"""Background task handling and IPC helpers for mpv integration."""
from __future__ import annotations
import errno
import json
import os
import socket
import subprocess
import sys

from helper.logger import log
import threading
import time
from typing import IO, Iterable
def connect_ipc(path: str, timeout: float = 5.0) -> IO[bytes] | None:
    """Connect to the mpv IPC server located at *path*."""
    deadline = time.time() + timeout
    if not path:
        return None
    if os.name == 'nt':
        # mpv exposes a named pipe on Windows. Keep retrying until it is ready.
        while True:
            try:
                return open(path, 'r+b', buffering=0)
            except FileNotFoundError:
                if time.time() > deadline:
                    return None
                time.sleep(0.05)
            except OSError as exc:  # Pipe busy
                if exc.errno not in (errno.ENOENT, errno.EPIPE, errno.EBUSY):
                    raise
                if time.time() > deadline:
                    return None
                time.sleep(0.05)
    else:
        sock = socket.socket(socket.AF_UNIX)
        while True:
            try:
                sock.connect(path)
                return sock.makefile('r+b', buffering=0)
            except FileNotFoundError:
                if time.time() > deadline:
                    return None
                time.sleep(0.05)
            except OSError as exc:
                if exc.errno not in (errno.ENOENT, errno.ECONNREFUSED):
                    raise
                if time.time() > deadline:
                    return None
                time.sleep(0.05)
def ipc_sender(ipc: IO[bytes] | None):
    """Create a helper function for sending script messages via IPC."""
    if ipc is None:
        def _noop(_event: str, _payload: dict) -> None:
            return None
        return _noop
    lock = threading.Lock()
    def _send(event: str, payload: dict) -> None:
        message = json.dumps({'command': ['script-message', event, json.dumps(payload)]}, ensure_ascii=False)
        encoded = message.encode('utf-8') + b'\n'
        with lock:
            try:
                ipc.write(encoded)
                ipc.flush()
            except OSError:
                pass
    return _send
def iter_stream(stream: Iterable[str]) -> Iterable[str]:
    for raw in stream:
        yield raw.rstrip('\r\n')
def _run_task(args, parser) -> int:
    if not args.command:
        parser.error('run-task requires a command to execute (use "--" before the command).')
    env = os.environ.copy()
    for entry in args.env:
        key, sep, value = entry.partition('=')
        if not sep:
            parser.error(f'Invalid environment variable definition: {entry!r}')
        env[key] = value
    command = list(args.command)
    if command and command[0] == '--':
        command.pop(0)
    notifier = ipc_sender(connect_ipc(args.ipc, timeout=args.ipc_timeout))
    if not command:
        notifier('downlow-task-event', {
            'id': args.task_id,
            'event': 'error',
            'message': 'No command provided after separator',
        })
        log('[downlow.py] No command provided for run-task', file=sys.stderr)
        return 1
    if command and isinstance(command[0], str) and sys.executable:
        first = command[0].lower()
        if first in {'python', 'python3', 'py', 'python.exe', 'python3.exe', 'py.exe'}:
            command[0] = sys.executable
    if os.environ.get('DOWNLOW_DEBUG'):
        log(f"Launching command: {command}", file=sys.stderr)
    notifier('downlow-task-event', {
        'id': args.task_id,
        'event': 'start',
        'command': command,
        'cwd': args.cwd or os.getcwd(),
    })
    try:
        process = subprocess.Popen(
            command,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            cwd=args.cwd or None,
            env=env,
            text=True,
            bufsize=1,
            universal_newlines=True,
        )
    except FileNotFoundError as exc:
        notifier('downlow-task-event', {
            'id': args.task_id,
            'event': 'error',
            'message': f'Executable not found: {exc.filename}',
        })
        log(f"{exc}", file=sys.stderr)
        return 1
    stdout_lines: list[str] = []
    stderr_lines: list[str] = []
    def pump(stream: IO[str], label: str, sink: list[str]) -> None:
        for line in iter_stream(stream):
            sink.append(line)
            notifier('downlow-task-event', {
                'id': args.task_id,
                'event': label,
                'line': line,
            })
    threads = []
    if process.stdout:
        t_out = threading.Thread(target=pump, args=(process.stdout, 'stdout', stdout_lines), daemon=True)
        t_out.start()
        threads.append(t_out)
    if process.stderr:
        t_err = threading.Thread(target=pump, args=(process.stderr, 'stderr', stderr_lines), daemon=True)
        t_err.start()
        threads.append(t_err)
    return_code = process.wait()
    for t in threads:
        t.join(timeout=0.1)
    notifier('downlow-task-event', {
        'id': args.task_id,
        'event': 'exit',
        'returncode': return_code,
        'success': return_code == 0,
    })
    # Also mirror aggregated output to stdout/stderr for compatibility when IPC is unavailable.
    if stdout_lines:
        log('\n'.join(stdout_lines))
    if stderr_lines:
        log('\n'.join(stderr_lines), file=sys.stderr)
    return return_code