Add programmatic label and focus indicator to PIN entry field

features/lockscreen/impl/src/main/kotlin/io/element/android/features/lockscreen/impl/components/PinEntryTextField.kt

@@ -15,15 +15,23 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.ExperimentalLayoutApi
 import androidx.compose.foundation.layout.FlowRow
-import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.BasicTextField
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+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.focus.onFocusChanged
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.clearAndSetSemantics
+import androidx.compose.ui.semantics.contentDescription
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.unit.dp
 import io.element.android.compound.theme.ElementTheme
@@ -32,23 +40,34 @@ import io.element.android.features.lockscreen.impl.pin.model.PinEntry
 import io.element.android.libraries.designsystem.preview.ElementPreview
 import io.element.android.libraries.designsystem.preview.PreviewsDayNight
 import io.element.android.libraries.designsystem.theme.pinDigitBg
+import io.element.android.libraries.ui.strings.CommonPlurals
+import io.element.android.libraries.ui.strings.CommonStrings
 
 @Composable
 fun PinEntryTextField(
     pinEntry: PinEntry,
     isSecured: Boolean,
     onValueChange: (String) -> Unit,
     modifier: Modifier = Modifier,
+    initialIsFocus: Boolean = false,
 ) {
+    var isFocused by remember { mutableStateOf(initialIsFocus) }
+    val filledCount = pinEntry.digits.count { it is PinDigit.Filled }
+    val pinFieldLabel = stringResource(CommonStrings.a11y_pin_field)
+    val digitsEnteredLabel = pluralStringResource(CommonPlurals.a11y_digits_entered, filledCount, filledCount)
     BasicTextField(
-        modifier = modifier,
+        modifier = modifier
+            .onFocusChanged { isFocused = it.isFocused }
+            .clearAndSetSemantics {
+                contentDescription = "$pinFieldLabel, $digitsEnteredLabel"
+            },
         value = pinEntry.toText(),
         onValueChange = {
             onValueChange(it)
         },
         keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.NumberPassword),
         decorationBox = {
-            PinEntryRow(pinEntry = pinEntry, isSecured = isSecured)
+            PinEntryRow(pinEntry = pinEntry, isSecured = isSecured, isFocused = isFocused)
         }
     )
 }
@@ -58,13 +77,19 @@ fun PinEntryTextField(
 private fun PinEntryRow(
     pinEntry: PinEntry,
     isSecured: Boolean,
+    isFocused: Boolean,
 ) {
     FlowRow(
         horizontalArrangement = Arrangement.spacedBy(8.dp, alignment = Alignment.CenterHorizontally),
         verticalArrangement = Arrangement.spacedBy(8.dp),
     ) {
-        for (digit in pinEntry.digits) {
-            PinDigitView(digit = digit, isSecured = isSecured)
+        val focusedIndex = pinEntry.digits.indexOfFirst { it is PinDigit.Empty }
+        pinEntry.digits.forEachIndexed { index, digit ->
+            PinDigitView(
+                digit = digit,
+                isSecured = isSecured,
+                isFocused = isFocused && index == focusedIndex
+            )
         }
     }
 }
@@ -73,11 +98,16 @@ private fun PinEntryRow(
 private fun PinDigitView(
     digit: PinDigit,
     isSecured: Boolean,
+    isFocused: Boolean,
 ) {
     val shape = RoundedCornerShape(8.dp)
     val appearanceModifier = when (digit) {
         PinDigit.Empty -> {
-            Modifier.border(1.dp, ElementTheme.colors.iconPrimary, shape)
+            if (isFocused) {
+                Modifier.border(2.dp, ElementTheme.colors.borderFocused, shape)
+            } else {
+                Modifier.border(1.dp, ElementTheme.colors.iconPrimary, shape)
+            }
         }
         is PinDigit.Filled -> {
             Modifier.background(ElementTheme.colors.pinDigitBg, shape)
@@ -108,18 +138,19 @@ private fun PinDigitView(
 internal fun PinEntryTextFieldPreview() {
     ElementPreview {
         val pinEntry = PinEntry.createEmpty(4).fillWith("12")
-        Column {
-            PinEntryTextField(
-                pinEntry = pinEntry,
-                isSecured = true,
-                onValueChange = {},
-            )
-            Spacer(modifier = Modifier.size(16.dp))
-            PinEntryTextField(
-                pinEntry = pinEntry,
-                isSecured = false,
-                onValueChange = {},
-            )
+        Column(
+            verticalArrangement = Arrangement.spacedBy(16.dp),
+        ) {
+            listOf(true, false).forEach { isSecured ->
+                listOf(true, false).forEach { initialIsFocus ->
+                    PinEntryTextField(
+                        pinEntry = pinEntry,
+                        isSecured = isSecured,
+                        initialIsFocus = initialIsFocus,
+                        onValueChange = {},
+                    )
+                }
+            }
         }
     }
 }