# -----------------------------------------------------------------------------
# Copyright (C) 2026 Iliyas Jorio.
# This file is part of GitFourchette, distributed under the GNU GPL v3.
# For full terms, see the included LICENSE file.
# -----------------------------------------------------------------------------

"""
PyQt6/PySide6/PyQt5 compatibility layer
"""

# GitFourchette's preferred Qt binding is PyQt6, but you can use another
# binding via the QT_API environment variable. Values recognized by QT_API:
#       pyqt6
#       pyside6
#       pyqt5
# NOTE: PyQt5 support is deprecated and will be removed soon.
# PySide2 is not supported at all.
#
# If you're running unit tests, use the PYTEST_QT_API environment variable instead.
# If you're packaging the app, you may prefer to force a binding via appconsts.py.

import enum as _enum
import json as _json
import logging as _logging
import os as _os
import sys as _sys
import typing as _typing
from contextlib import suppress as _suppress

from gitfourchette.appconsts import *

_logger = _logging.getLogger(__name__)

_qtBindingOrder = ["pyqt6", "pyside6", "pyqt5"]

QT5 = False
QT6 = False
PYSIDE6 = False
PYQT5 = False
PYQT6 = False
MACOS = False
WINDOWS = False

if APP_FREEZE_QT:  # in frozen apps (PyInstaller, AppImage, Flatpak), target a fixed API
    _qtBindingOrder = [APP_FREEZE_QT]
    _qtBindingBootPref = _qtBindingOrder[0]
else:
    _qtBindingBootPref = _os.environ.get("QT_API", "").lower()

# If QT_API isn't set, see if the app's prefs file specifies a preferred Qt binding
if not _qtBindingBootPref:
    if _sys.platform == "darwin":
        _prefsPath = _os.path.expanduser("~/Library/Preferences")
    else:
        _prefsPath = _os.environ.get("XDG_CONFIG_HOME", _os.path.expanduser("~/.config"))
    _prefsPath = _os.path.join(_prefsPath, APP_SYSTEM_NAME, "prefs.json")
    with _suppress(OSError, ValueError):
        with open(_prefsPath, encoding="utf-8") as _f:
            _jsonPrefs = _json.load(_f)
        _qtBindingBootPref = _jsonPrefs.get("forceQtApi", "").lower()

if _qtBindingBootPref:
    if _qtBindingBootPref not in _qtBindingOrder:
        # Don't touch default binding order if user passed in an unsupported binding name.
        # Pass _qtBindingBootPref on to application code so it can complain.
        _logger.warning(f"Unrecognized Qt binding name: '{_qtBindingBootPref}'")
    else:
        # Move preferred binding to front of list
        _qtBindingOrder.remove(_qtBindingBootPref)
        _qtBindingOrder.insert(0, _qtBindingBootPref)

_logger.debug(f"Qt binding order is: {_qtBindingOrder}")

QT_BINDING = ""
QT_BINDING_VERSION = ""

def _bail(message: str):
    _sys.stderr.write(message + "\n")
    if QT_BINDING:
        _app = QApplication([])
        QMessageBox.critical(None, APP_DISPLAY_NAME, message)
    _sys.exit(1)

for _tentative in _qtBindingOrder:
    assert _tentative.islower()

    with _suppress(ImportError):
        if _tentative == "pyside6":
            from PySide6.QtCore import *
            from PySide6.QtWidgets import *
            from PySide6.QtGui import *
            from PySide6 import __version__ as QT_BINDING_VERSION
            QT_BINDING = "PySide6"
            QT6 = PYSIDE6 = True
        elif _tentative == "pyqt6":
            from PyQt6.QtCore import *
            from PyQt6.QtWidgets import *
            from PyQt6.QtGui import *
            QT_BINDING_VERSION = PYQT_VERSION_STR
            QT_BINDING = "PyQt6"
            QT6 = PYQT6 = True
        elif _tentative == "pyqt5":
            from PyQt5.QtCore import *
            from PyQt5.QtWidgets import *
            from PyQt5.QtGui import *
            QT_BINDING_VERSION = PYQT_VERSION_STR
            QT_BINDING = "PyQt5"
            QT5 = PYQT5 = True
        else:
            _logger.warning(f"Unsupported Qt binding {_tentative}")

    if QT_BINDING:
        break  # We've successfully imported a binding, stop looking at candidates
else:
    _bail("No Qt binding found. Please install PyQt6 or PySide6.")

# -----------------------------------------------------------------------------
# Tweak initial environment variables

# Keep Qt from faking bold face with some variable fonts (see issue #10).
# This looks nicer out of the box in Ubuntu 24.10 and Fedora 41 (KDE spin).
# This is supposedly fixed in Qt 6.7 (https://bugreports.qt.io/browse/QTBUG-112136)
# but I've seen it occur with Qt 6.8 still.
_os.environ["QT_NO_SYNTHESIZED_BOLD"] = "1"

# -----------------------------------------------------------------------------
# Set up platform constants

QT_BINDING_BOOTPREF = _qtBindingBootPref
KERNEL = QSysInfo.kernelType().lower()
MACOS = KERNEL == "darwin"
WINDOWS = KERNEL == "winnt"
FREEDESKTOP = not MACOS and not WINDOWS
FLATPAK = FREEDESKTOP and _os.path.exists("/.flatpak-info")
FLATPAK_ID = _os.environ.get("FLATPAK_ID", "")
PYINSTALLER_MEIPASS = getattr(_sys, "frozen", False) and getattr(_sys, "_MEIPASS", "") or ""
XDG_RUNTIME_DIR = _os.environ.get("XDG_RUNTIME_DIR", "")
GNOME = "GNOME" in _os.environ.get("XDG_CURRENT_DESKTOP", "").upper().split(":")  # e.g. "ubuntu:GNOME"
KDE = "KDE" in _os.environ.get("XDG_CURRENT_DESKTOP", "").upper().split(":")
WAYLAND = _os.environ.get("XDG_SESSION_TYPE", "").upper() == "WAYLAND"
OFFSCREEN = _os.environ.get("QT_QPA_PLATFORM", "").upper() == "OFFSCREEN"

# Capture environment variables that were set on boot.
# These values will not be forwarded explicitly to subprocess environments.
INITIAL_ENVIRONMENT = _os.environ.copy()

# -----------------------------------------------------------------------------
# Try to import optional modules

# Test mode stuff
HAS_QTEST = False
with _suppress(ImportError):
    if PYQT6:
        from PyQt6.QtTest import QAbstractItemModelTester, QTest, QSignalSpy
    elif PYQT5:
        from PyQt5.QtTest import QAbstractItemModelTester, QTest, QSignalSpy
    elif PYSIDE6:
        from PySide6.QtTest import QAbstractItemModelTester, QTest, QSignalSpy
    HAS_QTEST = True

# Try to import QtDBus on Linux
HAS_QTDBUS = False
if FREEDESKTOP:
    with _suppress(ImportError):
        if PYSIDE6:
            from PySide6.QtDBus import *
        elif PYQT6:
            from PyQt6.QtDBus import *
        elif PYQT5:
            from PyQt5.QtDBus import *
        else:
            raise ImportError("QtDBus")
        HAS_QTDBUS = True

try:
    if PYQT6:
        from PyQt6.QtSvg import QSvgRenderer
    elif PYSIDE6:
        from PySide6.QtSvg import QSvgRenderer
    elif PYQT5:
        from PyQt5.QtSvg import QSvgRenderer
    else:
        raise ImportError("QtSvg")
except ImportError:
    _bail(f"{QT_BINDING} was found, but {QT_BINDING}'s bindings for QtSvg are missing.\n\nYour Linux distribution probably provides them as a separate package. Please install it and try again.")

# -----------------------------------------------------------------------------
# Patch some holes and incompatibilities in Qt bindings

# Match PyQt signal/slot names with PySide6
if PYQT5 or PYQT6:
    Signal = pyqtSignal
    SignalInstance = pyqtBoundSignal
    Slot = pyqtSlot

if PYSIDE6:
    def _QCommandLineParser_addOptions(self, options):
        for o in options:
            self.addOption(o)

    QCommandLineParser.addOptions = _QCommandLineParser_addOptions

    # Unlike PyQt5/6, PySide6's QtWidgets module doesn't export QWIDGETSIZE_MAX
    try:
        _dummy = QWIDGETSIZE_MAX
    except NameError:
        QWIDGETSIZE_MAX = 16777215

if QT5:
    # Disable "What's this?" in Qt 5 dialog box title bars (Qt 6 sets this off by default.)
    QCoreApplication.setAttribute(Qt.ApplicationAttribute.AA_DisableWindowContextHelpButton)

    # QMouseEvent.pos() is deprecated in Qt 6, so we don't use it.
    # Fill in QMouseEvent.position() for Qt 5.
    def _QMouseEvent_position(self):
        return QPointF(self.pos())

    QMouseEvent.position = _QMouseEvent_position

    # Some of these QFontDatabase functions became static in Qt 6, but they weren't in Qt 5.
    _QFontDatabase_families = QFontDatabase.families
    _QFontDatabase_isFixedPitch = QFontDatabase.isFixedPitch
    _QFontDatabase_isPrivateFamily = QFontDatabase.isPrivateFamily
    QFontDatabase.families = lambda *a, **k: _QFontDatabase_families(QFontDatabase(), *a, **k)
    QFontDatabase.isFixedPitch = lambda *a, **k: _QFontDatabase_isFixedPitch(QFontDatabase(), *a, **k)
    QFontDatabase.isPrivateFamily = lambda *a, **k: _QFontDatabase_isPrivateFamily(QFontDatabase(), *a, **k)

# Return Consolas as default fixed font instead of Courier New on Windows.
if WINDOWS:
    def _QFontDatabase_systemFont_override(type: QFontDatabase.SystemFont):
        font = _QFontDatabase_systemFont(type)
        if type == QFontDatabase.SystemFont.FixedFont:
            font.setFamily("Consolas")
        return font

    _QFontDatabase_systemFont = QFontDatabase.systemFont
    QFontDatabase.systemFont = _QFontDatabase_systemFont_override

# Qt 6.7 replaces QCheckBox.stateChanged with checkStateChanged.
if not hasattr(QCheckBox, 'checkStateChanged'):
    # Note: this forwards an int, not a real CheckState, but the values are the same.
    QCheckBox.checkStateChanged = QCheckBox.stateChanged

# Pythonic iterator for QTextFragments in a QTextBlock. Use this instead of QTextBlock.__iter__,
# which in PySide6 is an inconvenient QTextBlock::iterator, and in PyQt6 isn't implemented at all.
def _QTextBlock_fragments(block: QTextBlock) -> _typing.Generator[QTextFragment, None, None]:
    iterator = block.begin()  # QTextBlock::iterator
    while not iterator.atEnd():
        fragment = iterator.fragment()
        if fragment.isValid():
            yield iterator.fragment()
        iterator += 1
QTextBlock.fragments = _QTextBlock_fragments

# Custom "selected, no focus" icon mode.
QIcon.Mode.SelectedInactive = QIcon.Mode(4)


# -----------------------------------------------------------------------------
# Verbose QObject destructors

if APP_VERBOSEDEL:
    def _QObject_dtor(obj: QObject):
        cls = obj.__class__
        if cls.__module__.startswith(QT_BINDING + "."):  # Skip standard Qt objects
            return

        message = f"QObject.__del__ {cls.__name__}"
        app = QApplication.instance()
        if app and app.thread() is not QThread.currentThread():
            message += " !!!DANGER!!! QObject destroyed outside of UI thread!"

        _logger.info(message)

    assert not hasattr(QObject, "__del__")
    QObject.__del__ = _QObject_dtor
    _logger.info("Verbose QObject destructors enabled")


# -----------------------------------------------------------------------------
# Utility functions

def qAppName():
    """ User-facing application name. Shorthand for QApplication.applicationDisplayName(). """
    return QApplication.applicationDisplayName()


def qTempDir():
    """ Path to temporary directory for this session. """
    return QApplication.instance().tempDir.path()
