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

"""
***************************************************************************
    FieldsMapper.py
    ---------------------
    Date                 : October 2014
    Copyright            : (C) 2014 by Arnaud Morvan
    Email                : arnaud dot morvan at camptocamp 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.                                   *
*                                                                         *
***************************************************************************
"""
from __future__ import print_function
from builtins import str
from builtins import range

__author__ = 'Arnaud Morvan'
__date__ = 'October 2014'
__copyright__ = '(C) 2014, Arnaud Morvan'

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

__revision__ = '$Format:%H$'

from qgis.core import (QgsField,
                       QgsExpression,
                       QgsDistanceArea,
                       QgsProject,
                       QgsFeature,
                       GEO_NONE,
                       QgsApplication,
                       QgsProcessingUtils)
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterTable
from processing.core.parameters import Parameter
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector


class FieldsMapper(GeoAlgorithm):

    INPUT_LAYER = 'INPUT_LAYER'
    FIELDS_MAPPING = 'FIELDS_MAPPING'
    OUTPUT_LAYER = 'OUTPUT_LAYER'

    def __init__(self):
        GeoAlgorithm.__init__(self)
        self.mapping = None

    def icon(self):
        return QgsApplication.getThemeIcon("/providerQgis.svg")

    def svgIconPath(self):
        return QgsApplication.iconPath("providerQgis.svg")

    def group(self):
        return self.tr('Vector table tools')

    def name(self):
        return 'refactorfields'

    def displayName(self):
        return self.tr('Refactor fields')

    def defineCharacteristics(self):
        self.addParameter(ParameterTable(self.INPUT_LAYER,
                                         self.tr('Input layer'),
                                         False))

        class ParameterFieldsMapping(Parameter):

            default_metadata = {
                'widget_wrapper': 'processing.algs.qgis.ui.FieldsMappingPanel.FieldsMappingWidgetWrapper'
            }

            def __init__(self, name='', description='', parent=None):
                Parameter.__init__(self, name, description)
                self.parent = parent
                self.value = []

            def getValueAsCommandLineParameter(self):
                return '"' + str(self.value) + '"'

            def setValue(self, value):
                if value is None:
                    return False
                if isinstance(value, list):
                    self.value = value
                    return True
                if isinstance(value, str):
                    try:
                        self.value = eval(value)
                        return True
                    except Exception as e:
                        # fix_print_with_import
                        print(str(e))  # display error in console
                        return False
                return False

        self.addParameter(ParameterFieldsMapping(self.FIELDS_MAPPING,
                                                 self.tr('Fields mapping'),
                                                 self.INPUT_LAYER))
        self.addOutput(OutputVector(self.OUTPUT_LAYER,
                                    self.tr('Refactored'),
                                    base_input=self.INPUT_LAYER))

    def processAlgorithm(self, context, feedback):
        layer = self.getParameterValue(self.INPUT_LAYER)
        mapping = self.getParameterValue(self.FIELDS_MAPPING)
        output = self.getOutputFromName(self.OUTPUT_LAYER)

        layer = dataobjects.getLayerFromString(layer)
        fields = []
        expressions = []

        da = QgsDistanceArea()
        da.setSourceCrs(layer.crs())
        da.setEllipsoid(QgsProject.instance().ellipsoid())

        exp_context = layer.createExpressionContext()

        for field_def in mapping:
            fields.append(QgsField(name=field_def['name'],
                                   type=field_def['type'],
                                   len=field_def['length'],
                                   prec=field_def['precision']))

            expression = QgsExpression(field_def['expression'])
            expression.setGeomCalculator(da)
            expression.setDistanceUnits(QgsProject.instance().distanceUnits())
            expression.setAreaUnits(QgsProject.instance().areaUnits())
            expression.prepare(exp_context)
            if expression.hasParserError():
                raise GeoAlgorithmExecutionException(
                    self.tr(u'Parser error in expression "{}": {}')
                    .format(str(expression.expression()),
                            str(expression.parserErrorString())))
            expressions.append(expression)

        writer = output.getVectorWriter(fields, layer.wkbType(), layer.crs(), context)

        # Create output vector layer with new attributes
        error_exp = None
        inFeat = QgsFeature()
        outFeat = QgsFeature()
        features = QgsProcessingUtils.getFeatures(layer, context)
        count = QgsProcessingUtils.featureCount(layer, context)
        if count > 0:
            total = 100.0 / count
            for current, inFeat in enumerate(features):
                rownum = current + 1

                geometry = inFeat.geometry()
                outFeat.setGeometry(geometry)

                attrs = []
                for i in range(0, len(mapping)):
                    field_def = mapping[i]
                    expression = expressions[i]
                    exp_context.setFeature(inFeat)
                    exp_context.lastScope().setVariable("row_number", rownum)
                    value = expression.evaluate(exp_context)
                    if expression.hasEvalError():
                        error_exp = expression
                        break

                    attrs.append(value)
                outFeat.setAttributes(attrs)

                writer.addFeature(outFeat)

                feedback.setProgress(int(current * total))
        else:
            feedback.setProgress(100)

        del writer

        if error_exp is not None:
            raise GeoAlgorithmExecutionException(
                self.tr(u'Evaluation error in expression "{}": {}')
                    .format(str(error_exp.expression()),
                            str(error_exp.parserErrorString())))