import { PIIDetection, PIIType } from './detectors.js';
/**
* Pseudonymizer - replaces PII with numbered placeholders
* and supports optional restoration
*/
export class Pseudonymizer {
private counters: Map<PIIType, number> = new Map();
/**
* Pseudonymize text by replacing PII with placeholders
* Returns the modified text and a mapping for restoration
*/
pseudonymize(
text: string,
detections: PIIDetection[]
): { text: string; mappings: Map<string, string> } {
const mappings = new Map<string, string>();
let result = text;
let offset = 0;
// Reset counters for consistent numbering
this.counters.clear();
for (const detection of detections) {
const placeholder = this.generatePlaceholder(detection.type);
mappings.set(placeholder, detection.value);
// Replace in text (accounting for previous replacements)
const start = detection.startIndex + offset;
const end = detection.endIndex + offset;
result = result.substring(0, start) + placeholder + result.substring(end);
// Adjust offset for next replacement
offset += placeholder.length - detection.value.length;
}
return { text: result, mappings };
}
/**
* Restore placeholders in text with original values
*/
restore(text: string, mappings: Map<string, string>): string {
let result = text;
for (const [placeholder, original] of mappings) {
// Use global replace to handle multiple occurrences
result = result.replace(
new RegExp(this.escapeRegex(placeholder), 'g'),
original
);
}
return result;
}
/**
* Generate a placeholder for a PII type
*/
private generatePlaceholder(type: PIIType): string {
const count = (this.counters.get(type) || 0) + 1;
this.counters.set(type, count);
const typeLabels: Record<PIIType, string> = {
email: 'EMAIL',
phone: 'PHONE',
ssn: 'SSN',
api_key: 'API_KEY',
credit_card: 'CARD',
ip_address: 'IP',
custom: 'REDACTED',
};
return `[${typeLabels[type]}_${count}]`;
}
/**
* Escape special regex characters in a string
*/
private escapeRegex(str: string): string {
return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}
/**
* Reset counters (for testing)
*/
reset(): void {
this.counters.clear();
}
}
