"""
技术论坛与技术分享网站 - 后端API (重构版)
"""

from flask import Flask, request, jsonify, send_file
from flask_cors import CORS
import jwt
import datetime
import os
from pathlib import Path

# 导入配置和模型
import sys
sys.path.insert(0, str(Path(__file__).parent.parent))
from config import SECRET_KEY, LLM_BASE_URL, LLM_API_KEY, LLM_MODEL, DATABASE_PATH, BACKEND_PORT
from models import Database, UserModel, PostModel, ReplyModel, TopicModel

app = Flask(__name__, static_folder='../frontend', static_url_path='')
CORS(app)

# 初始化数据库
db = Database(DATABASE_PATH)
user_model = UserModel(db)
post_model = PostModel(db)
reply_model = ReplyModel(db)
topic_model = TopicModel(db)

# ============ 辅助函数 ============

def generate_token(user_id):
    return jwt.encode({
        'user_id': user_id,
        'exp': datetime.datetime.utcnow() + datetime.timedelta(days=30)
    }, SECRET_KEY, algorithm='HS256')

def verify_token(token):
    try:
        return jwt.decode(token, SECRET_KEY, algorithms=['HS256'])
    except:
        return None

def get_current_user():
    token = request.headers.get('Authorization', '').replace('Bearer ', '')
    if not token:
        return None
    data = verify_token(token)
    if not data:
        return None
    return user_model.get_by_id(data['user_id'])

# ============ 页面路由 ============

@app.route('/')
def index():
    return send_file('../frontend/index.html')

@app.route('/login')
def login_page():
    return send_file('../frontend/login.html')

@app.route('/register')
def register_page():
    return send_file('../frontend/register.html')

@app.route('/post/<post_id>')
def post_page(post_id):
    return send_file('../frontend/post.html')

@app.route('/topic/<topic_id>')
def topic_page(topic_id):
    return send_file('../frontend/topic.html')

@app.route('/user/<user_id>')
def user_page(user_id):
    return send_file('../frontend/user.html')

@app.route('/create')
def create_page():
    return send_file('../frontend/create.html')

# ============ API: 用户认证 ============

@app.route('/api/register', methods=['POST'])
def api_register():
    data = request.json
    
    username = data.get('username', '').strip()
    email = data.get('email', '').strip().lower()
    phone = data.get('phone', '').strip()
    password = data.get('password', '')
    confirm_password = data.get('confirm_password', '')
    
    # 验证
    if not username or len(username) < 2:
        return jsonify({'error': '用户名至少2个字符'}), 400
    if not email or '@' not in email:
        return jsonify({'error': '请输入有效的邮箱地址'}), 400
    if not password or len(password) < 6:
        return jsonify({'error': '密码至少6个字符'}), 400
    if password != confirm_password:
        return jsonify({'error': '两次密码不一致'}), 400
    
    # 检查是否已存在
    if user_model.get_by_username(username):
        return jsonify({'error': '用户名已存在'}), 400
    if user_model.get_by_email(email):
        return jsonify({'error': '邮箱已注册'}), 400
    
    # 创建用户
    user_id = user_model.create(username, email, phone, password)
    user = user_model.get_by_id(user_id)
    
    token = generate_token(user_id)
    
    return jsonify({
        'success': True,
        'token': token,
        'user': {
            'id': user_id,
            'username': username,
            'email': email,
            'avatar': user['avatar']
        }
    })

@app.route('/api/login', methods=['POST'])
def api_login():
    data = request.json
    
    login_name = data.get('username', '').strip()
    password = data.get('password', '')
    
    if not login_name or not password:
        return jsonify({'error': '请输入用户名和密码'}), 400
    
    # 查找用户
    user = user_model.get_by_username(login_name)
    if not user:
        user = user_model.get_by_email(login_name)
    
    if not user:
        return jsonify({'error': '用户不存在'}), 400
    
    if not user_model.verify_password(user, password):
        return jsonify({'error': '密码错误'}), 400
    
    token = generate_token(user['id'])
    
    return jsonify({
        'success': True,
        'token': token,
        'user': {
            'id': user['id'],
            'username': user['username'],
            'email': user['email'],
            'avatar': user['avatar'],
            'bio': user.get('bio', '')
        }
    })

@app.route('/api/user')
def api_current_user():
    user = get_current_user()
    if not user:
        return jsonify({'error': '未登录'}), 401
    
    return jsonify({
        'id': user['id'],
        'username': user['username'],
        'email': user['email'],
        'phone': user.get('phone', ''),
        'avatar': user['avatar'],
        'bio': user.get('bio', ''),
        'posts_count': user_model.get_posts_count(user['id']),
        'replies_count': user_model.get_replies_count(user['id']),
        'created_at': user['created_at']
    })

@app.route('/api/user/<user_id>')
def api_user_profile(user_id):
    user = user_model.get_by_id(user_id)
    if not user:
        return jsonify({'error': '用户不存在'}), 404
    
    # 获取用户的帖子
    posts, total = post_model.get_all()
    user_posts = []
    for post in posts:
        if post['author_id'] == user_id:
            user_posts.append({
                'id': post['id'],
                'title': post['title'],
                'type': post['type'],
                'likes': len(post['likes']),
                'replies': len(reply_model.get_by_post(post['id'])),
                'created_at': post['created_at']
            })
    
    return jsonify({
        'user': {
            'id': user_id,
            'username': user['username'],
            'avatar': user['avatar'],
            'bio': user.get('bio', ''),
            'posts_count': user_model.get_posts_count(user['id']),
            'replies_count': user_model.get_replies_count(user['id']),
            'created_at': user['created_at']
        },
        'posts': user_posts
    })

# ============ API: 技术交流帖子 ============

@app.route('/api/posts')
def api_posts():
    post_type = request.args.get('type')
    tag = request.args.get('tag')
    page = int(request.args.get('page', 1))
    per_page = int(request.args.get('per_page', 20))
    
    posts, total = post_model.get_all(post_type, tag, page, per_page)
    
    post_list = []
    for post in posts:
        author = user_model.get_by_id(post['author_id']) or {}
        post_list.append({
            'id': post['id'],
            'title': post['title'],
            'type': post['type'],
            'content_preview': post['content'][:150] + '...' if len(post['content']) > 150 else post['content'],
            'author': {
                'id': post['author_id'],
                'username': author.get('username', '未知'),
                'avatar': author.get('avatar', '')
            },
            'tags': post['tags'],
            'likes': len(post['likes']),
            'replies': len(reply_model.get_by_post(post['id'])),
            'views': post['views'],
            'created_at': post['created_at'],
            'is_pinned': post['is_pinned']
        })
    
    return jsonify({
        'posts': post_list,
        'total': total,
        'page': page,
        'per_page': per_page
    })

@app.route('/api/posts', methods=['POST'])
def api_create_post():
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    data = request.json
    
    title = data.get('title', '').strip()
    content = data.get('content', '').strip()
    post_type = data.get('type', 'discussion')
    tags = data.get('tags', [])
    
    if not title or len(title) < 5:
        return jsonify({'error': '标题至少5个字符'}), 400
    if not content or len(content) < 10:
        return jsonify({'error': '内容至少10个字符'}), 400
    
    post_id = post_model.create(title, content, post_type, user['id'], tags)
    
    return jsonify({
        'success': True,
        'post_id': post_id
    })

@app.route('/api/posts/<post_id>')
def api_post_detail(post_id):
    post = post_model.get_by_id(post_id)
    if not post:
        return jsonify({'error': '帖子不存在'}), 404
    
    # 增加浏览量
    post_model.increment_views(post_id)
    post['views'] += 1
    
    author = user_model.get_by_id(post['author_id']) or {}
    
    # 获取回复
    replies = reply_model.get_by_post(post_id)
    reply_list = []
    for reply in replies:
        reply_author = user_model.get_by_id(reply['author_id']) or {}
        reply_list.append({
            'id': reply['id'],
            'content': reply['content'],
            'author': {
                'id': reply['author_id'],
                'username': reply_author.get('username', '未知'),
                'avatar': reply_author.get('avatar', '')
            },
            'likes': len(reply['likes']),
            'created_at': reply['created_at'],
            'reply_to': reply.get('reply_to')
        })
    
    return jsonify({
        'id': post_id,
        'title': post['title'],
        'content': post['content'],
        'type': post['type'],
        'author': {
            'id': post['author_id'],
            'username': author.get('username', '未知'),
            'avatar': author.get('avatar', ''),
            'bio': author.get('bio', '')
        },
        'tags': post['tags'],
        'likes': len(post['likes']),
        'views': post['views'],
        'replies': reply_list,
        'created_at': post['created_at'],
        'updated_at': post.get('updated_at', post['created_at'])
    })

@app.route('/api/posts/<post_id>/reply', methods=['POST'])
def api_reply_post(post_id):
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    data = request.json
    content = data.get('content', '').strip()
    reply_to = data.get('reply_to')
    
    if not content:
        return jsonify({'error': '回复内容不能为空'}), 400
    
    post = post_model.get_by_id(post_id)
    if not post:
        return jsonify({'error': '帖子不存在'}), 404
    
    reply_id = reply_model.create(post_id, content, user['id'], reply_to)
    
    return jsonify({
        'success': True,
        'reply_id': reply_id
    })

@app.route('/api/posts/<post_id>/like', methods=['POST'])
def api_like_post(post_id):
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    post = post_model.get_by_id(post_id)
    if not post:
        return jsonify({'error': '帖子不存在'}), 404
    
    liked, likes_count = post_model.add_like(post_id, user['id'])
    
    return jsonify({
        'success': True,
        'liked': liked,
        'likes_count': likes_count
    })

# ============ API: 工具分享主题 ============

@app.route('/api/topics')
def api_topics():
    topics = topic_model.get_all()
    
    topic_list = []
    for topic in topics:
        author = user_model.get_by_id(topic['author_id']) or {}
        topic_list.append({
            'id': topic['id'],
            'name': topic['name'],
            'description': topic['description'][:100] + '...' if len(topic.get('description', '')) > 100 else topic.get('description', ''),
            'icon': topic.get('icon', '🔧'),
            'author': {
                'id': topic['author_id'],
                'username': author.get('username', '未知')
            },
            'sub_topics_count': len(topic_model.get_sub_topics(topic['id'])),
            'questions_count': len(topic_model.get_questions(topic['id'])),
            'followers': len(topic['followers']),
            'created_at': topic['created_at']
        })
    
    topic_list.sort(key=lambda x: x['followers'], reverse=True)
    
    return jsonify(topic_list)

@app.route('/api/topics', methods=['POST'])
def api_create_topic():
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    data = request.json
    
    name = data.get('name', '').strip()
    description = data.get('description', '').strip()
    icon = data.get('icon', '🔧')
    
    if not name:
        return jsonify({'error': '主题名称不能为空'}), 400
    
    topic_id = topic_model.create(name, description, icon, user['id'])
    
    return jsonify({
        'success': True,
        'topic_id': topic_id
    })

@app.route('/api/topics/<topic_id>')
def api_topic_detail(topic_id):
    topic = topic_model.get_by_id(topic_id)
    if not topic:
        return jsonify({'error': '主题不存在'}), 404
    
    author = user_model.get_by_id(topic['author_id']) or {}
    
    # 获取子主题
    sub_topics = topic_model.get_sub_topics(topic_id)
    sub_list = []
    for st in sub_topics:
        st_author = user_model.get_by_id(st['author_id']) or {}
        sub_list.append({
            'id': st['id'],
            'title': st['title'],
            'content': st['content'],
            'author': st_author,
            'created_at': st['created_at']
        })
    
    # 获取问题
    questions = topic_model.get_questions(topic_id)
    q_list = []
    for q in questions:
        q_author = user_model.get_by_id(q['author_id']) or {}
        answers = []
        for a in q['answers']:
            a_author = user_model.get_by_id(a['author_id']) or {}
            answers.append({
                'id': a['id'],
                'content': a['content'],
                'author': {
                    'id': a['author_id'],
                    'username': a_author.get('username', '未知'),
                    'avatar': a_author.get('avatar', '')
                },
                'likes': len(a['likes']),
                'created_at': a['created_at']
            })
        q_list.append({
            'id': q['id'],
            'title': q['title'],
            'content': q.get('content', ''),
            'author': {
                'id': q['author_id'],
                'username': q_author.get('username', '未知'),
                'avatar': q_author.get('avatar', '')
            },
            'answers': answers,
            'views': q.get('views', 0),
            'created_at': q['created_at']
        })
    
    return jsonify({
        'id': topic_id,
        'name': topic['name'],
        'description': topic.get('description', ''),
        'icon': topic.get('icon', '🔧'),
        'author': {
            'id': topic['author_id'],
            'username': author.get('username', '未知'),
            'avatar': author.get('avatar', '')
        },
        'sub_topics': sub_list,
        'questions': q_list,
        'followers': len(topic['followers']),
        'created_at': topic['created_at']
    })

@app.route('/api/topics/<topic_id>/subtopic', methods=['POST'])
def api_add_subtopic(topic_id):
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    data = request.json
    title = data.get('title', '').strip()
    content = data.get('content', '').strip()
    
    if not title:
        return jsonify({'error': '标题不能为空'}), 400
    
    topic = topic_model.get_by_id(topic_id)
    if not topic:
        return jsonify({'error': '主题不存在'}), 404
    
    subtopic_id = topic_model.add_sub_topic(topic_id, title, content, user['id'])
    
    return jsonify({'success': True, 'subtopic_id': subtopic_id})

@app.route('/api/topics/<topic_id>/question', methods=['POST'])
def api_add_question(topic_id):
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    data = request.json
    title = data.get('title', '').strip()
    content = data.get('content', '').strip()
    
    if not title:
        return jsonify({'error': '问题标题不能为空'}), 400
    
    topic = topic_model.get_by_id(topic_id)
    if not topic:
        return jsonify({'error': '主题不存在'}), 404
    
    question_id = topic_model.add_question(topic_id, title, content, user['id'])
    
    return jsonify({'success': True, 'question_id': question_id})

@app.route('/api/topics/<topic_id>/question/<question_id>/answer', methods=['POST'])
def api_answer_question(topic_id, question_id):
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    data = request.json
    content = data.get('content', '').strip()
    
    if not content:
        return jsonify({'error': '回答内容不能为空'}), 400
    
    topic = topic_model.get_by_id(topic_id)
    if not topic:
        return jsonify({'error': '主题不存在'}), 404
    
    answer_id = topic_model.add_answer(question_id, content, user['id'])
    
    return jsonify({'success': True, 'answer_id': answer_id})

@app.route('/api/topics/<topic_id>/follow', methods=['POST'])
def api_follow_topic(topic_id):
    user = get_current_user()
    if not user:
        return jsonify({'error': '请先登录'}), 401
    
    topic = topic_model.get_by_id(topic_id)
    if not topic:
        return jsonify({'error': '主题不存在'}), 404
    
    followed, followers_count = topic_model.add_follower(topic_id, user['id'])
    
    return jsonify({
        'success': True,
        'followed': followed,
        'followers_count': followers_count
    })

# ============ API: 标签 ============

@app.route('/api/tags')
def api_tags():
    tags = post_model.get_tags_stats()
    return jsonify([{'name': t[0], 'count': t[1]} for t in tags])

# ============ API: 搜索 ============

@app.route('/api/search')
def api_search():
    query = request.args.get('q', '').strip().lower()
    
    if not query:
        return jsonify({'posts': [], 'topics': []})
    
    # 搜索帖子
    posts, _ = post_model.get_all()
    matched_posts = []
    for post in posts:
        if query in post['title'].lower() or query in post['content'].lower():
            author = user_model.get_by_id(post['author_id']) or {}
            matched_posts.append({
                'id': post['id'],
                'title': post['title'],
                'type': post['type'],
                'author': author.get('username', '未知'),
                'created_at': post['created_at']
            })
    
    # 搜索主题
    topics = topic_model.get_all()
    matched_topics = []
    for topic in topics:
        if query in topic['name'].lower() or query in topic.get('description', '').lower():
            matched_topics.append({
                'id': topic['id'],
                'name': topic['name'],
                'icon': topic.get('icon', '🔧')
            })
    
    return jsonify({
        'posts': matched_posts[:20],
        'topics': matched_topics[:20]
    })

# ============ API: 健康检查 ============

@app.route('/api/health')
def api_health():
    return jsonify({'status': 'ok', 'service': 'tech-forum', 'port': BACKEND_PORT})

if __name__ == '__main__':
    print("=" * 50)
    print("技术论坛与技术分享网站")
    print("=" * 50)
    print(f"访问地址: http://localhost:{BACKEND_PORT}")
    print("=" * 50)
    
    app.run(host='0.0.0.0', port=BACKEND_PORT, debug=True)