"""Persistence for comparison sessions.

Outputs under config.DATA_DIR (set DATA_DIR=/data on Hugging Face Spaces with
persistent storage so they survive restarts):
  - sessions/<session_id>.json : the full session, overwritten every turn. Always
    complete (even if the user never picks a preferred response).
  - requests.jsonl            : one line per turn, EVERY request that is made
    (appended unconditionally, including turns that errored).
  - comparisons.jsonl         : one line per turn the user explicitly saves to the
    dataset, capturing the chosen `preferred`.
  - issues.jsonl              : one line per response the user flags as having an
    issue.
"""

import json
import os
from datetime import datetime

import config


def _sessions_dir() -> str:
    path = os.path.join(config.DATA_DIR, "sessions")
    os.makedirs(path, exist_ok=True)
    return path


def _data_path(filename: str) -> str:
    os.makedirs(config.DATA_DIR, exist_ok=True)
    return os.path.join(config.DATA_DIR, filename)


def new_session(system_prompt: str, intro: str, temperature: float, max_tokens: int) -> dict:
    """Create a fresh session record (in-memory)."""
    now = datetime.now()
    session_id = now.strftime("%Y%m%d-%H%M%S-%f")
    return {
        "session_id": session_id,
        "created_at": now.isoformat(),
        "system_prompt": system_prompt,
        "intro": intro,
        "temperature": temperature,
        "max_tokens": max_tokens,
        "backends": [
            {k: b.get(k) for k in ("key", "label", "type", "model", "endpoint_id", "deployment")}
            for b in config.BACKENDS
        ],
        "turns": [],
    }


def save_session(session: dict) -> str:
    """Overwrite the session JSON on disk. Returns the file path."""
    path = os.path.join(_sessions_dir(), f"{session['session_id']}.json")
    with open(path, "w", encoding="utf-8") as f:
        json.dump(session, f, ensure_ascii=False, indent=2)
    return path


def _record_for(session: dict, turn: dict) -> dict:
    """Flatten one turn with its session-level context for a JSONL line."""
    return {
        "session_id": session["session_id"],
        "system_prompt": session["system_prompt"],
        "intro": session["intro"],
        "temperature": session["temperature"],
        "max_tokens": session["max_tokens"],
        **turn,
    }


def append_request_log(session: dict, turn: dict) -> str:
    """Append EVERY turn (request + responses + metrics) to requests.jsonl."""
    path = _data_path("requests.jsonl")
    with open(path, "a", encoding="utf-8") as f:
        f.write(json.dumps(_record_for(session, turn), ensure_ascii=False) + "\n")
    return path


def append_to_dataset(session: dict, turn: dict) -> str:
    """Append one turn (with its preferred pick) to comparisons.jsonl."""
    path = _data_path("comparisons.jsonl")
    with open(path, "a", encoding="utf-8") as f:
        f.write(json.dumps(_record_for(session, turn), ensure_ascii=False) + "\n")
    return path


def append_issue(record: dict) -> str:
    """Append one flagged-issue record to issues.jsonl."""
    path = _data_path("issues.jsonl")
    with open(path, "a", encoding="utf-8") as f:
        f.write(json.dumps(record, ensure_ascii=False) + "\n")
    return path