import wx

from .backend_agg import FigureCanvasAgg
from .backend_wx import (
    _BackendWx, _FigureCanvasWxBase, FigureFrameWx,
    NavigationToolbar2Wx as NavigationToolbar2WxAgg)


class FigureFrameWxAgg(FigureFrameWx):
    def get_canvas(self, fig):
        return FigureCanvasWxAgg(self, -1, fig)


class FigureCanvasWxAgg(FigureCanvasAgg, _FigureCanvasWxBase):
    """
    The FigureCanvas contains the figure and does event handling.

    In the wxPython backend, it is derived from wxPanel, and (usually)
    lives inside a frame instantiated by a FigureManagerWx. The parent
    window probably implements a wxSizer to control the displayed
    control size - but we give a hint as to our preferred minimum
    size.
    """

    def draw(self, drawDC=None):
        """
        Render the figure using agg.
        """
        FigureCanvasAgg.draw(self)

        self.bitmap = _convert_agg_to_wx_bitmap(self.get_renderer(), None)
        self._isDrawn = True
        self.gui_repaint(drawDC=drawDC, origin='WXAgg')

    def blit(self, bbox=None):
        """
        Transfer the region of the agg buffer defined by bbox to the display.
        If bbox is None, the entire buffer is transferred.
        """
        if bbox is None:
            self.bitmap = _convert_agg_to_wx_bitmap(self.get_renderer(), None)
            self.gui_repaint()
            return

        l, b, w, h = bbox.bounds
        r = l + w
        t = b + h
        x = int(l)
        y = int(self.bitmap.GetHeight() - t)

        srcBmp = _convert_agg_to_wx_bitmap(self.get_renderer(), None)
        srcDC = wx.MemoryDC()
        srcDC.SelectObject(srcBmp)

        destDC = wx.MemoryDC()
        destDC.SelectObject(self.bitmap)

        destDC.Blit(x, y, int(w), int(h), srcDC, x, y)

        destDC.SelectObject(wx.NullBitmap)
        srcDC.SelectObject(wx.NullBitmap)
        self.gui_repaint()


def _convert_agg_to_wx_bitmap(agg, bbox):
    """
    Convert the region of the agg buffer bounded by bbox to a wx.Bitmap.  If
    bbox is None, the entire buffer is converted.
    Note: agg must be a backend_agg.RendererAgg instance.
    """
    if bbox is None:
        # agg => rgba buffer -> bitmap
        return wx.Bitmap.FromBufferRGBA(int(agg.width), int(agg.height),
                                        agg.buffer_rgba())
    else:
        # agg => rgba buffer -> bitmap => clipped bitmap
        l, b, width, height = bbox.bounds
        r = l + width
        t = b + height

        srcBmp = wx.Bitmap.FromBufferRGBA(int(agg.width), int(agg.height),
                                          agg.buffer_rgba())
        srcDC = wx.MemoryDC()
        srcDC.SelectObject(srcBmp)

        destBmp = wx.Bitmap(int(width), int(height))
        destDC = wx.MemoryDC()
        destDC.SelectObject(destBmp)

        x = int(l)
        y = int(int(agg.height) - t)
        destDC.Blit(0, 0, int(width), int(height), srcDC, x, y)

        srcDC.SelectObject(wx.NullBitmap)
        destDC.SelectObject(wx.NullBitmap)

        return destBmp


@_BackendWx.export
class _BackendWxAgg(_BackendWx):
    FigureCanvas = FigureCanvasWxAgg
    _frame_class = FigureFrameWxAgg