Implement VM

app/build.gradle

@@ -1,6 +1,8 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-parcelize'
+apply plugin: 'com.google.devtools.ksp'
+apply plugin: 'dagger.hilt.android.plugin'
 apply plugin: 'com.google.firebase.crashlytics'
 apply plugin: 'com.google.gms.google-services'
 
@@ -61,6 +63,10 @@ dependencies {
     implementation 'androidx.appcompat:appcompat:1.8.0'
     implementation 'androidx.core:core-ktx:1.19.0'
     implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.11.0'
+    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.11.0'
+    implementation 'androidx.activity:activity-ktx:1.8.0'
+    implementation "com.google.dagger:hilt-android:$hilt_version"
+    ksp "com.google.dagger:hilt-compiler:$hilt_version"
     implementation 'androidx.constraintlayout:constraintlayout:2.2.2'
     implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.2.0'
     testImplementation 'junit:junit:4.13.2'

app/src/main/AndroidManifest.xml

@@ -4,6 +4,7 @@
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
 
     <application
+        android:name=".CourseGrabApplication"
         android:allowBackup="true"
         android:fullBackupContent="@xml/backup_descriptor"
         android:icon="@mipmap/ic_launcher"

app/src/main/java/com/cornellappdev/coursegrab/CourseDetailsActivity.kt

@@ -2,34 +2,31 @@ package com.cornellappdev.coursegrab
 
 import android.content.Context
 import android.os.Bundle
-import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.Button
 import android.widget.ImageView
 import android.widget.TextView
 import android.widget.Toast
+import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.cornellappdev.coursegrab.databinding.ActivityCourseDetailsBinding
 import com.cornellappdev.coursegrab.models.Course
 import com.cornellappdev.coursegrab.models.SearchResult
-import com.cornellappdev.coursegrab.networking.CourseGrabRepository
+import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.launch
 
+@AndroidEntryPoint
 class CourseDetailsActivity : AppCompatActivity() {
     private lateinit var binding: ActivityCourseDetailsBinding
 
-    private lateinit var sectionsRecyclerView: RecyclerView
-    private lateinit var sectionsViewAdapter: RecyclerView.Adapter<*>
-    private lateinit var sectionsViewManager: RecyclerView.LayoutManager
-
-    private val repository: CourseGrabRepository by lazy {
-        CourseGrabRepository(PreferencesHelper(this))
-    }
+    private val viewModel: CourseDetailsViewModel by viewModels()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -44,44 +41,26 @@ class CourseDetailsActivity : AppCompatActivity() {
         binding.courseDetails.text =
             if (courseDetails.sections.isNotEmpty()) courseDetails.sections.first().instructors.first() else "To Be Assigned"
 
-        // Available Courses Adapter
-        sectionsViewManager = LinearLayoutManager(this@CourseDetailsActivity)
-        sectionsViewAdapter = SectionAdapter(courseDetails.sections, this@CourseDetailsActivity)
-
-        sectionsRecyclerView = binding.sectionsRecyclerview.apply {
-            layoutManager = sectionsViewManager
-            adapter = sectionsViewAdapter
+        binding.sectionsRecyclerview.apply {
+            layoutManager = LinearLayoutManager(this@CourseDetailsActivity)
+            adapter = SectionAdapter(courseDetails.sections, this@CourseDetailsActivity)
         }
 
-        binding.backBtn.setOnClickListener { finish() }
-    }
-
-    fun addCourse(courseId: Int, context: Context) {
         lifecycleScope.launch {
-            repository.addTracking(courseId).onFailure { error ->
-                Log.e(TAG, "Failed to track course $courseId", error)
-                Toast.makeText(
-                    context,
-                    error.message ?: "Couldn't track that course.",
-                    Toast.LENGTH_SHORT
-                ).show()
+            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                viewModel.trackingErrors.collect { error ->
+                    Toast.makeText(this@CourseDetailsActivity, error, Toast.LENGTH_SHORT).show()
+                }
             }
         }
-    }
 
-    fun removeCourse(courseId: Int, context: Context) {
-        lifecycleScope.launch {
-            repository.removeTracking(courseId).onFailure { error ->
-                Log.e(TAG, "Failed to untrack course $courseId", error)
-                Toast.makeText(
-                    context,
-                    error.message ?: "Couldn't remove that course.",
-                    Toast.LENGTH_SHORT
-                ).show()
-            }
-        }
+        binding.backBtn.setOnClickListener { finish() }
     }
 
+    fun addCourse(courseId: Int) = viewModel.addCourse(courseId)
+
+    fun removeCourse(courseId: Int) = viewModel.removeCourse(courseId)
+
     class SectionAdapter(
         private val availableCourses: List<Course>,
         private val context: Context
@@ -108,7 +87,7 @@ class CourseDetailsActivity : AppCompatActivity() {
         override fun onBindViewHolder(holder: ViewHolder, position: Int) {
 
             holder.sectionTitle.text = availableCourses[position].section
-            holder.sectionStatus.setImageResource(if (availableCourses[position].status == "OPEN") R.drawable.ic_status_open else R.drawable.ic_status_closed)
+            holder.sectionStatus.setImageResource(if (availableCourses[position].isOpen) R.drawable.ic_status_open else R.drawable.ic_status_closed)
 
             //change tracking text
             holder.trackText.text = availableCourses[position].num_tracking.toString() + " Tracking"
@@ -121,8 +100,7 @@ class CourseDetailsActivity : AppCompatActivity() {
 
             holder.removeButton.setOnClickListener {
                 (context as CourseDetailsActivity).removeCourse(
-                    availableCourses[position].catalog_num,
-                    context
+                    availableCourses[position].catalog_num
                 )
                 holder.removeButton.visibility = View.GONE
                 holder.trackButton.visibility = View.VISIBLE
@@ -136,8 +114,7 @@ class CourseDetailsActivity : AppCompatActivity() {
 
             holder.trackButton.setOnClickListener {
                 (context as CourseDetailsActivity).addCourse(
-                    availableCourses[position].catalog_num,
-                    context
+                    availableCourses[position].catalog_num
                 )
                 holder.trackButton.visibility = View.GONE
                 holder.removeButton.visibility = View.VISIBLE
@@ -153,8 +130,4 @@ class CourseDetailsActivity : AppCompatActivity() {
         // Return the size of your dataset (invoked by the layout manager)
         override fun getItemCount() = availableCourses.size
     }
-
-    companion object {
-        private const val TAG = "CourseDetailsActivity"
-    }
 }

app/src/main/java/com/cornellappdev/coursegrab/CourseDetailsViewModel.kt

@@ -0,0 +1,43 @@
+package com.cornellappdev.coursegrab
+
+import android.util.Log
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.cornellappdev.coursegrab.networking.CourseGrabRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.receiveAsFlow
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class CourseDetailsViewModel @Inject constructor(
+    private val repository: CourseGrabRepository
+) : ViewModel() {
+
+    private val _trackingErrors = Channel<String>(Channel.BUFFERED)
+    val trackingErrors = _trackingErrors.receiveAsFlow()
+
+    fun addCourse(courseId: Int) = track(courseId, adding = true)
+
+    fun removeCourse(courseId: Int) = track(courseId, adding = false)
+
+    private fun track(courseId: Int, adding: Boolean) {
+        viewModelScope.launch {
+            val result = if (adding) repository.addTracking(courseId)
+            else repository.removeTracking(courseId)
+
+            result.onFailure { error ->
+                Log.e(TAG, "Failed to ${if (adding) "track" else "untrack"} $courseId", error)
+                _trackingErrors.send(
+                    error.message ?: if (adding) "Couldn't track that course."
+                    else "Couldn't remove that course."
+                )
+            }
+        }
+    }
+
+    private companion object {
+        const val TAG = "CourseDetailsViewModel"
+    }
+}

app/src/main/java/com/cornellappdev/coursegrab/CourseGrabApplication.kt

@@ -0,0 +1,7 @@
+package com.cornellappdev.coursegrab
+
+import android.app.Application
+import dagger.hilt.android.HiltAndroidApp
+
+@HiltAndroidApp
+class CourseGrabApplication : Application()