#!/usr/bin/env python3
"""
CADDesigner React Web UI startup script.
"""

import argparse
import os
from pathlib import Path
import shutil
import subprocess
import sys


project_root = Path(__file__).parent
frontend_root = project_root / "frontend"


def resolve_browser_host(host: str) -> str:
    """Convert a bind address to a display address better suited for browser access."""
    if host in {"0.0.0.0", "::"}:
        return "localhost"
    return host


def resolve_api_url(api_url: str | None) -> str:
    """Resolve the API address that the React UI should connect to."""
    if api_url:
        return api_url.rstrip("/")

    env_api_url = os.getenv("CADDESIGNER_API_URL")
    if env_api_url:
        return env_api_url.rstrip("/")

    return "http://127.0.0.1:8000"


def resolve_package_manager() -> tuple[str, str]:
    """Prefer pnpm, then fall back to npm."""
    pnpm_cmd = shutil.which("pnpm")
    if pnpm_cmd:
        return pnpm_cmd, "pnpm"

    npm_cmd = shutil.which("npm")
    if npm_cmd:
        return npm_cmd, "npm"

    raise RuntimeError("Neither pnpm nor npm was found. Please install a Node.js package manager first.")


def ensure_frontend_ready(debug: bool = False) -> tuple[str, str]:
    """Ensure React frontend dependencies are ready and return package manager information."""
    if not frontend_root.is_dir():
        raise RuntimeError(f"React frontend directory does not exist: {frontend_root}")

    package_manager_cmd, package_manager_name = resolve_package_manager()

    if not (frontend_root / "node_modules").exists():
        print(
            f"React frontend dependencies are not installed yet; running {package_manager_name} install ..."
        )
        install_result = subprocess.run(
            [package_manager_cmd, "install"],
            cwd=frontend_root,
        )
        if install_result.returncode != 0:
            raise RuntimeError(
                f"{package_manager_name} install failed; unable to start React UI"
            )
        if debug:
            print("React frontend dependencies installed successfully")

    return package_manager_cmd, package_manager_name


def launch_react_app(args) -> None:
    """Start the standalone React Web UI (Vite)."""
    package_manager_cmd, package_manager_name = ensure_frontend_ready(debug=args.debug)
    api_url = resolve_api_url(args.api_url)
    display_host = resolve_browser_host(args.host)

    env = os.environ.copy()
    env["VITE_API_BASE_URL"] = api_url
    env["CADDESIGNER_API_PROXY_TARGET"] = api_url

    print("Starting CADDesigner React Web UI...")
    print("=" * 60)
    print(f"React UI address: http://{display_host}:{args.port}")
    print(f"API proxy target: {api_url}")
    print(f"Frontend package manager: {package_manager_name}")
    print(f"Frontend directory: {frontend_root}")
    if args.debug:
        print("Debug mode: enabled")
    print("Press Ctrl+C to stop the service")
    print("=" * 60)

    extra_args_separator = ["--"] if package_manager_name == "npm" else []
    cmd = [
        package_manager_cmd,
        "run",
        "dev",
        *extra_args_separator,
        "--host",
        args.host,
        "--port",
        str(args.port),
        "--strictPort",
    ]

    os.chdir(frontend_root)
    os.execvpe(package_manager_cmd, cmd, env)


def main():
    """Main function."""
    parser = argparse.ArgumentParser(
        description="CADDesigner React Web UI launcher",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog="""
Usage examples:
  # Start React UI with the default configuration
  %(prog)s

  # Customize the listening address
  %(prog)s --host 0.0.0.0 --port 7861

  # Connect to a remote API server; React forwards requests through the proxy
  %(prog)s --api-url http://192.168.1.100:8000

Environment variable:
  CADDESIGNER_API_URL    API server address (default: http://localhost:8000)
        """,
    )

    parser.add_argument(
        "--host",
        default="0.0.0.0",
        help="Web UI server host address (default: 0.0.0.0)",
    )

    parser.add_argument(
        "--port",
        type=int,
        default=7860,
        help="Web UI server port (default: 7860)",
    )

    parser.add_argument(
        "--api-url",
        default=None,
        help="CADDesigner API server address (default: http://localhost:8000)",
    )

    parser.add_argument(
        "--debug",
        action="store_true",
        help="Enable debug mode",
    )

    args = parser.parse_args()

    try:
        launch_react_app(args)
    except KeyboardInterrupt:
        print("\nUser canceled; exiting...")
    except Exception as exc:
        print(f"Startup failed: {exc}")
        if args.debug:
            import traceback

            traceback.print_exc()
        sys.exit(1)


if __name__ == "__main__":
    main()