#!/usr/bin/env python3
"""
start.py — Start the AI Video Upscaler web application.

Usage:
    python start.py                  # Start on default port 8000 (binds to 0.0.0.0 for LAN access)
    python start.py --port 9000      # Start on a custom port
    python start.py --host 127.0.0.1  # Bind to loopback only (no LAN access)
"""

import argparse
import os
import signal
import socket
import subprocess
import sys
import time
import webbrowser

# ── Paths ────────────────────────────────────────────────────────────────────
BASE_DIR   = os.path.dirname(os.path.abspath(__file__))
PID_FILE   = os.path.join(BASE_DIR, ".uvicorn.pid")
LOG_FILE   = os.path.join(BASE_DIR, "server.log")
# Detect the right Python interpreter:
# 1. If running inside an activated venv, use that interpreter
# 2. Otherwise look for venv/ then .venv/ in the project
if sys.prefix != sys.base_prefix:
    # Already inside an activated venv — use it
    VENV_PYTHON = sys.executable
else:
    VENV_PYTHON = os.path.join(BASE_DIR, "venv", "bin", "python")
    if not os.path.isfile(VENV_PYTHON):
        VENV_PYTHON = os.path.join(BASE_DIR, ".venv", "bin", "python")
    if not os.path.isfile(VENV_PYTHON):
        VENV_PYTHON = sys.executable  # last resort: system python


def _is_running(pid: int) -> bool:
    """Check whether a process with the given PID is still alive and is our server."""
    try:
        os.kill(pid, 0)
    except OSError:
        return False

    # Check /proc/{pid}/cmdline to verify it's our server process
    try:
        cmdline_path = f"/proc/{pid}/cmdline"
        if os.path.exists(cmdline_path):
            with open(cmdline_path, "r") as f:
                cmdline = f.read()
                # Check for indicators of our server
                return "uvicorn" in cmdline or "app.main" in cmdline
    except Exception:
        pass
    # If we can't read cmdline, default to True (safer fallback)
    return True


def _read_pid() -> int | None:
    """Read and validate the PID from the pidfile."""
    if not os.path.isfile(PID_FILE):
        return None
    try:
        pid = int(open(PID_FILE).read().strip())
        return pid if _is_running(pid) else None
    except (ValueError, OSError):
        return None


def _get_local_ip() -> str:
    """Get the primary local network IP address."""
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        # Dummy connection to google DNS to get local route IP
        s.connect(("8.8.8.8", 80))
        ip = s.getsockname()[0]
    except Exception:
        try:
            ip = socket.gethostbyname(socket.gethostname())
        except Exception:
            ip = "127.0.0.1"
    finally:
        s.close()
    return ip


def start(host: str, port: int, open_browser: bool = True) -> None:
    existing = _read_pid()
    if existing:
        print(f"⚠  Server is already running (PID {existing}).")
        if host == "0.0.0.0":
            local_ip = _get_local_ip()
            print(f"   → Local:   http://localhost:{port}")
            if local_ip and local_ip != "127.0.0.1":
                print(f"   → Network: http://{local_ip}:{port}")
        else:
            print(f"   → http://{host}:{port}")
        return

    print(f"🚀 Starting AI Video Upscaler …")
    print(f"   Host : {host}")
    print(f"   Port : {port}")
    print(f"   Log  : {LOG_FILE}")

    log_fh = open(LOG_FILE, "a")

    proc = subprocess.Popen(
        [
            VENV_PYTHON, "-m", "uvicorn",
            "app.main:app",
            "--host", host,
            "--port", str(port),
        ],
        cwd=BASE_DIR,
        stdout=log_fh,
        stderr=log_fh,
        start_new_session=True,   # detach from terminal
    )

    # Write PID
    with open(PID_FILE, "w") as f:
        f.write(str(proc.pid))

    # Wait briefly to make sure it didn't crash immediately
    time.sleep(1.5)
    if proc.poll() is not None:
        print("❌ Server failed to start. Check server.log for details.")
        os.remove(PID_FILE)
        sys.exit(1)

    url = f"http://{'localhost' if host == '0.0.0.0' else host}:{port}"
    print(f"✅ Server started (PID {proc.pid})")
    if host == "0.0.0.0":
        local_ip = _get_local_ip()
        print(f"   → Local:   http://localhost:{port}")
        if local_ip and local_ip != "127.0.0.1":
            print(f"   → Network: http://{local_ip}:{port}")
    else:
        print(f"   → {url}")

    if open_browser:
        webbrowser.open(url)


# ── CLI ──────────────────────────────────────────────────────────────────────
if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Start the AI Video Upscaler")
    parser.add_argument("--host", default="0.0.0.0",
                        help="Bind address (default: 0.0.0.0 to bind all interfaces, use 127.0.0.1 for local loopback only)")
    parser.add_argument("--port", type=int, default=8000,
                        help="Port to listen on (default: 8000)")
    parser.add_argument("--no-browser", action="store_true",
                        help="Don't open the browser automatically")
    args = parser.parse_args()

    start(args.host, args.port, open_browser=not args.no_browser)