Update colors

Add average to NotenActivity
Fix Bugs in NotenActivity and FachActivity

app/src/main/java/com/schoolapp/cleverclass/NotenActivity.kt

@@ -1,6 +1,8 @@
 package com.schoolapp.cleverclass
 
+import android.content.Context
 import android.content.Intent
+import android.content.SharedPreferences
 import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
@@ -12,28 +14,48 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.ArrowBack
+import androidx.compose.material3.BottomAppBar
 import androidx.compose.material3.Button
 import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
 import com.schoolapp.cleverclass.ui.theme.CleverClassTheme
 import com.schoolapp.cleverclass.ui.theme.TextOnColouredButton
 
+val subjects = listOf("Biologie","Chemie","Deutsch","Englisch","Ethik","Evangelisch","Französisch",
+    "Geographie","Geschichte","Informatik","Katolisch","Kunst","Latein","Mathe","Musik","Physik",
+    "Pulitik und Gesellschaft","Sport","Wirtschaft")
+
+val colors = listOf(
+    Color(0xFF69F0AE),
+    Color(0xFFEEFF41),
+    Color(0xFFFFAB40),
+    Color(0xFF18FFFF),
+    Color(0xFFB2FF59))
+
 class NotenActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -54,41 +76,91 @@ class NotenActivity : ComponentActivity() {
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun NotenContent(activity: ComponentActivity){
-    Column() {
-        TopAppBar(
-            colors = TopAppBarDefaults.centerAlignedTopAppBarColors(MaterialTheme.colorScheme.primaryContainer),
-            title = {
-                Text(text = "Noten",
-                    style = MaterialTheme.typography.headlineSmall
-                )},
-            navigationIcon = {
-                IconButton(onClick = { activity.finish() }) {
-                    Icon(
-                        imageVector = Icons.Filled.ArrowBack,
-                        contentDescription = null,
-                        modifier = Modifier.size(28.dp)
-                    )
-                }
-            },
-            modifier = Modifier.fillMaxWidth()
-        )
+    val sharedPreferences = activity.getSharedPreferences("gradeAverages", Context.MODE_PRIVATE)
 
-        Column(modifier = Modifier.verticalScroll(rememberScrollState())) {
-            FachButton(color = Color(0xFF69F0AE), text = "Deutsch", 0, 3.66f, activity)
-            FachButton(color = Color(0xFFEEFF41), text = "Mathe",2, 1.56f, activity)
-            FachButton(color = Color(0xFFFFAB40), text = "Englisch",2, 2.27f, activity)
-            FachButton(color = Color(0xFF18FFFF), text = "Latein",2, 4.75f, activity)
-            FachButton(color = Color(0xFFB2FF59), text = "Französisch",2, 2.33f, activity)
+    var allAverage by remember {
+        mutableStateOf(calculateAllAverage(loadAllAverages(sharedPreferences)))
+    }
+
+    Scaffold(
+        topBar = {
+            TopAppBar(
+                colors = TopAppBarDefaults.centerAlignedTopAppBarColors(MaterialTheme.colorScheme.primaryContainer),
+                title = {
+                    Text(text = "Noten",
+                        style = MaterialTheme.typography.headlineSmall,
+                        color = MaterialTheme.colorScheme.onPrimaryContainer
+                    )},
+                navigationIcon = {
+                    IconButton(onClick = { activity.finish() }) {
+                        Icon(
+                            imageVector = Icons.Filled.ArrowBack,
+                            contentDescription = null,
+                            modifier = Modifier.size(28.dp),
+                            tint = MaterialTheme.colorScheme.onPrimaryContainer
+                        )
+                    }
+                },
+                modifier = Modifier.fillMaxWidth()
+            )
+        },
+        bottomBar = {
+            BottomAppBar(
+                containerColor = MaterialTheme.colorScheme.primaryContainer,
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .height(64.dp)
+            ) {
+                Row (modifier = Modifier
+                    .fillMaxWidth()
+                    .align(Alignment.CenterVertically)){
+                    Spacer(modifier = Modifier.width(16.dp))
+                    Text(text = "Gesamtschnitt:",
+                        style = MaterialTheme.typography.headlineSmall)
+                    Spacer(modifier = Modifier.weight(1f))
+                    Text(
+                        text = "Ø" + formatFloat(allAverage),
+                        style = MaterialTheme.typography.headlineSmall)
+                    Spacer(modifier = Modifier.width(16.dp))
+                }
+            }
+        }
+    ) {innerPadding ->
+        Column(modifier = Modifier
+            .verticalScroll(rememberScrollState())
+            .padding(innerPadding))
+        {
+            subjects.forEach { name ->
+                FachButton(
+                    color = colors.random(),
+                    subject = name,
+                    saWeight = 2,
+                    activity = activity,
+                    sharedPreferences = sharedPreferences,
+                    onAvgChange = { allAverage = calculateAllAverage(loadAllAverages(sharedPreferences)) }
+                )
+            }
+            Spacer(modifier = Modifier.height(16.dp))
         }
     }
 }
 
 @Composable
-fun FachButton(color : Color, text : String, saWeight: Int, average : Float, activity : ComponentActivity){
+fun FachButton(
+    color : Color,
+    subject : String,
+    saWeight: Int, activity :
+    ComponentActivity,
+    sharedPreferences: SharedPreferences,
+    onAvgChange: () -> Unit){
+    var avg by remember {
+        mutableStateOf(sharedPreferences.getFloat(subject, 0.0f))
+    }
+
     Button(
         onClick = {
             val intent = Intent(activity, FachActivity::class.java).apply {
-                putExtra(FachActivity.NAME_KEY, text)
+                putExtra(FachActivity.NAME_KEY, subject)
                 putExtra(FachActivity.WEIGHT_KEY, saWeight)
             }
             activity.startActivity(intent) },
@@ -100,13 +172,54 @@ fun FachButton(color : Color, text : String, saWeight: Int, average : Float, act
             .padding(start = 16.dp, end = 16.dp, top = 16.dp)
     ) {
         Row(modifier = Modifier.fillMaxWidth()) {
-            Text(text = text,
+            Text(text = subject,
                 color = TextOnColouredButton,
                 style = MaterialTheme.typography.labelMedium)
             Spacer(modifier = Modifier.weight(1f))
-            Text(text = "Ø$average",
+            Text(text = "Ø${formatFloat(avg)}",
                 color = TextOnColouredButton,
                 style = MaterialTheme.typography.labelMedium)
         }
     }
-}
+
+    // changes state when Shared Preference is updated
+    val observer = remember {
+        SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
+            if (key == subject) {
+                avg = sharedPreferences.getFloat(subject, 0.0f)
+                onAvgChange()
+            }
+        }
+    }
+
+    // handles observer creation and disposal
+    DisposableEffect(Unit) {
+        sharedPreferences.registerOnSharedPreferenceChangeListener(observer)
+        onDispose {
+            sharedPreferences.unregisterOnSharedPreferenceChangeListener(observer)
+        }
+    }
+}
+
+fun calculateAllAverage(avgs: List<Float>): Float{
+    var total = 0.0f
+    var number = 0
+
+    avgs.forEach{ avg ->
+        if (avg != 0.0f && !avg.isNaN()){
+            total += avg
+            number += 1
+        }
+    }
+    return (total / number)
+}
+
+fun loadAllAverages(sharedPreferences: SharedPreferences): List<Float>{
+    val avgs = emptyList<Float>().toMutableList()
+
+    subjects.forEach { name ->
+        avgs += sharedPreferences.getFloat(name, 0.0f)
+    }
+
+    return avgs
+}