"""Versioned, single-threaded CPU study runner with fail-fast validation."""
from __future__ import annotations
import argparse
import datetime as dt
import hashlib
import importlib.metadata
import json
import os
from pathlib import Path
import platform
import resource
import shutil
import subprocess
import sys
import time


def digest(path):
    return hashlib.sha256(path.read_bytes()).hexdigest()


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--config", type=Path, required=True)
    parser.add_argument("--run-id", required=True)
    args = parser.parse_args()
    root = Path(__file__).resolve().parents[1]
    if not args.run_id.startswith("run-") or "/" in args.run_id or ".." in args.run_id:
        raise ValueError("Unsafe run id")
    run_dir = root / "results" / args.run_id
    run_dir.mkdir(parents=True, exist_ok=False)
    for name in ("logs", "source", "figures"):
        (run_dir/name).mkdir()
    shutil.copy2(args.config, run_dir/"config.json")
    source_files = sorted((root/"src").glob("*.py"))
    for file in source_files:
        shutil.copy2(file,run_dir/"source"/file.name)
    if (root/"PROTOCOL.md").exists():
        shutil.copy2(root/"PROTOCOL.md",run_dir/"PROTOCOL.md")
    if (root/"docs").exists():
        shutil.copytree(root/"docs",run_dir/"docs")
    versions = {name:importlib.metadata.version(name) for name in ("numpy","scipy","matplotlib")}
    status = {"run_id":args.run_id,"status":"RUNNING","started_utc":dt.datetime.now(dt.timezone.utc).isoformat(),
              "python":sys.version,"platform":platform.platform(),"packages":versions,
              "config_sha256":digest(run_dir/"config.json"),
              "source_sha256":{file.name:digest(file) for file in source_files},"stages":[]}
    def save():
        tmp = run_dir/"status.pending.json"
        tmp.write_text(json.dumps(status,indent=2,allow_nan=False)+"\n")
        tmp.replace(run_dir/"status.json")
    save()
    env = os.environ.copy()
    env.update(OMP_NUM_THREADS="1",OPENBLAS_NUM_THREADS="1",MKL_NUM_THREADS="1",NUMEXPR_NUM_THREADS="1",MPLBACKEND="Agg",PYTHONUNBUFFERED="1")
    def limits():
        resource.setrlimit(resource.RLIMIT_AS,(8*1024**3,8*1024**3))
    stages = [("regression","verify_main_examples.py",None),
              ("e1","e1_model_execution.py","e1.json"),
              ("e2","e2_pilot.py","e2.json"),
              ("e3","e3_policy_lp.py","e3.json"),
              ("plots","plot_results.py",None)]
    overall = time.monotonic()
    try:
        for name,script,output in stages:
            row = {"stage":name,"status":"RUNNING"}
            status["stages"].append(row)
            save()
            command = [sys.executable,str(run_dir/"source"/script)]
            if output:
                command += ["--config",str(run_dir/"config.json"),"--output",str(run_dir/output)]
            if name == "plots":
                command += ["--run-dir",str(run_dir)]
            t = time.monotonic()
            print(f"START {name}",flush=True)
            with (run_dir/"logs"/(name+".log")).open("w") as log:
                result = subprocess.run(command,stdout=log,stderr=subprocess.STDOUT,env=env,
                                        timeout=max(1,2700-(time.monotonic()-overall)),preexec_fn=limits)
            row.update(returncode=result.returncode,runtime_seconds=time.monotonic()-t,
                       status="COMPLETE" if result.returncode==0 else "FAILED")
            save()
            print(f"END {name}: {row['status']} ({row['runtime_seconds']:.1f}s)",flush=True)
            if result.returncode:
                raise RuntimeError(f"Stage {name} failed; retained logs in {run_dir}")
        status["status"]="COMPLETE"
    except Exception as exc:
        status["status"]="FAILED"
        status["error"]=repr(exc)
        if status["stages"] and status["stages"][-1]["status"]=="RUNNING":
            status["stages"][-1]["status"]="FAILED"
        raise
    finally:
        status["finished_utc"]=dt.datetime.now(dt.timezone.utc).isoformat()
        status["runtime_seconds"]=time.monotonic()-overall
        save()


if __name__ == "__main__":
    main()