from flask import Flask, redirect, url_for
from flask_login import LoginManager, current_user  # 添加 current_user 导入
from config.config import config
from app.models import db, User, Student  # 添加 Student 导入
import os
import json  # 添加 json 导入
from datetime import datetime, timedelta  # 添加 datetime 和 timedelta 导入


def create_app(config_name=None):
    if config_name is None:
        config_name = os.environ.get('FLASK_ENV', 'default')

    app = Flask(__name__)
    app.config.from_object(config[config_name])

    # 初始化扩展
    db.init_app(app)

    # 初始化Flask-Login
    login_manager = LoginManager()
    login_manager.init_app(app)
    login_manager.login_view = 'auth.login'
    login_manager.login_message = '请先登录后访问此页面。'
    login_manager.login_message_category = 'info'

    @app.template_filter('fromjson')
    def from_json(value):
        try:
            return json.loads(value)
        except:
            return {}

    @app.template_filter('strptime')
    def strptime_filter(value, format_string):
        try:
            return datetime.strptime(value, format_string)
        except:
            return None

    @app.template_filter('calculate_duration')
    def calculate_duration(start_time, end_time, date_str):
        try:
            if not start_time or not end_time:
                return None

            start_datetime = datetime.strptime(f"{date_str} {start_time}", '%Y-%m-%d %H:%M:%S')
            end_datetime = datetime.strptime(f"{date_str} {end_time}", '%Y-%m-%d %H:%M:%S')

            # 如果结束时间小于开始时间，说明跨天了
            if end_datetime < start_datetime:
                end_datetime += timedelta(days=1)

            duration = (end_datetime - start_datetime).total_seconds() / 3600
            return round(duration, 1)
        except:
            return None

    @app.context_processor
    def utility_processor():
        def get_current_student():
            # 添加安全检查
            if not current_user.is_authenticated:
                return None
            if current_user.is_admin():
                return None
            return Student.query.filter_by(student_number=current_user.student_number).first()

        return dict(get_current_student=get_current_student)

    # 注册Python内置函数到Jinja2环境
    app.jinja_env.globals.update(
        max=max,
        min=min,
        abs=abs,
        round=round,
        len=len,
        int=int,
        float=float,
        str=str,
        sum=sum,
        enumerate=enumerate,
        zip=zip
    )

    @login_manager.user_loader
    def load_user(user_id):
        return User.query.get(int(user_id))

    # 注册蓝图
    from app.routes.auth import auth_bp
    from app.routes.student import student_bp
    from app.routes.admin import admin_bp

    app.register_blueprint(auth_bp, url_prefix='/auth')
    app.register_blueprint(student_bp, url_prefix='/student')
    app.register_blueprint(admin_bp, url_prefix='/admin')

    # 注册模板全局函数
    from app.utils import get_pending_leaves_count
    app.jinja_env.globals.update(
        get_pending_leaves_count=get_pending_leaves_count,
        # 移除这行，因为我们已经通过 context_processor 注册了
        # get_current_student=get_current_student
    )

    # 主页路由
    @app.route('/')
    def index():
        if current_user.is_authenticated:
            if current_user.is_admin():
                return redirect(url_for('admin.dashboard'))
            else:
                return redirect(url_for('student.dashboard'))
        return redirect(url_for('auth.login'))

    # 创建数据库表
    with app.app_context():
        db.create_all()

    return app