"""
Thread that runs to create QImages for MainWindow's preview label.
Processes a queue of component lists.
"""

from PyQt6 import QtCore, QtGui, uic
from PyQt6.QtCore import pyqtSignal, pyqtSlot
from PIL import Image
from PIL.ImageQt import ImageQt
from queue import Queue, Empty
import os
import logging

from ..toolkit.frame import Checkerboard
from ..toolkit import disableWhenOpeningProject


log = logging.getLogger("AVP.Gui.PreviewThread")


class Worker(QtCore.QObject):

    imageCreated = pyqtSignal(QtGui.QImage)
    error = pyqtSignal(str)

    def __init__(self, core, settings, queue):
        super().__init__()
        self.core = core
        self.settings = settings
        width = int(self.settings.value("outputWidth"))
        height = int(self.settings.value("outputHeight"))
        self.queue = queue
        self.background = Checkerboard(width, height)

    @disableWhenOpeningProject
    @pyqtSlot(list)
    def createPreviewImage(self, components):
        dic = {
            "components": components,
        }
        self.queue.put(dic)
        log.debug("Preview thread id: {}".format(int(QtCore.QThread.currentThreadId())))

    @pyqtSlot()
    def process(self):
        try:
            nextPreviewInformation = self.queue.get(block=False)
            while self.queue.qsize() >= 2:
                try:
                    self.queue.get(block=False)
                except Empty:
                    continue
            width = int(self.settings.value("outputWidth"))
            height = int(self.settings.value("outputHeight"))
            if self.background.width != width or self.background.height != height:
                self.background = Checkerboard(width, height)

            frame = self.background.copy()
            log.info("Creating new preview frame")
            components = nextPreviewInformation["components"]
            for component in reversed(components):
                try:
                    component.lockSize(width, height)
                    newFrame = component.previewRender()
                    component.unlockSize()
                    frame = Image.alpha_composite(frame, newFrame)

                except ValueError as e:
                    errMsg = (
                        "Bad frame returned by %s's preview renderer. "
                        "%s. New frame size was %s*%s; should be %s*%s."
                        % (
                            str(component),
                            str(e).capitalize(),
                            newFrame.width,
                            newFrame.height,
                            width,
                            height,
                        )
                    )
                    log.critical(errMsg)
                    self.error.emit(errMsg)
                    break
                except RuntimeError as e:
                    log.error(str(e))
            else:
                # We must store a reference to this QImage
                # or else Qt will garbage-collect it on the C++ side
                self.frame = ImageQt(frame)
                self.imageCreated.emit(QtGui.QImage(self.frame))

        except Empty:
            True