import type { AnalyticsEvent, PrivacyConfig, ScreenEvent, UserTraits } from '../types';
import { deepClone, setNestedValue } from '../utils';

const DEFAULT_MASK = '***';

// Common PII field names to auto-detect
const KNOWN_PII_FIELDS = ['email', 'phone', 'password', 'ssn', 'credit_card', 'card_number'];

/**
 * Handles GDPR/privacy concerns:
 * - opt-out / opt-in toggle
 * - masks configured PII fields before events leave the device
 */
export class PrivacyManager {
  private config: PrivacyConfig;
  private optedOut: boolean;
  private maskFields: string[];

  constructor(config: PrivacyConfig = {}) {
    this.config = config;
    this.optedOut = config.defaultOptOut ?? false;
    this.maskFields = [
      ...KNOWN_PII_FIELDS,
      ...(config.maskFields ?? []),
    ];
  }

  optOut(): void {
    this.optedOut = true;
  }

  optIn(): void {
    this.optedOut = false;
  }

  isOptedIn(): boolean {
    return !this.optedOut;
  }

  sanitizeEvent(event: AnalyticsEvent): AnalyticsEvent {
    const cloned = deepClone(event);
    if (cloned.properties) {
      cloned.properties = this.maskObject(cloned.properties);
    }
    return cloned;
  }

  sanitizeScreenEvent(event: ScreenEvent): ScreenEvent {
    const cloned = deepClone(event);
    if (cloned.properties) {
      cloned.properties = this.maskObject(cloned.properties);
    }
    return cloned;
  }

  sanitizeTraits(traits: UserTraits): UserTraits {
    return this.maskObject(deepClone(traits)) as UserTraits;
  }

  private maskObject(obj: Record<string, any>): Record<string, any> {
    const maskValue = this.config.maskValue ?? DEFAULT_MASK;

    const walk = (target: Record<string, any>, path = ''): Record<string, any> => {
      const result: Record<string, any> = {};
      for (const key of Object.keys(target)) {
        const fullPath = path ? `${path}.${key}` : key;
        const value = target[key];

        const shouldMask = this.maskFields.some(
          (field) =>
            key.toLowerCase() === field.toLowerCase() ||
            fullPath.toLowerCase() === field.toLowerCase()
        );

        if (shouldMask) {
          result[key] = maskValue;
        } else if (value !== null && typeof value === 'object' && !Array.isArray(value)) {
          result[key] = walk(value, fullPath);
        } else {
          result[key] = value;
        }
      }
      return result;
    };

    return walk(obj);
  }
}