import os
import mysql.connector
from mysql.connector import pooling
from flask import Flask, jsonify, request
from flask_cors import CORS
from datetime import datetime

# --- 從環境變數讀取資料庫連線資訊 ---
# os.environ.get() 會嘗試讀取環境變數，如果找不到，則使用後面的預設值
# 這讓程式碼在本地 (使用預設值) 和 Zeabur (使用環境變數) 都能運作
DB_CONFIG = {
    'user': os.environ.get('DB_USER', 'A023'),
    'password': os.environ.get('DB_PASSWORD', 'UkrHhx76kCCM'),
    'host': os.environ.get('DB_HOST', 'mysql.theaken.com'),
    'port': int(os.environ.get('DB_PORT', 33306)),
    'database': os.environ.get('DB_NAME', 'db_A023'),
}

# --- 建立應用程式與啟用 CORS ---
app = Flask(__name__)
CORS(app)

# --- 建立資料庫連線池 ---
connection_pool = None
try:
    connection_pool = mysql.connector.pooling.MySQLConnectionPool(
        pool_name="api_pool",
        pool_size=5,
        **DB_CONFIG
    )
    print("資料庫連線池建立成功！")
except mysql.connector.Error as err:
    print(f"資料庫連線池建立失敗: {err}")

# --- 統一回應格式的輔助函式 ---
def create_response(status, data, message, code):
    return jsonify({
        "status": status,
        "code": code,
        "message": message,
        "data": data
    }), code

def create_error_response(message, code):
    return create_response("error", None, message, code)

# --- API Endpoint: /menu ---
@app.route('/menu', methods=['GET'])
def get_menu_by_date():
    menu_date_str = request.args.get('date')

    if not menu_date_str:
        return create_error_response("The 'date' parameter is required.", 400)

    try:
        datetime.strptime(menu_date_str, '%Y-%m-%d')
    except ValueError:
        return create_error_response("Invalid date format. Please use YYYY-MM-DD.", 400)

    if not connection_pool:
        return create_error_response("Database connection not available.", 503)

    conn = None
    cursor = None
    try:
        conn = connection_pool.get_connection()
        cursor = conn.cursor(dictionary=True)

        query = ("SELECT main_course, side_dish, addon "
                 "FROM menu_items WHERE menu_date = %s")
        
        cursor.execute(query, (menu_date_str,))
        menu_items = cursor.fetchall()

        if not menu_items:
            return create_response("success", [], "no menu found", 200)
        
        return create_response("success", menu_items, "Menu retrieved successfully.", 200)

    except mysql.connector.Error as err:
        return create_error_response(f"Database error: {err}", 500)
    except Exception as e:
        return create_error_response(f"An unexpected error occurred: {e}", 500)
    finally:
        if cursor:
            cursor.close()
        if conn and conn.is_connected():
            conn.close()

# --- 全域錯誤處理 ---
@app.errorhandler(404)
def not_found(error):
    return create_error_response("Resource not found.", 404)

@app.errorhandler(405)
def method_not_allowed(error):
    return create_error_response("Method not allowed.", 405)

# --- 啟動應用程式 ---
if __name__ == '__main__':
    # Zeabur 會透過 Gunicorn 啟動，這段主要用於本地測試
    # Zeabur 會自動注入 PORT 環境變數
    port = int(os.environ.get('PORT', 5000))
    app.run(host='0.0.0.0', port=port, debug=False) # 正式環境 debug 應為 False