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

"""
/***************************************************************************
Name                 : DB Manager
Description          : Database manager plugin for QGIS
Date                 : May 23, 2011
copyright            : (C) 2011 by Giuseppe Sucameli
email                : brush.tyler@gmail.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 PyQt4.QtCore import *
from PyQt4.QtGui import *

from qgis.gui import QgsMapCanvas, QgsMapCanvasLayer
from qgis.core import QgsVectorLayer, QgsMapLayerRegistry

from .db_plugins.plugin import DbError, Table

class LayerPreview(QgsMapCanvas):
  def __init__(self, parent=None):
    QgsMapCanvas.__init__(self, parent)
    self.setCanvasColor(QColor(255,255,255))

    self.item = None
    self.dirty = False

    # reuse settings from QGIS
    settings = QSettings()
    self.enableAntiAliasing( settings.value( "/qgis/enable_anti_aliasing", False, type=bool ) )
    self.useImageToRender( settings.value( "/qgis/use_qimage_to_render", False, type=bool ) )
    action = settings.value( "/qgis/wheel_action", 0, type=float )
    zoomFactor = settings.value( "/qgis/zoom_factor", 2, type=int )
    self.setWheelAction( QgsMapCanvas.WheelAction(action), zoomFactor )

    self._clear()


  def refresh(self):
    self.setDirty(True)
    self.loadPreview( self.item )

  def loadPreview(self, item, force=False):
    if item == self.item and not self.dirty:
      return
    self._clear()
    if item is None:
      return

    if isinstance(item, Table) and item.type in [Table.VectorType, Table.RasterType]:
      # update the preview, but first let the manager chance to show the canvas
      runPrev = lambda: self._loadTablePreview( item )
      QTimer.singleShot(50, runPrev)
    else:
      return

    self.item = item
    self.connect(self.item, SIGNAL('aboutToChange'), self.setDirty)

  def setDirty(self, val=True):
    self.dirty = val

  def _clear(self):
    """ remove any layers from preview canvas """
    if self.item is not None:
      self.disconnect(self.item, SIGNAL('aboutToChange'), self.setDirty)
    self.item = None
    self.dirty = False

    self.currentLayerId = None
    self.setLayerSet( [] )

  def _loadTablePreview(self, table, limit=False):
    """ if has geometry column load to map canvas """
    QApplication.setOverrideCursor(QCursor(Qt.WaitCursor))
    self.setRenderFlag(False)
    newLayerId = None

    if table.geomType:
      # limit the query result if required
      if limit and table.rowCount > 1000:
        uniqueField = table.getValidQGisUniqueFields(True)
        if uniqueField == None:
          QMessageBox.warning(self, QApplication.translate("DBManagerPlugin", "Sorry"), QApplication.translate("DBManagerPlugin", "Unable to find a valid unique field"))
          return

        uri = table.database().uri()
        uri.setDataSource("", u"(SELECT * FROM %s LIMIT 1000)" % table.quotedName(), table.geomColumn, "", uniqueField.name)
        provider = table.database().dbplugin().providerName()
        vl = QgsVectorLayer(uri.uri(), table.name, provider)
      else:
        vl = table.toMapLayer()

      if not vl.isValid():
        self.setLayerSet( [] )
      else:
        newLayerId = vl.id() if hasattr(vl, 'id') else vl.id()
        self.setLayerSet( [ QgsMapCanvasLayer(vl) ] )
        QgsMapLayerRegistry.instance().addMapLayers([vl], False)
        self.zoomToFullExtent()

    # remove old layer (if any) and set new
    if self.currentLayerId:
      QgsMapLayerRegistry.instance().removeMapLayers([self.currentLayerId], False)
    self.currentLayerId = newLayerId

    self.setRenderFlag(True)
    QApplication.restoreOverrideCursor()