// ZK-CBDC Validation: Mode 1 - ZK-Balance Proofs (zkBP)
import { Prisma } from '@prisma/client';
// Prove wallet has sufficient funds without revealing amount

import prisma from '@/shared/database/prisma';
import { v4 as uuidv4 } from 'uuid';
import { logger } from '@/infrastructure/monitoring/logger';


export interface ZkBalanceProofRequest {
  walletId: string;
  requiredAmount: string; // Amount to prove (not revealed in proof)
  currencyCode: string;
}

export interface ZkBalanceProof {
  proofId: string;
  proofData: string;
  publicInputs: {
    walletId: string;
    currencyCode: string;
    sufficient: boolean; // Only this is revealed, not the actual amount
  };
}

export class ZkBalanceProofService {
  /**
   * Generate ZK-Balance Proof
   * Proves wallet has >= requiredAmount without revealing the actual balance
   */
  async generateBalanceProof(request: ZkBalanceProofRequest): Promise<ZkBalanceProof> {
    const proofId = `ZKBP-${uuidv4()}`;

    // Get wallet balance (in production, this would be done securely)
    const wallet = await this.getWalletBalance(request.walletId, request.currencyCode);

    if (!wallet) {
      throw new Error('Wallet not found');
    }

    const actualBalance = parseFloat(wallet.balance);
    const requiredAmount = parseFloat(request.requiredAmount);

    // Check if balance is sufficient
    const sufficient = actualBalance >= requiredAmount;

    if (!sufficient) {
      throw new Error('Insufficient balance');
    }

    // Generate ZK proof (simplified - in production would use actual ZK library)
    // The proof demonstrates: balance >= requiredAmount without revealing balance
    const proofData = await this.generateZkProof({
      balance: actualBalance,
      requiredAmount,
      walletId: request.walletId,
    });

    // Create proof record
    await prisma.zkProof.create({
      data: {
        proofId,
        walletId: request.walletId,
        proofType: 'zkBP',
        proofData: proofData as string,
        publicInputs: {
          walletId: request.walletId,
          currencyCode: request.currencyCode,
          sufficient: true,
        } as Prisma.InputJsonValue,
        verificationKey: 'default_zkbp_vk', // In production, use actual verification key
        status: 'verified',
        verifiedAt: new Date(),
      },
    });

    logger.info('ZK-CBDC: Generated ZK-Balance Proof', {
      proofId,
      walletId: request.walletId,
      sufficient,
    });

    return {
      proofId,
      proofData,
      publicInputs: {
        walletId: request.walletId,
        currencyCode: request.currencyCode,
        sufficient: true,
      },
    };
  }

  /**
   * Verify ZK-Balance Proof
   */
  async verifyBalanceProof(proofId: string): Promise<boolean> {
    const proof = await prisma.zkProof.findUnique({
      where: { proofId },
    });

    if (!proof || proof.proofType !== 'zkBP') {
      return false;
    }

    // Verify proof (simplified - in production would use ZK verification)
    const isValid = await this.verifyZkProof(proof.proofData, proof.publicInputs as Prisma.InputJsonValue);

    if (isValid) {
      await prisma.zkProof.update({
        where: { proofId },
        data: {
          status: 'verified',
          verifiedAt: new Date(),
        },
      });
    }

    return isValid;
  }

  /**
   * Get wallet balance (internal)
   */
  private async getWalletBalance(walletId: string, currencyCode: string) {
    // In production, this would query CBDC wallet system
    // For now, simplified lookup
    return await prisma.bankAccount.findFirst({
      where: {
        accountNumber: walletId,
        currencyCode,
        assetType: 'cbdc',
      },
      select: {
        balance: true,
      },
    });
  }

  /**
   * Generate ZK proof (placeholder - in production would use circom/snarkjs)
   */
  private async generateZkProof(data: {
    balance: number;
    requiredAmount: number;
    walletId: string;
  }): Promise<string> {
    // In production, this would:
    // 1. Create circuit witness
    // 2. Generate proof using snarkjs or similar
    // 3. Return proof data

    // For now, return a placeholder proof
    return JSON.stringify({
      type: 'zkBP',
      balance: data.balance,
      requiredAmount: data.requiredAmount,
      proof: 'placeholder_zk_proof',
    });
  }

  /**
   * Verify ZK proof (placeholder)
   */
  private async verifyZkProof(proofData: string, publicInputs: Record<string, unknown>): Promise<boolean> {
    // In production, this would:
    // 1. Parse proof data
    // 2. Verify using snarkjs or similar
    // 3. Return verification result

    // For now, simplified check
    try {
      const proof = JSON.parse(proofData);
      return proof.type === 'zkBP' && publicInputs.sufficient === true;
    } catch {
      return false;
    }
  }
}

export const zkBalanceProofService = new ZkBalanceProofService();

