More fix for PR comments

1. Clarified component positions with modifiers
2. Removed unnecessary comments
3. Simplified JsonParser

Author: wenli-cai

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/App.kt

@@ -10,8 +10,8 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import com.squareup.workflow1.traceviewer.model.Node
-import com.squareup.workflow1.traceviewer.ui.InfoPanel
 import com.squareup.workflow1.traceviewer.ui.RenderDiagram
+import com.squareup.workflow1.traceviewer.ui.RightInfoPanel
 import com.squareup.workflow1.traceviewer.ui.StateSelectTab
 import com.squareup.workflow1.traceviewer.util.SandboxBackground
 import com.squareup.workflow1.traceviewer.util.UploadFile
@@ -29,38 +29,38 @@ public fun App(
   var workflowFrames by remember { mutableStateOf<List<Node>>(emptyList()) }
   var frameIndex by remember { mutableIntStateOf(0) }
 
-  Box {
+  Box(
+    modifier = modifier
+  ) {
     // Main content
     if (selectedTraceFile != null) {
       SandboxBackground {
         RenderDiagram(
           traceFile = selectedTraceFile!!,
-          traceInd = frameIndex,
+          frameInd = frameIndex,
           onFileParse = { workflowFrames = it },
           onNodeSelect = { selectedNode = it }
         )
       }
     }
 
-    // Top trace selector row
     StateSelectTab(
       frames = workflowFrames,
       currentIndex = frameIndex,
       onIndexChange = { frameIndex = it },
       modifier = Modifier.align(Alignment.TopCenter)
     )
 
-    // Right side information panel
-    InfoPanel(selectedNode)
+    RightInfoPanel(selectedNode)
 
-    // Bottom left upload button
-    val onReset = {
-      selectedNode = null
-      frameIndex = 0
-    }
+    // The states are reset when a new file is selected.
     UploadFile(
-      onReset = onReset,
-      onFileSelect = { selectedTraceFile = it }
+      onFileSelect = {
+        selectedTraceFile = it
+        selectedNode = null
+        frameIndex = 0
+      },
+      modifier = Modifier.align(Alignment.BottomStart)
     )
   }
 }

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/Main.kt

@@ -1,12 +1,14 @@
 package com.squareup.workflow1.traceviewer
 
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.Modifier
 import androidx.compose.ui.window.singleWindowApplication
 
 /**
  * Main entry point for the desktop application, see [README.md] for more details.
  */
 fun main() {
   singleWindowApplication(title = "Workflow Trace Viewer") {
-    App()
+    App(Modifier.fillMaxSize())
   }
 }

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/ui/WorkflowInfoPanel.kt

@@ -33,11 +33,11 @@ import com.squareup.workflow1.traceviewer.model.Node
  * @param selectedNode The currently selected workflow node, or null if no node is selected.
  */
 @Composable
-public fun InfoPanel(
+public fun RightInfoPanel(
   selectedNode: Node?,
   modifier: Modifier = Modifier
 ) {
-  // This row is ordered RTL
+  // This row is aligned to the right of the screen.
   Row {
     Spacer(modifier = Modifier.weight(1f))
 
@@ -51,28 +51,23 @@ public fun InfoPanel(
         .align(Alignment.Top)
     ) {
       Icon(
-        imageVector = if (panelOpen) Filled.KeyboardArrowLeft else Filled.KeyboardArrowRight,
+        imageVector = if (panelOpen) Filled.KeyboardArrowRight else Filled.KeyboardArrowLeft,
         contentDescription = if (panelOpen) "Close Panel" else "Open Panel",
         modifier = Modifier
       )
     }
 
-    // based on open/close, display the node details (Column)
     if (panelOpen) {
-      PanelDetails(
+      NodePanelDetails(
         selectedNode,
         Modifier.fillMaxWidth(.35f)
       )
     }
   }
 }
 
-/**
- * The text details of the selected node. This should be closely coupled with the [Node]
- * data class to see what information should be displayed.
- */
 @Composable
-private fun PanelDetails(
+private fun NodePanelDetails(
   node: Node?,
   modifier: Modifier = Modifier
 ) {

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/ui/WorkflowTree.kt

@@ -20,7 +20,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
 import com.squareup.workflow1.traceviewer.model.Node
-import com.squareup.workflow1.traceviewer.util.fetchTrace
+import com.squareup.workflow1.traceviewer.util.parseTrace
 import io.github.vinceglb.filekit.PlatformFile
 
 /**
@@ -30,22 +30,22 @@ import io.github.vinceglb.filekit.PlatformFile
 @Composable
 public fun RenderDiagram(
   traceFile: PlatformFile,
-  traceInd: Int,
+  frameInd: Int,
   onFileParse: (List<Node>) -> Unit,
   onNodeSelect: (Node) -> Unit,
 ) {
-  var nodes by remember { mutableStateOf<List<Node>>(emptyList()) }
+  var frames by remember { mutableStateOf<List<Node>>(emptyList()) }
   var isLoading by remember { mutableStateOf(true) }
 
   LaunchedEffect(traceFile) {
     isLoading = true
-    nodes = fetchTrace(traceFile)
-    onFileParse(nodes)
+    frames = parseTrace(traceFile)
+    onFileParse(frames)
     isLoading = false
   }
 
   if (!isLoading) {
-    DrawTree(nodes[traceInd], onNodeSelect)
+    DrawTree(frames[frameInd], onNodeSelect)
   }
 
   // TODO: catch errors and display UI here
@@ -68,10 +68,9 @@ private fun DrawTree(
       .fillMaxSize(),
     horizontalAlignment = Alignment.CenterHorizontally,
   ) {
-    // draws the node itself
     DrawNode(node, onNodeSelect)
 
-    // draws the node's children recursively
+    // Draws the node's children recursively.
     Row(
       horizontalArrangement = Arrangement.Center,
       verticalAlignment = Alignment.Top

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/util/JsonParser.kt

@@ -1,6 +1,5 @@
 package com.squareup.workflow1.traceviewer.util
 
-import androidx.compose.ui.Modifier
 import com.squareup.moshi.JsonAdapter
 import com.squareup.moshi.JsonDataException
 import com.squareup.moshi.Moshi
@@ -12,31 +11,25 @@ import io.github.vinceglb.filekit.readString
 import java.io.IOException
 
 /**
- * Parses the data from the given file and initiates the workflow tree
- */
-public suspend fun fetchTrace(
-  file: PlatformFile?,
-  modifier: Modifier = Modifier
-): List<Node> {
-  val jsonString = file?.readString()
-  return jsonString?.let { parseTrace(it) } ?: emptyList()
-}
-
-/**
- * Parses a JSON string into [Node] with Moshi adapters. Moshi automatically throws JsonDataException
+ * Parses a given file's JSON String into [Node] with Moshi adapters. Moshi automatically throws JsonDataException
  * and IOException
  * @throws JsonDataException malformed JSON data or an error reading.
  * @throws IOException JSON is correct, but mismatch between class and JSON structure.
  */
-public fun parseTrace(
-  json: String
+public suspend fun parseTrace(
+  file: PlatformFile,
 ): List<Node> {
+  val jsonString = file.readString()
+
   val moshi = Moshi.Builder()
     .add(KotlinJsonAdapterFactory())
     .build()
 
   val workflowList = Types.newParameterizedType(List::class.java, Node::class.java)
   val workflowAdapter: JsonAdapter<List<Node>> = moshi.adapter(workflowList)
-  val root = workflowAdapter.fromJson(json) ?: emptyList()
-  return root
+  val trace = workflowAdapter.fromJson(jsonString)
+  if (trace == null) {
+    throw JsonDataException("Could not parse JSON")
+  }
+  return trace
 }

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/util/UploadFile.kt

@@ -1,14 +1,11 @@
 package com.squareup.workflow1.traceviewer.util
 
-import androidx.compose.foundation.layout.Box
-import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material.Button
 import androidx.compose.material.ButtonDefaults.buttonColors
 import androidx.compose.material.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
@@ -23,36 +20,27 @@ import io.github.vinceglb.filekit.dialogs.compose.rememberFilePickerLauncher
  */
 @Composable
 public fun UploadFile(
-  onReset: () -> Unit,
   onFileSelect: (PlatformFile?) -> Unit,
   modifier: Modifier = Modifier,
 ) {
-  Box(
-    modifier
-      .padding(16.dp)
-      .fillMaxSize()
+  val launcher = rememberFilePickerLauncher(
+    type = FileKitType.File(listOf("json", "txt")),
+    title = "Select Workflow Trace File"
   ) {
-    val launcher = rememberFilePickerLauncher(
-      type = FileKitType.File(listOf("json", "txt")),
-      title = "Select Workflow Trace File"
-    ) {
-      onReset()
-      onFileSelect(it)
-    }
+    onFileSelect(it)
+  }
 
-    Button(
-      onClick = { launcher.launch() },
-      modifier = Modifier
-        .align(Alignment.BottomStart),
-      shape = CircleShape,
-      colors = buttonColors(Color.Black)
-    ) {
-      Text(
-        text = "+",
-        color = Color.White,
-        fontSize = 24.sp,
-        fontWeight = androidx.compose.ui.text.font.FontWeight.Bold
-      )
-    }
+  Button(
+    onClick = { launcher.launch() },
+    modifier = modifier.padding(16.dp),
+    shape = CircleShape,
+    colors = buttonColors(Color.Black)
+  ) {
+    Text(
+      text = "+",
+      color = Color.White,
+      fontSize = 24.sp,
+      fontWeight = androidx.compose.ui.text.font.FontWeight.Bold
+    )
   }
 }