trading-platform-backend-v2/src/modules/payments/services/refund.service.ts

/**
 * Refund Service
 * Handles financial.refunds operations with approval flow
 */

import { db } from '../../../shared/database';
import type { Refund, RefundRow, RequestRefundInput, RefundStatus } from '../types/financial.types';

// ============================================================================
// Transform Functions
// ============================================================================

function transformRefund(row: RefundRow): Refund {
  return {
    id: row.id,
    paymentId: row.payment_id,
    amount: parseFloat(row.amount),
    currency: row.currency,
    reason: row.reason,
    reasonCode: row.reason_code,
    notes: row.notes,
    status: row.status as RefundStatus,
    stripeRefundId: row.stripe_refund_id,
    stripeFailureReason: row.stripe_failure_reason,
    requestedBy: row.requested_by,
    approvedBy: row.approved_by,
    approvedAt: row.approved_at ? new Date(row.approved_at) : null,
    rejectedAt: row.rejected_at ? new Date(row.rejected_at) : null,
    rejectionReason: row.rejection_reason,
    createdAt: new Date(row.created_at),
    processedAt: row.processed_at ? new Date(row.processed_at) : null,
    completedAt: row.completed_at ? new Date(row.completed_at) : null,
    failedAt: row.failed_at ? new Date(row.failed_at) : null,
  };
}

// ============================================================================
// Query Functions
// ============================================================================

export async function getRefundById(id: string): Promise<Refund | null> {
  const result = await db.query<RefundRow>(
    'SELECT * FROM financial.refunds WHERE id = $1',
    [id]
  );
  return result.rows[0] ? transformRefund(result.rows[0]) : null;
}

export async function getRefundsForPayment(paymentId: string): Promise<Refund[]> {
  const result = await db.query<RefundRow>(
    'SELECT * FROM financial.refunds WHERE payment_id = $1 ORDER BY created_at DESC',
    [paymentId]
  );
  return result.rows.map(transformRefund);
}

export async function getPendingRefunds(): Promise<Refund[]> {
  const result = await db.query<RefundRow>(
    `SELECT * FROM financial.refunds WHERE status = 'pending' ORDER BY created_at ASC`
  );
  return result.rows.map(transformRefund);
}

export async function getRefundsByStatus(status: RefundStatus): Promise<Refund[]> {
  const result = await db.query<RefundRow>(
    'SELECT * FROM financial.refunds WHERE status = $1 ORDER BY created_at DESC',
    [status]
  );
  return result.rows.map(transformRefund);
}

export async function getRefundsByUser(userId: string): Promise<Refund[]> {
  const result = await db.query<RefundRow>(
    'SELECT * FROM financial.refunds WHERE requested_by = $1 ORDER BY created_at DESC',
    [userId]
  );
  return result.rows.map(transformRefund);
}

// ============================================================================
// Mutation Functions
// ============================================================================

export async function requestRefund(
  requestedBy: string,
  input: RequestRefundInput
): Promise<Refund> {
  const result = await db.query<RefundRow>(
    `INSERT INTO financial.refunds
     (payment_id, amount, reason, reason_code, notes, requested_by, status)
     VALUES ($1, $2, $3, $4, $5, $6, 'pending')
     RETURNING *`,
    [
      input.paymentId,
      input.amount,
      input.reason || null,
      input.reasonCode || null,
      input.notes || null,
      requestedBy,
    ]
  );
  return transformRefund(result.rows[0]);
}

export async function approveRefund(
  id: string,
  approvedBy: string
): Promise<Refund | null> {
  const result = await db.query<RefundRow>(
    `UPDATE financial.refunds
     SET status = 'processing', approved_by = $2, approved_at = NOW()
     WHERE id = $1 AND status = 'pending'
     RETURNING *`,
    [id, approvedBy]
  );
  return result.rows[0] ? transformRefund(result.rows[0]) : null;
}

export async function rejectRefund(
  id: string,
  rejectedBy: string,
  reason: string
): Promise<Refund | null> {
  const result = await db.query<RefundRow>(
    `UPDATE financial.refunds
     SET status = 'cancelled', rejected_at = NOW(), rejection_reason = $3
     WHERE id = $1 AND status = 'pending'
     RETURNING *`,
    [id, rejectedBy, reason]
  );
  return result.rows[0] ? transformRefund(result.rows[0]) : null;
}

export async function completeRefund(
  id: string,
  stripeRefundId: string
): Promise<Refund | null> {
  const result = await db.query<RefundRow>(
    `UPDATE financial.refunds
     SET status = 'succeeded', stripe_refund_id = $2, completed_at = NOW(), processed_at = NOW()
     WHERE id = $1
     RETURNING *`,
    [id, stripeRefundId]
  );
  return result.rows[0] ? transformRefund(result.rows[0]) : null;
}

export async function failRefund(
  id: string,
  failureReason: string
): Promise<Refund | null> {
  const result = await db.query<RefundRow>(
    `UPDATE financial.refunds
     SET status = 'failed', stripe_failure_reason = $2, failed_at = NOW()
     WHERE id = $1
     RETURNING *`,
    [id, failureReason]
  );
  return result.rows[0] ? transformRefund(result.rows[0]) : null;
}

// ============================================================================
// Refund Service Object (Alternative Export)
// ============================================================================

export const refundService = {
  getById: getRefundById,
  getForPayment: getRefundsForPayment,
  getPending: getPendingRefunds,
  getByStatus: getRefundsByStatus,
  getByUser: getRefundsByUser,
  request: requestRefund,
  approve: approveRefund,
  reject: rejectRefund,
  complete: completeRefund,
  fail: failRefund,
};