#!/usr/bin/env python3
"""Enforce build-before-query freezing for a WorkSurface-Build unit."""

from __future__ import annotations

import argparse
import hashlib
import json
import shutil
from pathlib import Path
from typing import Any


SENTINEL = ".worksurface_build_run"


def write_json(path: Path, value: Any) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(json.dumps(value, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")


def sha256_file(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def canonical_json(value: Any) -> bytes:
    return json.dumps(value, ensure_ascii=False, sort_keys=True, separators=(",", ":")).encode("utf-8")


def artifact_hashes(artifacts: Path) -> dict[str, str]:
    return {
        str(path.relative_to(artifacts)): "sha256:" + sha256_file(path)
        for path in sorted(artifacts.rglob("*")) if path.is_file()
    }


def load_state(run: Path) -> dict[str, Any]:
    if not (run / SENTINEL).exists():
        raise RuntimeError(f"not a WorkSurface-Build run: {run}")
    return json.loads((run / "state.json").read_text(encoding="utf-8"))


def start(release: Path, unit_type: str, unit_id: str, run: Path) -> None:
    if run.exists():
        raise RuntimeError(f"run directory already exists: {run}")
    index_name = "task_units.jsonl" if unit_type == "task" else "persona_units.jsonl"
    rows = [json.loads(line) for line in (release / "public" / index_name).read_text().splitlines() if line]
    row = next((item for item in rows if item["unit_id"] == unit_id), None)
    if row is None:
        raise KeyError(f"unknown unit: {unit_id}")
    unit_path = release / row["unit_spec"]
    unit = json.loads(unit_path.read_text(encoding="utf-8"))
    run.mkdir(parents=True)
    (run / SENTINEL).write_text("WorkSurface-Build run\n", encoding="utf-8")
    (run / "artifacts").mkdir()
    shutil.copy2(unit_path, run / "builder_input.json")
    write_json(run / "state.json", {
        "status": "BUILDING",
        "release": str(release.resolve()),
        "unit_type": unit_type,
        "unit_id": unit_id,
        "workspace": str((unit_path.parent / unit["workspace"]).resolve()),
        "hidden_task_commitment": unit["hidden_task_commitment"],
    })
    print(json.dumps({"run": str(run.resolve()), "workspace": str((unit_path.parent / unit["workspace"]).resolve())}, indent=2))


def freeze(run: Path, build_cost: dict[str, Any]) -> None:
    state = load_state(run)
    if state["status"] != "BUILDING":
        raise RuntimeError(f"cannot freeze run in state {state['status']}")
    hashes = artifact_hashes(run / "artifacts")
    if not hashes:
        raise RuntimeError("Builder produced no artifact files")
    manifest = {
        "unit_id": state["unit_id"],
        "artifact_hashes": hashes,
        "build_cost": build_cost,
    }
    write_json(run / "artifact_manifest.json", manifest)
    lock = "sha256:" + hashlib.sha256(canonical_json(manifest)).hexdigest()
    (run / "freeze.lock").write_text(lock + "\n", encoding="utf-8")
    state["status"] = "FROZEN"
    state["freeze_lock"] = lock
    write_json(run / "state.json", state)
    print(json.dumps({"status": "FROZEN", "artifacts": len(hashes), "freeze_lock": lock}, indent=2))


def verify(run: Path) -> dict[str, Any]:
    state = load_state(run)
    if state["status"] not in {"FROZEN", "SERVING"}:
        raise RuntimeError(f"run is not frozen: {state['status']}")
    manifest = json.loads((run / "artifact_manifest.json").read_text(encoding="utf-8"))
    current = artifact_hashes(run / "artifacts")
    ok = current == manifest["artifact_hashes"]
    result = {"ok": ok, "expected_files": len(manifest["artifact_hashes"]), "current_files": len(current)}
    if not ok:
        result["changed_paths"] = sorted(set(current) ^ set(manifest["artifact_hashes"]))
    return result


def release_questions(run: Path) -> None:
    state = load_state(run)
    result = verify(run)
    if not result["ok"]:
        raise RuntimeError("frozen artifacts changed before question release")
    release = Path(state["release"])
    if state["unit_type"] == "task":
        source = release / "private" / "serve_questions" / f"{state['unit_id']}.jsonl"
    else:
        source = release / "private" / "persona_serve_questions" / f"{state['unit_id']}.jsonl"
    shutil.copy2(source, run / "serve_questions.jsonl")
    state["status"] = "SERVING"
    write_json(run / "state.json", state)
    print(json.dumps({"status": "SERVING", "questions": len(source.read_text().splitlines())}, indent=2))


def parse_cost(value: str) -> dict[str, Any]:
    path = Path(value)
    if path.exists():
        return json.loads(path.read_text(encoding="utf-8"))
    parsed = json.loads(value)
    if not isinstance(parsed, dict):
        raise ValueError("build cost must be a JSON object")
    return parsed


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    commands = parser.add_subparsers(dest="command", required=True)
    start_p = commands.add_parser("start")
    start_p.add_argument("--release", type=Path, required=True)
    start_p.add_argument("--unit-type", choices=("task", "persona"), required=True)
    start_p.add_argument("--unit-id", required=True)
    start_p.add_argument("--run", type=Path, required=True)
    freeze_p = commands.add_parser("freeze")
    freeze_p.add_argument("--run", type=Path, required=True)
    freeze_p.add_argument("--build-cost", required=True, help="JSON object or JSON file")
    release_p = commands.add_parser("release-questions")
    release_p.add_argument("--run", type=Path, required=True)
    verify_p = commands.add_parser("verify")
    verify_p.add_argument("--run", type=Path, required=True)
    args = parser.parse_args()

    if args.command == "start":
        start(args.release, args.unit_type, args.unit_id, args.run)
    elif args.command == "freeze":
        freeze(args.run, parse_cost(args.build_cost))
    elif args.command == "release-questions":
        release_questions(args.run)
    else:
        result = verify(args.run)
        print(json.dumps(result, indent=2))
        if not result["ok"]:
            raise SystemExit(1)


if __name__ == "__main__":
    main()