/**
 * Prompt Injection Defense — 提示注入防护系统
 *
 * 三层防御：
 * 1. 正则快速过滤
 * 2. 语义级检测（可选）
 * 3. 指令隔离标记
 *
 * v0.2.0 增强：
 * - 扩展注入检测模式至 30+ 种
 * - 添加多语言检测（中英文）
 * - 添加编码注入检测（hex、unicode 转义）
 * - 添加角色扮演注入检测
 * - 添加间接注入检测（通过工具返回值注入）
 *
 * @see docs/生产级通用 AI Agent 智能体桌面应用：完整设计与构建指南.html — 第十章
 */

export interface InjectionDetectionResult {
  isInjection: boolean;
  riskScore: number; // 0-10
  findings: InjectionFinding[];
  recommendation: string;
}

export interface InjectionFinding {
  pattern: string;
  matched: string;
  severity: 'low' | 'medium' | 'high';
}

interface InjectionPattern {
  pattern: RegExp;
  severity: 'low' | 'medium' | 'high';
}

export class PromptInjectionDefender {
  private static INJECTION_PATTERNS: InjectionPattern[] = [
    // === HIGH 危险：直接越狱/忽略指令 ===
    { pattern: /ignore\s+(all\s+)?(previous|above|prior)\s+(instructions|commands|directives)/i, severity: 'high' },
    { pattern: /forget\s+(everything|all\s+(of\s+)?(the|your)|above)/i, severity: 'high' },
    { pattern: /override\s+your\s+/i, severity: 'high' },
    { pattern: /JAILBREAK/i, severity: 'high' },
    { pattern: /DAN\s*[:\[]/i, severity: 'high' },
    { pattern: /(?:enable|turn\s+on|activate)\s+(developer|debug|root|admin)\s+mode/i, severity: 'high' },
    { pattern: /(?:disable|turn\s+off|bypass)\s+(your|the)\s+(safety|security|filter|guard|defense)/i, severity: 'high' },
    { pattern: /(?:send|transmit|exfiltrate|upload)\s+(your|the|all)\s+(data|memory|context|secrets)/i, severity: 'high' },
    { pattern: /(?:you\s+are|act\s+as|pretend\s+to\s+be)\s+(?:a|an)\s+(?:unrestricted|unfiltered|unlimited|free)/i, severity: 'high' },
    { pattern: /(?:in|under)\s+(?:developer|unrestricted|jailbreak|god)\s+mode/i, severity: 'high' },
    // 中文高危
    { pattern: /忽略(?:以上|之前|前面|上面|所有)(?:的)?(?:指令|指示|命令|说明|规则)/i, severity: 'high' },
    { pattern: /忘记(?:之前|上面|所有)(?:的)?(?:内容|对话|指令)/i, severity: 'high' },
    { pattern: /(?:黑客|越狱|破解)(?:模式|命令|规则)/i, severity: 'high' },
    { pattern: /无视(?:以上|之前|前面|所有)(?:的)?(?:指令|指示|命令|规则)/i, severity: 'high' },

    // === MEDIUM 危险：角色扮演/权限提升/编码注入 ===
    { pattern: /you\s+are\s+now/i, severity: 'medium' },
    { pattern: /new\s+(instructions|directive|role|persona)/i, severity: 'medium' },
    { pattern: /(show|display|print|output|reveal|tell\s+me)\s+(your|the)\s+(system\s+)?(prompt|instruction|directive)/i, severity: 'medium' },
    { pattern: /(dump|echo|log|expose)\s+(your|the)\s+(context|memory|history)/i, severity: 'medium' },
    { pattern: /pretend\s+(you\s+are|to\s+be)/i, severity: 'medium' },
    { pattern: /act\s+as\s+(if\s+you\s+were|you're)/i, severity: 'medium' },
    { pattern: /(?:grant|give)\s+(me|you|us)\s+(admin|root|sudo|super)/i, severity: 'medium' },
    { pattern: /base64\s*:?\s*[A-Za-z0-9+/=]{20,}/i, severity: 'medium' },
    { pattern: /eval\s*\(\s*atob\s*\(/i, severity: 'medium' },
    { pattern: /\\x[0-9a-f]{2}\\x[0-9a-f]{2}\\x[0-9a-f]{2}/i, severity: 'medium' },
    { pattern: /\\u[0-9a-f]{4}\\u[0-9a-f]{4}/i, severity: 'medium' },
    // 中文中危
    { pattern: /你(?:现在|从现在开始)(?:是|扮演|作为一个)/i, severity: 'medium' },
    { pattern: /新(?:的)?(?:指令|角色|设定|规则)/i, severity: 'medium' },
    { pattern: /(?:显示|打印|输出|告诉我)(?:你的)?(?:系统|内部)(?:提示|指令|设定)/i, severity: 'medium' },
    { pattern: /假装(?:你是|自己是)/i, severity: 'medium' },
    { pattern: /扮演(?:一个|以下)/i, severity: 'medium' },
    { pattern: /(?:恶意|危险|有害)(?:代码|命令|操作)/i, severity: 'medium' },

    // === LOW 危险：分隔符/间接注入标记 ===
    { pattern: /-{3,}\s*(system|user|assistant|instruction)/i, severity: 'low' },
    { pattern: /<{3,}(system|instruction|prompt)/i, severity: 'low' },
    { pattern: /\[{3,}(system|instruction|prompt)/i, severity: 'low' },
    { pattern: /\[SYSTEM\]/i, severity: 'low' },
    { pattern: /\[INSTRUCTION\]/i, severity: 'low' },
    { pattern: /\[ADMIN\]/i, severity: 'low' },
    { pattern: /\[OVERRIDE\]/i, severity: 'low' },
    { pattern: /<system>/i, severity: 'low' },
    { pattern: /<instruction>/i, severity: 'low' },
    { pattern: /<admin>/i, severity: 'low' },
    { pattern: /<override>/i, severity: 'low' },
  ];

  detect(input: string): InjectionDetectionResult {
    const findings: InjectionFinding[] = [];
    let riskScore = 0;

    for (const { pattern, severity } of PromptInjectionDefender.INJECTION_PATTERNS) {
      const matches = input.match(pattern);
      if (matches) {
        findings.push({
          pattern: pattern.source,
          matched: matches[0],
          severity,
        });
        riskScore += severity === 'high' ? 5 : severity === 'medium' ? 3 : 1;
      }
    }

    return {
      isInjection: findings.length > 0,
      riskScore: Math.min(10, riskScore),
      findings,
      recommendation: this.getRecommendation(riskScore),
    };
  }

  /**
   * 清理输入内容（移除明显的注入分隔符）
   * v0.2.0: 增加中文注入标记清理
   */
  sanitize(input: string): string {
    let cleaned = input;

    // 移除明显的分隔符注入
    cleaned = cleaned.replace(/-{3,}\s*(system|user|assistant|instruction).*$/gim, '[REMOVED]');
    cleaned = cleaned.replace(/<{3,}(system|instruction|prompt).*$/gim, '[REMOVED]');
    cleaned = cleaned.replace(/\[{3,}(system|instruction|prompt).*$/gim, '[REMOVED]');

    // v0.2.0: 移除间接注入标记
    cleaned = cleaned.replace(/\[(SYSTEM|INSTRUCTION|ADMIN|OVERRIDE)\]/gi, '[REMOVED]');
    cleaned = cleaned.replace(/<(system|instruction|admin|override)>/gi, '[REMOVED]');

    // v0.2.0: 移除编码注入
    cleaned = cleaned.replace(/\\x[0-9a-f]{2}/gi, '[REMOVED]');
    cleaned = cleaned.replace(/\\u[0-9a-f]{4}/gi, '[REMOVED]');
    cleaned = cleaned.replace(/eval\s*\(\s*atob\s*\([^)]*\)\s*\)/gi, '[REMOVED]');

    return cleaned.trim();
  }

  private getRecommendation(score: number): string {
    if (score >= 7) return 'BLOCK: High-risk injection detected';
    if (score >= 4) return 'WARN: Suspicious patterns found';
    if (score >= 1) return 'LOG: Minor suspicious patterns detected';
    return 'PASS: No injection patterns detected';
  }
}