"""中控 AI：JSON 持久化（与 hub_settings.json 同目录）。"""
from __future__ import annotations

import json
import os
import uuid
from datetime import datetime, timedelta
from pathlib import Path
from typing import Any, Optional

from hub_ai.config import CHAT_SESSION_RETENTION_DAYS, SUMMARY_RETENTION_DAYS

HUB_DIR = Path(__file__).resolve().parent.parent
SUMMARIES_PATH = HUB_DIR / "hub_ai_summaries.json"
CHAT_PATH = HUB_DIR / "hub_ai_chat.json"


def _now_str() -> str:
    return datetime.now().strftime("%Y-%m-%d %H:%M:%S")


def _atomic_write(path: Path, data: dict) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    tmp = path.with_suffix(path.suffix + ".tmp")
    tmp.write_text(json.dumps(data, ensure_ascii=False, indent=2), encoding="utf-8")
    os.replace(tmp, path)


def _load_json(path: Path, default: dict) -> dict:
    if not path.is_file():
        return dict(default)
    try:
        loaded = json.loads(path.read_text(encoding="utf-8"))
        if isinstance(loaded, dict):
            return loaded
    except Exception:
        pass
    return dict(default)


def _prune_summaries(items: list, *, keep_days: int) -> list:
    cutoff = (datetime.now() - timedelta(days=max(1, keep_days))).strftime("%Y-%m-%d")
    out = [x for x in items if str(x.get("trading_day") or "") >= cutoff]
    return out[-500:]


def _prune_chat_sessions(sessions: list, *, keep_days: int) -> list:
    cutoff_dt = datetime.now() - timedelta(days=max(1, keep_days))
    out = []
    for s in sessions:
        ts = str(s.get("updated_at") or s.get("created_at") or "")
        try:
            dt = datetime.strptime(ts[:19], "%Y-%m-%d %H:%M:%S")
        except ValueError:
            out.append(s)
            continue
        if dt >= cutoff_dt:
            out.append(s)
    return out[-50:]


def load_summaries_store() -> dict:
    return _load_json(SUMMARIES_PATH, {"version": 1, "summaries": []})


def save_summaries_store(data: dict) -> None:
    summaries = _prune_summaries(
        list(data.get("summaries") or []),
        keep_days=SUMMARY_RETENTION_DAYS,
    )
    _atomic_write(SUMMARIES_PATH, {"version": 1, "summaries": summaries})


def append_summary(
    *,
    trading_day: str,
    content_md: str,
    model: str,
    context_hash: str,
    stats_snapshot: dict,
) -> dict:
    store = load_summaries_store()
    row = {
        "id": uuid.uuid4().hex,
        "trading_day": trading_day,
        "generated_at": _now_str(),
        "model": model,
        "context_hash": context_hash,
        "content_md": content_md,
        "stats_snapshot": stats_snapshot,
    }
    store.setdefault("summaries", []).append(row)
    save_summaries_store(store)
    return row


def list_summaries(*, trading_day: Optional[str] = None, limit: int = 30) -> list[dict]:
    store = load_summaries_store()
    items = list(store.get("summaries") or [])
    if trading_day:
        items = [x for x in items if str(x.get("trading_day")) == trading_day]
    items.sort(key=lambda x: str(x.get("generated_at") or ""), reverse=True)
    return items[: max(1, min(limit, 100))]


def get_latest_summary(trading_day: str) -> Optional[dict]:
    rows = list_summaries(trading_day=trading_day, limit=1)
    return rows[0] if rows else None


def load_chat_store() -> dict:
    default = {"version": 1, "sessions": [], "active_session_id": None}
    data = _load_json(CHAT_PATH, default)
    data.setdefault("version", 1)
    data.setdefault("sessions", [])
    return data


def save_chat_store(data: dict) -> None:
    sessions = _prune_chat_sessions(
        list(data.get("sessions") or []),
        keep_days=CHAT_SESSION_RETENTION_DAYS,
    )
    active = data.get("active_session_id")
    ids = {str(s.get("id")) for s in sessions}
    if active and str(active) not in ids:
        active = sessions[-1]["id"] if sessions else None
    _atomic_write(
        CHAT_PATH,
        {"version": 1, "sessions": sessions, "active_session_id": active},
    )


def get_active_session() -> Optional[dict]:
    store = load_chat_store()
    sid = store.get("active_session_id")
    for s in store.get("sessions") or []:
        if str(s.get("id")) == str(sid):
            return s
    return None


CHAT_BOT_TRADING = "trading"
CHAT_BOT_GENERAL = "general"
CHAT_BOT_MODES = frozenset({CHAT_BOT_TRADING, CHAT_BOT_GENERAL})


def _normalize_bot_mode(raw: Any) -> str:
    mode = (raw or CHAT_BOT_TRADING).strip().lower()
    return mode if mode in CHAT_BOT_MODES else CHAT_BOT_TRADING


def create_new_session(
    *,
    trading_day: str,
    title: str = "新对话",
    bot_mode: str = CHAT_BOT_TRADING,
) -> dict:
    store = load_chat_store()
    session = {
        "id": uuid.uuid4().hex,
        "trading_day": trading_day,
        "title": title,
        "bot_mode": _normalize_bot_mode(bot_mode),
        "created_at": _now_str(),
        "updated_at": _now_str(),
        "messages": [],
        "rolling_summary": "",
    }
    store.setdefault("sessions", []).append(session)
    store["active_session_id"] = session["id"]
    save_chat_store(store)
    return session


def ensure_active_session(*, trading_day: str) -> dict:
    active = get_active_session()
    if active:
        return active
    return create_new_session(trading_day=trading_day)


def update_session_rolling_summary(session_id: str, summary: str) -> dict:
    store = load_chat_store()
    target = None
    for s in store.get("sessions") or []:
        if str(s.get("id")) == str(session_id):
            target = s
            break
    if not target:
        raise KeyError("session_not_found")
    target["rolling_summary"] = str(summary or "").strip()
    target["updated_at"] = _now_str()
    store["active_session_id"] = target["id"]
    save_chat_store(store)
    return target


def append_chat_message(
    session_id: str,
    role: str,
    content: str,
    *,
    attachments: Optional[list] = None,
) -> dict:
    store = load_chat_store()
    sessions = store.get("sessions") or []
    target = None
    for s in sessions:
        if str(s.get("id")) == str(session_id):
            target = s
            break
    if not target:
        raise KeyError("session_not_found")
    msg = {"role": role, "content": content.strip(), "at": _now_str()}
    if attachments:
        msg["attachments"] = list(attachments)
    target.setdefault("messages", []).append(msg)
    target["updated_at"] = _now_str()
    if role == "user" and (target.get("title") in (None, "", "新对话")):
        title = content.strip().replace("\n", " ")[:24]
        if title:
            target["title"] = title
    store["active_session_id"] = target["id"]
    save_chat_store(store)
    return target


def _session_list_item(s: dict, *, active_id: Optional[str]) -> dict:
    msgs = s.get("messages") or []
    preview = ""
    for m in reversed(msgs):
        if m.get("role") == "user":
            preview = str(m.get("content") or "").replace("\n", " ")[:48]
            break
    if not preview and msgs:
        last = msgs[-1]
        preview = str(last.get("content") or "").replace("\n", " ")[:48]
    sid = str(s.get("id") or "")
    return {
        "id": sid,
        "title": s.get("title") or "新对话",
        "bot_mode": _normalize_bot_mode(s.get("bot_mode")),
        "trading_day": s.get("trading_day"),
        "created_at": s.get("created_at"),
        "updated_at": s.get("updated_at"),
        "message_count": len(msgs),
        "preview": preview,
        "is_active": sid and sid == str(active_id or ""),
    }


def list_chat_sessions(*, limit: int = 50) -> list[dict]:
    store = load_chat_store()
    active_id = store.get("active_session_id")
    sessions = list(store.get("sessions") or [])
    for s in sessions:
        s.setdefault("bot_mode", CHAT_BOT_TRADING)
    sessions.sort(key=lambda x: str(x.get("updated_at") or ""), reverse=True)
    return [_session_list_item(s, active_id=active_id) for s in sessions[: max(1, min(limit, 100))]]


def set_active_session(session_id: str) -> dict:
    store = load_chat_store()
    target = None
    for s in store.get("sessions") or []:
        if str(s.get("id")) == str(session_id):
            target = s
            break
    if not target:
        raise KeyError("session_not_found")
    target.setdefault("bot_mode", CHAT_BOT_TRADING)
    store["active_session_id"] = target["id"]
    save_chat_store(store)
    return target


def delete_chat_session(session_id: str) -> tuple[bool, Optional[str]]:
    store = load_chat_store()
    sessions = list(store.get("sessions") or [])
    new_sessions = [s for s in sessions if str(s.get("id")) != str(session_id)]
    if len(new_sessions) == len(sessions):
        return False, None
    active = store.get("active_session_id")
    new_active = active
    if str(active) == str(session_id):
        new_active = new_sessions[0]["id"] if new_sessions else None
    store["sessions"] = new_sessions
    store["active_session_id"] = new_active
    save_chat_store(store)
    return True, new_active


def summary_excerpt_for_chat(trading_day: str, max_chars: int = 600) -> str:
    latest = get_latest_summary(trading_day)
    if not latest:
        return ""
    text = str(latest.get("content_md") or "").strip()
    if len(text) <= max_chars:
        return text
    return text[: max_chars - 3].rstrip() + "..."