Add API for finding routes

Gemfile

@@ -43,7 +43,9 @@ group :development, :test do
   gem "brakeman", require: false
   gem "rubocop-rails-omakase", require: false
 
-  gem 'factory_bot_rails'
-  gem 'rspec-rails'
-end
+  gem "factory_bot_rails"
+  gem "rspec-rails"
 
+  gem "pry-byebug"
+  gem "pry-rails"
+end

Gemfile.lock

@@ -82,6 +82,8 @@ GEM
     brakeman (7.1.0)
       racc
     builder (3.3.0)
+    byebug (12.0.0)
+    coderay (1.1.3)
     concurrent-ruby (1.3.5)
     connection_pool (2.5.3)
     crass (1.0.6)
@@ -139,6 +141,7 @@ GEM
       net-pop
       net-smtp
     marcel (1.0.4)
+    method_source (1.1.0)
     mini_mime (1.1.5)
     minitest (5.25.5)
     msgpack (1.8.0)
@@ -186,6 +189,14 @@ GEM
       prettyprint
     prettyprint (0.2.0)
     prism (1.4.0)
+    pry (0.15.2)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    pry-byebug (3.11.0)
+      byebug (~> 12.0)
+      pry (>= 0.13, < 0.16)
+    pry-rails (0.3.11)
+      pry (>= 0.13.0)
     psych (5.2.6)
       date
       stringio
@@ -347,6 +358,8 @@ DEPENDENCIES
   factory_bot_rails
   kamal
   pg (>= 1.1)
+  pry-byebug
+  pry-rails
   puma (>= 5.0)
   rails (~> 8.0.2, >= 8.0.2.1)
   rspec-rails

app/controllers/api/v1/flight_searches_controller.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Api
+  module V1
+    class FlightSearchesController < ApplicationController
+      before_action :check_departure_dates, only: [ :index ]
+
+      def index
+        search_params = params.permit(:carrier, :origin_iata, :destination_iata, :departure_from, :departure_to)
+
+        routes = FlightRouteSearchService.call(search_params)
+
+        render json: routes, status: (routes.any? ? :ok : :not_found)
+      end
+
+      private
+
+      def check_departure_dates
+        if params[:departure_from].blank? || params[:departure_to].blank?
+          render json: [], status: :unprocessable_entity
+        end
+      end
+    end
+  end
+end

app/models/permitted_route.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Schema Information
 #
 # Table name: permitted_routes
@@ -14,4 +16,4 @@
 
 class PermittedRoute < ApplicationRecord
   validates :carrier, :origin_iata, :destination_iata, presence: true
-end
+end

app/models/segment.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Schema Information
 #
 # Table name: segments
@@ -16,4 +18,4 @@
 class Segment < ApplicationRecord
   validates :airline, :segment_number, presence: true
   validates :origin_iata, :destination_iata, presence: true, length: { is: 3 }
-end
+end

app/services/flight_route/finder.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module FlightRoute
+  class Finder
+    def self.call(carrier:, origin:, destination:)
+      query = <<-SQL.squish
+        WITH transferpoint_routes AS (
+          SELECT
+            pr.id,
+            pr.origin_iata,
+            pr.destination_iata,
+            tp AS transferpoint
+          FROM permitted_routes pr
+          CROSS JOIN LATERAL unnest(COALESCE(pr.transfer_iata_codes, ARRAY[]::text[])) AS tp
+          WHERE pr.origin_iata = '#{origin}' AND pr.destination_iata = '#{destination}' AND pr.carrier = '#{carrier}'#{' '}
+        ),
+        direct_only AS (
+          SELECT
+            pr.id,
+            pr.origin_iata,
+            pr.destination_iata,
+            NULL::text AS transferpoint
+          FROM permitted_routes pr
+          WHERE pr.direct = true
+            AND pr.origin_iata = '#{origin}'
+            AND pr.destination_iata = '#{destination}'
+            AND pr.carrier = '#{carrier}'
+        )
+        SELECT
+          id,
+          origin_iata,
+          destination_iata,
+          CASE
+            WHEN transferpoint IS NULL THEN ARRAY[origin_iata, destination_iata]
+            ELSE ARRAY[origin_iata, transferpoint, destination_iata]#{' '}
+          END AS route
+        FROM (
+          SELECT * FROM transferpoint_routes
+          UNION ALL
+          SELECT * FROM direct_only
+        ) all_routes
+        ORDER BY id, route;
+      SQL
+
+      ActiveRecord::Base.connection.execute(query).to_a.map do |row|
+        row["route"] = row["route"].delete("{}").split(",")
+        row
+      end
+    end
+  end
+end

app/services/flight_route/validator.rb

@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+module FlightRoute
+  class Validator
+    MIN_CONNECTION_TIME = 480.minutes   # 8 часов
+    MAX_CONNECTION_TIME = 2880.minutes  # 48 часов
+
+    class << self
+      def available_routes(routes, airline:, departure_from:, departure_to:)
+        segments_map = build_segments_map(routes, airline, departure_from, departure_to)
+
+        routes.map do |route_hash|
+          route = route_hash[:route] || route_hash["route"]
+          segments_sequence = route_segments(route, segments_map)
+          next unless segments_sequence
+
+          {
+              origin_iata: segments_sequence.first.origin_iata,
+              destination_iata: segments_sequence.last.destination_iata,
+              departure_time: segments_sequence.first.std,
+              arrival_time: segments_sequence.last.sta,
+              segments: segments_sequence.map do |s|
+                {
+                    carrier: s.airline,
+                    segment_number: s.segment_number,
+                    origin_iata: s.origin_iata,
+                    destination_iata: s.destination_iata,
+                    std: s.std,
+                    sta: s.sta
+                }
+              end
+          }
+        end.compact
+      end
+
+      private
+
+      def expand_route(route)
+        route.flat_map { |point| point.length > 3 ? point.scan(/.{3}/) : [ point ] }
+      end
+
+      def route_segments(route, segments_map)
+        expanded_route = expand_route(route)
+        segments_sequence = []
+
+        expanded_route.each_cons(2) do |from_iata, to_iata|
+          possible_segments = segments_map[[ from_iata, to_iata ]] || []
+          return nil if possible_segments.empty?
+
+          if segments_sequence.empty?
+            segment = possible_segments.first
+          else
+            prev = segments_sequence.last
+            segment = possible_segments.find do |s|
+              layover = s.std - prev.sta
+              layover >= MIN_CONNECTION_TIME && layover <= MAX_CONNECTION_TIME
+            end
+          end
+
+          return nil unless segment
+          segments_sequence << segment
+        end
+
+        segments_sequence
+      end
+
+      def build_segments_map(routes, airline, departure_from, departure_to)
+        from = Date.parse(departure_from).beginning_of_day
+        to   = Date.parse(departure_to).end_of_day
+
+        pairs = routes.flat_map do |route_hash|
+          route = route_hash[:route] || route_hash["route"]
+          expand_route(route).each_cons(2).to_a
+        end.uniq
+
+        segments = Segment.where([ pairs.map { |from, to| "(origin_iata = ? AND destination_iata = ?)" }.join(" OR "), *pairs.flatten ])
+                     .where(airline: airline)
+                     .where(std: from..to)
+                     .order(:std)
+
+        segments_map = Hash.new { |h, k| h[k] = [] }
+        segments.each { |s| segments_map[[ s.origin_iata, s.destination_iata ]] << s }
+        segments_map
+      end
+    end
+  end
+end

app/services/flight_route_search_service.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+class FlightRouteSearchService
+  def self.call(params)
+    new(params).call
+  end
+
+  def initialize(params)
+    @carrier = params[:carrier]
+    @origin_iata = params[:origin_iata]
+    @destination_iata = params[:destination_iata]
+    @departure_from = params[:departure_from]
+    @departure_to = params[:departure_to]
+  end
+
+  def call
+    routes = FlightRoute::Finder.call(carrier: @carrier, origin: @origin_iata, destination: @destination_iata)
+    available_routes = []
+
+    if routes.any?
+      available_routes = FlightRoute::Validator.available_routes(
+        routes,
+        airline: @carrier,
+        departure_from: @departure_from,
+        departure_to: @departure_to
+      )
+    end
+
+    available_routes
+  end
+end

config/routes.rb

@@ -7,4 +7,10 @@
 
   # Defines the root path route ("/")
   # root "posts#index"
+
+  namespace :api do
+    namespace :v1 do
+      resources :flight_searches, only: [ :index ]
+    end
+  end
 end