# app.py

from fastapi import FastAPI, HTTPException
from starlette.responses import JSONResponse
import requests
import re
import xml.etree.ElementTree as ET
from datetime import datetime, timedelta, timezone
import logging
import html

# --- 配置日誌 ---
logging.basicConfig(level=logging.INFO)

# --- 初始化 FastAPI 應用 ---
app = FastAPI(
    title="台灣地震速報 API",
    description="一個從台灣中央氣象署(CWA)公開預警XML Feed中，擷取最新地震速報的API。https://cwadayi-app-show-pws.hf.space/cwa-earthquakes",
    version="1.0.0",
)

# --- Geocode 與縣市名稱的對照字典 ---
GEOCODE_MAP = {
    "10002": "宜蘭縣", "10004": "新竹縣", "10005": "苗栗縣",
    "10007": "彰化縣", "10008": "南投縣", "10009": "雲林縣",
    "10010": "嘉義縣", "10013": "屏東縣", "10014": "臺東縣",
    "10015": "花蓮縣", "10016": "澎湖縣", "10017": "基隆市",
    "10018": "新竹市", "10020": "嘉義市", "63": "臺北市",
    "64": "高雄市", "65": "新北市", "66": "臺中市",
    "67": "臺南市", "68": "桃園市", "09007": "連江縣",
    "09020": "金門縣"
}

# --- 核心功能函式 ---
def get_cwa_earthquakes():
    """
    抓取並解析 CWA 地震速報 Feed，回傳結構化的 Python 列表。
    """
    timestamp = int(datetime.now().timestamp())
    feed_url = f"https://cbs.tw/files/rssatomfeed.xml?_={timestamp}"
    keywords = ["中央氣象署", "氣象署"]
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36',
        'Cache-Control': 'no-cache',
        'Pragma': 'no-cache'
    }

    try:
        response = requests.get(feed_url, headers=headers, timeout=15)
        response.raise_for_status()

        xml_content = response.content.decode('utf-8')
        xml_content = re.sub(' xmlns="[^"]+"', '', xml_content, count=1)
        root = ET.fromstring(xml_content)
        
        earthquake_alerts = []

        for entry in root.findall('entry'):
            summary_text = ''
            for tag_name in ['summary', 'description']:
                content_tag = entry.find(tag_name)
                if content_tag is not None and content_tag.text:
                    summary_text = content_tag.text
                    break
            
            title_tag = entry.find('title')
            title = title_tag.text if title_tag is not None else ""
            
            is_earthquake_alert = "地震速報" in title
            is_from_cwa = any(keyword in summary_text for keyword in keywords)

            if is_earthquake_alert and is_from_cwa:
                sent_tag = entry.find('sent')
                published_time = sent_tag.text if sent_tag is not None else "N/A"

                area_desc = ''
                affected_counties = []
                area_tag = entry.find('area')
                if area_tag is not None:
                    area_desc_tag = area_tag.find('areadesc')
                    area_desc = area_desc_tag.text if area_desc_tag is not None else ''

                    for geocode_tag in area_tag.findall('geocode'):
                        value_tag = geocode_tag.find('value')
                        if value_tag is not None:
                            code = value_tag.text
                            location_name = GEOCODE_MAP.get(code, f"未知代碼({code})")
                            affected_counties.append(location_name)
                
                alert = {
                    "title": html.unescape(title),
                    "publish_time": published_time,
                    "summary": html.unescape(summary_text),
                    "affected_area_desc": html.unescape(area_desc),
                    "affected_counties": affected_counties
                }
                earthquake_alerts.append(alert)
        
        return earthquake_alerts

    except requests.exceptions.RequestException as e:
        logging.error(f"無法從 CWA 取得資料: {e}")
        raise HTTPException(status_code=503, detail="無法連接到 CWA 資料來源")
    except ET.ParseError as e:
        logging.error(f"XML 資料解析失敗: {e}")
        raise HTTPException(status_code=500, detail="解析 CWA 資料時發生錯誤")
    except Exception as e:
        logging.error(f"發生未預期的錯誤: {e}")
        raise HTTPException(status_code=500, detail=f"發生內部錯誤: {e}")

# --- API 端點 ---
@app.get("/")
def root():
    """
    根目錄端點，提供 API 簡介和範例連結。
    """
    return {
        "message": "歡迎使用台灣地震速報 API - https://cwadayi-app-show-pws.hf.space/cwa-earthquakes",
        "documentation": "/docs",
        "earthquake_feed_endpoint": "/cwa-earthquakes"
    }

@app.get("/cwa-earthquakes")
async def get_earthquakes_endpoint():
    """
    提供最新的地震速報。
    https://cwadayi-app-show-pws.hf.space/cwa-earthquakes
    此端點會從 CWA 的公開預警 Feed 中擷取資料，
    篩選出來自「中央氣象署」的「地震速報」，
    並以 JSON 格式回傳。
    """
    alerts = get_cwa_earthquakes()
    tw_tz = timezone(timedelta(hours=8))
    last_updated = datetime.now(tw_tz).isoformat()
    
    return JSONResponse(content={
        "last_updated": last_updated,
        "source": "台灣中央氣象署 (CWA)",
        "alerts": alerts
    })