// DeFi Swap Service
// On-chain swaps with SCB oversight

import prisma from '@/shared/database/prisma';
import { Decimal } from '@prisma/client/runtime/library';
import { v4 as uuidv4 } from 'uuid';


export interface SwapRequest {
  moduleId: string;
  poolId?: string;
  sourceAssetType: string;
  targetAssetType: string;
  sourceAmount: string;
  participantBankId: string;
  scbOversight?: boolean;
}

export interface SwapResult {
  swapId: string;
  targetAmount: string;
  exchangeRate: string;
  onChainTxHash?: string;
  status: string;
}

export class DeFiSwapService {
  /**
   * Execute swap
   */
  async executeSwap(
    request: SwapRequest
  ): Promise<SwapResult> {
    const module = await prisma.deFiModule.findUnique({
      where: { moduleId: request.moduleId },
    });

    if (!module) {
      throw new Error(`Module not found: ${request.moduleId}`);
    }

    if (module.status !== 'active') {
      throw new Error(`Module is not active: ${module.status}`);
    }

    // Calculate exchange rate (simplified - in production would use AMM formula)
    const exchangeRate = await this.calculateExchangeRate(
      request.sourceAssetType,
      request.targetAssetType,
      request.poolId
    );

    const sourceAmount = new Decimal(request.sourceAmount);
    const targetAmount = sourceAmount.mul(exchangeRate);

    // Generate on-chain transaction hash (mock)
    const onChainTxHash = request.scbOversight !== false
      ? `TX-${uuidv4()}`
      : undefined;

    // Create swap record
    const swapId = `SWAP-${uuidv4()}`;
    const swap = await prisma.deFiSwap.create({
      data: {
        swapId,
        moduleId: request.moduleId,
        poolId: request.poolId || null,
        sourceAssetType: request.sourceAssetType,
        targetAssetType: request.targetAssetType,
        sourceAmount,
        targetAmount,
        exchangeRate,
        participantBankId: request.participantBankId,
        scbOversight: request.scbOversight !== false,
        onChainTxHash: onChainTxHash || null,
        status: 'executed',
        executedAt: new Date(),
      },
    });

    return {
      swapId: swap.swapId,
      targetAmount: swap.targetAmount.toString(),
      exchangeRate: swap.exchangeRate.toString(),
      onChainTxHash: swap.onChainTxHash || undefined,
      status: swap.status,
    };
  }

  /**
   * Calculate exchange rate
   */
  private async calculateExchangeRate(
    sourceAssetType: string,
    targetAssetType: string,
    poolId?: string
  ): Promise<Decimal> {
    // In production, would use AMM formula (e.g., constant product)
    // For now, return 1:1 rate
    return new Decimal(1);
  }

  /**
   * Get swap history
   */
  async getSwapHistory(
    moduleId: string,
    limit: number = 10
  ): Promise<any[]> {
    const swaps = await prisma.deFiSwap.findMany({
      where: { moduleId },
      orderBy: { executedAt: 'desc' },
      take: limit,
    });

    return swaps;
  }

  /**
   * Get swap by ID
   */
  async getSwap(swapId: string): Promise<any | null> {
    const swap = await prisma.deFiSwap.findUnique({
      where: { swapId },
      include: {
        module: true,
        pool: true,
      },
    });

    return swap;
  }
}

export const defiSwapService = new DeFiSwapService();

