feat(app): create Reminder as UI component

app/src/main/kotlin/com/intelligentbackpack/app/view/Reminder.kt

@@ -0,0 +1,123 @@
+package com.intelligentbackpack.app.view
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Button
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.livedata.observeAsState
+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.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.navigation.NavHostController
+import androidx.navigation.compose.rememberNavController
+import com.intelligentbackpack.app.ui.common.CalendarTopBar
+import com.intelligentbackpack.app.ui.common.SchoolSupplyCard
+import com.intelligentbackpack.app.viewmodel.ReminderViewModel
+import java.time.LocalDate
+
+/**
+ * UI component that represents the reminder.
+ *
+ * @param navController the navigation controller.
+ * @param reminderViewModel the view model.
+ */
+@Composable
+fun Reminder(
+    navController: NavHostController,
+    reminderViewModel: ReminderViewModel = viewModel(
+        factory = ReminderViewModel.Factory,
+    ),
+) {
+    Column(
+        modifier = Modifier.fillMaxSize(),
+        verticalArrangement = Arrangement.Top,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        var openErrorDialog by remember { mutableStateOf(false) }
+        var error by remember { mutableStateOf("") }
+        if (openErrorDialog) {
+            AlertDialog(
+                onDismissRequest = {
+                    openErrorDialog = false
+                },
+                title = {
+                    Text(text = "Reminder error")
+                },
+                text = {
+                    Text(error)
+                },
+                confirmButton = {
+                },
+                dismissButton = {
+                    Button(
+                        onClick = {
+                            openErrorDialog = false
+                        },
+                    ) {
+                        Text("Ok")
+                    }
+                },
+            )
+        }
+        var isBackpackAssociated by remember { mutableStateOf(false) }
+        var selectedDate by remember { mutableStateOf(LocalDate.now()) }
+        val missing by reminderViewModel.missing.observeAsState(emptyList())
+        LaunchedEffect(key1 = Unit) {
+            reminderViewModel.isBackpackAssociated({
+                if (it) {
+                    isBackpackAssociated = true
+                    reminderViewModel.getReminders(selectedDate) { message ->
+                        error = message
+                        openErrorDialog = true
+                    }
+                } else {
+                    isBackpackAssociated = false
+                }
+            }, {
+                error = it
+                openErrorDialog = true
+            })
+        }
+        CalendarTopBar { date ->
+            selectedDate = date
+            if (isBackpackAssociated) {
+                reminderViewModel.getReminders(selectedDate) {
+                    error = it
+                    openErrorDialog = true
+                }
+            }
+        }
+        if (!isBackpackAssociated) {
+            Text(text = "No backpack associated")
+        } else {
+            LazyColumn(
+                modifier = Modifier.fillMaxSize(),
+                horizontalAlignment = Alignment.CenterHorizontally,
+                verticalArrangement = Arrangement.spacedBy(8.dp, Alignment.Top),
+            ) {
+                items(missing) { missing ->
+                    SchoolSupplyCard(navHostController = navController, schoolSupply = missing)
+                }
+            }
+        }
+    }
+}
+
+@Preview
+@Composable
+fun ReminderPreview() {
+    val navController = rememberNavController()
+    Reminder(navController)
+}