# -*- coding: utf-8 -*-
#-----------------------------------------------------------
#
# Random selection within subsets
#
# A QGIS plugin for randomly selecting features from
# within multiple user defined subsets based on an input field.
#
# Copyright (C) 2008  Carson Farmer
#
# EMAIL: carson.farmer (at) gmail.com
# WEB  : www.geog.uvic.ca/spar/carson
#
#-----------------------------------------------------------
#
# licensed under the terms of GNU GPL 2
#
# 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.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
#--------------------------------------------------------------------
from PyQt4.QtCore import *
from PyQt4.QtGui import *
import random, ftools_utils
from qgis.core import *
from ui_frmSubsetSelect import Ui_Dialog

class Dialog(QDialog, Ui_Dialog):

    def __init__(self, iface):
        QDialog.__init__(self)
        self.iface = iface
        # Set up the user interface from Designer.
        self.setupUi(self)
        QObject.connect(self.inShape, SIGNAL("currentIndexChanged(QString)"), self.update)
        self.setWindowTitle(self.tr("Random selection within subsets"))
        self.buttonOk = self.buttonBox_2.button( QDialogButtonBox.Ok )
        # populate layer list
        self.progressBar.setValue(0)
        mapCanvas = self.iface.mapCanvas()
        layers = ftools_utils.getLayerNames([QGis.Point, QGis.Line, QGis.Polygon])
        self.inShape.addItems(layers)

    def update(self, inputLayer):
        self.inField.clear()
        changedLayer = ftools_utils.getVectorLayerByName(inputLayer)
        changedField = ftools_utils.getFieldList(changedLayer)
        for i in changedField:
            self.inField.addItem(unicode(changedField[i].name()))
        maxFeatures = changedLayer.dataProvider().featureCount()
        self.spnNumber.setMaximum( maxFeatures )

    def accept(self):
        self.buttonOk.setEnabled( False )
        if self.inShape.currentText() == "":
            QMessageBox.information(self, self.tr("Random selection within subsets"), self.tr("Please specify input vector layer"))
        elif self.inField.currentText() == "":
            QMessageBox.information(self, self.tr("Random selection within subsets"), self.tr("Please specify an input field"))
        else:
            inVect = self.inShape.currentText()
            uidField = self.inField.currentText()
            if self.rdoNumber.isChecked():
                value = self.spnNumber.value()
                perc = False
            else:
                value = self.spnPercent.value()
                perc = True
            self.compute(inVect, uidField, value, perc, self.progressBar)
            self.progressBar.setValue(100)
        self.progressBar.setValue(0)
        self.buttonOk.setEnabled( True )

    def compute(self, inVect, inField, value, perc, progressBar):
        mlayer = ftools_utils.getMapLayerByName(inVect)
        mlayer.removeSelection(True)
        vlayer = ftools_utils.getVectorLayerByName(inVect)
        vprovider = vlayer.dataProvider()
        allAttrs = vprovider.attributeIndexes()
        vprovider.select(allAttrs)
        index = vprovider.fieldNameIndex(inField)
        #unique = []
        #vprovider.uniqueValues(index, unique)
        unique = ftools_utils.getUniqueValues(vprovider, int(index))
        inFeat = QgsFeature()
        selran = []
        nFeat = vprovider.featureCount() * len(unique)
        nElement = 0
        self.progressBar.setValue(0)
        self.progressBar.setRange(0, nFeat)
        if not len(unique) == mlayer.featureCount():
            for i in unique:
                vprovider.rewind()
                FIDs= []
                while vprovider.nextFeature(inFeat):
                    atMap = inFeat.attributeMap()
                    if atMap[index] == QVariant(i):
                        FID = inFeat.id()
                        FIDs.append(FID)
                    nElement += 1
                    self.progressBar.setValue(nElement)
                if perc: selVal = int(round((value / 100.0000) * len(FIDs), 0))
                else: selVal = value
                if selVal >= len(FIDs): selFeat = FIDs
                else: selFeat = random.sample(FIDs, selVal)
                selran.extend(selFeat)
            mlayer.setSelectedFeatures(selran)
        else:
            mlayer.setSelectedFeatures(range(0, mlayer.featureCount()))