From 71dab5c590a12ab962e124f419b524b1dc1bf7de Mon Sep 17 00:00:00 2001
From: Rakantor <rakantor.dev@gmail.com>
Date: Fri, 4 Nov 2022 17:43:23 +0100
Subject: [PATCH] Add option for students to mark courses as favorites

---
 components/CourseList.vue | 69 +++++++++++++++++++++++++++++++++++++
 pages/dashboard.vue       | 71 +++++++++++++++++++++++----------------
 plugins/user.js           |  6 ++--
 store/index.js            | 13 +++++++
 4 files changed, 128 insertions(+), 31 deletions(-)
 create mode 100644 components/CourseList.vue

diff --git a/components/CourseList.vue b/components/CourseList.vue
new file mode 100644
index 0000000..a78eecf
--- /dev/null
+++ b/components/CourseList.vue
@@ -0,0 +1,69 @@
+<template>
+  <v-row>
+    <v-col v-for="(course, id) in courses" :key="id" cols="12" lg="6">
+      <v-card width="100%" @click="openCourse(id)">
+        <v-row no-gutters class="flex-nowrap">
+          <v-col cols="auto">
+            <v-img
+              src="https://www.onlinecollegeplan.com/wp-content/uploads/2018/05/computer-programming.jpg"
+              :width="imgSize"
+              :height="imgSize"
+              class="rounded-l-lg"
+            ></v-img>
+          </v-col>
+          <v-col cols="auto" class="flex-grow-1 flex-shrink-0">
+            <v-card-title class="text--secondary text-subtitle-1">{{ id.toUpperCase() }}</v-card-title>
+            <v-card-subtitle class="text--primary text-h6 text-wrap">{{ course.name }}</v-card-subtitle>
+          </v-col>
+          <v-col cols="auto">
+            <v-btn icon @click.stop="isFavoriteCourse(id) ? addToFavorites(id, false) : addToFavorites(id, true)">
+              <v-icon>{{ isFavoriteCourse(id) ? 'mdi-heart' : 'mdi-heart-outline' }}</v-icon>
+            </v-btn>
+          </v-col>
+        </v-row>
+      </v-card>
+    </v-col>
+  </v-row>
+</template>
+
+<script>
+import { doc, updateDoc, arrayUnion, arrayRemove } from 'firebase/firestore'
+
+export default {
+  name: 'CourseList',
+  props: {
+    courses: {
+      type: Object,
+      required: true
+    }
+  },
+  data () {
+    return {
+      imgSize: 125
+    }
+  },
+  methods: {
+    openCourse (courseID) {
+      this.$store.commit('setSelectedCourse', courseID)
+      this.$router.push(`courses/${courseID}`)
+    },
+    isFavoriteCourse (courseID) {
+      return this.$store.state.user.courses && this.$store.state.user.courses.includes(courseID)
+    },
+    addToFavorites (courseID, add) {
+      const gameRef = doc(this.$db, `benutzer/${this.$auth.currentUser.uid}`)
+
+      // Atomically add a new answer to the "player[ID]answers" array field.
+      updateDoc(gameRef, {
+        kurse: add ? arrayUnion(courseID) : arrayRemove(courseID)
+      }).then((empty) => {
+        // Query execution was successful
+        add ? this.$store.commit('addFavoriteCourse', courseID) : this.$store.commit('removeFavoriteCourse', courseID)
+      }).catch((error) => {
+        // Failed to update the game; display error message
+        this.$toast({ content: error, color: 'error' })
+      })
+    }
+  }
+}
+</script>
diff --git a/pages/dashboard.vue b/pages/dashboard.vue
index 8bd4717..aa2a3da 100644
--- a/pages/dashboard.vue
+++ b/pages/dashboard.vue
@@ -1,26 +1,31 @@
 <template>
-  <v-container fluid>
+  <v-container v-if="!coursesLoaded" fluid fill-height>
+    <v-card color="transparent" class="mx-auto">
+      <v-progress-circular indeterminate color="primary" size="32"></v-progress-circular>
+    </v-card>
+  </v-container>
+  <v-container v-else fluid>
     <v-row>
-      <v-col v-if="$store.getters.isAdmin" cols="12">
-        <AddCourse />
+      <v-col cols="12">
+        <v-tabs v-model="tab" color="primary" background-color="transparent" centered>
+          <v-tab>Meine Kurse ({{ Object.keys(userCourses).length }})</v-tab>
+          <v-tab>Alle Kurse ({{ Object.keys(allCourses).length }})</v-tab>
+        </v-tabs>
       </v-col>
-      <v-col v-for="(course, id) in courses" :key="id" cols="12" lg="6">
-        <v-card flat width="100%" class="rounded-lg" @click="openCourse(id)">
-          <v-row no-gutters class="flex-nowrap">
-            <v-col cols="auto">
-              <v-img
-                src="https://www.onlinecollegeplan.com/wp-content/uploads/2018/05/computer-programming.jpg"
-                :width="imgSize"
-                :height="imgSize"
-                class="rounded-l-lg"
-              ></v-img>
-            </v-col>
-            <v-col cols="auto">
-              <v-card-title class="text--secondary text-subtitle-1">{{ id.toUpperCase() }}</v-card-title>
-              <v-card-subtitle class="text--primary text-h6 text-wrap">{{ course.name }}</v-card-subtitle>
-            </v-col>
-          </v-row>
-        </v-card>
+      <v-col cols="12">
+        <v-tabs-items v-model="tab" style="background-color: transparent !important;">
+          <v-tab-item>
+            <CourseList :courses="userCourses" />
+          </v-tab-item>
+          <v-tab-item>
+            <v-row v-if="$store.getters.isAdmin">
+              <v-col cols="12">
+                <AddCourse />
+              </v-col>
+            </v-row>
+            <CourseList :courses="allCourses" />
+          </v-tab-item>
+        </v-tabs-items>
       </v-col>
     </v-row>
   </v-container>
@@ -29,6 +34,7 @@
 <script>
 import _cloneDeep from 'lodash-es/cloneDeep'
 import { collection, getDocs } from 'firebase/firestore'
+import _isEmpty from 'lodash-es/isEmpty'
 
 export default {
   name: 'DashboardPage',
@@ -38,17 +44,22 @@ export default {
   },
   data () {
     return {
-      imgSize: 125
+      coursesLoaded: false,
+      tab: 0
     }
   },
   computed: {
-    courses () {
+    allCourses () {
       return this.$store.state.courses
+    },
+    userCourses () {
+      return this.$store.getters.getFavoriteCourses
     }
   },
   created () {
     // Load all courses from the database and convert to JS object
-    getDocs(collection(this.$db, 'kurse')).then(querySnapshot => {
+    getDocs(collection(this.$db, 'kurse'))
+    .then(querySnapshot => {
       const courses = {}
       querySnapshot.forEach((doc) => {
         // doc.data() is never undefined for query doc snapshots
@@ -57,13 +68,15 @@ export default {
 
       // Save courses in Vuex store
       this.$store.commit('setCourses', _cloneDeep(courses))
+
+      // Switch to the "All Courses" tab (index = 1) if the student doesn't have any favorite courses
+      this.tab = _isEmpty(this.userCourses) ? 1 : 0
+      this.coursesLoaded = true
+    })
+    .catch((error) => {
+      // Couldn't get list of courses from the db; display error message
+      this.$toast({ content: error, color: 'error' })
     })
-  },
-  methods: {
-    openCourse (courseID) {
-      this.$store.commit('setSelectedCourse', courseID)
-      this.$router.push(`courses/${courseID}`)
-    }
   }
 }
 </script>
diff --git a/plugins/user.js b/plugins/user.js
index d56f8b9..491a1e8 100644
--- a/plugins/user.js
+++ b/plugins/user.js
@@ -1,6 +1,7 @@
 export class User {
-  constructor (displayName, gamesStarted) {
+  constructor (displayName, courses, gamesStarted) {
     this.displayName = displayName
+    this.courses = courses
     this.gamesStarted = []
 
     if (gamesStarted && gamesStarted.length > 0) {
@@ -21,11 +22,12 @@ export const UserConverter = {
 
     return {
       anzeigename: user.displayName,
+      kurse: user.courses,
       spieleBegonnen
     }
   },
   fromFirestore: (snapshot, options) => {
     const data = snapshot.data(options)
-    return new User(data.anzeigename, data.spieleBegonnen)
+    return new User(data.anzeigename, data.kurse, data.spieleBegonnen)
   }
 }
\ No newline at end of file
diff --git a/store/index.js b/store/index.js
index ec3df28..622675e 100644
--- a/store/index.js
+++ b/store/index.js
@@ -1,3 +1,5 @@
+import _pick from 'lodash-es/pick'
+
 export const state = () => ({
   firebaseInitialized: false,
   idTokenResult: null,
@@ -12,6 +14,10 @@ export const getters = {
   },
   getCourseByID: (state) => (courseID) => {
     return state.courses[courseID]
+  },
+  getFavoriteCourses (state) {
+    // Ref: https://lodash.com/docs/#pick
+    return _pick(state.courses, state.user.courses)
   }
 }
 
@@ -31,6 +37,13 @@ export const mutations = {
   setCourses (state, courses) {
     state.courses = courses
   },
+  addFavoriteCourse (state, courseID) {
+    state.user.courses.push(courseID)
+  },
+  removeFavoriteCourse (state, courseID) {
+    const index = state.user.courses.findIndex(e => e === courseID)
+    state.user.courses.splice(index, 1)
+  },
   setCourse (state, { courseID, courseData }) {
     this._vm.$set(state.courses, courseID, courseData)
   },