// HSM Integration Service - Mock implementation with real interface

import crypto from 'crypto';
import { IdentityType } from '@/shared/types';

export interface HSMKey {
  keyId: string;
  keyType: 'ECC-521' | 'RSA-4096' | 'AES-256';
  publicKey: string;
  status: 'active' | 'suspended' | 'destroyed';
  createdAt: Date;
}

export interface HSMSignature {
  signature: string;
  algorithm: string;
  keyId: string;
  timestamp: Date;
}

/**
 * HSM Service Interface
 * Modes: HSM_MODE=mock (default) uses software crypto for development.
 *        HSM_MODE=real requires actual HSM hardware/API - throws if not integrated.
 * Set HSM_MODE=real only when HSM provider (AWS CloudHSM, Thales, etc.) is configured.
 */
export class HSMService {
  private keys: Map<string, HSMKey> = new Map();
  private readonly mockHSMEnabled: boolean;

  constructor() {
    const mode = process.env.HSM_MODE || process.env.HSM_ENABLED;
    this.mockHSMEnabled = mode !== 'real' && mode !== 'false';
  }

  /**
   * Generate a new key pair in HSM
   */
  async generateKeyPair(
    keyType: 'ECC-521' | 'RSA-4096' = 'ECC-521',
    label?: string
  ): Promise<HSMKey> {
    if (this.mockHSMEnabled) {
      // Mock implementation - in production, this would call HSM hardware
      const keyId = `HSM-${Date.now()}-${crypto.randomBytes(8).toString('hex')}`;
      
      let publicKey: string;
      if (keyType === 'ECC-521') {
        const { publicKey: pubKey } = crypto.generateKeyPairSync('ec', {
          namedCurve: 'secp521r1',
          publicKeyEncoding: { type: 'spki', format: 'pem' },
        });
        publicKey = pubKey;
      } else {
        const { publicKey: pubKey } = crypto.generateKeyPairSync('rsa', {
          modulusLength: 4096,
          publicKeyEncoding: { type: 'spki', format: 'pem' },
        });
        publicKey = pubKey;
      }

      const key: HSMKey = {
        keyId,
        keyType,
        publicKey,
        status: 'active',
        createdAt: new Date(),
      };

      this.keys.set(keyId, key);
      return key;
    }

    throw new Error(
      'Real HSM required: Set HSM_MODE=mock for development, or integrate HSM provider (AWS CloudHSM, Thales) for production'
    );
  }

  /**
   * Sign data using HSM key
   */
  async sign(data: string, keyId: string): Promise<HSMSignature> {
    const key = this.keys.get(keyId);
    if (!key || key.status !== 'active') {
      throw new Error(`HSM key not found or inactive: ${keyId}`);
    }

    if (this.mockHSMEnabled) {
      // Mock implementation
      const sign = crypto.createSign('SHA256');
      sign.update(data);
      
      // In mock mode, we'd need the private key, but in real HSM, signing happens in hardware
      // For now, we'll create a mock signature
      const signature = crypto.randomBytes(64).toString('hex');

      return {
        signature,
        algorithm: key.keyType === 'ECC-521' ? 'ECDSA-SHA256' : 'RSA-SHA256',
        keyId,
        timestamp: new Date(),
      };
    }

    // In production, call actual HSM signing API
    throw new Error('Real HSM signing not implemented - use mock mode');
  }

  /**
   * Verify signature using HSM key
   */
  async verify(data: string, signature: string, keyId: string): Promise<boolean> {
    const key = this.keys.get(keyId);
    if (!key) {
      return false;
    }

    if (this.mockHSMEnabled) {
      // Mock implementation - in production, verification might also happen in HSM
      // For now, we'll do a simple check
      return signature.length > 0;
    }

    throw new Error(
      'Real HSM verification required: Set HSM_MODE=mock for development'
    );
  }

  /**
   * Get key information
   */
  async getKey(keyId: string): Promise<HSMKey | null> {
    return this.keys.get(keyId) || null;
  }

  /**
   * Suspend a key
   */
  async suspendKey(keyId: string): Promise<void> {
    const key = this.keys.get(keyId);
    if (key) {
      key.status = 'suspended';
      this.keys.set(keyId, key);
    }
  }

  /**
   * Activate a suspended key
   */
  async activateKey(keyId: string): Promise<void> {
    const key = this.keys.get(keyId);
    if (key) {
      key.status = 'active';
      this.keys.set(keyId, key);
    }
  }

  /**
   * Destroy a key (cryptographic shred)
   */
  async destroyKey(keyId: string): Promise<void> {
    const key = this.keys.get(keyId);
    if (key) {
      key.status = 'destroyed';
      this.keys.set(keyId, key);
    }
  }

  /**
   * Rotate a key (generate new, mark old for destruction)
   */
  async rotateKey(
    oldKeyId: string,
    keyType: 'ECC-521' | 'RSA-4096' = 'ECC-521'
  ): Promise<HSMKey> {
    const newKey = await this.generateKeyPair(keyType);
    await this.destroyKey(oldKeyId);
    return newKey;
  }
}

export const hsmService = new HSMService();

