Unwrap patch promises and remove double parsing

web/src/lib/components/diff/ConciseDiffView.svelte

@@ -13,7 +13,6 @@
         type SearchSegment,
     } from "$lib/components/diff/concise-diff-view.svelte";
     import Spinner from "$lib/components/Spinner.svelte";
-    import { type StructuredPatch } from "diff";
     import { onDestroy } from "svelte";
     import { type MutableValue } from "$lib/util";
     import { box } from "svelte-toolbelt";
@@ -33,7 +32,7 @@
         cacheKey,
     }: ConciseDiffViewProps<K> = $props();
 
-    const parsedPatch: Promise<StructuredPatch> = $derived.by(async () => {
+    const parsedPatch = $derived.by(() => {
         if (rawPatchContent !== undefined) {
             return parseSinglePatch(rawPatchContent);
         } else if (patch !== undefined) {

web/src/lib/components/diff/concise-diff-view.svelte.ts

@@ -676,6 +676,19 @@ async function makeHunk(
     return { lines };
 }
 
+export function patchHeaderDiffOnly(patch: StructuredPatch): boolean {
+    if (patch.hunks.length === 0) {
+        return false;
+    }
+    let onlyHeaderChanges = true;
+    for (let j = 0; j < patch.hunks.length; j++) {
+        if (hasNonHeaderChanges(patch.hunks[j].lines)) {
+            onlyHeaderChanges = false;
+        }
+    }
+    return onlyHeaderChanges;
+}
+
 export function hasNonHeaderChanges(contentLines: string[]) {
     for (const line of contentLines) {
         if (lineHasNonHeaderChange(line)) {
@@ -1013,7 +1026,7 @@ export function parseSinglePatch(rawPatchContent: string): StructuredPatch {
 
 export interface ConciseDiffViewProps<K> {
     rawPatchContent?: string;
-    patch?: Promise<StructuredPatch>;
+    patch?: StructuredPatch;
 
     syntaxHighlighting?: boolean;
     syntaxHighlightingTheme?: BundledTheme;
@@ -1030,7 +1043,7 @@ export interface ConciseDiffViewProps<K> {
 }
 
 export type ConciseDiffViewStateProps<K> = ReadableBoxedValues<{
-    patch: Promise<StructuredPatch>;
+    patch: StructuredPatch;
 
     syntaxHighlighting: boolean;
     syntaxHighlightingTheme: BundledTheme | undefined;

web/src/lib/diff-viewer-multi-file.svelte.ts

@@ -1,12 +1,12 @@
 import { fetchGithubCommitDiff, fetchGithubComparison, fetchGithubPRComparison, type FileStatus, getGithubToken, type GithubDiff } from "./github.svelte";
-import { type StructuredPatch, parsePatch } from "diff";
+import { type StructuredPatch } from "diff";
 import {
     ConciseDiffViewCachedState,
     DEFAULT_THEME_DARK,
     DEFAULT_THEME_LIGHT,
-    hasNonHeaderChanges,
     isNoNewlineAtEofLine,
     parseSinglePatch,
+    patchHeaderDiffOnly,
 } from "$lib/components/diff/concise-diff-view.svelte";
 import type { BundledTheme } from "shiki";
 import { browser } from "$app/environment";
@@ -150,8 +150,8 @@ export type CommonFileDetails = {
 
 export type TextFileDetails = CommonFileDetails & {
     type: "text";
-    patchText: string;
-    structuredPatch: Promise<StructuredPatch>;
+    structuredPatch: StructuredPatch;
+    patchHeaderDiffOnly: boolean;
 };
 
 export type ImageFileDetails = CommonFileDetails & {
@@ -160,13 +160,14 @@ export type ImageFileDetails = CommonFileDetails & {
 };
 
 export function makeTextDetails(fromFile: string, toFile: string, status: FileStatus, patchText: string): TextFileDetails {
+    const patch = parseSinglePatch(patchText);
     return {
         type: "text",
         fromFile,
         toFile,
         status,
-        patchText,
-        structuredPatch: (async () => parseSinglePatch(patchText))(),
+        structuredPatch: patch,
+        patchHeaderDiffOnly: patchHeaderDiffOnly(patch),
     };
 }
 
@@ -285,45 +286,6 @@ export function getFileStatusProps(status: FileStatus): FileStatusProps {
     }
 }
 
-export function findHeaderChangeOnlyPatches(fileDetails: FileDetails[]) {
-    const patchStrings = fileDetails.map((details) => {
-        if (details.type === "text") {
-            return details.patchText;
-        }
-        return undefined;
-    });
-
-    const result: boolean[] = [];
-
-    for (let i = 0; i < patchStrings.length; i++) {
-        const patchString = patchStrings[i];
-        if (patchString === undefined || patchString.length === 0) {
-            result.push(false);
-            continue;
-        }
-        // TODO: Parsing twice is wasteful
-        const patches = parsePatch(patchString);
-        if (patches.length !== 1) {
-            result.push(false);
-            continue;
-        }
-        const patch = patches[0];
-        if (patch.hunks.length === 0) {
-            result.push(false);
-            continue;
-        }
-        let onlyHeaderChanges = true;
-        for (let j = 0; j < patch.hunks.length; j++) {
-            if (hasNonHeaderChanges(patch.hunks[j].lines)) {
-                onlyHeaderChanges = false;
-            }
-        }
-        result.push(onlyHeaderChanges);
-    }
-
-    return result;
-}
-
 export type ViewerStatistics = {
     addedLines: number;
     removedLines: number;
@@ -368,19 +330,22 @@ export class MultiFileDiffViewerState {
 
     readonly fileTreeFilterDebounced = new Debounced(() => this.fileTreeFilter, 500);
     readonly searchQueryDebounced = new Debounced(() => this.searchQuery, 500);
-    readonly stats: Promise<ViewerStatistics> = $derived(this.countStats());
+    readonly stats: ViewerStatistics = $derived(this.countStats());
     readonly fileTreeRoots: TreeNode<FileTreeNodeData>[] = $derived(makeFileTree(this.fileDetails));
     readonly filteredFileDetails: FileDetails[] = $derived(
         this.fileTreeFilterDebounced.current ? this.fileDetails.filter((f) => this.filterFile(f)) : this.fileDetails,
     );
-    readonly patchHeaderDiffOnly: boolean[] = $derived(findHeaderChangeOnlyPatches(this.fileDetails));
     readonly searchResults: Promise<SearchResults> = $derived(this.findSearchResults());
 
     private constructor() {
         // Auto-check all patch header diff only diffs
         $effect(() => {
-            for (let i = 0; i < this.patchHeaderDiffOnly.length; i++) {
-                if (this.patchHeaderDiffOnly[i] && this.checked[i] === undefined) {
+            for (let i = 0; i < this.fileDetails.length; i++) {
+                const details = this.fileDetails[i];
+                if (details.type !== "text") {
+                    continue;
+                }
+                if (details.patchHeaderDiffOnly && this.checked[i] === undefined) {
                     this.checked[i] = true;
                 }
             }
@@ -543,7 +508,7 @@ export class MultiFileDiffViewerState {
         return false;
     }
 
-    private async countStats(): Promise<ViewerStatistics> {
+    private countStats(): ViewerStatistics {
         let addedLines = 0;
         let removedLines = 0;
         const fileAddedLines: number[] = [];
@@ -554,7 +519,7 @@ export class MultiFileDiffViewerState {
             if (details.type !== "text") {
                 continue;
             }
-            const diff = await details.structuredPatch;
+            const diff = details.structuredPatch;
 
             for (let j = 0; j < diff.hunks.length; j++) {
                 const hunk = diff.hunks[j];

web/src/routes/+page.svelte

@@ -283,11 +283,7 @@
         </div>
         <div class="flex flex-row items-center gap-2 px-3 pb-2">
             <SidebarToggle class="data-[side=right]:order-10" />
-            {#await viewer.stats}
-                <DiffStats />
-            {:then stats}
-                <DiffStats add={stats.addedLines} remove={stats.removedLines} />
-            {/await}
+            <DiffStats add={viewer.stats.addedLines} remove={viewer.stats.removedLines} />
             <DiffSearch />
         </div>
         <div class="flex flex-1 flex-col border-t">
@@ -325,7 +321,7 @@
                                 {/if}
                             </div>
                         {/if}
-                        {#if !viewer.collapsed[index] && value.type === "text" && (!viewer.patchHeaderDiffOnly[index] || !globalOptions.omitPatchHeaderOnlyHunks)}
+                        {#if !viewer.collapsed[index] && value.type === "text" && (!value.patchHeaderDiffOnly || !globalOptions.omitPatchHeaderOnlyHunks)}
                             <div class="mb border-b">
                                 <ConciseDiffView
                                     patch={value.structuredPatch}

web/src/routes/FileHeader.svelte

@@ -28,6 +28,8 @@
             });
         }
     }
+
+    let patchHeaderDiffOnly = $derived(value.type === "text" && value.patchHeaderDiffOnly);
 </script>
 
 {#snippet fileName()}
@@ -97,19 +99,15 @@
     onkeyup={(event) => event.key === "Enter" && viewer.scrollToFile(index, { autoExpand: false, smooth: true })}
 >
     {#if value.type === "text"}
-        {#await viewer.stats}
-            <DiffStats brief />
-        {:then stats}
-            <DiffStats brief add={stats.fileAddedLines[index]} remove={stats.fileRemovedLines[index]} />
-        {/await}
+        <DiffStats brief add={viewer.stats.fileAddedLines[index]} remove={viewer.stats.fileRemovedLines[index]} />
     {/if}
     {@render fileName()}
     <div class="ms-0.5 ml-auto flex items-center gap-2">
-        {#if viewer.patchHeaderDiffOnly[index]}
+        {#if patchHeaderDiffOnly}
             <span class="rounded-sm bg-neutral-3 px-1.5">Patch-header-only diff</span>
         {/if}
         {@render actionsPopover()}
-        {#if !viewer.patchHeaderDiffOnly[index] || !globalOptions.omitPatchHeaderOnlyHunks || value.type === "image"}
+        {#if !patchHeaderDiffOnly || !globalOptions.omitPatchHeaderOnlyHunks || value.type === "image"}
             {@render collapseToggle()}
         {/if}
     </div>