From 00467ba31c4b70ef27d16737940ade1d48a059cc Mon Sep 17 00:00:00 2001
From: estib <stron@me.com>
Date: Mon, 31 Mar 2025 11:13:22 +0200
Subject: [PATCH] Unified diff: File deletions can't be partially selected
MIME-Version: 1.0
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Don’t let the user partially select the hunk if they are file deletions
---
 .../src/components/v3/UnifiedDiffView.svelte  | 12 ++++++---
 apps/desktop/src/lib/hunks/hunk.ts            | 25 +++++++++++++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/apps/desktop/src/components/v3/UnifiedDiffView.svelte b/apps/desktop/src/components/v3/UnifiedDiffView.svelte
index 7e0ecb0ebd..4986b32e12 100644
--- a/apps/desktop/src/components/v3/UnifiedDiffView.svelte
+++ b/apps/desktop/src/components/v3/UnifiedDiffView.svelte
@@ -3,6 +3,7 @@
 	import HunkContextMenu from '$components/v3/HunkContextMenu.svelte';
 	import LineSelection from '$components/v3/unifiedDiffLineSelection.svelte';
 	import { DiffService } from '$lib/hunks/diffService.svelte';
+	import { canBePartiallySelected, type DiffHunk } from '$lib/hunks/hunk';
 	import { Project } from '$lib/project/project';
 	import {
 		ChangeSelectionService,
@@ -13,7 +14,6 @@
 	import { getContextStoreBySymbol, inject } from '@gitbutler/shared/context';
 	import HunkDiff from '@gitbutler/ui/HunkDiff.svelte';
 	import type { TreeChange } from '$lib/hunks/change';
-	import type { DiffHunk } from '$lib/hunks/hunk';
 	import type { LineId } from '@gitbutler/ui/utils/diffParsing';
 
 	type Props = {
@@ -173,8 +173,14 @@
 						diffFont={$userSettings.diffFont}
 						diffContrast={$userSettings.diffContrast}
 						inlineUnifiedDiffs={$userSettings.inlineUnifiedDiffs}
-						onLineClick={(p) =>
-							lineSelection.toggleStageLines(selection, hunk, p, diff.subject.hunks)}
+						onLineClick={(p) => {
+							if (!canBePartiallySelected(diff.subject)) {
+								const select = selection === undefined;
+								updateStage(hunk, select, diff.subject.hunks);
+								return;
+							}
+							lineSelection.toggleStageLines(selection, hunk, p, diff.subject.hunks);
+						}}
 						onChangeStage={(selected) => {
 							updateStage(hunk, selected, diff.subject.hunks);
 						}}
diff --git a/apps/desktop/src/lib/hunks/hunk.ts b/apps/desktop/src/lib/hunks/hunk.ts
index 30f2dba3ec..5ae6af2409 100644
--- a/apps/desktop/src/lib/hunks/hunk.ts
+++ b/apps/desktop/src/lib/hunks/hunk.ts
@@ -247,3 +247,28 @@ export type Patch = {
 	/** All non-overlapping hunks, including their context lines. */
 	readonly hunks: DiffHunk[];
 };
+
+export function isFileDeletionHunk(hunk: DiffHunk): boolean {
+	return hunk.newStart === 1 && hunk.newLines === 0;
+}
+
+export function isFileAdditionHunk(hunk: DiffHunk): boolean {
+	return hunk.oldStart === 1 && hunk.oldLines === 0;
+}
+
+export function canBePartiallySelected(patch: Patch): boolean {
+	if (patch.hunks.length === 0) {
+		// Should never happen, but just in case
+		return false;
+	}
+
+	if (patch.hunks.length === 1 && isFileDeletionHunk(patch.hunks[0]!)) {
+		// Only one hunk and it's a file deletion
+		return false;
+	}
+
+	// TODO: Check if the hunks come from the diff filter
+	// See: https://github.com/gitbutlerapp/gitbutler/pull/7893
+
+	return true;
+}