feat: Adds dark theme support for public portal [CW-2525] (#7979)

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

spec/helpers/portal_helper_spec.rb

@@ -0,0 +1,60 @@
+require 'rails_helper'
+
+describe PortalHelper do
+  describe '#generate_portal_bg_color' do
+    context 'when theme is dark' do
+      it 'returns the correct color mix with black' do
+        expect(helper.generate_portal_bg_color('#ff0000', 'dark')).to eq(
+          'color-mix(in srgb, #ff0000 10%, black)'
+        )
+      end
+    end
+
+    context 'when theme is not dark' do
+      it 'returns the correct color mix with white' do
+        expect(helper.generate_portal_bg_color('#ff0000', 'light')).to eq(
+          'color-mix(in srgb, #ff0000 10%, white)'
+        )
+      end
+    end
+
+    context 'when provided with various colors' do
+      it 'adjusts the color mix appropriately' do
+        expect(helper.generate_portal_bg_color('#00ff00', 'dark')).to eq(
+          'color-mix(in srgb, #00ff00 10%, black)'
+        )
+        expect(helper.generate_portal_bg_color('#0000ff', 'light')).to eq(
+          'color-mix(in srgb, #0000ff 10%, white)'
+        )
+      end
+    end
+  end
+
+  describe '#generate_portal_bg' do
+    context 'when theme is dark' do
+      it 'returns the correct background with dark grid image and color mix with black' do
+        expected_bg = 'background: url(/assets/images/hc/grid_dark.svg) color-mix(in srgb, #ff0000 10%, black)'
+        expect(helper.generate_portal_bg('#ff0000', 'dark')).to eq(expected_bg)
+      end
+    end
+
+    context 'when theme is not dark' do
+      it 'returns the correct background with light grid image and color mix with white' do
+        expected_bg = 'background: url(/assets/images/hc/grid.svg) color-mix(in srgb, #ff0000 10%, white)'
+        expect(helper.generate_portal_bg('#ff0000', 'light')).to eq(expected_bg)
+      end
+    end
+
+    context 'when provided with various colors' do
+      it 'adjusts the background appropriately for dark theme' do
+        expected_bg = 'background: url(/assets/images/hc/grid_dark.svg) color-mix(in srgb, #00ff00 10%, black)'
+        expect(helper.generate_portal_bg('#00ff00', 'dark')).to eq(expected_bg)
+      end
+
+      it 'adjusts the background appropriately for light theme' do
+        expected_bg = 'background: url(/assets/images/hc/grid.svg) color-mix(in srgb, #0000ff 10%, white)'
+        expect(helper.generate_portal_bg('#0000ff', 'light')).to eq(expected_bg)
+      end
+    end
+  end
+end