// TwoWayTempConverter Corrected Example
// Source code file: MainActivity.kt

package it372.ssmith.twowaytempconverter
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.material3.Button
import androidx.compose.material3.RadioButton
import androidx.compose.material3.Text
import androidx.compose.material3.TextField
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContent {
            MainLayout()
        }
    }
}

@Composable
fun MainLayout( ) {

    // State variable for selected radiobutton
    var radioState = remember { mutableStateOf(0) }

    // Contents of TextField
    var tfContents = remember { mutableStateOf("") }

    // Label of TextField
    var tfLabel = remember {
        mutableStateOf("Enter Celsius value:")
    }

    // Result to put in Text
    var textResult = remember { mutableStateOf("") }

    Column(modifier = Modifier
        .padding(all = 50.dp)
        .background(color = Color(0xFFE0E0FF))
        .fillMaxSize( ),
        horizontalAlignment = Alignment.CenterHorizontally) {
        Row(modifier = Modifier.fillMaxWidth( )
            .padding(top = 20.dp),
            horizontalArrangement = Arrangement.Center) {
            RadioButton(selected = radioState.value == 0,
                onClick = {
                    radioState.value = 0
                    tfLabel.value = "Enter Celsius value."
                    textResult.value = ""
                } )

            Text(text = "C to F", fontSize = 25.sp)

            RadioButton(selected= radioState.value == 1,
                onClick = {
                    radioState.value = 1;
                    tfLabel.value = "Enter Fahrenheit value."
                    textResult.value = ""
                } )

            Text(text = "F to C", fontSize = 25.sp)
        }

        TextField(value = tfContents.value,
            label = { Text(text = tfLabel.value,
                           fontSize = 15.sp) },
            onValueChange = {
                tfContents.value = it
                textResult.value = ""
            },
            modifier = Modifier
                .size(width = 200.dp, height = 75.dp)
                .background(color = Color(0xFFFFE0E0))
                .fillMaxWidth( ),
            textStyle = TextStyle.Default.copy(fontSize = 25.sp))

            Button(onClick = {
                if (radioState.value == 0) {
                    var fahrenheit = "NaN"
                    tfContents.value.toDoubleOrNull( )?.let {
                        fahrenheit = "%.2f".format(9.0 * it / 5.0 + 32.0)
                        textResult.value = fahrenheit
                    }
                }
                else  {
                    var celsius = "NaN"
                    tfContents.value.toDoubleOrNull( )?.let {
                        celsius = "%.2f".format(5.0 * (it - 32.0) / 9.0)
                        textResult.value = celsius
                    }
                }
            }, modifier = Modifier.padding(top = 20.dp)) {

                Text(text = "Convert Temperature", fontSize = 25.sp)
            }

        Text(text = textResult.value, fontSize = 25.sp,
            modifier = Modifier
                .padding(top = 20.dp)
                .background(color = Color.White)
                .size(width = 200.dp, height = 50.dp)
        )
    }
}

@Preview(showBackground = true)
@Composable
fun MainLayoutPreview() {
    MainLayout( )
}