# --- routers/leaf_options.py ---
from fastapi import APIRouter, BackgroundTasks, HTTPException, Request, Body
from fastapi.responses import StreamingResponse
from pydantic import BaseModel
from typing import List
import json, os, asyncio, re

from cmts_scraper import sync_cmts_leaves_async
from shared import CMTS_DEVICE

router = APIRouter(tags=["Options"])
CACHE_FILE = "cmts_leaf_options_cache.json"

# ==========================================
# 🌟 全域廣播機制 (SSE)
# ==========================================
IS_SCANNING = False
active_clients = set()

async def broadcast_message(message_dict: dict):
    """將訊息推播給所有連線中的前端"""
    dead_clients = set()
    
    # 🌟 關鍵修復 1：SSE 協定嚴格要求必須以 "data: " 開頭，並以 "\n\n" 結尾
    message_str = f"data: {json.dumps(message_dict)}\n\n"
    
    for client_queue in active_clients:
        try:
            await client_queue.put(message_str)
        except Exception:
            dead_clients.add(client_queue)
    for dead in dead_clients:
        active_clients.discard(dead)

@router.get("/cmts-leaf-options/stream")
async def sse_stream(request: Request):
    """前端一載入就會連上這個路由，持續監聽廣播"""
    client_queue = asyncio.Queue()
    active_clients.add(client_queue)
    
    async def event_generator():
        try:
            while True:
                try:
                    message = await asyncio.wait_for(client_queue.get(), timeout=2.0)
                    yield message
                except asyncio.TimeoutError:
                    if await request.is_disconnected():
                        break
                    # 🌟 關鍵修復 2：每 2 秒發送一個空註解，防止瀏覽器因閒置而自動斷線
                    yield ": keepalive\n\n"
        finally:
            active_clients.discard(client_queue)
            
    return StreamingResponse(event_generator(), media_type="text/event-stream")

@router.get("/scan-status")
async def get_scan_status():
    global IS_SCANNING
    return {"is_scanning": IS_SCANNING}

# ==========================================
# 🌟 快取讀取與背景掃描任務
# ==========================================
class SyncOptionsRequest(BaseModel):
    leaf_paths: List[str]

@router.get("/cmts-leaf-options")
async def get_leaf_options():
    if not os.path.exists(CACHE_FILE): return {}
    with open(CACHE_FILE, "r", encoding="utf-8") as f:
        return json.load(f)

async def run_scan_task(paths: List[str]):
    """在背景執行的爬蟲任務，並將進度廣播出去"""
    global IS_SCANNING
    try:
        await broadcast_message({"event": "scan_start"})
        
        # 呼叫爬蟲 (帶入設備連線資訊)
        async for chunk in sync_cmts_leaves_async(
            host=CMTS_DEVICE.get("host"),
            username=CMTS_DEVICE.get("username"),
            password=CMTS_DEVICE.get("password"),
            leaf_paths=paths
        ):
            if isinstance(chunk, str):
                await broadcast_message(json.loads(chunk))
            else:
                await broadcast_message(chunk)
                
        await broadcast_message({"event": "done"})
    except Exception as e:
        await broadcast_message({"event": "error", "message": str(e)})
    finally:
        IS_SCANNING = False

@router.post("/cmts-leaf-options/sync")
async def sync_leaf_options(request: SyncOptionsRequest, background_tasks: BackgroundTasks):
    """前端點擊掃描時，只負責觸發背景任務並立即回傳 JSON"""
    global IS_SCANNING

    if not request.leaf_paths: 
        raise HTTPException(status_code=400)

    if IS_SCANNING:
        return {"status": "busy", "message": "⚠️ 掃描任務正在執行中，請勿重複點擊！"}
    
    IS_SCANNING = True
    
    cmts_query_paths = []
    for p in request.leaf_paths:
        clean_p = p.replace("::", " ")
        clean_p = re.sub(r"\s*\[\d+\]", "", clean_p)
        cmts_query_paths.append(clean_p)
    
    cmts_query_paths = list(dict.fromkeys(cmts_query_paths))
    
    # 將任務丟入背景執行，並立刻回傳 JSON 給前端
    background_tasks.add_task(run_scan_task, cmts_query_paths)
    return {"status": "started"}

# ==========================================
# 🌟 清除快取 API (對應 api.js 的 POST 請求)
# ==========================================
@router.post("/clear_cache")
async def clear_specific_cache(paths_to_clear: list = Body(...)):
    cleared_count = 0
    if not os.path.exists(CACHE_FILE):
        return {"status": "success", "cleared_count": 0, "message": "快取檔案不存在"}

    try:
        with open(CACHE_FILE, "r", encoding="utf-8") as f:
            cache_data = json.load(f)
            
        for path in paths_to_clear:
            if path in cache_data:
                del cache_data[path]
                cleared_count += 1
                
        if cleared_count > 0:
            with open(CACHE_FILE, "w", encoding="utf-8") as f:
                json.dump(cache_data, f, ensure_ascii=False, indent=4)
                
        return {"status": "success", "cleared_count": cleared_count}
        
    except Exception as e:
        return {"status": "error", "message": f"清除快取時發生錯誤: {str(e)}"}