import subprocess
import threading
from collections import deque
from collections.abc import Callable

from PySide6.QtCore import QObject, Signal
from PySide6.QtGui import QCloseEvent
from PySide6.QtWidgets import (
    QHBoxLayout,
    QLabel,
    QMainWindow,
    QPlainTextEdit,
    QPushButton,
    QVBoxLayout,
    QWidget,
)

from core_lib.qt import messagebox


class _ProcessSignals(QObject):
    output = Signal(str)
    # Windows may return an unsigned 32-bit exit code (for example
    # 0xFFFFFFFF), which does not fit in Qt's signed Signal(int).
    finished = Signal(object)
    read_failed = Signal(str)


class ProcessLogWindow(QMainWindow):
    """
    A Simple client log view
    """

    def __init__(self, app, process: subprocess.Popen, profile_id: str, title: str = "Game Log",
                 parent: QWidget | None = None, finished_callback: Callable[[str, int], None]=None) -> None:
        super().__init__(parent)
        self.app = app
        self.process = process
        self.profile_id = profile_id
        self._signals = _ProcessSignals(self)
        self._last_error_message: str | None = None
        self._stderr_lines: deque[str] = deque(maxlen=500)

        self.setWindowTitle(self.app.tr_text(title))
        self.resize(700, 720)

        container = QWidget(self)
        layout = QVBoxLayout(container)
        controls = QHBoxLayout()

        self.status_label = QLabel(self.app.tr_text("Running (PID {pid})", pid=process.pid))
        self.kill_button = QPushButton(self.app.tr_text("Kill Process"))
        self.kill_button.clicked.connect(self.kill_process)

        self.log_output = QPlainTextEdit()
        self.log_output.setReadOnly(True)
        self.log_output.setLineWrapMode(QPlainTextEdit.LineWrapMode.NoWrap)
        self.log_output.setMaximumBlockCount(10000)

        controls.addWidget(self.status_label)
        controls.addStretch()
        controls.addWidget(self.kill_button)
        layout.addLayout(controls)
        layout.addWidget(self.log_output)
        self.setCentralWidget(container)

        self._signals.output.connect(self.log_output.appendPlainText)
        self._signals.finished.connect(self._process_finished)
        self._signals.read_failed.connect(self._read_failed)

        self.finished_callback = finished_callback

        self._stdout_reader = threading.Thread(
            target=self._read_stdout,
            name=f"process-stdout-{process.pid}",
            daemon=True,
        )
        self._stderr_reader = threading.Thread(
            target=self._read_stderr,
            name=f"process-stderr-{process.pid}",
            daemon=True,
        )
        self._waiter = threading.Thread(
            target=self._wait_for_process,
            name=f"process-wait-{process.pid}",
            daemon=True,
        )
        self._stdout_reader.start()
        self._stderr_reader.start()
        self._waiter.start()

    def append_message(self, message: str) -> None:
        self.log_output.appendPlainText(message)

    @property
    def last_error_message(self) -> str | None:
        return self._last_error_message

    def _read_stdout(self) -> None:
        try:
            if self.process.stdout is not None:
                for line in self.process.stdout:
                    self._signals.output.emit(line.rstrip("\r\n"))
        except Exception as exc:
            self._signals.read_failed.emit(str(exc))

    def _read_stderr(self) -> None:
        try:
            if self.process.stderr is not None:
                for line in self.process.stderr:
                    message = line.rstrip("\r\n").strip()
                    if message:
                        self._last_error_message = message
                        self._stderr_lines.append(message)
        except Exception as exc:
            self._signals.read_failed.emit(str(exc))

    def _wait_for_process(self) -> None:
        exit_code = self._normalize_exit_code(self.process.wait())
        self._stdout_reader.join()
        self._stderr_reader.join()
        self._signals.finished.emit(exit_code)

    @staticmethod
    def _normalize_exit_code(exit_code: int) -> int:
        # Avoid some system (WINDOWS) give exit code that overflow in 32bit integer
        if exit_code > 0x7FFFFFFF:
            return exit_code - 0x100000000
        return exit_code

    def kill_process(self) -> None:
        if self.process.poll() is not None:
            self._process_finished(
                self._normalize_exit_code(self.process.returncode or 0)
            )
            return

        self.kill_button.setEnabled(False)
        self.status_label.setText(self.app.tr_text("Killing process..."))

        try:
            self.process.kill()
        except Exception as exc:
            self.kill_button.setEnabled(True)
            self.status_label.setText(self.app.tr_text("Unable to kill process"))
            self.append_message(f"[launcher] Unable to kill process: {exc}")

    def _process_finished(self, exit_code: int) -> None:
        self.kill_button.setEnabled(False)
        self.status_label.setText(self.app.tr_text(
            "Process exited with code {exit_code}", exit_code=exit_code
        ))
        self.append_message(f"[launcher] Process exited with code {exit_code}.")

        if exit_code != 0 and self._last_error_message:
            self.append_message(
                f"[launcher] Last error: {self._last_error_message}"
            )

        if exit_code != 0:
            error_content = "\n".join(self._stderr_lines)
            if not error_content:
                error_content = (
                    "The client did not write an error message to stderr.\n"
                    f"Process exit code: {exit_code}"
                )

            messagebox.error_with_plain_text(
                self,
                title=self.app.tr_text("Minecraft Client Error"),
                message=self.app.tr_text(
                    "Minecraft exited with code {exit_code}.", exit_code=exit_code
                ),
                content=error_content,
            )

        if callable(self.finished_callback):
            self.finished_callback(self.profile_id, exit_code)

    def _read_failed(self, message: str) -> None:
        self.append_message(f"[launcher] Unable to read process output: {message}")
        if self.process.poll() is not None:
            self._process_finished(
                self._normalize_exit_code(self.process.returncode or 0)
            )

    def closeEvent(self, event: QCloseEvent) -> None:
        # Closing the log window must not stop the game. The process remains
        # available through this window instance and can be shown again.
        event.accept()