import os.path

from PyQt4 import QtGui
from PyQt4.QtCore import *

from qgis.core import *

from sextante.core.GeoAlgorithm import GeoAlgorithm
from sextante.core.QGisLayers import QGisLayers
from sextante.core.SextanteLog import SextanteLog

from sextante.parameters.ParameterVector import ParameterVector
from sextante.parameters.ParameterString import ParameterString
from sextante.outputs.OutputVector import OutputVector

from sextante.ftools import FToolsUtils as utils

class SumLines(GeoAlgorithm):

    LINES = "LINES"
    POLYGONS = "POLYGONS"
    LEN_FIELD = "LEN_FIELD"
    COUNT_FIELD = "COUNT_FIELD"
    OUTPUT = "OUTPUT"

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

    def defineCharacteristics(self):
        self.name = "Sum line lengths"
        self.group = "Analysis tools"

        self.addParameter(ParameterVector(self.LINES, "Lines", ParameterVector.VECTOR_TYPE_LINE))
        self.addParameter(ParameterVector(self.POLYGONS, "Polygons", ParameterVector.VECTOR_TYPE_POLYGON))
        self.addParameter(ParameterString(self.LEN_FIELD, "Lines length field name", "LENGTH"))
        self.addParameter(ParameterString(self.COUNT_FIELD, "Lines count field name", "COUNT"))

        self.addOutput(OutputVector(self.OUTPUT, "Result"))

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

        lineLayer = QGisLayers.getObjectFromUri(self.getParameterValue(self.LINES))
        polyLayer = QGisLayers.getObjectFromUri(self.getParameterValue(self.POLYGONS))
        lengthFieldName = self.getParameterValue(self.LEN_FIELD)
        countFieldName = self.getParameterValue(self.COUNT_FIELD)

        output = self.getOutputValue(self.OUTPUT)

        polyProvider = polyLayer.dataProvider()
        lineProvider = lineLayer.dataProvider()
        if polyProvider.crs() != lineProvider.crs():
            SextanteLog.addToLog(SextanteLog.LOG_WARNING,
                                 "CRS warning: Input layers have non-matching CRS. This may cause unexpected results.")

        idxLength, fieldList = utils.findOrCreateField(polyLayer, polyLayer.pendingFields(), lengthFieldName)
        idxCount, fieldList = utils.findOrCreateField(polyLayer, fieldList, countFieldName)

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fieldList,
                     polyProvider.geometryType(), polyProvider.crs())

        spatialIndex = utils.createSpatialIndex(lineProvider)

        lineProvider.rewind()
        lineProvider.select()

        allAttrs = polyLayer.pendingAllAttributesList()
        polyLayer.select(allAttrs)

        ftLine = QgsFeature()
        ftPoly = QgsFeature()
        outFeat = QgsFeature()
        inGeom = QgsGeometry()
        outGeom = QgsGeometry()
        distArea = QgsDistanceArea()

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

        while polyLayer.nextFeature(ftPoly):
            inGeom = QgsGeometry(ftPoly.geometry())
            atMap = ftPoly.attributeMap()
            count = 0
            length = 0
            hasIntersections = False
            lines = spatialIndex.intersects(inGeom.boundingBox())
            if len(lines) > 0:
                hasIntersections = True

            if hasIntersections:
                for i in lines:
                    lineProvider.featureAtId(int(i), ftLine)
                    tmpGeom = QgsGeometry(ftLine.geometry())
                    if inGeom.intersects(tmpGeom):
                        outGeom = inGeom.intersection(tmpGeom)
                        length += distArea.measure(outGeom)
                        count += 1

            outFeat.setGeometry(inGeom)
            outFeat.setAttributeMap(atMap)
            outFeat.addAttribute(idxLength, QVariant(length))
            outFeat.addAttribute(idxCount, QVariant(count))
            writer.addFeature(outFeat)

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

        del writer