// Stablecoin Audit Service
// HSM-signed audit generation

import prisma from '@/shared/database/prisma';
import type { Prisma } from '@prisma/client';
import { v4 as uuidv4 } from 'uuid';
import { createHash } from 'crypto';


export interface AuditRequest {
  stablecoinId: string;
  auditType: string; // daily_reserve, hsm_signed, zk_proof
}

export interface AuditResult {
  auditId: string;
  hsmSignature?: string;
  zkProof?: string;
  status: string;
}

export class StablecoinAuditService {
  /**
   * Create audit
   */
  async createAudit(request: AuditRequest): Promise<AuditResult> {
    const stablecoin = await prisma.sovereign_stablecoins.findUnique({
      where: { stablecoinId: request.stablecoinId },
      include: {
        stablecoin_collaterals: {
          where: { status: 'active' },
        },
      },
    });

    if (!stablecoin) {
      throw new Error(`Stablecoin not found: ${request.stablecoinId}`);
    }

    // Prepare audit data
    const auditData = {
      stablecoinId: request.stablecoinId,
      totalSupply: stablecoin.totalSupply.toString(),
      collaterals: stablecoin.stablecoin_collaterals.map(coll => ({
        assetType: coll.assetType,
        amount: coll.amount.toString(),
        valuation: coll.valuation.toString(),
      })),
      auditDate: new Date().toISOString(),
      auditType: request.auditType,
    };

    let hsmSignature: string | undefined;
    let zkProof: string | undefined;

    // Generate HSM signature if requested
    if (request.auditType === 'hsm_signed' || request.auditType === 'daily_reserve') {
      hsmSignature = await this.generateHSMSignature(auditData);
    }

    // Generate ZK proof if requested
    if (request.auditType === 'zk_proof') {
      zkProof = await this.generateZKProof(auditData);
    }

    // Create audit record
    const auditId = `AUDIT-${uuidv4()}`;
    const audit = await prisma.stablecoin_audits.create({
      data: {
        id: uuidv4(),
        auditId,
        stablecoinId: request.stablecoinId,
        auditDate: new Date(),
        auditType: request.auditType,
        hsmSignature: hsmSignature || null,
        zkProof: zkProof || null,
        auditResult: auditData as Prisma.InputJsonValue,
        status: 'pending',
        createdAt: new Date(),
        updatedAt: new Date(),
      },
    });

    return {
      auditId: audit.auditId,
      hsmSignature: audit.hsmSignature || undefined,
      zkProof: audit.zkProof || undefined,
      status: audit.status,
    };
  }

  /**
   * Generate HSM signature
   */
  private async generateHSMSignature(auditData: any): Promise<string> {
    // In production, this would call actual HSM
    // For now, generate a hash-based signature
    const dataString = JSON.stringify(auditData);
    const hash = createHash('sha3-256').update(dataString).digest('hex');
    return `HSM-SIG-${hash}`;
  }

  /**
   * Generate zero-knowledge proof
   */
  private async generateZKProof(auditData: any): Promise<string> {
    // In production, this would use actual ZK proof library
    // For now, generate a proof hash
    const dataString = JSON.stringify(auditData);
    const proof = createHash('sha3-256').update(dataString + 'ZK_PROOF').digest('hex');
    return `ZK-PROOF-${proof}`;
  }

  /**
   * Verify audit
   */
  async verifyAudit(auditId: string): Promise<boolean> {
    const audit = await prisma.stablecoin_audits.findUnique({
      where: { auditId },
    });

    if (!audit) {
      return false;
    }

    // Verify HSM signature if present
    if (audit.hsmSignature) {
      const expectedSignature = await this.generateHSMSignature(audit.auditResult);
      if (audit.hsmSignature !== expectedSignature) {
        return false;
      }
    }

    // Verify ZK proof if present
    if (audit.zkProof) {
      const expectedProof = await this.generateZKProof(audit.auditResult);
      if (audit.zkProof !== expectedProof) {
        return false;
      }
    }

    await prisma.stablecoin_audits.update({
      where: { auditId },
      data: {
        status: 'verified',
        verifiedAt: new Date(),
      },
    });

    return true;
  }

  /**
   * Get audit history
   */
  async getAuditHistory(
    stablecoinId: string,
    limit: number = 10
  ): Promise<any[]> {
    const audits = await prisma.stablecoin_audits.findMany({
      where: { stablecoinId },
      orderBy: { auditDate: 'desc' },
      take: limit,
    });

    return audits;
  }
}

export const stablecoinAuditService = new StablecoinAuditService();

