#!/usr/bin/env python3
""" Main entry point for the application. """

import sys
import threading
import traceback
import logging
import urllib.request

from PyQt5.QtWidgets import QApplication
from PyQt5.QtCore import Qt

from vasl_templates.main_window import MainWindow
from vasl_templates.webapp import app as webapp

# ---------------------------------------------------------------------

class LoggerProxy:
    """Redirect messages to Python logging."""
    def __init__( self, logger, level ):
        self.logger = logger
        self.level = level
        self.closed = False
    def write( self, msg ):
        """Output a message."""
        if isinstance(msg, bytes):
            msg = msg.decode( "utf-8" )
        msg = msg.rstrip()
        if msg:
            self.logger.log( self.level, msg )
    def flush( self ):
        """Flush the output stream."""
        pass

# ---------------------------------------------------------------------

def main():
    """Main entry point for the application."""

    # connect stdout/stderr to Python logging
    # NOTE: Logging to the console causes crashes on Windows if we are frozen, so don't do that!
    sys.stdout = LoggerProxy( logging, logging.INFO )
    sys.stderr = LoggerProxy( logging, logging.WARNING )

    # start the webapp server
    port = webapp.config["FLASK_PORT_NO"]
    def webapp_thread():
        """Run the webapp server."""
        try:
            webapp.run( host="localhost", port=port, use_reloader=False )
        except Exception as ex:
            logging.critical( "WEBAPP SERVER EXCEPTION: %s", ex )
            logging.critical( traceback.format_exc() )
            raise
    thread = threading.Thread( target=webapp_thread )
    thread.start()

    # check if we should disable OpenGL
    # Using the QWebEngineView crashes on Windows 7 in a VM. It uses OpenGL, which is
    # apparently not well supported on Windows, and is dependent on the graphics card driver:
    #   https://stackoverflow.com/a/50393872
    #   https://stackoverflow.com/questions/33090346/is-there-any-way-to-use-qtwebengine-without-opengl
    # Switching to software rendering (AA_UseSoftwareOpenGL) got things going :shrug:
    # Also see: https://doc.qt.io/qt-5/windows-requirements.html
    opengl_type = webapp.config.get( "OPENGL_TYPE" )
    if opengl_type:
        logging.info( "Setting OpenGL: %s", opengl_type )
        opengl_type = getattr( Qt, opengl_type )
        QApplication.setAttribute( opengl_type )

    # run the application
    app = QApplication( sys.argv )
    url = "http://localhost:{}/main".format( port )
    main_window = MainWindow( url )
    main_window.show()
    ret_code = app.exec_()

    # shutdown the webapp server
    url = "http://localhost:{}/shutdown".format( port )
    urllib.request.urlopen( url ).read()
    thread.join()

    return ret_code

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

if __name__ == "__main__":
    sys.exit( main() )