# -*- coding: utf-8 -*-

"""
***************************************************************************
    ShortestPathPointToPoint.py
    ---------------------
    Date                 : November 2016
    Copyright            : (C) 2016 by Alexander Bruy
    Email                : alexander dot bruy at gmail dot com
***************************************************************************
*                                                                         *
*   This program is free software; you can redistribute it and/or modify  *
*   it under the terms of the GNU General Public License as published by  *
*   the Free Software Foundation; either version 2 of the License, or     *
*   (at your option) any later version.                                   *
*                                                                         *
***************************************************************************
"""

__author__ = 'Alexander Bruy'
__date__ = 'November 2016'
__copyright__ = '(C) 2016, Alexander Bruy'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

import os
from collections import OrderedDict

from qgis.PyQt.QtCore import QVariant, QCoreApplication
from qgis.PyQt.QtGui import QIcon

from qgis.core import (QgsWkbTypes,
                       QgsUnitTypes,
                       QgsFeature,
                       QgsFeatureSink,
                       QgsGeometry,
                       QgsFields,
                       QgsField,
                       QgsProcessing,
                       QgsProcessingException,
                       QgsProcessingOutputNumber,
                       QgsProcessingParameterEnum,
                       QgsProcessingParameterPoint,
                       QgsProcessingParameterField,
                       QgsProcessingParameterNumber,
                       QgsProcessingParameterString,
                       QgsProcessingParameterFeatureSource,
                       QgsProcessingParameterFeatureSink,
                       QgsProcessingParameterDefinition)
from qgis.analysis import (QgsVectorLayerDirector,
                           QgsNetworkDistanceStrategy,
                           QgsNetworkSpeedStrategy,
                           QgsGraphBuilder,
                           QgsGraphAnalyzer
                           )

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm

pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]


class ShortestPathPointToPoint(QgisAlgorithm):

    INPUT = 'INPUT'
    START_POINT = 'START_POINT'
    END_POINT = 'END_POINT'
    STRATEGY = 'STRATEGY'
    DIRECTION_FIELD = 'DIRECTION_FIELD'
    VALUE_FORWARD = 'VALUE_FORWARD'
    VALUE_BACKWARD = 'VALUE_BACKWARD'
    VALUE_BOTH = 'VALUE_BOTH'
    DEFAULT_DIRECTION = 'DEFAULT_DIRECTION'
    SPEED_FIELD = 'SPEED_FIELD'
    DEFAULT_SPEED = 'DEFAULT_SPEED'
    TOLERANCE = 'TOLERANCE'
    TRAVEL_COST = 'TRAVEL_COST'
    OUTPUT = 'OUTPUT'

    def icon(self):
        return QIcon(os.path.join(pluginPath, 'images', 'networkanalysis.svg'))

    def group(self):
        return self.tr('Network analysis')

    def groupId(self):
        return 'networkanalysis'

    def __init__(self):
        super().__init__()

    def initAlgorithm(self, config=None):
        self.DIRECTIONS = OrderedDict([
            (self.tr('Forward direction'), QgsVectorLayerDirector.DirectionForward),
            (self.tr('Backward direction'), QgsVectorLayerDirector.DirectionBackward),
            (self.tr('Both directions'), QgsVectorLayerDirector.DirectionBoth)])

        self.STRATEGIES = [self.tr('Shortest'),
                           self.tr('Fastest')
                           ]

        self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
                                                              self.tr('Vector layer representing network'),
                                                              [QgsProcessing.TypeVectorLine]))
        self.addParameter(QgsProcessingParameterPoint(self.START_POINT,
                                                      self.tr('Start point')))
        self.addParameter(QgsProcessingParameterPoint(self.END_POINT,
                                                      self.tr('End point')))
        self.addParameter(QgsProcessingParameterEnum(self.STRATEGY,
                                                     self.tr('Path type to calculate'),
                                                     self.STRATEGIES,
                                                     defaultValue=0))

        params = []
        params.append(QgsProcessingParameterField(self.DIRECTION_FIELD,
                                                  self.tr('Direction field'),
                                                  None,
                                                  self.INPUT,
                                                  optional=True))
        params.append(QgsProcessingParameterString(self.VALUE_FORWARD,
                                                   self.tr('Value for forward direction'),
                                                   optional=True))
        params.append(QgsProcessingParameterString(self.VALUE_BACKWARD,
                                                   self.tr('Value for backward direction'),
                                                   optional=True))
        params.append(QgsProcessingParameterString(self.VALUE_BOTH,
                                                   self.tr('Value for both directions'),
                                                   optional=True))
        params.append(QgsProcessingParameterEnum(self.DEFAULT_DIRECTION,
                                                 self.tr('Default direction'),
                                                 list(self.DIRECTIONS.keys()),
                                                 defaultValue=2))
        params.append(QgsProcessingParameterField(self.SPEED_FIELD,
                                                  self.tr('Speed field'),
                                                  None,
                                                  self.INPUT,
                                                  optional=True))
        params.append(QgsProcessingParameterNumber(self.DEFAULT_SPEED,
                                                   self.tr('Default speed (km/h)'),
                                                   QgsProcessingParameterNumber.Double,
                                                   5.0, False, 0, 99999999.99))
        params.append(QgsProcessingParameterNumber(self.TOLERANCE,
                                                   self.tr('Topology tolerance'),
                                                   QgsProcessingParameterNumber.Double,
                                                   0.0, False, 0, 99999999.99))

        for p in params:
            p.setFlags(p.flags() | QgsProcessingParameterDefinition.FlagAdvanced)
            self.addParameter(p)

        self.addOutput(QgsProcessingOutputNumber(self.TRAVEL_COST,
                                                 self.tr('Travel cost')))
        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT,
                                                            self.tr('Shortest path'),
                                                            QgsProcessing.TypeVectorLine))

    def name(self):
        return 'shortestpathpointtopoint'

    def displayName(self):
        return self.tr('Shortest path (point to point)')

    def processAlgorithm(self, parameters, context, feedback):
        network = self.parameterAsSource(parameters, self.INPUT, context)
        startPoint = self.parameterAsPoint(parameters, self.START_POINT, context, network.sourceCrs())
        endPoint = self.parameterAsPoint(parameters, self.END_POINT, context, network.sourceCrs())
        strategy = self.parameterAsEnum(parameters, self.STRATEGY, context)

        directionFieldName = self.parameterAsString(parameters, self.DIRECTION_FIELD, context)
        forwardValue = self.parameterAsString(parameters, self.VALUE_FORWARD, context)
        backwardValue = self.parameterAsString(parameters, self.VALUE_BACKWARD, context)
        bothValue = self.parameterAsString(parameters, self.VALUE_BOTH, context)
        defaultDirection = self.parameterAsEnum(parameters, self.DEFAULT_DIRECTION, context)
        speedFieldName = self.parameterAsString(parameters, self.SPEED_FIELD, context)
        defaultSpeed = self.parameterAsDouble(parameters, self.DEFAULT_SPEED, context)
        tolerance = self.parameterAsDouble(parameters, self.TOLERANCE, context)

        fields = QgsFields()
        fields.append(QgsField('start', QVariant.String, '', 254, 0))
        fields.append(QgsField('end', QVariant.String, '', 254, 0))
        fields.append(QgsField('cost', QVariant.Double, '', 20, 7))

        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                               fields, QgsWkbTypes.LineString, network.sourceCrs())

        directionField = -1
        if directionField:
            directionField = network.fields().lookupField(directionFieldName)
        speedField = -1
        if speedFieldName:
            speedField = network.fields().lookupField(speedFieldName)

        director = QgsVectorLayerDirector(network,
                                          directionField,
                                          forwardValue,
                                          backwardValue,
                                          bothValue,
                                          defaultDirection)

        distUnit = context.project().crs().mapUnits()
        multiplier = QgsUnitTypes.fromUnitToUnitFactor(distUnit, QgsUnitTypes.DistanceMeters)
        if strategy == 0:
            strategy = QgsNetworkDistanceStrategy()
        else:
            strategy = QgsNetworkSpeedStrategy(speedField,
                                               defaultSpeed,
                                               multiplier * 1000.0 / 3600.0)
            multiplier = 3600

        director.addStrategy(strategy)
        builder = QgsGraphBuilder(network.sourceCrs(),
                                  True,
                                  tolerance)
        feedback.pushInfo(QCoreApplication.translate('ShortestPathPointToPoint', 'Building graph…'))
        snappedPoints = director.makeGraph(builder, [startPoint, endPoint], feedback)

        feedback.pushInfo(QCoreApplication.translate('ShortestPathPointToPoint', 'Calculating shortest path…'))
        graph = builder.graph()
        idxStart = graph.findVertex(snappedPoints[0])
        idxEnd = graph.findVertex(snappedPoints[1])

        tree, costs = QgsGraphAnalyzer.dijkstra(graph, idxStart, 0)
        if tree[idxEnd] == -1:
            raise QgsProcessingException(
                self.tr('There is no route from start point to end point.'))

        route = [graph.vertex(idxEnd).point()]
        cost = costs[idxEnd]
        current = idxEnd
        while current != idxStart:
            current = graph.edge(tree[current]).fromVertex()
            route.append(graph.vertex(current).point())

        route.reverse()

        feedback.pushInfo(QCoreApplication.translate('ShortestPathPointToPoint', 'Writing results…'))
        geom = QgsGeometry.fromPolylineXY(route)
        feat = QgsFeature()
        feat.setFields(fields)
        feat['start'] = startPoint.toString()
        feat['end'] = endPoint.toString()
        feat['cost'] = cost / multiplier
        feat.setGeometry(geom)
        sink.addFeature(feat, QgsFeatureSink.FastInsert)

        results = {}
        results[self.TRAVEL_COST] = cost / multiplier
        results[self.OUTPUT] = dest_id
        return results
