// SCI Sovereign EVM (SEVM)
// Smart contract execution for CBDC workflows, FX swaps, commodity redemptions, settlement contracts

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


export interface SevmContractDeployRequest {
  zoneId: string;
  contractType: 'cbdc_workflow' | 'fx_swap' | 'commodity_redemption' | 'settlement_contract';
  contractCode: string;
  deployerBankId: string;
}

export interface SevmContractExecutionRequest {
  contractId: string;
  functionName: string;
  parameters: Record<string, unknown>;
  callerBankId: string;
}

export class SciSevmService {
  /**
   * Deploy smart contract to SEVM
   */
  async deployContract(request: SevmContractDeployRequest): Promise<{ contractId: string; contractAddress: string }> {
    const contractId = `SEVM-${uuidv4()}`;
    const contractAddress = this.generateContractAddress(contractId);

    // Calculate contract hash
    const contractHash = createHash('sha256').update(request.contractCode).digest('hex');

    // Deploy contract
    await prisma.sevmContract.create({
      data: {
        contractId,
        zoneId: request.zoneId,
        contractType: request.contractType,
        contractAddress,
        contractCode: request.contractCode,
        contractHash,
        deployerBankId: request.deployerBankId,
        status: 'deployed',
        deployedAt: new Date(),
      },
    });

    logger.info('SCI SEVM: Contract deployed', {
      contractId,
      contractAddress,
      contractType: request.contractType,
      zoneId: request.zoneId,
    });

    return { contractId, contractAddress };
  }

  /**
   * Execute smart contract function
   */
  async executeContract(request: SevmContractExecutionRequest): Promise<{ executionId: string; result: unknown }> {
    const executionId = `SEVM-EXEC-${uuidv4()}`;

    // Get contract
    const contract = await prisma.sevmContract.findUnique({
      where: { contractId: request.contractId },
    });

    if (!contract) {
      throw new Error('Contract not found');
    }

    if (contract.status !== 'active' && contract.status !== 'deployed') {
      throw new Error('Contract is not active');
    }

    // Verify caller has permission (simplified)
    const hasPermission = await this.verifyExecutionPermission(
      request.contractId,
      request.callerBankId
    );

    if (!hasPermission) {
      throw new Error('Caller does not have permission to execute contract');
    }

    // Execute contract function (simplified - in production would use actual EVM)
    const result = await this.executeContractFunction(
      contract.contractCode,
      request.functionName,
      request.parameters
    );

    logger.info('SCI SEVM: Contract executed', {
      executionId,
      contractId: request.contractId,
      functionName: request.functionName,
    });

    return { executionId, result };
  }

  /**
   * Generate contract address
   */
  private generateContractAddress(contractId: string): string {
    const hash = createHash('sha256').update(contractId).digest('hex');
    return `0x${hash.substring(0, 40)}`; // Ethereum-style address format
  }

  /**
   * Verify execution permission
   */
  private async verifyExecutionPermission(contractId: string, callerBankId: string): Promise<boolean> {
    const contract = await prisma.sevmContract.findUnique({
      where: { contractId },
    });

    if (!contract) {
      return false;
    }

    // Check if caller is deployer or has explicit permission
    // Simplified: only deployer can execute
    return contract.deployerBankId === callerBankId;
  }

  /**
   * Execute contract function (simplified)
   */
  private async executeContractFunction(
    contractCode: string,
    functionName: string,
    parameters: Record<string, unknown>
  ): Promise<unknown> {
    // In production, this would:
    // 1. Parse contract code
    // 2. Execute function in SEVM runtime
    // 3. Return result

    // For now, return a placeholder result
    return {
      functionName,
      parameters,
      executed: true,
      timestamp: new Date().toISOString(),
    };
  }

  /**
   * Get contract by address
   */
  async getContractByAddress(contractAddress: string) {
    return await prisma.sevmContract.findUnique({
      where: { contractAddress },
    });
  }
}

export const sciSevmService = new SciSevmService();

