"""Incremental, crash-safe JSON output. Each agent's output is (over)written atomically
after every research round and again at finalize, so a hang or power loss mid-run still
leaves the best-so-far result on disk under state/output/<trade_date>/<persona>.json.
"""

from __future__ import annotations

import os
from pathlib import Path

from agents.schemas import AgentOutput, RunManifest


def _atomic_write(path: Path, text: str) -> None:
    tmp = path.with_suffix(path.suffix + ".tmp")
    tmp.write_text(text)
    os.replace(tmp, path)  # atomic on the same filesystem


class Checkpointer:
    def __init__(self, output_dir: Path, trade_date: str):
        self.dir = Path(output_dir) / trade_date
        self.dir.mkdir(parents=True, exist_ok=True)

    def agent_path(self, persona_id: str) -> Path:
        return self.dir / f"{persona_id}.json"

    def write(self, output: AgentOutput) -> None:
        _atomic_write(self.agent_path(output.persona_id), output.model_dump_json(indent=2))

    def write_manifest(self, manifest: RunManifest) -> None:
        _atomic_write(self.dir / "_manifest.json", manifest.model_dump_json(indent=2))