512 - Implementing a phones API

app/controllers/phones_controller.rb

@@ -1,8 +1,61 @@
 # frozen_string_literal: true
 
 class PhonesController < ApplicationController
+  def index
+    category_id = params.require :category_id
+
+    relation = get_all_resources(category_id)
+    render json: PhonesPresenter.present(relation)
+  end
+
+  def show
+    resource = Phone.find([params[:id]])
+    render json: PhonesPresenter.present(resource)
+  end
+
+  def get_all_resources(category_id)
+    relation = if category_id == "all"
+                  phones.where(status: Phone.statuses[:approved])
+               else
+                 # TODO: This can be simplified once we remove categories from resources
+                 phones
+                   .joins(:addresses)
+                   .where(categories_join_string, category_id, category_id)
+                   .where(status: Phone.statuses[:approved])
+                   .order(sort_order)
+               end
+    relation
+  end
+
   def destroy
     phone = Phone.find params[:id]
     phone.delete
   end
+
+  def phones
+    # Note: We *must* use #preload instead of #includes to force Rails to make a
+    # separate query per table. Otherwise, it creates one large query with many
+    # joins, which amplifies the amount of data being sent between Rails and the
+    # DB by several orders of magnitude due to duplication of tuples.
+    Phone.preload(:phones [:categories])
+  end
+
+  def categories_join_string
+    <<~'SQL'
+      phones.id IN (
+        (
+          SELECT resources.id
+            FROM resources
+            INNER JOIN categories_resources ON resources.id = categories_resources.resource_id
+            WHERE categories_resources.category_id = ?
+        ) UNION (
+          SELECT resources.id
+            FROM resources
+            INNER JOIN services ON resources.id = services.resource_id
+            INNER JOIN categories_services ON services.id = categories_services.service_id
+            WHERE categories_services.category_id = ?
+        )
+      )
+    SQL
+  end
 end

swagger/v1/swagger.json

@@ -1590,6 +1590,40 @@
           "application/json"
         ]
       }
+    },
+    "/phones/{id}": {
+      "get": {
+        "responses": {
+          "200": {
+            "examples": {
+              "application/json": {
+                    "id": "string",
+                    "number": "string",
+                    "extension": "string",
+                    "service_type": "string",
+                    "country_code": "string"
+              }
+            },
+            "description": "Phone Response"
+          }
+        },
+        "parameters": [
+          {
+            "name": "id",
+            "in": "path",
+            "type": "integer",
+            "description": "Phone ID",
+            "required": true
+          }
+        ],
+        "tags": [
+          "phones"
+        ],
+        "summary": "Retrieves phone numbers by id",
+        "produces" : [
+          "application/json"
+        ]
+      }
     }
   }
 }