer = QgsVectorLayer(uri, layer_name, "ogr")
            return bool(layer and getattr(layer, "isValid", lambda: False)())
    except Exception:
        pass

    return False