"""
Image viewer widget.
"""

import os
import logging
import numpy as np
import matplotlib
import matplotlib.image as mpimg

from PyQt5 import QtWidgets

from sas.sascalc.dataloader.manipulations import reader2D_converter

import sas.qtgui.Utilities.GuiUtils as GuiUtils
from sas.qtgui.Plotting.Plotter2D import Plotter2D
from sas.qtgui.Plotting.PlotterData import Data2D
from sas.sascalc.dataloader.data_info import Detector

# Local UI
from sas.qtgui.Utilities.UI.ImageViewerUI import Ui_ImageViewerUI
from sas.qtgui.Utilities.UI.ImageViewerOptionsUI import Ui_ImageViewerOptionsUI
matplotlib.interactive(False)

class ImageViewer(QtWidgets.QMainWindow, Ui_ImageViewerUI):
    """
    Implemented as QMainWindow to enable easy menus
    """
    def __init__(self, parent=None):
        super(ImageViewer, self).__init__(parent._parent)

        self.parent = parent
        self.setupUi(self)

        # Other globals
        self.plotter = None
        self.hbox = None
        self.filename = None
        self.is_png = False
        self.image = None

        # disable menu items on empty canvas
        self.disableMenus()

        # set up menu item triggers
        self.addTriggers()

    def disableMenus(self):
        """
        All menu items but "Load File" and "Help" should be disabled
        when no data is present
        """
        self.actionSave_Image.setEnabled(False)
        self.actionPrint_Image.setEnabled(False)
        self.actionCopy_Image.setEnabled(False)
        self.actionConvert_to_Data.setEnabled(False)

    def enableMenus(self):
        """
        Enable all menu items when data is present
        """
        self.actionSave_Image.setEnabled(True)
        self.actionPrint_Image.setEnabled(True)
        self.actionCopy_Image.setEnabled(True)
        self.actionConvert_to_Data.setEnabled(True)

    def addTriggers(self):
        """
        Trigger definitions for all menu/toolbar actions.
        """
        # File
        self.actionLoad_Image.triggered.connect(self.actionLoadImage)
        self.actionSave_Image.triggered.connect(self.actionSaveImage)
        self.actionPrint_Image.triggered.connect(self.actionPrintImage)
        # Edit
        self.actionCopy_Image.triggered.connect(self.actionCopyImage)
        # Image
        self.actionConvert_to_Data.triggered.connect(self.actionConvertToData)
        # Help
        self.actionHow_To.triggered.connect(self.actionHowTo)

    def actionLoadImage(self):
        """
        Image loader given files extensions
        """
        wildcards = "Images (*.bmp *.gif *jpeg *jpg *.png *tif *.tiff) ;;"\
                    "Bitmap (*.bmp *.BMP);; "\
                    "GIF (*.gif *.GIF);; "\
                    "JPEG (*.jpg  *.jpeg *.JPG *.JPEG);; "\
                    "PNG (*.png *.PNG);; "\
                    "TIFF (*.tif *.tiff *.TIF *.TIFF);; "\
                    "All files (*.*)"

        filepath = QtWidgets.QFileDialog.getOpenFileName(
            self, "Choose a file", "", wildcards)[0]

        if filepath:
            self.showImage(filepath)

    def actionSaveImage(self):
        """
        Use the internal MPL method for saving to file
        """
        if self.plotter is not None:
            self.plotter.onImageSave()

    def actionPrintImage(self):
        """
        Display printer dialog and print the MPL widget area
        """
        if self.plotter is not None:
            self.plotter.onImagePrint()

    def actionCopyImage(self):
        """
        Copy MPL widget area to buffer
        """
        if self.plotter is not None:
            self.plotter.onClipboardCopy()

    def actionConvertToData(self):
        """
        Show the options dialog and if accepted, send data to conversion
        """
        options = ImageViewerOptions(self)
        if options.exec_() != QtWidgets.QDialog.Accepted:
            return

        (xmin, xmax, ymin, ymax, zscale) = options.getState()
        image = self.image
        try:
            self.convertImage(image, xmin, xmax, ymin, ymax, zscale)
        except Exception as ex:
            err_msg = "Error occurred while converting Image to Data: " + str(ex)
            logging.error(err_msg)

    def actionHowTo(self):
        ''' Send the image viewer help URL to the help viewer '''
        location = "/user/qtgui/Calculators/image_viewer_help.html"
        self.parent.showHelp(location)

    def addPlotter(self):
        """
        Add a new plotter to the frame
        """
        self.plotter = Plotter2D(self, quickplot=True)

        # remove existing layout
        if self.hbox is not None:
            for i in range(self.hbox.count()):
                layout_item = self.hbox.itemAt(i)
                self.hbox.removeItem(layout_item)
            self.hbox.addWidget(self.plotter)
        else:
            # add the plotter to the QLayout
            self.hbox = QtWidgets.QHBoxLayout()
            self.hbox.addWidget(self.plotter)
            self.imgFrame.setLayout(self.hbox)

    def showImage(self, filename):
        """
        Show the requested image in the main frame
        """
        self.filename = os.path.basename(filename)
        _, extension = os.path.splitext(self.filename)
        try:
            # Note that matplotlib only reads png natively.
            # Any other formats (tiff, jpeg, etc) are passed
            # to PIL which seems to have a problem in version
            # 1.1.7 that causes a close error which shows up in
            # the log file.  This does not seem to have any adverse
            # effects.  PDB   --- September 17, 2017.
            self.image = mpimg.imread(filename)
            self.is_png = extension.lower() == '.png'
            self.addPlotter()
            ax = self.plotter.ax
            flipped_image = np.flipud(self.image)
            origin = None
            if self.is_png:
                origin = 'lower'
            self.plotter.imageShow(flipped_image, origin=origin)
            if not self.is_png:
                ax.set_ylim(ax.get_ylim()[::-1])
            ax.set_xlabel('x [pixel]')
            ax.set_ylabel('y [pixel]')
            self.plotter.figure.subplots_adjust(left=0.15, bottom=0.1,
                                                right=0.95, top=0.95)
            title = 'Picture: ' + self.filename
            self.setWindowTitle(title)
            self.plotter.draw()
        except IOError as ex:
            err_msg = "Failed to load '%s'.\n" % self.filename
            logging.error(err_msg+str(ex))
            return
        except Exception as ex:
            err_msg = "Failed to show '%s'.\n" % self.filename
            logging.error(err_msg+str(ex))
            return

        # Loading successful - enable menu items
        self.enableMenus()

    def convertImage(self, rgb, xmin, xmax, ymin, ymax, zscale):
        """
        Convert image to data2D
        """
        x_len = len(rgb[0])
        y_len = len(rgb)
        x_vals = np.linspace(xmin, xmax, num=x_len)
        y_vals = np.linspace(ymin, ymax, num=y_len)
        # Instantiate data object
        output = Data2D()
        output.filename = self.filename
        output.id = output.filename
        detector = Detector()
        detector.pixel_size.x = None
        detector.pixel_size.y = None
        # Store the sample to detector distance
        detector.distance = None
        output.detector.append(detector)
        # Initiazed the output data object
        output.data = zscale * self.rgb2gray(rgb)
        output.err_data = np.zeros([x_len, y_len])
        output.mask = np.ones([x_len, y_len], dtype=bool)
        output.xbins = x_len
        output.ybins = y_len
        output.x_bins = x_vals
        output.y_bins = y_vals
        output.qx_data = np.array(x_vals)
        output.qy_data = np.array(y_vals)
        output.xmin = xmin
        output.xmax = xmax
        output.ymin = ymin
        output.ymax = ymax
        output.xaxis('\\rm{Q_{x}}', r'\AA^{-1}')
        output.yaxis('\\rm{Q_{y}}', r'\AA^{-1}')
        # Store loading process information
        output.meta_data['loader'] = self.filename.split('.')[-1] + "Reader"
        output.is_data = True
        try:
            output = reader2D_converter(output)
        except Exception as ex:
            err_msg = "Image conversion failed: '%s'.\n" % str(ex)
            logging.error(err_msg)

        # Create item and add to the data explorer
        try:
            item = GuiUtils.createModelItemWithPlot(output, output.filename)
            self.parent.communicate.updateModelFromPerspectiveSignal.emit(item)
        except Exception as ex:
            err_msg = "Failed to create new index '%s'.\n" % str(ex)
            logging.error(err_msg)

    def rgb2gray(self, rgb):
        """
        RGB to Grey
        """
        if self.is_png:
            # png image limits: 0 to 1, others 0 to 255
            #factor = 255.0
            rgb = rgb[::-1]
        if rgb.ndim == 2:
            grey = np.rollaxis(rgb, axis=0)
        else:
            red, green, blue = np.rollaxis(rgb[..., :3], axis=-1)
            grey = 0.299 * red + 0.587 * green + 0.114 * blue
        max_i = rgb.max()
        factor = 255.0/max_i
        grey *= factor
        return np.array(grey)

class ImageViewerOptions(QtWidgets.QDialog, Ui_ImageViewerOptionsUI):
    """
    Logics for the image viewer options UI
    """
    def __init__(self, parent=None):
        super(ImageViewerOptions, self).__init__(parent)

        self.parent = parent
        self.setupUi(self)

        # fill in defaults
        self.addDefaults()

        # add validators
        self.addValidators()

    def addDefaults(self):
        """
        Fill out textedits with default values
        """
        zscale_default = 1.0
        xmin_default = -0.3
        xmax_default = 0.3
        ymin_default = -0.3
        ymax_default = 0.3

        self.txtZmax.setText(str(zscale_default))
        self.txtXmin.setText(str(xmin_default))
        self.txtXmax.setText(str(xmax_default))
        self.txtYmin.setText(str(ymin_default))
        self.txtYmax.setText(str(ymax_default))

    def addValidators(self):
        """
        Define simple validators on line edits
        """
        self.txtXmin.setValidator(GuiUtils.DoubleValidator())
        self.txtXmax.setValidator(GuiUtils.DoubleValidator())
        self.txtYmin.setValidator(GuiUtils.DoubleValidator())
        self.txtYmax.setValidator(GuiUtils.DoubleValidator())
        zvalidator = GuiUtils.DoubleValidator()
        zvalidator.setBottom(0.0)
        zvalidator.setTop(255.0)
        self.txtZmax.setValidator(zvalidator)

    def getState(self):
        """
        return current state of the widget
        """
        zscale = float(self.txtZmax.text())
        xmin = float(self.txtXmin.text())
        xmax = float(self.txtXmax.text())
        ymin = float(self.txtYmin.text())
        ymax = float(self.txtYmax.text())

        return (xmin, xmax, ymin, ymax, zscale)
