AddMedicationScreen.kt

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun AddMedicationScreen() {
    // Previously implememted.
    var numberOfDosage by rememberSaveable { mutableStateOf("1") }
    var recurrence by rememberSaveable { mutableStateOf(Recurrence.Daily.name) }
    
    Column(
        modifier = Modifier
            .padding(16.dp, 16.dp)
            .verticalScroll(rememberScrollState()),
        verticalArrangement = Arrangement.spacedBy(8.dp)
    ) {
      
        // Previously implememted.

        Spacer(modifier = Modifier.padding(4.dp))

        var isMaxDoseError by rememberSaveable { mutableStateOf(false) }
        Row(
            horizontalArrangement = Arrangement.spacedBy(16.dp)
        ) {
            val maxDose = 3

            Column(
                verticalArrangement = Arrangement.spacedBy(8.dp)
            ) {
                Text(
                    text = stringResource(id = R.string.dosage),
                    style = MaterialTheme.typography.bodyLarge
                )
                TextField(
                    modifier = Modifier.width(128.dp),
                    value = numberOfDosage,
                    onValueChange = {
                        if (it.length < maxDose) {
                            isMaxDoseError = false
                            numberOfDosage = it
                        } else {
                            isMaxDoseError = true
                        }
                    },
                    trailingIcon = {
                        if (isMaxDoseError) {
                            Icon(
                                imageVector = Icons.Filled.Info,
                                contentDescription = "Error",
                                tint = MaterialTheme.colorScheme.error
                            )
                        }
                    },
                    placeholder = { Text(text = "e.g. 1") },
                    isError = isMaxDoseError,
                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number)
                )
            }
            RecurrenceDropdownMenu { recurrence = it }
        }

        if (isMaxDoseError) {
            Text(
                text = "You cannot have more than 99 dosage per day.",
                color = MaterialTheme.colorScheme.error,
                style = MaterialTheme.typography.bodySmall,
            )
        }
    }
}