Implement minimap on left config support in minimap element

lib/minimap-element.coffee

@@ -10,23 +10,52 @@ class MinimapElement extends HTMLElement
   domPollingInterval: 100
   domPollingIntervalId: null
   domPollingPaused: false
+  displayMinimapOnLeft: false
 
   createdCallback: ->
     @subscriptions = new CompositeDisposable
     @initializeContent()
 
-  attach: ->
-    @getTextEditorElementRoot().appendChild(this)
+    @subscriptions.add atom.config.observe 'minimap.displayMinimapOnLeft', (displayMinimapOnLeft) =>
+      swapPosition = @attached and displayMinimapOnLeft isnt @displayMinimapOnLeft
+      @displayMinimapOnLeft = displayMinimapOnLeft
+
+      @swapMinimapPosition() if swapPosition
 
   attachedCallback: ->
     @domPollingIntervalId = setInterval((=> @pollDOM()), @domPollingInterval)
     @measureHeightAndWidth()
     @requestUpdate()
+    @attached = true
 
   detachedCallback: ->
+    @attached = false
 
   attributeChangedCallback: (attrName, oldValue, newValue) ->
 
+  attach: ->
+    return if @attached
+    @swapMinimapPosition()
+
+  swapMinimapPosition: ->
+    if @displayMinimapOnLeft
+      @attachToLeft()
+    else
+      @attachToRight()
+
+  attachToLeft: ->
+    root = @getTextEditorElementRoot()
+    root.insertBefore(this, root.children[0])
+
+  attachToRight: ->
+    @getTextEditorElementRoot().appendChild(this)
+
+  detach: ->
+    return unless @attached
+    return unless @parentNode?
+
+    @parentNode.removeChild(this)
+
   getModel: -> @minimap
 
   setModel: (@minimap) ->

spec/minimap-element-spec.coffee

@@ -147,3 +147,11 @@ describe 'MinimapElement', ->
 
           expect(canvas.offsetWidth).toEqual(minimapElement.offsetWidth)
           expect(canvas.offsetHeight).toEqual(minimapElement.offsetHeight + minimap.getLineHeight())
+
+    describe 'when displayMinimapOnLeft setting is true', ->
+      beforeEach ->
+        atom.config.set 'minimap.displayMinimapOnLeft', true
+
+      it 'moves the attached to the left', ->
+        expect(Array::indexOf.call(editorElement.shadowRoot.children, minimapElement)).toEqual(0)
+        nextAnimationFrame()