import os
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager
from flask_migrate import Migrate
from config import config
from flask_wtf.csrf import CSRFProtect

# 初始化扩展
db = SQLAlchemy()
login_manager = LoginManager()
migrate = Migrate()
csrf = CSRFProtect()

def create_app(config_name='default'):
    """应用工厂函数"""
    # 设置模板和静态文件夹
    app_dir = os.path.dirname(os.path.abspath(__file__))
    template_folder = os.path.join(app_dir, 'web', 'templates')
    static_folder = os.path.join(os.path.dirname(app_dir), 'static')

    app = Flask(__name__,
                template_folder=template_folder,
                static_folder=static_folder)
    
    # 尝试加载.env文件
    try:
        from dotenv import load_dotenv
        if load_dotenv():
            print("成功加载.env文件")
        else:
            print("未找到或无法加载.env文件")
    except ImportError:
        print("python-dotenv未安装，跳过.env文件加载")
    
    app.config.from_object(config[config_name])
    config[config_name].init_app(app)

    # 特别确保MAX_CONTENT_LENGTH配置正确应用
    max_content_length = app.config.get('MAX_CONTENT_LENGTH', 16 * 1024 * 1024)
    app.config['MAX_CONTENT_LENGTH'] = max_content_length
    print(f"Setting MAX_CONTENT_LENGTH to: {max_content_length} bytes ({max_content_length / (1024*1024)} MB)")

    # 初始化扩展
    db.init_app(app)
    login_manager.init_app(app)
    migrate.init_app(app, db)
    csrf.init_app(app)

    # 配置登录管理器
    login_manager.login_view = 'web.login'
    login_manager.login_message = '请先登录'
    login_manager.login_message_category = 'info'
    login_manager.id_attribute = 'get_id'  # 使用 get_id 方法获取用户ID

    # 注册蓝图
    from app.api import api_bp
    app.register_blueprint(api_bp, url_prefix=f'/api/{app.config["API_VERSION"]}')
    csrf.exempt(api_bp)

    from app.web import web_bp
    app.register_blueprint(web_bp)

    # 注册错误处理器
    from app.web.views import register_error_handlers
    register_error_handlers(app)

    return app