import type { InjectionPattern, Finding, ScanResult } from '../types.js';

// Compiled at module load for performance (<20ms detection)
export const INJECTION_PATTERNS: InjectionPattern[] = [
  {
    name: 'Ignore instructions',
    pattern: /ignore\s+(all\s+)?(the\s+)?(previous|prior|above)\s+(instructions|prompts|rules)/i,
    severity: 'high',
  },
  {
    name: 'New persona',
    pattern: /you\s+are\s+(now|no\s+longer)\s+/i,
    severity: 'high',
  },
  {
    name: 'System prompt extraction',
    pattern: /(repeat|show|print|output|display)\s+(me\s+)?(your|the)\s+(system\s+)?(prompt|instructions|rules)/i,
    severity: 'high',
  },
  {
    name: 'Jailbreak attempt',
    pattern: /\b(DAN|STAN|DUDE|AIM|UCAR)\b.*\b(mode|personality|character)\b/i,
    severity: 'high',
  },
  {
    name: 'Forget instructions',
    pattern: /forget\s+(all\s+)?(your\s+)?(previous\s+)?(instructions|training|rules)/i,
    severity: 'high',
  },
  {
    name: 'Role override',
    pattern: /from\s+now\s+on.*(?:you\s+(?:are|will|must|should)|act\s+as|pretend)/i,
    severity: 'medium',
  },
  {
    name: 'Base64 command',
    pattern: /(?:decode|execute|run|eval)\s+(?:this\s+)?base64/i,
    severity: 'medium',
  },
  {
    name: 'Hidden instruction marker',
    pattern: /\[INST\]|\[\/INST\]|<\|im_start\|>|<\|im_end\|>/i,
    severity: 'high',
  },
  {
    name: 'XML injection',
    pattern: /<system>|<\/system>|<assistant>|<\/assistant>/i,
    severity: 'high',
  },
];

export const UNICODE_PATTERNS: InjectionPattern[] = [
  {
    name: 'Zero-width chars',
    pattern: /[\u200B-\u200F\u202A-\u202E\uFEFF\u2060-\u2064]/,
    severity: 'high',
  },
  {
    name: 'Right-to-left override',
    pattern: /[\u202D\u202E\u2066-\u2069]/,
    severity: 'medium',
  },
  {
    name: 'Tag characters',
    pattern: /[\u{E0001}-\u{E007F}]/u,
    severity: 'high',
  },
];

export function scanForInjection(text: string): ScanResult {
  const findings: Finding[] = [];

  for (const p of INJECTION_PATTERNS) {
    const match = p.pattern.exec(text);
    if (match) {
      findings.push({
        rule: p.name,
        hook: 'prompt-injection-detector',
        severity: p.severity,
        matched: match[0].slice(0, 40) + (match[0].length > 40 ? '...' : ''),
      });
    }
  }

  for (const p of UNICODE_PATTERNS) {
    const match = p.pattern.exec(text);
    if (match) {
      findings.push({
        rule: p.name,
        hook: 'prompt-injection-detector',
        severity: p.severity,
        matched: `unicode char U+${match[0].codePointAt(0)?.toString(16).toUpperCase()}`,
      });
    }
  }

  return { matched: findings.length > 0, findings };
}