🔧 [Day 1 - Afternoon] Backend Core Services Implementation

[uozopio]

📋 Task Overview

Sprint Day: Day 1 - Afternoon Session
Time Slot: 14:00 - 18:00 (4 hours)
Task Type: Individual Backend Development
Estimated Duration: 4 hours
Dependencies: Core Services Foundation (Issue #5)

🎯 Objectives

Complete the implementation of core backend services including full EscrowService with transaction management, PaymentService with Jetcheckout integration, and comprehensive API route handlers with validation and error handling.

📝 Detailed Requirements

1. Complete EscrowService Implementation (1.5 hours)

• Implement full transaction lifecycle management:
  • createEscrowTransaction() with full validation
  • updateTransactionStatus() with state machine integration
  • getTransactionById() with related data loading
  • listUserTransactions() with pagination and filtering
  • cancelTransaction() with refund triggering
  • completeTransaction() with fund release logic
• Add business rule validations:
  • Minimum/maximum transaction amounts
  • User verification requirements
  • Product category-specific rules
  • Time-based constraints (expiry handling)
• Implement activity logging:
  • Log all state transitions
  • Track user actions with metadata
  • Store IP addresses and user agents
• Add transaction search capabilities:
  • Search by transaction number
  • Filter by status, date range, amount
  • Sort by multiple fields

2. PaymentService with Jetcheckout Integration (1.5 hours)

• Implement Jetcheckout API integration:
  • initializePayment() with proper payload structure
  • generateSecurityHash() using merchant credentials
  • verifyPaymentHash() for webhook validation
  • parseWebhookPayload() with type safety
• Create payment processing methods:
  • Handle credit card payments with 3D Secure
  • Support saved card functionality
  • Implement partial payment logic
  • Add payment retry mechanism
• Build webhook handling:
  • Set up webhook endpoint structure
  • Implement signature verification
  • Handle success/failure callbacks
  • Add idempotency checks
• Add payment utilities:
  • Currency conversion helpers
  • Fee calculation methods
  • Payment method validation
  • Transaction reconciliation

3. API Route Handlers Implementation (2 hours)

• Escrow API Routes (/api/escrow/*):

  • POST /api/escrow/create - Create new escrow with validation
  • GET /api/escrow/[id] - Get transaction with authorization
  • PUT /api/escrow/[id]/status - Update status with state validation
  • GET /api/escrow/list - List user transactions with pagination
  • POST /api/escrow/[id]/cancel - Cancel with refund logic
  • POST /api/escrow/[id]/complete - Complete transaction
  • GET /api/escrow/[id]/activity - Get activity log

• Payment API Routes (/api/payment/*):

  • POST /api/payment/initialize - Start payment process
  • POST /api/payment/webhook - Handle gateway callbacks
  • GET /api/payment/verify/[ref] - Verify payment status
  • POST /api/payment/refund - Process refunds
  • GET /api/payment/methods - Get available payment methods

• Admin API Routes (/api/admin/*):

  • GET /api/admin/transactions - List all transactions
  • GET /api/admin/dashboard/stats - Dashboard statistics
  • PUT /api/admin/transaction/[id] - Admin override actions
  • GET /api/admin/users - List platform users
  • GET /api/admin/disputes - View active disputes

• Common Middleware:

  • Authentication middleware using Clerk
  • Request validation with Zod schemas
  • Rate limiting per endpoint
  • Error handling wrapper
  • Request/response logging

🔧 Technical Context

API Design Standards

• RESTful Principles: Proper HTTP methods and status codes
• Input Validation: Zod schemas for all endpoints
• Error Responses: Consistent error format with codes
• Authentication: JWT validation via Clerk
• Authorization: Role-based access control (RBAC)

Jetcheckout Integration Details

Database Optimization

• Use database transactions for multi-step operations
• Implement proper indexing for frequent queries
• Add connection pooling for performance
• Use select/include wisely to avoid N+1 queries

Security Considerations

• Validate all inputs against injection attacks
• Implement rate limiting (100 req/min per user)
• Log all sensitive operations
• Sanitize error messages for production
• Add CORS configuration

✅ Acceptance Criteria

• All API endpoints return proper responses
• Payment integration can process test transactions
• State machine enforces valid transitions
• Error handling covers all edge cases
• API routes have proper authentication
• Admin endpoints require admin role
• All services have TypeScript types
• Basic integration tests pass

👥 Developer Assignment

Lead Developer: @uozopio (Umut)
Role: Backend Core Services & API Development
Availability for Questions: Slack #dev-backend channel

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This task is part of the 2-day MVP sprint for the Paylox Escrow System