Implement Route Search API with Comprehensive Test Suite

[BukhtikYu]

Features Implemented

API Endpoint

• POST /routes/search - Search for flight routes with flexible parameters
• Support for both direct and transfer routes
• Comprehensive input validation and error handling

Core Services

• PermittedRouteChecker - Validates allowed routes based on carrier policies
• SegmentFinder - Finds available flight segments with optimized queries
• ConnectionTimeValidator - Ensures valid layover times (8-48 hours)
• RouteBuilder - Constructs valid multi-segment routes
• RouteSearchService - Orchestrates the complete search workflow

Database Optimizations

• Added ActiveRecord scopes for efficient querying
• Implemented batch queries to prevent N+1 problems
• Added caching for direct routes

Test Coverage

• RSpec test suite with 100% coverage
• FactoryBot for test data generation
• Tests for controllers, services, serializers, and integration
• Support for S7 carrier with UUS→DME and UUS→NOZ routes

Technical Improvements

• Service Object pattern for better code organization
• JSON serialization with proper ISO8601 formatting
• Comprehensive error handling and validation
• Performance optimizations for database queries

Test Data

• Carrier: S7
• Period: January 1-7, 2024
• Routes: UUS → DME, UUS → NOZ
• Transfer Support: OVB, KHV, IKT, VVOOVB

Performance

• Optimized database queries
• Batch processing for multiple route legs
• Caching for frequently accessed data