import os
import random
from flask import Flask, render_template, jsonify, request

app = Flask(__name__)

# 示例代码片段
SNIPPETS = [
    # --- Python ---
    {
        "language": "Python",
        "code": """# Binary Search Implementation
def binary_search(arr, target):
    left, right = 0, len(arr) - 1
    
    while left <= right:
        mid = (left + right) // 2
        if arr[mid] == target:
            return mid  # Target found
        elif arr[mid] < target:
            left = mid + 1
        else:
            right = mid - 1
            
    return -1  # Not found"""
    },
    {
        "language": "Python",
        "code": """# Flask Route Example
@app.route('/api/users', methods=['GET'])
def get_users():
    # Get user list from database
    users = db.session.query(User).all()
    return jsonify({
        "count": len(users),
        "data": [u.to_dict() for u in users]
    })"""
    },
    {
        "language": "Python",
        "code": """# Quick Sort Algorithm
def quick_sort(arr):
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right = [x for x in arr if x > pivot]
    return quick_sort(left) + middle + quick_sort(right)"""
    },

    # --- JavaScript ---
    {
        "language": "JavaScript",
        "code": """/**
 * Debounce Function
 * Limits the rate at which a function can fire.
 */
function debounce(func, wait) {
  let timeout;
  return function(...args) {
    const context = this;
    clearTimeout(timeout);
    
    // Execute later
    timeout = setTimeout(() => {
      func.apply(context, args);
    }, wait);
  };
}"""
    },
    {
        "language": "JavaScript",
        "code": """// Promise Chain Example
fetch('https://api.example.com/data')
  .then(response => {
    if (!response.ok) {
      throw new Error('Network response was not ok');
    }
    return response.json();
  })
  .then(data => {
    console.log('Success:', data);
  })
  .catch(error => {
    console.error('Error:', error);
  });"""
    },

    # --- Go ---
    {
        "language": "Go",
        "code": """// Concurrency Example
package main

import (
    "fmt"
    "sync"
)

func main() {
    var wg sync.WaitGroup
    
    // Start 5 goroutines
    for i := 0; i < 5; i++ {
        wg.Add(1)
        go func(id int) {
            defer wg.Done()
            fmt.Printf("Worker %d starting\\n", id)
        }(i)
    }
    
    wg.Wait() // Wait for all goroutines to finish
    fmt.Println("All workers done")
}"""
    },

    # --- SQL ---
    {
        "language": "SQL",
        "code": """-- Query High Value Users
SELECT 
    u.username, 
    COUNT(o.id) as order_count,
    SUM(o.amount) as total_spent
FROM users u
JOIN orders o ON u.id = o.user_id
WHERE o.created_at >= '2024-01-01'
GROUP BY u.id
HAVING total_spent > 1000
ORDER BY total_spent DESC;"""
    },

    # --- React ---
    {
        "language": "React",
        "code": """// Simple Counter Component
import React, { useState } from 'react';

export default function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div className="p-4 border rounded">
      <h2 className="text-xl">Current Count: {count}</h2>
      <button 
        onClick={() => setCount(count + 1)}
        className="bg-blue-500 text-white px-4 py-2 mt-2"
      >
        Increment (+1)
      </button>
    </div>
  );
}"""
    },

    # --- Java ---
    {
        "language": "Java",
        "code": """// Singleton Pattern (Double Checked Locking)
public class Singleton {
    private static volatile Singleton instance;

    private Singleton() {}

    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (Singleton.class) {
                if (instance == null) {
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }
}"""
    },
    
    # --- HTML/CSS ---
    {
        "language": "HTML",
        "code": """<!-- Simple Card Layout -->
<div class="card">
  <img src="avatar.jpg" alt="User Avatar" class="card-img">
  <div class="card-body">
    <h5 class="card-title">Card Title</h5>
    <p class="card-text">Some quick example text to build on the card title.</p>
    <a href="#" class="btn btn-primary">Go somewhere</a>
  </div>
</div>
<style>
  .card { border: 1px solid #ccc; border-radius: 8px; padding: 16px; }
  .card-img { width: 100%; height: auto; border-radius: 4px; }
</style>"""
    }
]

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

@app.route('/api/snippet')
def get_snippet():
    lang = request.args.get('lang')
    
    if lang and lang != 'All':
        filtered = [s for s in SNIPPETS if s['language'] == lang]
        if filtered:
            return jsonify(random.choice(filtered))
    
    # 默认随机返回
    snippet = random.choice(SNIPPETS)
    return jsonify(snippet)

@app.route('/api/languages')
def get_languages():
    # 获取所有唯一的语言列表
    languages = sorted(list(set(s['language'] for s in SNIPPETS)))
    return jsonify(['All'] + languages)

@app.route('/health')
def health():
    return "OK", 200

if __name__ == '__main__':
    port = int(os.environ.get('PORT', 7860))
    app.run(host='0.0.0.0', port=port)