from __future__ import annotations

import json
import subprocess
import time
from datetime import UTC, datetime
from pathlib import Path
from typing import Any


def init_queue(path: Path) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    if not path.exists():
        path.write_text("", encoding="utf-8")


def add_job(path: Path, name: str, command: str, cwd: str = ".", metadata: dict[str, Any] | None = None) -> dict[str, Any]:
    init_queue(path)
    job = {
        "id": f"{int(time.time() * 1000)}-{name}",
        "name": name,
        "command": command,
        "cwd": cwd,
        "status": "pending",
        "created_at": datetime.now(UTC).isoformat(),
        "metadata": metadata or {},
    }
    with path.open("a", encoding="utf-8") as handle:
        handle.write(json.dumps(job, sort_keys=True) + "\n")
    return job


def read_jobs(path: Path) -> list[dict[str, Any]]:
    if not path.exists():
        return []
    jobs = []
    with path.open("r", encoding="utf-8") as handle:
        for line in handle:
            if line.strip():
                jobs.append(json.loads(line))
    return jobs


def run_next(path: Path, log_dir: Path) -> dict[str, Any] | None:
    jobs = read_jobs(path)
    for job in jobs:
        if job.get("status") == "pending":
            return _run_job(path, log_dir, jobs, job)
    return None


def _run_job(path: Path, log_dir: Path, jobs: list[dict[str, Any]], job: dict[str, Any]) -> dict[str, Any]:
    log_dir.mkdir(parents=True, exist_ok=True)
    job["status"] = "running"
    job["started_at"] = datetime.now(UTC).isoformat()
    _rewrite(path, jobs)
    log_path = log_dir / f"{job['id']}.log"
    with log_path.open("w", encoding="utf-8") as log:
        proc = subprocess.run(job["command"], cwd=job.get("cwd", "."), shell=True, text=True, stdout=log, stderr=subprocess.STDOUT)
    job["status"] = "complete" if proc.returncode == 0 else "failed"
    job["returncode"] = proc.returncode
    job["completed_at"] = datetime.now(UTC).isoformat()
    job["log_path"] = str(log_path)
    _rewrite(path, jobs)
    return job


def _rewrite(path: Path, jobs: list[dict[str, Any]]) -> None:
    with path.open("w", encoding="utf-8") as handle:
        for job in jobs:
            handle.write(json.dumps(job, sort_keys=True) + "\n")