"""
***************************************************************************
    HubDistancePoints.py
    ---------------------
    Date                 : May 2010
    Copyright            : (C) 2010 by Michael Minn
    Email                : pyqgis at michaelminn 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__ = 'Michael Minn'
__date__ = 'May 2010'
__copyright__ = '(C) 2010, Michael Minn'

from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsField,
                       QgsGeometry,
                       QgsFeatureSink,
                       QgsDistanceArea,
                       QgsFeature,
                       QgsFeatureRequest,
                       QgsSpatialIndex,
                       QgsWkbTypes,
                       QgsUnitTypes,
                       QgsProcessing,
                       QgsProcessingParameterFeatureSource,
                       QgsProcessingParameterField,
                       QgsProcessingParameterEnum,
                       QgsProcessingParameterFeatureSink,
                       QgsProcessingException)
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm


class HubDistancePoints(QgisAlgorithm):
    INPUT = 'INPUT'
    HUBS = 'HUBS'
    FIELD = 'FIELD'
    UNIT = 'UNIT'
    OUTPUT = 'OUTPUT'
    LAYER_UNITS = 'LAYER_UNITS'

    UNITS = [QgsUnitTypes.DistanceUnit.DistanceMeters,
             QgsUnitTypes.DistanceUnit.DistanceFeet,
             QgsUnitTypes.DistanceUnit.DistanceMiles,
             QgsUnitTypes.DistanceUnit.DistanceKilometers,
             LAYER_UNITS
             ]

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

    def groupId(self):
        return 'vectoranalysis'

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

    def initAlgorithm(self, config=None):
        self.units = [self.tr('Meters'),
                      self.tr('Feet'),
                      self.tr('Miles'),
                      self.tr('Kilometers'),
                      self.tr('Layer units')]

        self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
                                                              self.tr('Source points layer')))
        self.addParameter(QgsProcessingParameterFeatureSource(self.HUBS,
                                                              self.tr('Destination hubs layer')))
        self.addParameter(QgsProcessingParameterField(self.FIELD,
                                                      self.tr('Hub layer name attribute'), parentLayerParameterName=self.HUBS))
        self.addParameter(QgsProcessingParameterEnum(self.UNIT,
                                                     self.tr('Measurement unit'), self.units))

        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Hub distance'), QgsProcessing.SourceType.TypeVectorPoint))

    def name(self):
        return 'distancetonearesthubpoints'

    def displayName(self):
        return self.tr('Distance to nearest hub (points)')

    def processAlgorithm(self, parameters, context, feedback):
        if parameters[self.INPUT] == parameters[self.HUBS]:
            raise QgsProcessingException(
                self.tr('Same layer given for both hubs and spokes'))

        point_source = self.parameterAsSource(parameters, self.INPUT, context)
        if point_source is None:
            raise QgsProcessingException(self.invalidSourceError(parameters, self.INPUT))

        hub_source = self.parameterAsSource(parameters, self.HUBS, context)
        if hub_source is None:
            raise QgsProcessingException(self.invalidSourceError(parameters, self.HUBS))

        fieldName = self.parameterAsString(parameters, self.FIELD, context)

        units = self.UNITS[self.parameterAsEnum(parameters, self.UNIT, context)]

        fields = point_source.fields()
        fields.append(QgsField('HubName', QVariant.String))
        fields.append(QgsField('HubDist', QVariant.Double))

        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                               fields, QgsWkbTypes.Type.Point, point_source.sourceCrs())
        if sink is None:
            raise QgsProcessingException(self.invalidSinkError(parameters, self.OUTPUT))

        index = QgsSpatialIndex(hub_source.getFeatures(QgsFeatureRequest().setSubsetOfAttributes([]).setDestinationCrs(point_source.sourceCrs(), context.transformContext())))

        distance = QgsDistanceArea()
        distance.setSourceCrs(point_source.sourceCrs(), context.transformContext())
        distance.setEllipsoid(context.ellipsoid())

        # Scan source points, find nearest hub, and write to output file
        features = point_source.getFeatures()
        total = 100.0 / point_source.featureCount() if point_source.featureCount() else 0
        for current, f in enumerate(features):
            if feedback.isCanceled():
                break

            if not f.hasGeometry():
                sink.addFeature(f, QgsFeatureSink.Flag.FastInsert)
                continue

            src = f.geometry().boundingBox().center()

            neighbors = index.nearestNeighbor(src, 1)
            if len(neighbors) == 0:
                continue

            ft = next(hub_source.getFeatures(QgsFeatureRequest().setFilterFid(neighbors[0]).setSubsetOfAttributes([fieldName], hub_source.fields()).setDestinationCrs(point_source.sourceCrs(), context.transformContext())))
            closest = ft.geometry().boundingBox().center()
            hubDist = distance.measureLine(src, closest)

            if units != self.LAYER_UNITS:
                hub_dist_in_desired_units = distance.convertLengthMeasurement(hubDist, units)
            else:
                hub_dist_in_desired_units = hubDist

            attributes = f.attributes()
            attributes.append(ft[fieldName])
            attributes.append(hub_dist_in_desired_units)

            feat = QgsFeature()
            feat.setAttributes(attributes)

            feat.setGeometry(QgsGeometry.fromPointXY(src))

            sink.addFeature(feat, QgsFeatureSink.Flag.FastInsert)
            feedback.setProgress(int(current * total))

        return {self.OUTPUT: dest_id}
