Added lines numbers in diff view

src/main/kotlin/app/git/diff/Hunk.kt

@@ -2,7 +2,11 @@ package app.git.diff
 
 data class Hunk(val header: String, val lines: List<Line>)
 
-data class Line(val text: String, val oldLineNumber: Int, val newLineNumber: Int, val lineType: LineType)
+data class Line(val text: String, val oldLineNumber: Int, val newLineNumber: Int, val lineType: LineType) {
+    // lines numbers are stored based on 0 being the first one but on a file the first line is the 1, so increment it!
+    val displayOldLineNumber: Int = oldLineNumber + 1
+    val displayNewLineNumber: Int = newLineNumber + 1
+}
 
 enum class LineType {
     CONTEXT,

src/main/kotlin/app/ui/Diff.kt

@@ -2,7 +2,8 @@ package app.ui
 
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.*
-import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.text.selection.DisableSelection
 import androidx.compose.foundation.text.selection.SelectionContainer
 import androidx.compose.material.ButtonDefaults
 import androidx.compose.material.MaterialTheme
@@ -16,12 +17,15 @@ import androidx.compose.ui.text.font.FontFamily
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import app.git.DiffEntryType
+import app.git.diff.Hunk
+import app.git.diff.Line
 import app.git.diff.LineType
 import app.theme.primaryTextColor
 import app.ui.components.ScrollableLazyColumn
 import app.ui.components.SecondaryButton
 import app.viewmodels.DiffViewModel
 import org.eclipse.jgit.diff.DiffEntry
+import kotlin.math.max
 
 @Composable
 fun Diff(
@@ -41,36 +45,7 @@ fun Diff(
             .background(MaterialTheme.colors.background)
             .fillMaxSize()
     ) {
-        Row(
+        DiffHeader(diffEntry, onCloseDiffView)
-            modifier = Modifier.fillMaxWidth(),
-            verticalAlignment = Alignment.CenterVertically,
-        ) {
-            val filePath = if(diffEntry.newPath != "/dev/null")
-                diffEntry.newPath
-            else
-                diffEntry.oldPath
-
-            Text(
-                text = filePath,
-                color = MaterialTheme.colors.primaryTextColor,
-                fontSize = 16.sp,
-                modifier = Modifier.padding(horizontal = 16.dp),
-            )
-
-            Spacer(modifier = Modifier.weight(1f))
-
-            OutlinedButton(
-                modifier = Modifier
-                    .padding(vertical = 8.dp, horizontal = 16.dp),
-                onClick = onCloseDiffView,
-                colors = ButtonDefaults.buttonColors(
-                    backgroundColor = MaterialTheme.colors.background,
-                    contentColor = MaterialTheme.colors.primary,
-                )
-            ) {
-                Text("Close diff")
-            }
-        }
 
         val scrollState by diffViewModel.lazyListState.collectAsState()
         ScrollableLazyColumn(
@@ -78,14 +53,39 @@ fun Diff(
                 .fillMaxSize(),
             state = scrollState
         ) {
-            itemsIndexed(hunks) { index, hunk ->
+            item { Spacer(modifier = Modifier.height(16.dp)) }
-                val hunksSeparation = if (index == 0)
+            items(hunks) { hunk ->
-                    0.dp
+                HunkHeader(
-                else
+                    hunk = hunk,
-                    16.dp
+                    diffEntryType = diffEntryType,
+                    diffViewModel = diffViewModel,
+                )
+
+                SelectionContainer {
+                    Column {
+                        val oldHighestLineNumber = hunk.lines.maxOf { it.displayOldLineNumber }
+                        val newHighestLineNumber = hunk.lines.maxOf { it.displayNewLineNumber }
+                        val highestLineNumber = max(oldHighestLineNumber, newHighestLineNumber)
+                        val highestLineNumberLength = highestLineNumber.toString().count()
+
+                        hunk.lines.forEach { line ->
+                            DiffLine(highestLineNumberLength, line)
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+@Composable
+fun HunkHeader(
+    hunk: Hunk,
+    diffEntryType: DiffEntryType,
+    diffViewModel: DiffViewModel,
+) {
     Row(
     modifier = Modifier
-                        .padding(top = hunksSeparation)
     .background(MaterialTheme.colors.surface)
     .padding(vertical = 4.dp)
     .fillMaxWidth()
@@ -123,10 +123,44 @@ fun Diff(
             )
         }
     }
+}
 
-                SelectionContainer {
+@Composable
-                    Column {
+fun DiffHeader(diffEntry: DiffEntry, onCloseDiffView: () -> Unit) {
-                        hunk.lines.forEach { line ->
+    Row(
+        modifier = Modifier.fillMaxWidth(),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        val filePath = if(diffEntry.newPath != "/dev/null")
+            diffEntry.newPath
+        else
+            diffEntry.oldPath
+
+        Text(
+            text = filePath,
+            color = MaterialTheme.colors.primaryTextColor,
+            fontSize = 16.sp,
+            modifier = Modifier.padding(horizontal = 16.dp),
+        )
+
+        Spacer(modifier = Modifier.weight(1f))
+
+        OutlinedButton(
+            modifier = Modifier
+                .padding(vertical = 8.dp, horizontal = 16.dp),
+            onClick = onCloseDiffView,
+            colors = ButtonDefaults.buttonColors(
+                backgroundColor = MaterialTheme.colors.background,
+                contentColor = MaterialTheme.colors.primary,
+            )
+        ) {
+            Text("Close diff")
+        }
+    }
+}
+
+@Composable
+fun DiffLine(highestLineNumberLength: Int, line: Line) {
     val backgroundColor = when (line.lineType) {
         LineType.ADDED -> {
             Color(0x77a9d49b)
@@ -138,12 +172,34 @@ fun Diff(
             MaterialTheme.colors.background
         }
     }
+    Row (
+        modifier = Modifier
+            .background(backgroundColor)
+    ) {
+        val oldLineText = if(line.lineType == LineType.REMOVED || line.lineType == LineType.CONTEXT) {
+            formattedLineNumber(line.displayOldLineNumber, highestLineNumberLength)
+        } else
+            emptyLineNumber(highestLineNumberLength)
+
+        val newLineText = if(line.lineType == LineType.ADDED || line.lineType == LineType.CONTEXT) {
+            formattedLineNumber(line.displayNewLineNumber, highestLineNumberLength)
+        } else
+            emptyLineNumber(highestLineNumberLength)
+
+        DisableSelection {
+            LineNumber(
+                text = oldLineText,
+            )
+
+            LineNumber(
+                text = newLineText
+            )
+        }
 
         Text(
             text = line.text,
             modifier = Modifier
-                                    .background(backgroundColor)
+                .padding(start = 8.dp)
-                                    .padding(start = 16.dp)
                 .fillMaxWidth(),
             color = MaterialTheme.colors.primaryTextColor,
             maxLines = 1,
@@ -152,9 +208,45 @@ fun Diff(
         )
     }
 }
+
+@Composable
+fun LineNumber(text: String) {
+    Text(
+        text = text,
+        color = MaterialTheme.colors.primaryTextColor,
+        modifier = Modifier
+            .background(MaterialTheme.colors.surface)
+            .padding(horizontal = 4.dp),
+        fontFamily = FontFamily.Monospace,
+        fontSize = 14.sp,
+    )
 }
+
+
+fun formattedLineNumber(number: Int, charactersCount: Int): String {
+    val numberStr = number.toString()
+    return if(numberStr.count() == charactersCount)
+        numberStr
+    else {
+        val lengthDiff = charactersCount - numberStr.count()
+        val numberBuilder = StringBuilder()
+        // Add whitespaces before the numbers
+        repeat(lengthDiff) {
+            numberBuilder.append(" ")
         }
-        }
+        numberBuilder.append(numberStr)
+
+        numberBuilder.toString()
     }
 }
 
+fun emptyLineNumber(charactersCount: Int): String {
+    val numberBuilder = StringBuilder()
+    // Add whitespaces before the numbers
+    repeat(charactersCount) {
+        numberBuilder.append(" ")
+    }
+
+    return numberBuilder.toString()
+}
+