Add "new label" button to label management (#359)

Allow to create labels directly from Manage labels page. It uses the same fullscreen dialog style as adding other things.

Almost all of the code is reused the `NewTeam` component

Co-authored-by: David Košťál <kostal.david8@gmail.com>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/359
Reviewed-by: konrad <konrad@kola-entertainments.de>
Co-authored-by: profi248 <kostal.david8@gmail.com>
Co-committed-by: profi248 <kostal.david8@gmail.com>

src/router/index.js

@@ -19,6 +19,7 @@ import ListNamespaces from '../views/namespaces/ListNamespaces'
 import ListTeamsComponent from '../views/teams/ListTeams'
 // Label Handling
 import ListLabelsComponent from '../views/labels/ListLabels'
+import NewLabelComponent from '../views/labels/NewLabel'
 // Migration
 import MigrationComponent from '../views/migrator/Migrate'
 import MigrateServiceComponent from '../views/migrator/MigrateService'
@@ -253,6 +254,11 @@ export default new Router({
 			name: 'labels.index',
 			component: ListLabelsComponent,
 		},
+		{
+			path: '/labels/new',
+			name: 'labels.create',
+			component: NewLabelComponent,
+		},
 		{
 			path: '/migrate',
 			name: 'migrate.start',

src/views/labels/ListLabels.vue

@@ -1,5 +1,11 @@
 <template>
 	<div :class="{ 'is-loading': labelService.loading}" class="loader-container content">
+		<router-link :to="{name:'labels.create'}" class="button is-success button-right">
+			<span class="icon is-small">
+				<icon icon="plus"/>
+			</span>
+			New label
+		</router-link>
 		<h1>Manage labels</h1>
 		<p>
 			Click on a label to edit it.

src/views/labels/NewLabel.vue

@@ -0,0 +1,80 @@
+<template>
+	<div class="fullpage">
+		<a @click="back()" class="close">
+			<icon :icon="['far', 'times-circle']"/>
+		</a>
+		<h3>Create a new label</h3>
+		<form @keyup.esc="back()" @submit.prevent="newlabel">
+			<div class="field is-grouped">
+				<p class="control is-expanded" v-bind:class="{ 'is-loading': labelService.loading }">
+					<input
+						:class="{ 'disabled': labelService.loading }"
+						class="input"
+						placeholder="The label title goes here..." type="text"
+						v-focus
+						v-model="label.title"/>
+				</p>
+				<p class="control">
+					<button class="button is-success noshadow" type="submit">
+						<span class="icon is-small">
+							<icon icon="plus"/>
+						</span>
+						Add
+					</button>
+				</p>
+			</div>
+			<p class="help is-danger" v-if="showError && label.title === ''">
+				Please specify a title.
+			</p>
+		</form>
+	</div>
+</template>
+
+<script>
+import labelModel from '../../models/label'
+import labelService from '../../services/label'
+import {IS_FULLPAGE} from '@/store/mutation-types'
+import LabelModel from '../../models/label'
+import LabelService from '../../services/label'
+
+export default {
+	name: 'NewLabel',
+	data() {
+		return {
+			labelService: labelService,
+			label: labelModel,
+			showError: false,
+		}
+	},
+	created() {
+		this.labelService = new LabelService()
+		this.label = new LabelModel()
+		this.$store.commit(IS_FULLPAGE, true)
+	},
+	mounted() {
+		this.setTitle('Create a new label')
+	},
+	methods: {
+		newlabel() {
+
+			if (this.label.title === '') {
+				this.showError = true
+				return
+			}
+			this.showError = false
+
+			this.labelService.create(this.label)
+				.then(response => {
+					this.$router.push({name: 'labels.index', params: {id: response.id}})
+					this.success({message: 'The label was successfully created.'}, this)
+				})
+				.catch(e => {
+					this.error(e, this)
+				})
+		},
+		back() {
+			this.$router.go(-1)
+		},
+	},
+}
+</script>