import time
import json
import base64
from typing import List

DEBUG = True

class ProofOfWorkSolver:
    """解决 OpenAI Sentinel 的 Proof of Work challenge"""
    
    def __init__(self):
        # FNV-1a 常量
        self.FNV_OFFSET = 2166136261
        self.FNV_PRIME = 16777619
        
    def fnv1a_hash(self, data: str) -> str:
        """FNV-1a hash 算法"""
        hash_value = self.FNV_OFFSET
        
        for char in data:
            hash_value ^= ord(char)
            hash_value = (hash_value * self.FNV_PRIME) & 0xFFFFFFFF
        
        # 额外的混合步骤（从 JS 代码复制）
        hash_value ^= hash_value >> 16
        hash_value = (hash_value * 2246822507) & 0xFFFFFFFF
        hash_value ^= hash_value >> 13
        hash_value = (hash_value * 3266489909) & 0xFFFFFFFF
        hash_value ^= hash_value >> 16
        
        # 转为 8 位十六进制字符串
        return format(hash_value, '08x')
    
    def serialize_array(self, arr: List) -> str:
        """模拟 JS 的 T() 函数：JSON.stringify + Base64"""
        json_str = json.dumps(arr, separators=(',', ':'))
        return base64.b64encode(json_str.encode()).decode()
    
    def build_fingerprint_array(self, nonce: int, elapsed_ms: int) -> List:
        """构建指纹数组（简化版）"""
        return [
            0,           # [0] screen dimensions
            "",          # [1] timestamp
            0,           # [2] memory
            nonce,       # [3] nonce ← 关键
            "",          # [4] user agent
            "",          # [5] random element
            "",          # [6] script src
            "",          # [7] language
            "",          # [8] languages
            elapsed_ms,  # [9] elapsed time ← 关键
            "",          # [10] random function
            "",          # [11] keys
            "",          # [12] window keys
            0,           # [13] performance.now()
            "",          # [14] uuid
            "",          # [15] URL params
            0,           # [16] hardware concurrency
            0            # [17] timeOrigin
        ]
    
    def solve(self, seed: str, difficulty: str, max_iterations: int = 10000000) -> str:
        """
        解决 PoW challenge
        
        Args:
            seed: Challenge seed
            difficulty: 目标难度（十六进制字符串）
            max_iterations: 最大尝试次数
            
        Returns:
            序列化的答案（包含 nonce）
        """
        if DEBUG:
            print(f"[PoW] Solving challenge:")
            print(f"      Seed: {seed}")
            print(f"      Difficulty: {difficulty}")
        
        start_time = time.time()
        
        for nonce in range(max_iterations):
            elapsed_ms = int((time.time() - start_time) * 1000)
            
            # 构建指纹数组
            fingerprint = self.build_fingerprint_array(nonce, elapsed_ms)
            
            # 序列化
            serialized = self.serialize_array(fingerprint)
            
            # 计算 hash(seed + serialized)
            hash_input = seed + serialized
            hash_result = self.fnv1a_hash(hash_input)
            
            # 检查是否满足难度要求
            # 比较方式：hash 的前 N 位（作为整数）<= difficulty（作为整数）
            difficulty_len = len(difficulty)
            hash_prefix = hash_result[:difficulty_len]
            
            if hash_prefix <= difficulty:
                elapsed = time.time() - start_time
                if DEBUG:
                    print(f"[PoW] ✓ Found solution in {elapsed:.2f}s")
                    print(f"      Nonce: {nonce}")
                    print(f"      Hash: {hash_result}")
                    print(f"      Serialized: {serialized[:100]}...")
                
                # 返回 serialized + "~S" （表示成功）
                return serialized + "~S"
            
            # 每 100k 次迭代打印进度
            if DEBUG and nonce > 0 and nonce % 100000 == 0:
                print(f"[PoW] Tried {nonce:,} iterations...")
        
        raise Exception(f"Failed to solve PoW after {max_iterations:,} iterations")