import os
import re
from flask import Flask, jsonify, send_from_directory, render_template, request

app = Flask(__name__)
PROBLEMS_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'problems')

def parse_problem_metadata(filename):
    filepath = os.path.join(PROBLEMS_DIR, filename)
    with open(filepath, 'r', encoding='utf-8') as f:
        content = f.read()
    
    # 默认标题为文件名
    title = filename
    
    # 尝试解析 @title
    # 匹配 /** ... @title 标题 ... */ 或 // @title 标题
    title_match = re.search(r'@title\s+(.+)', content)
    if title_match:
        title = title_match.group(1).strip()
    
    # 解析 @category
    category_match = re.search(r'@category\s+(.+)', content)
    category = category_match.group(1).strip() if category_match else '练习题'

    # 解析 @pinned
    pinned_match = re.search(r'@pinned\s+(.+)', content)
    is_pinned = (pinned_match.group(1).strip().lower() == 'true') if pinned_match else False

    return {
        'id': filename,
        'title': title,
        'category': category,
        'pinned': is_pinned,
        'content': content,
        'ctime': os.path.getctime(filepath)
    }

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

@app.route('/api/problems', methods=['GET'])
def get_problems():
    files = [f for f in os.listdir(PROBLEMS_DIR) if f.endswith('.js') or f.endswith('.ts')]
    # 按创建时间倒序排序 (最新的在最前)
    files.sort(key=lambda x: os.path.getctime(os.path.join(PROBLEMS_DIR, x)), reverse=True)
    
    problems = []
    for f in files:
        try:
            problems.append(parse_problem_metadata(f))
        except Exception as e:
            print(f"Error parsing {f}: {e}")
            
    return jsonify(problems)

@app.route('/api/problems', methods=['POST'])
def create_problem():
    data = request.json
    filename = data.get('filename')
    category = data.get('category', '练习题')
    
    if not filename:
        return jsonify({'error': 'Filename is required'}), 400
    
    if not (filename.endswith('.js') or filename.endswith('.ts')):
        filename += '.js'
        
    filepath = os.path.join(PROBLEMS_DIR, filename)
    
    if os.path.exists(filepath):
        return jsonify({'error': 'File already exists'}), 409
        
    # 默认模板
    content = f"""/**
 * @title {filename}
 * @category {category}
 * @description 在此处添加题目描述
 */

function solve() {{
    // TODO: Implement solution
}}

console.log(solve());
"""
    
    try:
        with open(filepath, 'w', encoding='utf-8') as f:
            f.write(content)
        return jsonify(parse_problem_metadata(filename)), 201
    except Exception as e:
        return jsonify({'error': str(e)}), 500

@app.route('/api/problems/<path:filename>', methods=['GET'])
def get_problem_content(filename):
    return send_from_directory(PROBLEMS_DIR, filename)

@app.route('/api/problems/<path:filename>', methods=['PUT'])
def update_problem(filename):
    filepath = os.path.join(PROBLEMS_DIR, filename)
    
    if not os.path.exists(filepath):
        return jsonify({'error': 'File not found'}), 404
        
    data = request.json
    
    # Handle Rename
    new_filename = data.get('new_filename')
    if new_filename:
        if not (new_filename.endswith('.js') or new_filename.endswith('.ts')):
            new_filename += '.js'
            
        new_filepath = os.path.join(PROBLEMS_DIR, new_filename)
        if os.path.exists(new_filepath) and new_filename != filename:
            return jsonify({'error': 'Target filename already exists'}), 409
            
        try:
            os.rename(filepath, new_filepath)
            return jsonify(parse_problem_metadata(new_filename))
        except Exception as e:
            return jsonify({'error': str(e)}), 500

    # Handle Content Update
    content = data.get('content')
    if content is not None:
        try:
            with open(filepath, 'w', encoding='utf-8') as f:
                f.write(content)
            # 返回新的 metadata 以便前端更新标题
            return jsonify(parse_problem_metadata(filename))
        except Exception as e:
            return jsonify({'error': str(e)}), 500
            
    return jsonify({'error': 'No valid operation specified'}), 400

@app.route('/api/problems/<path:filename>', methods=['DELETE'])
def delete_problem(filename):
    filepath = os.path.join(PROBLEMS_DIR, filename)
    
    if not os.path.exists(filepath):
        return jsonify({'error': 'File not found'}), 404
        
    try:
        os.remove(filepath)
        return jsonify({'message': 'Deleted successfully'})
    except Exception as e:
        return jsonify({'error': str(e)}), 500

if __name__ == '__main__':
    # 确保 problems 目录存在
    if not os.path.exists(PROBLEMS_DIR):
        os.makedirs(PROBLEMS_DIR)
    app.run(host='0.0.0.0', port=7860, debug=True)