Implement discussion composition and creation

ember/app/components/discussions/composer-discussion.js

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+import Ember from 'ember';
+
+import TaggedArray from '../../utils/tagged-array';
+import { PositionEnum } from '../../controllers/composer';
+
+var precompileTemplate = Ember.Handlebars.compile;
+
+export default Ember.Component.extend(Ember.Evented, {
+	layoutName: 'components/discussions/composer-body',
+
+	submitLabel: 'Post Discussion',
+	titlePlaceholder: 'Discussion Title',
+	placeholder: '',
+	title: '',
+	content: '',
+	submit: null,
+	loading: false,
+
+	disabled: Ember.computed.equal('composer.position', PositionEnum.MINIMIZED),
+
+	didInsertElement: function() {
+		var controls = TaggedArray.create();
+		this.trigger('populateControls', controls);
+		this.set('controls', controls);
+	},
+
+	populateControls: function(controls) {
+		var title = Ember.Component.create({
+			tagName: 'h3',
+			layout: precompileTemplate('{{ui/controls/text-input value=component.title class="form-control" placeholder=component.titlePlaceholder disabled=component.disabled}}'),
+			component: this
+		});
+		controls.pushObjectWithTag(title, 'title');
+	},
+
+	actions: {
+		submit: function(content) {
+			this.get('submit')({
+				title: this.get('title'),
+				content: content
+			});
+		},
+
+		willExit: function(abort) {
+			// If the user has typed something, prompt them before exiting
+			// this composer state.
+			if ((this.get('title') || this.get('content')) && !confirm('You have not posted your discussion. Do you wish to discard it?')) {
+				abort();
+			}
+		},
+
+		reset: function() {
+			this.set('loading', false);
+			this.set('content', '');
+		}
+	}
+});

ember/app/components/ui/controls/text-input.js

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+import Ember from 'ember';
+
+export default Ember.TextField.extend({
+	didInsertElement: function() {
+		var component = this;
+		this.$().on('input', function() {
+			var empty = !$(this).val();
+			if (empty) {
+				$(this).val(component.get('placeholder'));
+			}
+			$(this).css('width', 0);
+			$(this).width($(this)[0].scrollWidth);
+			if (empty) {
+				$(this).val('');
+			}
+		});
+	}
+});