// InToCm Example
// Input a length in inches value in the TextField 
// then output the length in centimeters whenever 
// the textfield value changes.
// Output NaN for illegal input.

package it372.ssmith.intocm
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.Column
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
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.text.style.TextAlign
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import java.util.Locale

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

@Composable
fun MainLayout( ) {

    var valueInch = remember { mutableStateOf("0")}
    var valueCm = remember { mutableStateOf("0")}

    Column(modifier = Modifier
        .padding(20.dp),
        horizontalAlignment = Alignment.CenterHorizontally) {

        // Textfield contains a length in inches.
        TextField(value = valueInch.value,
            label = { Text("Enter a Length in Inches:") },
            onValueChange = {
                valueInch.value = it
                valueCm.value = "NaN"
                valueInch.value.toDoubleOrNull( )?.let {
                    valueCm.value = String.format("%.2f", it * 2.54)
                }
            },
            modifier = Modifier
                .padding(bottom = 50.dp, top = 50.dp,
                    start = 20.dp,  end = 20.dp)
                .size(width = 200.dp, height = 75.dp)
                .fillMaxWidth( ),
            textStyle = TextStyle.Default.copy(fontSize = 28.sp)
        )

        // Text element contains length in centimeters 
        Text(text = valueCm.value,
            modifier = Modifier
                .padding(bottom = 50.dp, top = 50.dp,
                    start = 20.dp,  end = 20.dp)
                .size(width = 200.dp, height = 50.dp)
                .background(Color(0xFFE0E0FF))
                .fillMaxWidth( ),
            fontSize = 25.sp,
            textAlign = TextAlign.Center
        )
    }
}

@Preview(showBackground = true)
@Composable
fun GreetingPreview() {
    MainLayout( )

}