separate application.js into separate initializers

closes #3588, closes #3605

app/assets/javascripts/active_admin/base.js.coffee

@@ -4,6 +4,6 @@
 #= require_self
 #= require_tree ./lib
 #= require_tree ./ext
-#= require ./application
+#= require_tree ./initializers
 
 window.ActiveAdmin = {}

app/assets/javascripts/active_admin/initializers/batch_actions.js.coffee

@@ -0,0 +1,7 @@
+$(document).on 'ready page:load', ->
+  # In order for index scopes to overflow properly onto the next line, we have
+  # to manually set its width based on the width of the batch action button.
+  if (batch_actions_selector = $('.table_tools .batch_actions_selector')).length
+    batch_actions_selector.next().css
+      width: "calc(100% - 10px - #{batch_actions_selector.outerWidth()}px)"
+      'float': 'right'

app/assets/javascripts/active_admin/initializers/datepicker.js.coffee

@@ -0,0 +1,10 @@
+$(document).on 'ready page:load', ->
+  $(document).on 'focus', 'input.datepicker:not(.hasDatepicker)', ->
+    input = $(@)
+
+    # Only create datepickers in compatible browsers
+    return if input[0].type is 'date'
+
+    defaults = dateFormat: 'yy-mm-dd'
+    options  = input.data 'datepicker-options'
+    input.datepicker $.extend(defaults, options)

app/assets/javascripts/active_admin/initializers/filters.js.coffee

@@ -0,0 +1,15 @@
+$(document).on 'ready page:load', ->
+  # Clear Filters button
+  $('.clear_filters_btn').click ->
+    params = window.location.search.slice(1).split('&')
+    regex = /^(q\[|q%5B|q%5b|page|commit)/
+    window.location.search = (param for param in params when not param.match(regex)).join('&')
+
+  # Filter form: don't send any inputs that are empty
+  $('.filter_form').submit ->
+    $(@).find(':input').filter(-> @value is '').prop 'disabled', true
+
+  # Filter form: for filters that let you choose the query method from
+  # a dropdown, apply that choice to the filter input field.
+  $('.filter_form_field.select_and_search select').change ->
+    $(@).siblings('input').prop name: "q[#{@value}]"

app/assets/javascripts/active_admin/initializers/tabs.js.coffee

@@ -0,0 +1,3 @@
+$(document).on 'ready page:load', ->
+  # Tab navigation
+  $('#active_admin_content .tabs').tabs()