"""聊天 Agent 共享工具：历史获取、格式化、存储"""

from dataclasses import dataclass
from datetime import datetime
from typing import Any, List

from langchain_core.messages import AIMessage, HumanMessage, SystemMessage

from app.core.redis import redis_service


def _human_ai_rows(history: list[dict]) -> list[dict]:
    """与 get_history_messages 一致：仅保留 human/ai，顺序与 Redis 列表一致。"""
    return [m for m in history if m.get("role") in ("human", "ai")]


def _lc_messages_from_rows(rows: list[dict]) -> list[HumanMessage | AIMessage]:
    out: list[HumanMessage | AIMessage] = []
    for msg in rows:
        role = msg.get("role")
        if role == "human":
            out.append(HumanMessage(content=msg["content"]))
        elif role == "ai":
            out.append(AIMessage(content=msg["content"]))
    return out


@dataclass(frozen=True)
class HistoryWithWindow:
    """单次 Redis 读取后的全量轮次计数 + 截断后注入 LLM 的消息列表。"""

    turn_total: int
    window: list[HumanMessage | AIMessage]


async def get_history_with_window(
    conversation_id: str,
    *,
    max_pairs: int,
    max_chars: int,
) -> HistoryWithWindow:
    """一次读取 Redis：turn_total 由全量 human/ai 条数得到；仅对窗口切片构造 LangChain 消息。"""
    history = await redis_service.get_conversation_history(conversation_id)
    human_ai = _human_ai_rows(history)
    turn_total = len(human_ai) // 2
    window_raw = human_ai[-(max_pairs * 2) :] if max_pairs > 0 else human_ai[:]
    window = _lc_messages_from_rows(window_raw)
    total_chars = 0
    start = len(window)
    for i in range(len(window) - 1, -1, -1):
        msg = window[i]
        content = getattr(msg, "content", "") or ""
        total_chars += len(content)
        if total_chars > max_chars:
            start = i + 1
            break
    else:
        start = 0
    if start < len(window) and isinstance(window[start], AIMessage):
        start += 1
    trimmed = window[start:]
    return HistoryWithWindow(turn_total=turn_total, window=trimmed)


async def get_history_messages(conversation_id: str) -> List[Any]:
    """从 Redis 获取对话历史"""
    history = await redis_service.get_conversation_history(conversation_id)
    return _lc_messages_from_rows(_human_ai_rows(history))


def format_history_string(messages: List[Any]) -> str:
    """将 LangChain 消息列表格式化为调试日志用多段文本（含 System，不静默跳过）。"""
    history_parts: list[str] = []
    for msg in messages:
        if isinstance(msg, SystemMessage):
            history_parts.append(f"System: {msg.content}")
        elif isinstance(msg, HumanMessage):
            history_parts.append(f"Human: {msg.content}")
        elif isinstance(msg, AIMessage):
            history_parts.append(f"Assistant: {msg.content}")
        else:
            content = getattr(msg, "content", None)
            history_parts.append(f"{type(msg).__name__}: {content}")
    return "\n\n".join(history_parts)


async def save_message(
    conversation_id: str,
    role: str,
    content: str,
    message_type: str = "text",
    voice_session_id: str | None = None,
    timestamp: datetime | str | int | None = None,
    audio_duration_seconds: int | None = None,
) -> None:
    """保存消息到 Redis"""
    await redis_service.add_message(
        conversation_id,
        role,
        content,
        message_type=message_type,
        voice_session_id=voice_session_id,
        timestamp=timestamp.isoformat()
        if isinstance(timestamp, datetime)
        else timestamp,
        audio_duration_seconds=audio_duration_seconds,
    )