import os.path

from PyQt4 import QtGui
from PyQt4.QtCore import *

from qgis.core import *

from sextante.core.GeoAlgorithm import GeoAlgorithm
from sextante.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from sextante.core.QGisLayers import QGisLayers

from sextante.parameters.ParameterVector import ParameterVector
from sextante.parameters.ParameterTableField import ParameterTableField

from sextante.outputs.OutputVector import OutputVector

from sextante.ftools import FToolsUtils as utils

class LinesIntersection(GeoAlgorithm):

    INPUT_A = "INPUT_A"
    INPUT_B = "INPUT_B"
    FIELD_A = "FIELD_A"
    FIELD_B = "FIELD_B"

    OUTPUT = "OUTPUT"

    def getIcon(self):
        return QtGui.QIcon(os.path.dirname(__file__) + "/icons/intersections.png")

    def defineCharacteristics(self):
        self.name = "Line intersections"
        self.group = "Analysis tools"

        self.addParameter(ParameterVector(self.INPUT_A, "Input layer", ParameterVector.VECTOR_TYPE_LINE))
        self.addParameter(ParameterVector(self.INPUT_B, "Intersect layer", ParameterVector.VECTOR_TYPE_LINE))
        self.addParameter(ParameterTableField(self.FIELD_A, "Input unique ID field", self.INPUT_A))
        self.addParameter(ParameterTableField(self.FIELD_B, "Intersect unique ID field", self.INPUT_B))

        self.addOutput(OutputVector(self.OUTPUT, "Output layer"))

    def processAlgorithm(self, progress):
        settings = QSettings()
        encoding = settings.value( "/UI/encoding", "System" ).toString()

        layerA = QGisLayers.getObjectFromUri(self.getParameterValue(self.INPUT_A))
        layerB = QGisLayers.getObjectFromUri(self.getParameterValue(self.INPUT_B))
        fieldA = self.getParameterValue(self.FIELD_A)
        fieldB = self.getParameterValue(self.FIELD_B)

        output = self.getOutputValue(self.OUTPUT)

        providerA = layerA.dataProvider()
        providerB = layerB.dataProvider()


        idxA = layerA.fieldNameIndex(fieldA)
        idxB = layerB.fieldNameIndex(fieldB)

        fieldList = {0 : layerA.pendingFields()[idxA],
                     1 : layerB.pendingFields()[idxB]
                    }

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fieldList,
                     QGis.WKBPoint, providerA.crs())

        spatialIndex = utils.createSpatialIndex(providerB)

        providerA.rewind()
        layerA.select([idxA])
        providerB.rewind()
        layerB.select([idxB])

        inFeatA = QgsFeature()
        inFeatB = QgsFeature()
        outFeat = QgsFeature()
        inGeom = QgsGeometry()
        tmpGeom = QgsGeometry()

        current = 0
        total = 100.0 / float(providerA.featureCount())
        hasIntersections = False

        while layerA.nextFeature(inFeatA):
            inGeom = inFeatA.geometry()
            hasIntersections = False
            lines = spatialIndex.intersects(inGeom.boundingBox())

            if len(lines) > 0:
                hasIntersections = True

            if hasIntersections:
                layerB.select([idxB])
                for i in lines:
                    layerB.featureAtId(int(i), inFeatB)
                    tmpGeom = QgsGeometry(inFeatB.geometry())

                    points = []
                    atMapA = inFeatA.attributeMap()
                    atMapB = inFeatB.attributeMap()

                    if inGeom.intersects(tmpGeom):
                        tempGeom = inGeom.intersection(tmpGeom)
                        if tempGeom.type() == QGis.Point:
                            if tempGeom.isMultipart():
                                points = tempGeom.asMultiPoint()
                            else:
                                points.append(tempGeom.asPoint())

                            for j in points:
                                outFeat.setGeometry(tempGeom.fromPoint(j))
                                outFeat.addAttribute(0, atMapA[idxA])
                                outFeat.addAttribute(1, atMapB[idxB])
                                writer.addFeature(outFeat)

            current += 1
            progress.setPercentage(int(current * total))

        del writer