feat: Interactively customize CSS variables

app/assets/javascripts/application.js

@@ -17,6 +17,7 @@
 //= require jquery.ui.autocomplete
 //= require highcharts
 //= require chartkick
+//= require ./vendor/debounce
 //= require_directory .
 //= require_directory ./channels
 //= require ./vendor/simplemde.min.js

app/assets/javascripts/theming-editor/theming-editor.js

@@ -0,0 +1,124 @@
+//= require ../vendor/pickr.min.js
+
+(function() {
+  function _onTextChange() {
+    var $input = $(this);
+    var variable = $input.attr('name');
+    var value = $input.val();
+
+    document.documentElement.style.setProperty(variable, value);
+    window.pickrs[variable].setColor(value, true);
+  }
+
+  function _onPickrChange(color, instance) {
+    var value = color ? '#' + color.toHEXA().join('') : '';
+    var $variable = $(instance.getRoot().root).parents('.theming-editor__variable');
+    $input = $variable.find('.theming-editor__input');
+    var variable = $input.attr('name');
+
+    // Don't update input if the user is typing in it
+    if (!$input.is(':focus')) {
+      $input.val(value);
+    }
+    // Update the picker button color (doesn't by default)
+    instance.applyColor(true);
+    // Update CSS property
+    document.documentElement.style.setProperty(variable, value);
+  }
+
+  function onSave() {
+    var $editor = $(this).parents('.theming-editor__wrapper');
+    var css = ':root {\n';
+    $editor.find('.theming-editor__input').each(function() {
+      var variable = $(this).attr('name');
+      var value = $(this).val();
+      css += '  ' + variable + ': ' + value + ';\n';
+    });
+    css += '}';
+    saveConfig(css);
+  }
+
+  function saveConfig(css) {
+    var data = {
+      hackathon_config: {
+        custom_css: css,
+      },
+    };
+    fetch('/manage/configs/custom_css', {
+      method: 'PATCH',
+      redirect: 'manual',
+      headers: {
+        'Content-Type': 'application/json',
+        'X-CSRF-Token': Rails.csrfToken(),
+      },
+      body: JSON.stringify(data),
+    })
+      .then(function(response) {
+        if (!response.ok && response.type != 'opaqueredirect') {
+          alert('There was an error attempting to save. Please try again or refresh the page.');
+          return;
+        }
+        window.location.replace('/manage/configs/exit_theming_editor');
+      })
+      .catch(function() {
+        alert('There was an error attempting to save. Please try again or refresh the page.');
+      });
+  }
+
+  var onTextChange = throttle(_onTextChange, 100);
+  var onPickrChange = throttle(_onPickrChange, 100);
+
+  function initHtml() {
+    var variables = Object.values(getComputedStyle(document.documentElement))
+      .filter(function(x) {
+        return x.startsWith('--primary');
+      })
+      .sort();
+    var $editor = $('#theming-editor');
+    var $variables = $editor.find('.theming-editor__variables');
+    var $variable_template = $editor.find('.theming-editor__variable').remove();
+    variables.forEach(function(variable) {
+      var $new_variable = $variable_template.clone();
+      var $code = $new_variable.find('.theming-editor__variable-name-code');
+      var $input = $new_variable.find('.theming-editor__input');
+      var value = getComputedStyle(document.documentElement)
+        .getPropertyValue(variable)
+        .trim();
+
+      $code.text(variable);
+      $input.val(value);
+      $input.attr('name', variable);
+      $input.on('input', onTextChange);
+      $variables.append($new_variable);
+    });
+    $editor.find('.theming-editor__button-save').on('click', onSave);
+  }
+
+  function initColorPickers() {
+    window.pickrs = {};
+    $('.theming-editor__color-picker').each(function() {
+      var $input = $(this)
+        .parents('.theming-editor__variable')
+        .find('.theming-editor__input');
+      var pickr = Pickr.create({
+        el: this,
+        default: $input.val(),
+        components: {
+          opacity: false,
+          hue: true,
+          interaction: false,
+        },
+      });
+      pickr.on('change', onPickrChange);
+      var variable = $input.attr('name');
+      window.pickrs[variable] = pickr;
+    });
+  }
+
+  function init() {
+    initHtml();
+    initColorPickers();
+  }
+
+  document.addEventListener('turbolinks:load', init);
+})();

app/assets/javascripts/manage/lib/debounce.js → app/assets/javascripts/vendor/debounce.js

@@ -18,3 +18,21 @@ function debounce(func, wait, immediate) {
     if (callNow) func.apply(context, args);
   };
 }
+
+// Returns a function, that, as long as it continues to be invoked, will only
+// trigger every N milliseconds. If `immediate` is passed, trigger the
+// function on the leading edge, instead of the trailing.
+function throttle(func, wait, immediate) {
+  var timeout;
+  return function() {
+    var context = this,
+      args = arguments;
+    var later = function() {
+      timeout = null;
+      if (!immediate) func.apply(context, args);
+    };
+    var callNow = immediate && !timeout;
+    if (!timeout) timeout = setTimeout(later, wait);
+    if (callNow) func.apply(context, args);
+  };
+}

app/assets/stylesheets/application.sass

@@ -21,13 +21,16 @@
 @import general/flashes
 @import general/main
 @import general/header
-@import general/table
 @import general/status-colors
+@import general/table
 @import forms/forms
 @import forms/confirmation
 
+@import general/theming-editor
+
 // media queries needs to be last
 @import general/media-queries
 
 // external dependencies
 @import font-awesome
+@import vendor/pickr.min

app/assets/stylesheets/general/_theming-editor.sass

@@ -0,0 +1,59 @@
+.theming-editor__wrapper
+  position: fixed
+  bottom: 10px
+  right: 10px
+  display: block
+  background: #fff
+  border: 3px solid #ccc
+  padding: 15px 20px
+  border-radius: 4px
+  max-width: 470px
+  max-height: 700px
+  overflow: auto
+
+.theming-editor__title
+  font-weight: bold
+  margin-bottom: 1em
+  font-size: 16px
+
+.theming-editor__variables
+  display: flex
+  flex-flow: row wrap
+  margin: -10px -10px 10px
+
+.theming-editor__variable
+  display: flex
+  flex-flow: column nowrap
+  margin: 10px
+  width: 200px
+
+.theming-editor__variable-name
+  color: #e83e8c
+  margin-bottom: 5px
+  font-size: 11px
+
+.theming-editor__input-group
+  display: flex
+  flex-flow: row nowrap
+  align-items: stretch
+
+.theming-editor__input-group .pickr
+  margin-left: 5px
+  display: flex
+  width: 80px
+  button
+    box-shadow: 0 3px 4px rgba(0,0,0,0.1)
+    display: flex
+    height: 100%
+    width: 100%
+
+input, textarea
+  &.theming-editor__input, &.theming-editor__input:focus
+    font-size: 12px
+    font-family: monospace
+    padding: 6px 9px
+    border: 1px solid #ccc
+    margin: 0
+
+.theming-editor__button-wrapper
+  margin-top: 1em

app/controllers/manage/configs_controller.rb

@@ -1,6 +1,6 @@
 class Manage::ConfigsController < Manage::ApplicationController
   before_action :limit_access_admin
-  before_action :get_config, only: [:edit, :update]
+  before_action :get_config, only: [:edit, :update, :update_only_css_variables]
 
   respond_to :html, :json
 
@@ -15,8 +15,8 @@ def edit
   def update
     key = @config.var.to_sym
     value = params[:hackathon_config][key]
-    value = true if value == 'true'
-    value = false if value == 'false'
+    value = true if value == "true"
+    value = false if value == "false"
     if @config.value != value
       @config.value = value
       @config.save
@@ -26,6 +26,35 @@ def update
     end
   end
 
+  def update_only_css_variables
+    key = @config.var.to_sym
+    old_value = @config.value.strip
+    posted_value = params[:hackathon_config][key].strip
+    if old_value.include? ':root {'
+      # Replace the old CSS variables and keep the extra css
+      start_index = old_value.index(':root {')
+      end_index = old_value.index('}', start_index) + 1
+      pre_value = old_value[0...start_index].rstrip
+      post_value = old_value[end_index..-1].lstrip
+      new_value = "#{pre_value}\n\n#{posted_value}\n\n#{post_value}".strip
+    else
+      # Prepend the variable definitions to the existing value
+      new_value = "#{posted_value}\n\n#{old_value}"
+    end
+    params[:hackathon_config][key] = new_value
+    update
+  end
+
+  def enter_theming_editor
+    cookies[:theming_editor] = true
+    redirect_to root_path
+  end
+
+  def exit_theming_editor
+    cookies.delete :theming_editor
+    redirect_to manage_configs_path
+  end
+
   private
 
   def get_config

app/views/layouts/_theming_editor.html.haml

@@ -0,0 +1,15 @@
+.theming-editor__wrapper#theming-editor
+  .theming-editor__title Custom CSS Variables
+  .theming-editor__variables
+    .theming-editor__variable
+      %small.theming-editor__variable-name
+        %code.theming-editor__variable-name-code my-variable
+      .theming-editor__input-group
+        %input.theming-editor__input{type: 'text'}
+        .theming-editor__color-picker
+
+  .theming-editor__button-wrapper
+    %button.theming-editor__button-save{type: 'button'} Save
+    = link_to 'Cancel', exit_theming_editor_manage_configs_path
+
+= javascript_include_tag "theming-editor/theming-editor.js", "data-turbolinks-eval": "false"

app/views/layouts/application.html.haml

@@ -26,3 +26,5 @@
       %section.section
         .container
           = yield
+    - if cookies[:theming_editor]
+      = render "layouts/theming_editor"

app/views/manage/configs/index.html.haml

@@ -15,6 +15,11 @@
             %small
               %code= key
           %p.text-muted= t("simple_form.hints.hackathon_config.#{key}").html_safe
+          - if key == 'custom_css'
+            %p
+              = link_to enter_theming_editor_manage_configs_path do
+                %span.fa.fa-paint-brush.icon-space-r-half
+                Interactive editor
           - if value == ''
             %p.mb-0
               %span.badge.badge-secondary Not set

config/initializers/assets.rb

@@ -12,4 +12,4 @@
 # application.js, application.css, and all non-JS/CSS in the app/assets
 # folder are already added.
 # Rails.application.config.assets.precompile += %w( admin.js admin.css )
-Rails.application.config.assets.precompile += %w[manage.css vendor/*.js vendor/*.css]
+Rails.application.config.assets.precompile += %w[manage.css vendor/*.js vendor/*.css theming-editor/*]

config/routes.rb

@@ -86,7 +86,11 @@
       post :mlh_info_applied, on: :collection
       post :mlh_info_checked_in, on: :collection
     end
-    resources :configs
+    resources :configs do
+      patch :update_only_css_variables, on: :member
+      get :enter_theming_editor, on: :collection
+      get :exit_theming_editor, on: :collection
+    end
     resources :trackable_events
     resources :trackable_tags
   end