"""Tiny stdlib HTTP server for the demo client page.

- Serves `index.html` (and other sibling files) from this directory.
- Exposes `GET /labels.json`, which parses the repo's
  `app/resources/consumable_classifier_labels.yaml` and returns its label
  list so the page can prefill the candidate-consumables input.

Run:
    python scripts/demo_client/server.py            # 127.0.0.1:38081
    python scripts/demo_client/server.py -p 9000    # custom port
"""

from __future__ import annotations

import argparse
import json
import re
import sys
from http import HTTPStatus
from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
from pathlib import Path
from typing import Any

SCRIPT_DIR = Path(__file__).resolve().parent
REPO_ROOT = SCRIPT_DIR.parents[1]
LABELS_YAML = REPO_ROOT / "app" / "resources" / "consumable_classifier_labels.yaml"


def _load_labels_with_pyyaml(path: Path) -> list[str] | None:
    try:
        import yaml  # type: ignore[import-untyped]
    except ImportError:
        return None
    try:
        data: Any = yaml.safe_load(path.read_text(encoding="utf-8"))
    except (OSError, yaml.YAMLError):
        return None
    if not isinstance(data, dict):
        return None
    names = data.get("names")
    if isinstance(names, dict):
        try:
            items = sorted(names.items(), key=lambda kv: int(kv[0]))
        except (TypeError, ValueError):
            items = list(names.items())
        return [str(v) for _, v in items]
    if isinstance(names, list):
        return [str(v) for v in names]
    return None


def _load_labels_fallback(path: Path) -> list[str]:
    """Minimal parser for the known labels.yaml shape: `<int>: <text>` under `names:`."""
    labels: list[tuple[int, str]] = []
    in_names = False
    pattern = re.compile(r"^\s+(\d+)\s*:\s*(.+?)\s*$")
    try:
        text = path.read_text(encoding="utf-8")
    except OSError:
        return []
    for line in text.splitlines():
        stripped = line.strip()
        if not stripped or stripped.startswith("#"):
            continue
        if stripped.startswith("names:"):
            in_names = True
            continue
        if in_names and not line.startswith((" ", "\t")):
            in_names = False
        if not in_names:
            continue
        match = pattern.match(line)
        if match:
            labels.append((int(match.group(1)), match.group(2)))
    labels.sort(key=lambda kv: kv[0])
    return [name for _, name in labels]


def load_labels() -> list[str]:
    if not LABELS_YAML.is_file():
        return []
    labels = _load_labels_with_pyyaml(LABELS_YAML)
    if labels is None:
        labels = _load_labels_fallback(LABELS_YAML)
    return labels


class DemoHandler(SimpleHTTPRequestHandler):
    def __init__(self, *args: Any, **kwargs: Any) -> None:
        super().__init__(*args, directory=str(SCRIPT_DIR), **kwargs)

    def do_GET(self) -> None:  # noqa: N802 (stdlib override)
        if self.path.split("?", 1)[0] == "/labels.json":
            self._send_labels()
            return
        super().do_GET()

    def _send_labels(self) -> None:
        body = json.dumps({"labels": load_labels()}, ensure_ascii=False).encode("utf-8")
        self.send_response(HTTPStatus.OK)
        self.send_header("Content-Type", "application/json; charset=utf-8")
        self.send_header("Content-Length", str(len(body)))
        self.send_header("Cache-Control", "no-store")
        self.end_headers()
        self.wfile.write(body)

    def log_message(self, format: str, *args: Any) -> None:  # noqa: A002
        sys.stderr.write(
            "[demo-client] %s - %s\n" % (self.address_string(), format % args)
        )


def main() -> None:
    parser = argparse.ArgumentParser(description="Operation room demo client server")
    parser.add_argument("--host", default="127.0.0.1")
    parser.add_argument("-p", "--port", type=int, default=38081)
    args = parser.parse_args()

    server = ThreadingHTTPServer((args.host, args.port), DemoHandler)
    url = f"http://{args.host}:{args.port}/"
    print(f"Demo client serving at {url}")
    print(f"  static dir : {SCRIPT_DIR}")
    print(f"  labels yaml: {LABELS_YAML}")
    print("Press Ctrl+C to stop.")
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        print("\nShutting down.")
    finally:
        server.server_close()


if __name__ == "__main__":
    main()