"""Command-line entry point: `dash-jsp <command>`."""

from __future__ import annotations

import argparse
import json
import sys
from pathlib import Path

import dash_jsp


def _cmd_solve(args: argparse.Namespace) -> int:
    """Solve a single instance file with the chosen method."""
    from dash_jsp.benchmarks.taillard import parse_taillard_text
    from dash_jsp.benchmarks.lawrence import parse_lawrence_text
    from dash_jsp.heuristics.rules import ALL_RULES, get_rule
    from dash_jsp.simulator.jsp_sim import simulate, simulate_with_dispatcher

    text = Path(args.instance).read_text()
    name = Path(args.instance).stem

    if args.format == "taillard":
        inst = parse_taillard_text(text, name)
    elif args.format == "lawrence":
        inst = parse_lawrence_text(text, name)
    else:
        raise ValueError(f"Unknown --format: {args.format}")

    method = args.method.lower()
    if method in ALL_RULES:
        result = simulate(inst, get_rule(method))
    elif method == "linucb":
        from dash_jsp.bandit.linucb import LinUCBDispatcher
        models_dir = Path(args.models_dir) if args.models_dir else None
        if models_dir and (models_dir / "bandit_linucb.npz").exists():
            dispatcher = LinUCBDispatcher.load(str(models_dir / "bandit_linucb.npz"))
        else:
            dispatcher = LinUCBDispatcher()
        result = simulate_with_dispatcher(inst, dispatcher, record_choices=True)
    elif method == "thompson":
        from dash_jsp.bandit.thompson import ThompsonDispatcher
        models_dir = Path(args.models_dir) if args.models_dir else None
        if models_dir and (models_dir / "bandit_thompson.npz").exists():
            dispatcher = ThompsonDispatcher.load(str(models_dir / "bandit_thompson.npz"))
        else:
            dispatcher = ThompsonDispatcher()
        result = simulate_with_dispatcher(inst, dispatcher, record_choices=True)
    else:
        print(f"Unknown method: {method}", file=sys.stderr)
        return 2

    out = {
        "instance": inst.name,
        "method": method,
        "makespan": result.makespan,
        "total_tardiness": result.total_tardiness,
        "avg_cycle_time": result.avg_cycle_time,
        "machine_utilization": result.machine_utilization,
        "n_dispatch_decisions": result.n_dispatch_decisions,
        "runtime_ms": result.runtime_ms,
        "optimum": inst.optimum,
        "optimality_gap_pct": (
            100.0 * (result.makespan - inst.optimum) / inst.optimum
            if inst.optimum else None
        ),
    }
    print(json.dumps(out, indent=2))
    return 0


def _cmd_serve(args: argparse.Namespace) -> int:  # pragma: no cover
    """Launch the FastAPI server."""
    import uvicorn
    uvicorn.run(
        "dash_jsp.api.server:app",
        host=args.host,
        port=args.port,
        reload=False,
    )
    return 0


def _cmd_version(_args: argparse.Namespace) -> int:
    print(f"dash-jsp {dash_jsp.__version__}")
    return 0


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        prog="dash-jsp",
        description="DASH-JSP: bandit-based dynamic heuristic switching for JSP",
    )
    sub = parser.add_subparsers(dest="cmd", required=True)

    # solve
    p_solve = sub.add_parser("solve", help="Solve a JSP instance file")
    p_solve.add_argument("instance", type=str, help="Path to instance .txt file")
    p_solve.add_argument(
        "--format",
        default="taillard",
        choices=["taillard", "lawrence"],
        help="Instance format",
    )
    p_solve.add_argument(
        "--method",
        default="linucb",
        help="fifo|edd|cr|atc|wspt|slack|linucb|thompson",
    )
    p_solve.add_argument(
        "--models-dir",
        default=None,
        help="Directory containing bandit model artifacts",
    )
    p_solve.set_defaults(fn=_cmd_solve)

    # serve
    p_serve = sub.add_parser("serve", help="Launch the REST API server")
    p_serve.add_argument("--host", default="0.0.0.0")
    p_serve.add_argument("--port", default=8000, type=int)
    p_serve.set_defaults(fn=_cmd_serve)

    # version
    p_version = sub.add_parser("version", help="Print version")
    p_version.set_defaults(fn=_cmd_version)

    return parser


def main(argv=None) -> int:
    parser = build_parser()
    args = parser.parse_args(argv)
    return args.fn(args)


if __name__ == "__main__":  # pragma: no cover
    raise SystemExit(main())