# -*- coding: utf-8 -*-
"""
小程序 AI 对话路由 —— SSE 流式对话、历史对话列表、消息查询。

端点清单：
- POST /api/ai/chat/stream                          — SSE 流式对话
- GET  /api/ai/conversations                        — 历史对话列表（分页）
- GET  /api/ai/conversations/{conversation_id}/messages — 对话消息列表
"""

from __future__ import annotations

import json
import logging
import os

from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.responses import StreamingResponse

from app.ai.bailian_client import BailianClient
from app.ai.conversation_service import ConversationService
from app.ai.apps.app1_chat import chat_stream
from app.ai.schemas import ChatStreamRequest, SSEEvent
from app.auth.dependencies import CurrentUser, get_current_user
from app.database import get_connection

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/ai", tags=["小程序 AI 对话"])


# ── 辅助：获取用户 nickname ──────────────────────────────────


def _get_user_nickname(user_id: int) -> str:
    """从 auth.users 查询用户 nickname，查不到返回空字符串。"""
    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                "SELECT nickname FROM auth.users WHERE id = %s",
                (user_id,),
            )
            row = cur.fetchone()
            return row[0] if row and row[0] else ""
    finally:
        conn.close()


# ── 辅助：获取用户主要角色 ───────────────────────────────────


def _get_user_role_label(roles: list[str]) -> str:
    """从角色列表提取主要角色标签，用于 AI 上下文。"""
    if "store_manager" in roles or "owner" in roles:
        return "管理者"
    if "assistant" in roles or "coach" in roles:
        return "助教"
    return "用户"


# ── 辅助：构建 BailianClient 实例 ────────────────────────────


def _get_bailian_client() -> BailianClient:
    """从环境变量构建 BailianClient，缺失时报错。"""
    api_key = os.environ.get("BAILIAN_API_KEY")
    base_url = os.environ.get("BAILIAN_BASE_URL")
    model = os.environ.get("BAILIAN_MODEL")
    if not api_key or not base_url or not model:
        raise RuntimeError(
            "百炼 API 环境变量缺失，需要 BAILIAN_API_KEY、BAILIAN_BASE_URL、BAILIAN_MODEL"
        )
    return BailianClient(api_key=api_key, base_url=base_url, model=model)


# ── SSE 流式对话 ─────────────────────────────────────────────


@router.post("/chat/stream")
async def ai_chat_stream(
    body: ChatStreamRequest,
    user: CurrentUser = Depends(get_current_user),
):
    """SSE 流式对话端点。

    接收用户消息，通过百炼 API 流式返回 AI 回复。
    每个 SSE 事件格式：data: {json}\n\n
    事件类型：chunk（文本片段）/ done（完成）/ error（错误）
    """
    if not body.message or not body.message.strip():
        raise HTTPException(
            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
            detail="消息内容不能为空",
        )

    nickname = _get_user_nickname(user.user_id)
    role_label = _get_user_role_label(user.roles)
    bailian = _get_bailian_client()
    conv_svc = ConversationService()

    async def event_generator():
        """SSE 事件生成器，逐事件 yield data: {json}\n\n 格式。"""
        try:
            async for event in chat_stream(
                message=body.message.strip(),
                user_id=user.user_id,
                nickname=nickname,
                role=role_label,
                site_id=user.site_id,
                source_page=body.source_page,
                page_context=body.page_context,
                screen_content=body.screen_content,
                bailian=bailian,
                conv_svc=conv_svc,
            ):
                yield f"data: {event.model_dump_json()}\n\n"
        except Exception as e:
            # 兜底：生成器内部异常也以 SSE error 事件返回
            logger.error("SSE 生成器异常: %s", e, exc_info=True)
            error_event = SSEEvent(type="error", message=str(e))
            yield f"data: {error_event.model_dump_json()}\n\n"

    return StreamingResponse(
        event_generator(),
        media_type="text/event-stream",
        headers={
            "Cache-Control": "no-cache",
            "Connection": "keep-alive",
            "X-Accel-Buffering": "no",  # nginx 禁用缓冲
        },
    )


# ── 历史对话列表 ─────────────────────────────────────────────


@router.get("/conversations")
async def list_conversations(
    page: int = 1,
    page_size: int = 20,
    user: CurrentUser = Depends(get_current_user),
):
    """查询当前用户的历史对话列表，按时间倒序，分页。"""
    if page < 1:
        page = 1
    if page_size < 1 or page_size > 100:
        page_size = 20

    conv_svc = ConversationService()
    conversations = conv_svc.get_conversations(
        user_id=user.user_id,
        site_id=user.site_id,
        page=page,
        page_size=page_size,
    )

    # 为每条对话附加首条消息预览
    result = []
    for conv in conversations:
        item = {
            "id": conv["id"],
            "app_id": conv["app_id"],
            "source_page": conv.get("source_page"),
            "created_at": conv["created_at"],
            "first_message_preview": None,
        }
        # 查询首条 user 消息作为预览
        messages = conv_svc.get_messages(conv["id"])
        for msg in messages:
            if msg["role"] == "user":
                content = msg["content"] or ""
                item["first_message_preview"] = content[:50] if len(content) > 50 else content
                break
        result.append(item)

    return result


# ── 对话消息列表 ─────────────────────────────────────────────


@router.get("/conversations/{conversation_id}/messages")
async def get_conversation_messages(
    conversation_id: int,
    user: CurrentUser = Depends(get_current_user),
):
    """查询指定对话的所有消息，按时间升序。

    验证对话归属当前用户和 site_id，防止越权访问。
    """
    # 先验证对话归属
    conn = get_connection()
    try:
        with conn.cursor() as cur:
            cur.execute(
                """
                SELECT id FROM biz.ai_conversations
                WHERE id = %s AND user_id = %s AND site_id = %s
                """,
                (conversation_id, str(user.user_id), user.site_id),
            )
            if not cur.fetchone():
                raise HTTPException(
                    status_code=status.HTTP_404_NOT_FOUND,
                    detail="对话不存在或无权访问",
                )
    finally:
        conn.close()

    conv_svc = ConversationService()
    messages = conv_svc.get_messages(conversation_id)

    return [
        {
            "id": msg["id"],
            "role": msg["role"],
            "content": msg["content"],
            "tokens_used": msg.get("tokens_used"),
            "created_at": msg["created_at"],
        }
        for msg in messages
    ]