import os
import sys
import re
import logging
import traceback
from xhtml2pdf import pisa

from PyQt5 import QtWidgets, QtCore
from PyQt5 import QtPrintSupport

import sas.qtgui.Utilities.GuiUtils as GuiUtils
import sas.qtgui.Utilities.ObjectLibrary as ObjectLibrary

from sas.qtgui.Utilities.UI.ReportDialogUI import Ui_ReportDialogUI


class ReportDialog(QtWidgets.QDialog, Ui_ReportDialogUI):
    """
    Class for stateless grid-like printout of model parameters for mutiple models
    """
    def __init__(self, parent=None, report_list=None):

        super(ReportDialog, self).__init__(parent._parent)
        self.setupUi(self)
        # disable the context help icon
        self.setWindowFlags(self.windowFlags() & ~QtCore.Qt.WindowContextHelpButtonHint)

        assert isinstance(report_list, list)
        assert len(report_list) == 3

        self.data_html, self.data_txt, self.data_images = report_list
        #self.save_location = None
        #if 'ReportDialog_directory' in ObjectLibrary.listObjects():
        self.save_location = ObjectLibrary.getObject('ReportDialog_directory')

        # Fill in the table from input data
        self.setupDialog(self.data_html)

        # Command buttons
        self.cmdPrint.clicked.connect(self.onPrint)
        self.cmdSave.clicked.connect(self.onSave)

    def setupDialog(self, output=None):
        """
        Display the HTML content in the browser.
        """
        if output is not None:
            self.txtBrowser.setHtml(output)

    def onPrint(self):
        """
        Display the print dialog and send the report to printer
        """
        # Define the printer
        printer = QtPrintSupport.QPrinter()

        # Display the print dialog
        dialog = QtPrintSupport.QPrintDialog(printer)
        dialog.setModal(True)
        dialog.setWindowTitle("Print")
        if dialog.exec_() != QtWidgets.QDialog.Accepted:
            return

        document = self.txtBrowser.document()
        try:
            # pylint chokes on this line with syntax-error
            # pylint: disable=syntax-error doesn't seem to help
            document.print(printer)
        except Exception as ex:
            # Printing can return various exceptions, let's catch them all
            logging.error("Print report failed with: " + str(ex))

    def onSave(self):
        """
        Display the Save As... prompt and save the report if instructed so
        """
        # Choose user's home directory
        if self.save_location is None:
            location = os.path.expanduser('~')
        else:
            location = self.save_location
        # Use a sensible filename default
        default_name = os.path.join(location, 'fit_report.pdf')

        kwargs = {
            'parent'   : self,
            'caption'  : 'Save Report',
            # don't use 'directory' in order to remember the previous user choice
            'directory': default_name,
            'filter'   : 'PDF file (*.pdf);;HTML file (*.html);;Text file (*.txt)',
            'options'  : QtWidgets.QFileDialog.DontUseNativeDialog}
        # Query user for filename.
        filename_tuple = QtWidgets.QFileDialog.getSaveFileName(**kwargs)
        filename = filename_tuple[0]
        if not filename:
            return
        extension = filename_tuple[1]
        self.save_location = os.path.dirname(filename)
        # lifetime of this widget is short - keep the reference elsewhere
        ObjectLibrary.addObject('ReportDialog_directory', self.save_location)

        try:
            # extract extension from filter
            # e.g. "PDF file (*.pdf)" -> ".pdf"
            ext = extension[extension.find("(")+2:extension.find(")")]
        except IndexError as ex:
            # (ext) not found...
            logging.error("Error while saving report. " + str(ex))
            return
        basename, extension = os.path.splitext(filename)
        if not extension:
            filename = '.'.join((filename, ext))

        # Create files with charts
        pictures = []
        if self.data_images is not None:
            pictures = self.getPictures(basename)

        # self.data_html contains all images at the end of the report, in base64 form;
        # replace them all with their saved on-disk filenames
        cleanr = re.compile('<img src.*$', re.DOTALL)
        replacement_name = ""
        html = self.data_html
        for picture in pictures:
            replacement_name += '<img src="'+ picture + '"><p></p>'
        replacement_name += '\n'
        # <img src="data:image/png;.*>  => <img src=filename>
        html = re.sub(cleanr, replacement_name, self.data_html)

        if ext.lower() == ".txt":
            txt_ascii = GuiUtils.replaceHTMLwithASCII(self.data_txt)
            self.onTXTSave(txt_ascii, filename)
        if ext.lower() == ".html":
            self.onHTMLSave(html, filename)
        if ext.lower() == ".pdf":
            html_utf = GuiUtils.replaceHTMLwithUTF8(html)
            pdf_success = self.HTML2PDF(html_utf, filename)
            # delete images used to create the pdf
            for pic_name in pictures:
                os.remove(pic_name)
            #open pdf viewer
            if pdf_success == 0:
                try:
                    if os.name == 'nt':  # Windows
                        os.startfile(filename)
                    elif sys.platform == "darwin":  # Mac
                        os.system("open %s" % filename)
                except Exception as ex:
                    # cannot open pdf.
                    # We don't know what happened in os.* , so broad Exception is required
                    logging.error(str(ex))

    def getPictures(self, basename):
        """
        Returns list of saved MPL figures
        """
        # save figures
        pictures = []
        for num, image in enumerate(self.data_images):
            pic_name = basename + '_img%s.png' % num
            # save the image for use with pdf writer
            image.savefig(pic_name)
            pictures.append(pic_name)
        return pictures

    @staticmethod
    def onTXTSave(data, filename):
        """
        Simple txt file serialization
        """
        with open(filename, 'w') as f:
            f.write(data)

    @staticmethod
    def onHTMLSave(html, filename):
        """
        HTML file write
        """
        with open(filename, 'w') as f:
            f.write(html)

    @staticmethod
    def HTML2PDF(data, filename):
        """
        Create a PDF file from html source string.
        Returns True is the file creation was successful.
        : data: html string
        : filename: name of file to be saved
        """
        try:
            # open output file for writing (truncated binary)
            with open(filename, "w+b") as resultFile:
                # convert HTML to PDF
                pisaStatus = pisa.CreatePDF(data.encode("UTF-8"),
                                            dest=resultFile,
                                            encoding='UTF-8')
                return pisaStatus.err
        except Exception as ex:
            # logging.error("Error creating pdf: " + str(ex))
            logging.error("Error creating pdf: " + traceback.format_exc())
        return False