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

"""
***************************************************************************
    RandomSelection.py
    ---------------------
    Date                 : August 2012
    Copyright            : (C) 2012 by Victor Olaya
    Email                : volayaf 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__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'

import random

from PyQt4.QtCore import *

from qgis.core import *

from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.tools import dataobjects

from processing.parameters.ParameterSelection import ParameterSelection
from processing.parameters.ParameterVector import ParameterVector
from processing.parameters.ParameterNumber import ParameterNumber

from processing.outputs.OutputVector import OutputVector

class RandomSelection(GeoAlgorithm):

    INPUT = "INPUT"
    OUTPUT = "OUTPUT"
    METHOD = "METHOD"
    NUMBER = "NUMBER"

    METHODS = ["Number of selected features",
               "Percentage of selected features"
              ]

    #===========================================================================
    # def getIcon(self):
    #    return QtGui.QIcon(os.path.dirname(__file__) + "/icons/random_selection.png")
    #===========================================================================

    def defineCharacteristics(self):
        self.allowOnlyOpenedLayers = True
        self.name = "Random selection"
        self.group = "Vector selection tools"

        self.addParameter(ParameterVector(self.INPUT, "Input layer", [ParameterVector.VECTOR_TYPE_ANY]))
        self.addParameter(ParameterSelection(self.METHOD, "Method", self.METHODS, 0))
        self.addParameter(ParameterNumber(self.NUMBER, "Number/percentage of selected features", 0, None, 10))
        self.addOutput(OutputVector(self.OUTPUT, "Selection", True))

    def processAlgorithm(self, progress):
        filename = self.getParameterValue(self.INPUT)
        layer = dataobjects.getObjectFromUri(filename)
        method = self.getParameterValue(self.METHOD)

        featureCount = layer.featureCount()
        value = int(self.getParameterValue(self.NUMBER))

        layer.removeSelection()

        if method == 0:
            if value > featureCount:
                raise GeoAlgorithmExecutionException("Selected number is greater than feature count. Choose a lower value and try again.")
        else:
            if value > 100:
                raise GeoAlgorithmExecutionException("Percentage can't be greater than 100. Set a different value and try again.")
            value = int(round((value / 100.0000), 4) * featureCount)

        selran = random.sample(xrange(0, featureCount), value)

        layer.setSelectedFeatures(selran)
        self.setOutputValue(self.OUTPUT, filename)