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

"""
***************************************************************************
    ServiceAreaFromPoint.py
    ---------------------
    Date                 : December 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__ = 'December 2016'
__copyright__ = '(C) 2016, Alexander Bruy'

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,
                       QgsGeometryUtils,
                       QgsFields,
                       QgsField,
                       QgsProcessing,
                       QgsProcessingException,
                       QgsProcessingParameterBoolean,
                       QgsProcessingParameterDistance,
                       QgsProcessingParameterEnum,
                       QgsProcessingParameterPoint,
                       QgsProcessingParameterField,
                       QgsProcessingParameterNumber,
                       QgsProcessingParameterString,
                       QgsProcessingParameterFeatureSink,
                       QgsProcessingParameterFeatureSource,
                       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 ServiceAreaFromPoint(QgisAlgorithm):

    INPUT = 'INPUT'
    START_POINT = 'START_POINT'
    STRATEGY = 'STRATEGY'
    TRAVEL_COST = 'TRAVEL_COST'
    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'
    INCLUDE_BOUNDS = 'INCLUDE_BOUNDS'
    OUTPUT = 'OUTPUT'
    OUTPUT_LINES = 'OUTPUT_LINES'

    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(QgsProcessingParameterEnum(self.STRATEGY,
                                                     self.tr('Path type to calculate'),
                                                     self.STRATEGIES,
                                                     defaultValue=0))
        self.addParameter(QgsProcessingParameterNumber(self.TRAVEL_COST,
                                                       self.tr('Travel cost (distance for "Shortest", time for "Fastest")'),
                                                       QgsProcessingParameterNumber.Double,
                                                       0.0, False, 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))
        params.append(QgsProcessingParameterDistance(self.TOLERANCE,
                                                     self.tr('Topology tolerance'),
                                                     0.0, self.INPUT, False, 0))
        params.append(QgsProcessingParameterBoolean(self.INCLUDE_BOUNDS,
                                                    self.tr('Include upper/lower bound points'),
                                                    defaultValue=False))

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

        lines_output = QgsProcessingParameterFeatureSink(self.OUTPUT_LINES,
                                                         self.tr('Service area (lines)'),
                                                         QgsProcessing.TypeVectorLine, optional=True)
        lines_output.setCreateByDefault(True)
        self.addParameter(lines_output)

        nodes_output = QgsProcessingParameterFeatureSink(self.OUTPUT,
                                                         self.tr('Service area (boundary nodes)'),
                                                         QgsProcessing.TypeVectorPoint, optional=True)
        nodes_output.setCreateByDefault(False)
        self.addParameter(nodes_output)

    def name(self):
        return 'serviceareafrompoint'

    def displayName(self):
        return self.tr('Service area (from point)')

    def processAlgorithm(self, parameters, context, feedback):
        network = self.parameterAsSource(parameters, self.INPUT, context)
        if network is None:
            raise QgsProcessingException(self.invalidSourceError(parameters, self.INPUT))

        startPoint = self.parameterAsPoint(parameters, self.START_POINT, context, network.sourceCrs())
        strategy = self.parameterAsEnum(parameters, self.STRATEGY, context)
        travelCost = self.parameterAsDouble(parameters, self.TRAVEL_COST, 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)

        include_bounds = True # default to true to maintain 3.0 API
        if self.INCLUDE_BOUNDS in parameters:
            include_bounds = self.parameterAsBoolean(parameters, self.INCLUDE_BOUNDS, context)

        directionField = -1
        if directionFieldName:
            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)

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

        feedback.pushInfo(QCoreApplication.translate('ServiceAreaFromPoint', 'Calculating service area…'))
        graph = builder.graph()
        idxStart = graph.findVertex(snappedPoints[0])

        tree, cost = QgsGraphAnalyzer.dijkstra(graph, idxStart, 0)
        vertices = set()
        points = []
        lines = []

        for vertex, start_vertex_cost in enumerate(cost):
            inbound_edge_index = tree[vertex]
            if inbound_edge_index == -1 and vertex != idxStart:
                # unreachable vertex
                continue

            if start_vertex_cost > travelCost:
                # vertex is too expensive, discard
                continue

            vertices.add(vertex)
            start_point = graph.vertex(vertex).point()

            # find all edges coming from this vertex
            for edge_id in graph.vertex(vertex).outgoingEdges():
                edge = graph.edge(edge_id)
                end_vertex_cost = start_vertex_cost + edge.cost(0)
                end_point = graph.vertex(edge.toVertex()).point()
                if end_vertex_cost <= travelCost:
                    # end vertex is cheap enough to include
                    vertices.add(edge.toVertex())
                    lines.append([start_point, end_point])
                else:
                    # travelCost sits somewhere on this edge, interpolate position
                    interpolated_end_point = QgsGeometryUtils.interpolatePointOnLineByValue(start_point.x(), start_point.y(), start_vertex_cost,
                                                                                            end_point.x(), end_point.y(), end_vertex_cost, travelCost)
                    points.append(interpolated_end_point)
                    lines.append([start_point, interpolated_end_point])

        for i in vertices:
            points.append(graph.vertex(i).point())

        feedback.pushInfo(QCoreApplication.translate('ServiceAreaFromPoint', 'Writing results…'))

        fields = QgsFields()
        fields.append(QgsField('type', QVariant.String, '', 254, 0))
        fields.append(QgsField('start', QVariant.String, '', 254, 0))

        feat = QgsFeature()
        feat.setFields(fields)

        (point_sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                                     fields, QgsWkbTypes.MultiPoint, network.sourceCrs())

        results = {}

        if point_sink is not None:
            results[self.OUTPUT] = dest_id
            geomPoints = QgsGeometry.fromMultiPointXY(points)
            feat.setGeometry(geomPoints)
            feat['type'] = 'within'
            feat['start'] = startPoint.toString()
            point_sink.addFeature(feat, QgsFeatureSink.FastInsert)

            if include_bounds:
                upperBoundary = []
                lowerBoundary = []

                vertices = []
                for i, v in enumerate(cost):
                    if v > travelCost and tree[i] != -1:
                        vertexId = graph.edge(tree[i]).fromVertex()
                        if cost[vertexId] <= travelCost:
                            vertices.append(i)

                for i in vertices:
                    upperBoundary.append(graph.vertex(graph.edge(tree[i]).toVertex()).point())
                    lowerBoundary.append(graph.vertex(graph.edge(tree[i]).fromVertex()).point())

                geomUpper = QgsGeometry.fromMultiPointXY(upperBoundary)
                geomLower = QgsGeometry.fromMultiPointXY(lowerBoundary)

                feat.setGeometry(geomUpper)
                feat['type'] = 'upper'
                feat['start'] = startPoint.toString()
                point_sink.addFeature(feat, QgsFeatureSink.FastInsert)

                feat.setGeometry(geomLower)
                feat['type'] = 'lower'
                feat['start'] = startPoint.toString()
                point_sink.addFeature(feat, QgsFeatureSink.FastInsert)

        (line_sink, line_dest_id) = self.parameterAsSink(parameters, self.OUTPUT_LINES, context,
                                                         fields, QgsWkbTypes.MultiLineString, network.sourceCrs())
        if line_sink is not None:
            results[self.OUTPUT_LINES] = line_dest_id
            geom_lines = QgsGeometry.fromMultiPolylineXY(lines)
            feat.setGeometry(geom_lines)
            feat['type'] = 'lines'
            feat['start'] = startPoint.toString()
            line_sink.addFeature(feat, QgsFeatureSink.FastInsert)

        return results
