Clear history UX/UI improved

- Show clear history button only when history view is fully expanded
- History view placeholder
- AlertDialog closes after clearing history
- List item height callback is called only once

core/base/src/main/res/values/strings.xml

@@ -1028,6 +1028,7 @@
     <string name="calculator_clear_history_label">Clear</string>
     <string name="calculator_clear_history_title">Clear history</string>
     <string name="calculator_clear_history_support">All expressions from history will be deleted forever. This action can\'t be undone!</string>
+    <string name="calculator_no_history">No history</string>
 
     <!--Precision-->
     <string name="precision_setting_support">Number of decimal places</string>

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorScreen.kt

@@ -18,7 +18,10 @@
 
 package com.sadellie.unitto.feature.calculator
 
+import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
 import androidx.compose.foundation.background
 import androidx.compose.foundation.gestures.Orientation
 import androidx.compose.foundation.gestures.draggable
@@ -101,6 +104,7 @@ private fun CalculatorScreen(
     evaluate: () -> Unit,
     clearHistory: () -> Unit
 ) {
+    var showClearHistoryButton by rememberSaveable { mutableStateOf(false) }
     var showClearHistoryDialog by rememberSaveable { mutableStateOf(false) }
     var draggedAmount by remember { mutableStateOf(0f) }
     val dragAmountAnimated by animateFloatAsState(draggedAmount)
@@ -113,6 +117,11 @@ private fun CalculatorScreen(
         navigateUpAction = navigateUpAction,
         colors = TopAppBarDefaults.topAppBarColors(MaterialTheme.colorScheme.surfaceVariant),
         actions = {
+            AnimatedVisibility(
+                visible = showClearHistoryButton,
+                enter = fadeIn(),
+                exit = fadeOut()
+            ) {
                 IconButton(
                     onClick = { showClearHistoryDialog = true },
                     content = {
@@ -123,6 +132,7 @@ private fun CalculatorScreen(
                     }
                 )
             }
+        }
     ) { paddingValues ->
         DragDownView(
             modifier = Modifier.padding(paddingValues),
@@ -153,10 +163,14 @@ private fun CalculatorScreen(
                             state = rememberDraggableState { delta ->
                                 draggedAmount = (draggedAmount + delta).coerceAtLeast(0f)
                             },
-                            onDragStopped = {
+                            onDragStopped = { _ ->
                                 // Snap to closest anchor (0, one history item, all history items)
                                 draggedAmount = listOf(0, historyItemHeight, maxDragAmount)
                                     .minBy { abs(draggedAmount.roundToInt() - it) }
+                                    .also {
+                                        // Show button only when fully history view is fully expanded
+                                        showClearHistoryButton = it == maxDragAmount
+                                    }
                                     .toFloat()
                             }
                         ),
@@ -218,12 +232,21 @@ private fun CalculatorScreen(
                 Text(stringResource(R.string.calculator_clear_history_support))
             },
             confirmButton = {
-                TextButton(onClick = clearHistory) { Text(stringResource(R.string.calculator_clear_history_label)) }
+                TextButton(
+                    onClick = {
+                        clearHistory()
+                        showClearHistoryDialog = false
+                    }
+                ) {
+                    Text(stringResource(R.string.calculator_clear_history_label))
+                }
             },
             dismissButton = {
-                TextButton(onClick = {
-                    showClearHistoryDialog = false
-                }) { Text(stringResource(R.string.cancel_label)) }
+                TextButton(
+                    onClick = { showClearHistoryDialog = false }
+                ) {
+                    Text(stringResource(R.string.cancel_label))
+                }
             },
             onDismissRequest = { showClearHistoryDialog = false }
         )
@@ -247,7 +270,7 @@ private fun PreviewCalculatorScreen() {
     ).map {
         HistoryItem(
             date = dtf.parse(it)!!,
-            expression = "12345123451234512345123451234512345123451234512345123451234512345",
+            expression = "12345".repeat(10),
             result = "67890"
         )
     }

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/components/HistoryList.kt

@@ -18,21 +18,35 @@
 
 package com.sadellie.unitto.feature.calculator.components
 
+import androidx.compose.foundation.background
 import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.rememberScrollState
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.History
+import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.layout.onPlaced
+import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
 import com.sadellie.unitto.core.ui.theme.NumbersTextStyleDisplayMedium
 import com.sadellie.unitto.data.model.HistoryItem
+import com.sadellie.unitto.feature.calculator.R
 import java.text.SimpleDateFormat
 import java.util.*
 
@@ -42,14 +56,56 @@ internal fun HistoryList(
     historyItems: List<HistoryItem>,
     historyItemHeightCallback: (Int) -> Unit
 ) {
+    val verticalArrangement by remember(historyItems) {
+        derivedStateOf {
+            if (historyItems.isEmpty()) {
+                Arrangement.Center
+            } else {
+                Arrangement.spacedBy(16.dp, Alignment.Bottom)
+            }
+        }
+    }
+
     LazyColumn(
         modifier = modifier,
-        reverseLayout = true
+        reverseLayout = true,
+        verticalArrangement = verticalArrangement
     ) {
-        items(historyItems) { historyItem ->
+        if (historyItems.isEmpty()) {
+            item {
                 Column(
-                Modifier.onPlaced { historyItemHeightCallback(it.size.height) }
+                    modifier = Modifier
+                        .onPlaced { historyItemHeightCallback(it.size.height) }
+                        .fillParentMaxWidth()
+                        .padding(vertical = 32.dp),
+                    verticalArrangement = Arrangement.Center,
+                    horizontalAlignment = Alignment.CenterHorizontally
                 ) {
+                    Icon(Icons.Default.History, null)
+                    Text(stringResource(R.string.calculator_no_history))
+                }
+            }
+        } else {
+            // We do this so that callback for items height is called only once
+            item {
+                HistoryListItem(
+                    modifier = Modifier.onPlaced { historyItemHeightCallback(it.size.height) },
+                    historyItem = historyItems.first()
+                )
+            }
+            items(historyItems.drop(1)) { historyItem ->
+                HistoryListItem(historyItem = historyItem)
+            }
+        }
+    }
+}
+
+@Composable
+private fun HistoryListItem(
+    modifier: Modifier = Modifier,
+    historyItem: HistoryItem
+) {
+    Column(modifier = modifier) {
         Text(
             text = historyItem.expression,
             maxLines = 1,
@@ -71,8 +127,6 @@ internal fun HistoryList(
             textAlign = TextAlign.End
         )
     }
-        }
-    }
 }
 
 @Preview
@@ -98,7 +152,9 @@ private fun PreviewHistoryList() {
     }
 
     HistoryList(
-        modifier = Modifier.fillMaxWidth(),
+        modifier = Modifier
+            .background(MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.5f))
+            .fillMaxSize(),
         historyItems = historyItems,
         historyItemHeightCallback = {}
     )