from qgis.core import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4 import QtGui
from os import path
from sextante.core.SextanteConfig import SextanteConfig

class QGisLayers:
    '''This class contains method to communicate SEXTANTE with the QGIS interface,
    mostly for retrieving layers and adding new ones to the QGIS canvas'''

    ALL_TYPES = -1
    iface = None;

    @staticmethod
    def getRasterLayers():
        layers = QGisLayers.iface.legendInterface().layers()
        raster = list()

        for layer in layers:
            if layer.type() == layer.RasterLayer:
                if layer.usesProvider() and layer.providerKey() == 'gdal':#only gdal file-based layers
                    raster.append(layer)
        return raster

    @staticmethod
    def getVectorLayers(shapetype=-1):
        layers = QGisLayers.iface.legendInterface().layers()
        vector = list()
        for layer in layers:
            if layer.type() == layer.VectorLayer:
                if shapetype == QGisLayers.ALL_TYPES or layer.geometryType() == shapetype:
                    uri = unicode(layer.source())
                    if not uri.endswith("csv") and not uri.endswith("dbf"):
                        vector.append(layer)
        return vector

    @staticmethod
    def getAllLayers():
        layers = []
        layers += QGisLayers.getRasterLayers();
        layers += QGisLayers.getVectorLayers();
        return layers

    @staticmethod
    def getTables():
        layers = QGisLayers.iface.legendInterface().layers()
        tables = list()
        for layer in layers:
            if layer.type() == layer.VectorLayer :
                uri = unicode(layer.source())
                if uri.endswith("csv") or uri.endswith("dbf"):
                    tables.append(layer)
        return tables

    @staticmethod
    def setInterface(iface):
        QGisLayers.iface = iface


    @staticmethod
    def loadList(layers):
        for layer in layers:
            QGisLayers.load(layer)

    @staticmethod
    def load(layer, name = None, crs = None, style  = None):
        if layer == None:
            return
        prjSetting = None
        settings = QSettings()
        if crs != None:
            prjSetting = settings.value("/Projections/defaultBehaviour")
            settings.setValue("/Projections/defaultBehaviour", QVariant(""))
        if name == None:
            name = path.split(layer)[1]
        qgslayer = QgsVectorLayer(layer, name , 'ogr')
        if qgslayer.isValid():
            if crs != None:
                qgslayer.setCrs(crs,False)
            if style == None:
                if qgslayer.geometryType == 0:
                    style = SextanteConfig.getSetting(SextanteConfig.VECTOR_POINT_STYLE)
                elif qgslayer.geometryType == 1:
                    style = SextanteConfig.getSetting(SextanteConfig.VECTOR_LINE_STYLE)
                else:
                    style = SextanteConfig.getSetting(SextanteConfig.VECTOR_POLYGON_STYLE)
            qgslayer.loadNamedStyle(style)
            QgsMapLayerRegistry.instance().addMapLayer(qgslayer)
        else:
            qgslayer = QgsRasterLayer(layer, name)
            if qgslayer.isValid():
                if crs != None:
                    qgslayer.setCrs(crs,False)
                if style == None:
                    style = SextanteConfig.getSetting(SextanteConfig.RASTER_STYLE)
                qgslayer.loadNamedStyle(style)
                QgsMapLayerRegistry.instance().addMapLayer(qgslayer)
                QGisLayers.iface.legendInterface().refreshLayerSymbology(qgslayer)
            else:
                if prjSetting:
                    settings.setValue("/Projections/defaultBehaviour", prjSetting)
                raise RuntimeError("Could not load layer: " + unicode(layer)
                                       +"\nCheck the SEXTANTE log to look for errors in algorithm execution")
        if prjSetting:
            settings.setValue("/Projections/defaultBehaviour", prjSetting)


    @staticmethod
    def loadFromDict(layersdict, crs):
        for name in layersdict.keys():
            QGisLayers.load(layersdict[name], name, crs)


    @staticmethod
    def getObjectFromUri(uri, forceLoad = True):
        if uri is None:
            return None
        layers = QGisLayers.getRasterLayers()
        for layer in layers:
            if layer.source() == uri:
                return layer
        layers = QGisLayers.getVectorLayers()
        for layer in layers:
            if layer.source() == uri:
                return layer
        if forceLoad:
            settings = QSettings()
            prjSetting = settings.value("/Projections/defaultBehaviour")
            settings.setValue("/Projections/defaultBehaviour", QVariant(""))
            #if is not opened, we open it
            layer = QgsVectorLayer(uri, uri , 'ogr')
            if layer.isValid():
                if prjSetting:
                    settings.setValue("/Projections/defaultBehaviour", prjSetting)
                return layer
            layer = QgsRasterLayer(uri, uri)
            if layer.isValid():
                if prjSetting:
                    settings.setValue("/Projections/defaultBehaviour", prjSetting)
                return layer
            if prjSetting:
                    settings.setValue("/Projections/defaultBehaviour", prjSetting)
        else:
            return None