from fastapi import FastAPI, HTTPException, Request
from fastapi.responses import JSONResponse
from fastapi.middleware.cors import CORSMiddleware
from starlette.responses import Response, StreamingResponse
from utils.params import DecodeContentParam, PatternContentParam, TopicSearchParam
from dotenv import load_dotenv, find_dotenv
from typing import Any, Dict, List, Optional

from tasks.decode import begin_decode_task
from tasks.detail import get_decode_detail_by_task_id
from tasks.pattern import begin_pattern_task
from tasks.topic_search import search_topics

from loguru import logger
import sys

logger.add(sink=sys.stderr, level="ERROR", backtrace=True, diagnose=True)

# 接口访问日志（与仅 ERROR 的 sink 并存，默认 stderr 仍会输出 INFO）
_MAX_ACCESS_LOG_BYTES = 8192


def _preview_bytes(data: bytes) -> str:
    if not data:
        return ""
    text = data.decode("utf-8", errors="replace")
    if len(text) > _MAX_ACCESS_LOG_BYTES:
        return text[:_MAX_ACCESS_LOG_BYTES] + f"...<truncated len={len(text)}>"
    return text

# 响应消息映射
RESPONSE_MSG_MAP = {
    0: "success",
    1002: "视频不存在",
    2001: "解构/聚类任务创建失败",
    -1: "failed",
    404: "任务不存在"
}

load_dotenv(find_dotenv(), override=False)
app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.middleware("http")
async def api_access_log_middleware(request: Request, call_next):
    """记录每个接口的请求（路径、查询、body）与响应（状态码、body）。"""
    body_bytes = await request.body()

    async def receive() -> dict:
        return {"type": "http.request", "body": body_bytes, "more_body": False}

    wrapped = Request(request.scope, receive)

    req_body_preview = _preview_bytes(body_bytes) if body_bytes else ""
    logger.info(
        "api_request method={} path={} query={} body={}",
        request.method,
        request.url.path,
        str(request.query_params),
        req_body_preview if req_body_preview else "<empty>",
    )

    response = await call_next(wrapped)

    if isinstance(response, StreamingResponse):
        logger.info(
            "api_response status={} path={} body=<streaming skipped>",
            response.status_code,
            request.url.path,
        )
        return response

    resp_chunks: List[bytes] = []
    async for chunk in response.body_iterator:
        resp_chunks.append(chunk)
    resp_body = b"".join(resp_chunks)
    resp_preview = _preview_bytes(resp_body) if resp_body else ""
    logger.info(
        "api_response status={} path={} body={}",
        response.status_code,
        request.url.path,
        resp_preview if resp_preview else "<empty>",
    )

    return Response(
        content=resp_body,
        status_code=response.status_code,
        headers=dict(response.headers),
        media_type=response.media_type,
    )


@app.exception_handler(HTTPException)
async def http_exception_handler(request: Request, exc: HTTPException):
    """统一处理 HTTPException，保证返回结构与其它接口一致"""
    msg = RESPONSE_MSG_MAP.get(exc.status_code, "failed")
    content = {
        "code": exc.status_code,
        "msg": msg,
        "data": None,
    }
    # 将异常 detail 写入 reason，便于排查问题
    if exc.detail:
        content["reason"] = str(exc.detail)
    return JSONResponse(status_code=200, content=content)

def _build_api_response(
    code: int,
    data: Any = None,
    reason: Optional[str] = None
) -> JSONResponse:
    """构建统一的API响应"""
    msg = RESPONSE_MSG_MAP.get(code, "failed")
    content = {
        "code": code,
        "msg": msg,
        "data": data
    }
    
    # 失败时添加 reason 字段
    if code != 0 and reason:
        content["reason"] = reason
    
    return JSONResponse(status_code=200, content=content)


@app.post("/api/v1/content/tasks/decode")
def decode_content(param: DecodeContentParam):
    """创建解构任务"""
    res = begin_decode_task(param)
    code = res.get("code", -1)
    task_id = res.get("task_id")
    reason = res.get("reason", "")

    
    
    return _build_api_response(
        code=code,
        data={"task_id": task_id} if task_id else None,
        reason=reason
    )

@app.get("/api/v1/content/tasks/{taskId}")
def get_task_detail(taskId: str):
    """获取任务详情"""
    result = get_decode_detail_by_task_id(taskId)
    
    # 任务不存在
    if result is None:
        return _build_api_response(code=404, data=None)
    
    # 直接返回结果（已经包含 code、msg、data、reason）
    return JSONResponse(status_code=200, content=result)

@app.post("/api/v1/content/tasks/pattern")
def pattern_content(param: PatternContentParam):
    """创建聚类任务"""
    res = begin_pattern_task(param)
    code = res.get("code", -1)
    task_id = res.get("task_id")
    reason = res.get("reason", "")
    
    return _build_api_response(
        code=code,
        data={"task_id": task_id} if task_id else None,
        reason=reason
    )


@app.post("/api/v1/content/topics/search")
def search_content_topics(param: TopicSearchParam):
    """视频选题检索：根据关键词在解构结果中匹配，返回匹配度最高的 top5"""
    results = search_topics(param)
    return _build_api_response(code=0, data=results)