handle chip and chip values operations

app/controllers/chip_values_controller.rb

@@ -0,0 +1,40 @@
+class ChipValuesController < ApplicationController
+
+  def create
+    if ChipValue.create_full_chip_value(chip_value_params)
+      json_response all_chips_response
+    else
+      error_response :bad_request
+    end
+  rescue StandardError
+    error_response :bad_request
+  end
+
+  def update
+    if ChipValue.update_full_chip_value(chip_value_params)
+      json_response all_chips_response
+    end
+  rescue StandardError
+    error_response :bad_request
+  end
+
+  def destroy
+    if ChipValue.destroy_full_chip_value(params[:id])
+      json_response all_chips_response
+    else
+      error_response :bad_request
+    end
+  rescue StandardError
+    error_response :bad_request
+  end
+
+  private
+
+  def chip_value_params
+    params.require(:chip_value).permit(:id, :base_chip_id, :secondary_chip_id, :value)
+  end
+
+  def all_chips_response
+    Chip.all.order(:name).to_json(include: :base_chip_values)
+  end
+end

app/controllers/chips_controller.rb

@@ -0,0 +1,29 @@
+class ChipsController < ApplicationController
+  def index
+    json_response Chip.all.order(:name).to_json(include: :base_chip_values)
+  end
+
+  def create
+    chip = Chip.new(chip_params)
+    if chip.save
+      json_response chip
+    else
+      error_response :bad_request
+    end
+  end
+
+  def destroy
+    chip_id = params[:id]
+    if chip_id.present? && Chip.destroy(chip_id)
+      index
+    else
+      error_response :bad_request
+    end
+  end
+
+  private
+
+  def chip_params
+    params.require(:chip).permit(:id, :name, :symbol, :enabled)
+  end
+end

app/models/chip.rb

@@ -0,0 +1,23 @@
+class Chip < ApplicationRecord
+  has_many :base_chip_values, class_name: "ChipValue", foreign_key: "base_chip_id", dependent: :delete_all
+  has_many :secondary_chip_values, class_name: "ChipValue", foreign_key: "secondary_chip_id", dependent: :delete_all
+
+  validates :name, uniqueness: true
+  validates :name, :symbol, presence: true
+
+  after_create :add_chip_values
+
+  private
+
+  # When new chip(currency) is added, add new record to the chip_values table for every existing chip(currency)
+  def add_chip_values
+    Chip.all.each do |chip|
+      next if chip.name == name
+
+      transaction do
+        ChipValue.new(base_chip: self, secondary_chip: chip, value: 0).save
+        ChipValue.new(base_chip: chip, secondary_chip: self, value: 0).save
+      end
+    end
+  end
+end

app/models/chip_value.rb

@@ -0,0 +1,53 @@
+class ChipValue < ApplicationRecord
+  belongs_to :base_chip, class_name: 'Chip'
+  belongs_to :secondary_chip, class_name: 'Chip'
+
+  validates :base_chip_id, uniqueness: { scope: :secondary_chip_id }
+
+  def self.create_full_chip_value(params)
+    base_chip_id = params[:base_chip_id]
+    secondary_chip_id = params[:secondary_chip_id]
+    value = params[:value].to_f
+
+    chips = Chip.where(id: [base_chip_id, secondary_chip_id])
+    base_chip = chips.first
+    secondary_chip = chips.second
+
+    mirrored_value = value.zero? ? 0 : (1 / value)
+
+    base_chip_value = ChipValue.new(base_chip: base_chip, secondary_chip: secondary_chip, value: value)
+    mirrored_chip_value = ChipValue.new(base_chip: secondary_chip, secondary_chip: base_chip, value: mirrored_value)
+
+    transaction do
+      base_chip_value.save
+      mirrored_chip_value.save
+    end
+  end
+
+  def self.update_full_chip_value(params)
+    id = params[:id]
+    new_value = params[:value].to_f
+    mirrored_value = new_value.zero? ? 0 : (1 / new_value)
+
+    chip_value = ChipValue.find(id)
+    mirrored_chip_value = ChipValue.where(base_chip_id: chip_value.secondary_chip_id, secondary_chip_id: chip_value.base_chip_id).first
+
+    chip_value.value = new_value
+    mirrored_chip_value.value = mirrored_value
+
+    transaction do
+      chip_value.save
+      mirrored_chip_value.save
+    end
+  end
+
+  def self.destroy_full_chip_value(id)
+    chip_value = ChipValue.find(id)
+    mirrored_chip_value = ChipValue.where(base_chip_id: chip_value.secondary_chip_id, secondary_chip_id: chip_value.base_chip_id).first
+
+    transaction do
+      chip_value.destroy
+      mirrored_chip_value.destroy
+    end
+  end
+end

config/routes.rb

@@ -1,8 +1,10 @@
 Rails.application.routes.draw do
   constraints format: :json do
-    resources :money_moves    
-    resources :homies  do 
-      collection do 
+    resources :money_moves
+    resources :chips, only: %i[index create destroy]
+    resources :chip_values, only: %i[create update destroy]
+    resources :homies do
+      collection do
         get 'cash'
       end
     end

db/migrate/20200827113649_create_chips.rb

@@ -0,0 +1,12 @@
+class CreateChips < ActiveRecord::Migration[5.2]
+  def change
+    create_table :chips do |t|
+      t.text :name, null: false
+      t.text :symbol, null: false
+      t.boolean :enabled, default: true
+      t.timestamps
+    end
+
+    add_index :chips, :name, unique: true
+  end
+end

db/migrate/20200827142428_create_chip_values.rb

@@ -0,0 +1,12 @@
+class CreateChipValues < ActiveRecord::Migration[5.2]
+  def change
+    create_table :chip_values do |t|
+      t.references :base_chip, foreign_key: { to_table: :chips }
+      t.references :secondary_chip, foreign_key: { to_table: :chips }
+      t.decimal :value, precision: 12, scale: 3, null: false
+      t.timestamps
+
+      t.index [:base_chip_id, :secondary_chip_id], unique: true
+    end
+  end
+end

db/schema.rb

@@ -10,11 +10,31 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_06_20_200006) do
+ActiveRecord::Schema.define(version: 2020_08_27_142428) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
+  create_table "chip_values", force: :cascade do |t|
+    t.bigint "base_chip_id"
+    t.bigint "secondary_chip_id"
+    t.decimal "value", precision: 12, scale: 3, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["base_chip_id", "secondary_chip_id"], name: "index_chip_values_on_base_chip_id_and_secondary_chip_id", unique: true
+    t.index ["base_chip_id"], name: "index_chip_values_on_base_chip_id"
+    t.index ["secondary_chip_id"], name: "index_chip_values_on_secondary_chip_id"
+  end
+
+  create_table "chips", force: :cascade do |t|
+    t.text "name", null: false
+    t.text "symbol", null: false
+    t.boolean "enabled", default: true
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["name"], name: "index_chips_on_name", unique: true
+  end
+
   create_table "homies", force: :cascade do |t|
     t.text "name", null: false
     t.integer "importance", default: 5, null: false
@@ -31,4 +51,6 @@ ActiveRecord::Schema.define(version: 2019_06_20_200006) do
     t.datetime "updated_at", null: false
   end
 
+  add_foreign_key "chip_values", "chips", column: "base_chip_id"
+  add_foreign_key "chip_values", "chips", column: "secondary_chip_id"
 end