Add ColorScale model and seed default color scale

Author: rossta

app/models/color_scale.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+class ColorScale < ApplicationRecord
+  APP_DEFAULT = {
+    name: "Custom Cerulean Blue",
+    weights: {
+      "50": "#f1f5fd",
+      "100": "#dfe8fa",
+      "200": "#c7d7f6",
+      "300": "#a1beef",
+      "400": "#749be6",
+      "500": "#537ade",
+      "600": "#3e5dd2",
+      "700": "#354bc0",
+      "800": "#313f9c",
+      "900": "#2c397c",
+      "950": "#1f244c"
+    }
+  }.freeze
+
+  VALID_WEIGHTS = %w[50 100 200 300 400 500 600 700 800 900 950].freeze
+
+  def self.find_or_create_default
+    find_or_create_by(name: APP_DEFAULT[:name]) do |cs|
+      APP_DEFAULT[:weights].each do |weight, value|
+        cs.set_weight(weight, value)
+      end
+    end
+  end
+
+  def set_weight(weight, value)
+    raise ArgumentError, "Invalid weight: #{weight}" unless VALID_WEIGHTS.include?(weight.to_s)
+
+    send(:"weight_#{weight}=", value)
+  end
+
+  def weights
+    VALID_WEIGHTS.each_with_object({}) do |weight, hash|
+      hash[weight] = send(:"weight_#{weight}")
+    end
+  end
+
+  def to_css
+    weights.map { |weight, value| "--color-#{name.dasherize}-#{weight}: #{value};" }.join("\n")
+  end
+end

db/seeds/development.rb

@@ -6,3 +6,5 @@
   u.password = password
   u.password_confirmation = password
 end
+
+ColorScale.find_or_create_default

db/seeds/production.rb

@@ -6,3 +6,5 @@
   u.password = password
   u.password_confirmation = password
 end
+
+ColorScale.find_or_create_default

spec/factories/color_scales.rb

@@ -0,0 +1,18 @@
+require "faker"
+
+FactoryBot.define do
+  factory :color_scale do
+    name { Faker::Color.color_name.titleize }
+    weight_50 { Faker::Color.hex_color }
+    weight_100 { Faker::Color.hex_color }
+    weight_200 { Faker::Color.hex_color }
+    weight_300 { Faker::Color.hex_color }
+    weight_400 { Faker::Color.hex_color }
+    weight_500 { Faker::Color.hex_color }
+    weight_600 { Faker::Color.hex_color }
+    weight_700 { Faker::Color.hex_color }
+    weight_800 { Faker::Color.hex_color }
+    weight_900 { Faker::Color.hex_color }
+    weight_950 { Faker::Color.hex_color }
+  end
+end

spec/models/color_scale_spec.rb

@@ -0,0 +1,35 @@
+require "rails_helper"
+
+RSpec.describe ColorScale, type: :model do
+  describe "self.find_or_create_default" do
+    it "should be idempotent" do
+      expect {
+        ColorScale.find_or_create_default
+      }.to change(ColorScale, :count).by(1)
+
+      expect {
+        ColorScale.find_or_create_default
+      }.not_to change(ColorScale, :count)
+    end
+  end
+
+  describe "#weights" do
+    it "should return a hash of all weights" do
+      color_scale = FactoryBot.build(:color_scale)
+
+      expect(color_scale.weights).to eq(
+        "50" => color_scale.weight_50,
+        "100" => color_scale.weight_100,
+        "200" => color_scale.weight_200,
+        "300" => color_scale.weight_300,
+        "400" => color_scale.weight_400,
+        "500" => color_scale.weight_500,
+        "600" => color_scale.weight_600,
+        "700" => color_scale.weight_700,
+        "800" => color_scale.weight_800,
+        "900" => color_scale.weight_900,
+        "950" => color_scale.weight_950
+      )
+    end
+  end
+end