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

"""
***************************************************************************
    TruncateTable.py
    -----------------------
    Date                 : January 2017
    Copyright            : (C) 2017 by Nyall Dawson
    Email                : nyall dot dawson 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__ = 'Nyall Dawson'
__date__ = 'January 2017'
__copyright__ = '(C) 2017, Nyall Dawson'

from qgis.core import (QgsProcessingAlgorithm,
                       QgsProcessingParameterVectorLayer,
                       QgsProcessingOutputVectorLayer,
                       QgsProcessingException)
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm


class TruncateTable(QgisAlgorithm):

    INPUT = 'INPUT'
    OUTPUT = 'OUTPUT'

    def tags(self):
        return self.tr('empty,delete,layer,clear,features').split(',')

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

    def groupId(self):
        return 'vectorgeneral'

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

    def initAlgorithm(self, config=None):
        self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT,
                                                            self.tr('Input Layer')))
        self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Truncated layer')))

    def flags(self):
        return super().flags() | QgsProcessingAlgorithm.FlagNoThreading

    def name(self):
        return 'truncatetable'

    def displayName(self):
        return self.tr('Truncate table')

    def processAlgorithm(self, parameters, context, feedback):
        layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
        provider = layer.dataProvider()

        if not provider.truncate():
            raise QgsProcessingException(
                self.tr('Could not truncate table.'))

        return {self.OUTPUT: layer.id()}
