"use client";
import { useEffect, useId, useMemo, useRef, useState } from "react";
import { LayoutGroup, motion, type Transition } from "motion/react";
import { cn } from "@/lib/utils";
export type DiffLineKind = "add" | "del" | "context";
export interface DiffLine {
id: string;
kind: DiffLineKind;
text: string;
oldNo?: number;
newNo?: number;
}
export interface DiffHunk {
id: string;
file: string;
header?: string;
lines: DiffLine[];
}
export type HunkVerdict = "pending" | "accepted" | "rejected";
export interface DiffReviewProps {
hunks?: DiffHunk[];
onAccept?: (hunk: DiffHunk) => void;
onReject?: (hunk: DiffHunk) => void;
defaultView?: "unified" | "split";
morphDuration?: number;
stiffness?: number;
damping?: number;
stagger?: number;
density?: "comfortable" | "compact";
showLineNumbers?: boolean;
contextLines?: number;
collapseDecided?: boolean;
addColor?: string;
delColor?: string;
accentColor?: string;
reducedMotion?: boolean;
className?: string;
}
const ROW = { comfortable: 24, compact: 20 } as const;
const STAGGER_CAP = 12;
const EASE = [0.22, 1, 0.36, 1] as const;
type Segment =
| { kind: "lines"; key: string; lines: DiffLine[] }
| { kind: "fold"; key: string; lines: DiffLine[] };
function foldContext(lines: DiffLine[], contextLines: number): Segment[] {
const out: Segment[] = [];
const push = (run: DiffLine[]) => {
if (run.length > 0) out.push({ kind: "lines", key: run[0].id, lines: run });
};
let i = 0;
while (i < lines.length) {
const start = i;
const context = lines[i].kind === "context";
while (i < lines.length && (lines[i].kind === "context") === context) i++;
const run = lines.slice(start, i);
if (!context) {
push(run);
continue;
}
const leading = start === 0 && i < lines.length;
const trailing = i === lines.length && start > 0;
const head = leading ? 0 : contextLines;
const tail = trailing ? 0 : contextLines;
const hiddenCount = run.length - head - tail;
if (hiddenCount <= 1) {
push(run);
continue;
}
push(run.slice(0, head));
out.push({
kind: "fold",
key: `fold:${run[head].id}`,
lines: run.slice(head, run.length - tail),
});
push(run.slice(run.length - tail));
}
return out;
}
function pairRows(lines: DiffLine[]) {
const rows: Array<{ key: string; left: DiffLine | null; right: DiffLine | null }> =
[];
let i = 0;
while (i < lines.length) {
if (lines[i].kind === "context") {
rows.push({ key: lines[i].id, left: lines[i], right: lines[i] });
i++;
continue;
}
const dels: DiffLine[] = [];
const adds: DiffLine[] = [];
while (i < lines.length && lines[i].kind === "del") dels.push(lines[i++]);
while (i < lines.length && lines[i].kind === "add") adds.push(lines[i++]);
const span = Math.max(dels.length, adds.length);
for (let k = 0; k < span; k++) {
const left = dels[k] ?? null;
const right = adds[k] ?? null;
rows.push({ key: (left ?? right)!.id, left, right });
}
}
return rows;
}
function tally(lines: DiffLine[]) {
let add = 0;
let del = 0;
for (const line of lines) {
if (line.kind === "add") add++;
else if (line.kind === "del") del++;
}
return { add, del };
}
const SIGN: Record<DiffLineKind, string> = { add: "+", del: "−", context: " " };
const SPOKEN: Record<DiffLineKind, string> = {
add: "Added, ",
del: "Removed, ",
context: "",
};
interface CellProps {
line: DiffLine | null;
number: "old" | "new" | "both";
travels: boolean;
uid: string;
compact: boolean;
showLineNumbers: boolean;
addColor: string;
delColor: string;
spring: Transition;
reveal: Transition | false;
}
function LineCell({
line,
number,
travels,
uid,
compact,
showLineNumbers,
addColor,
delColor,
spring,
reveal,
}: CellProps) {
const height = compact ? ROW.compact : ROW.comfortable;
if (!line) {
return (
<div
style={{ height }}
aria-hidden
className="bg-[repeating-linear-gradient(135deg,var(--sg-hairline)_0px,var(--sg-hairline)_1px,transparent_1px,transparent_6px)] opacity-40"
/>
);
}
const tint = line.kind === "add" ? addColor : line.kind === "del" ? delColor : null;
const gutter = compact ? "w-8" : "w-10";
return (
<div
className="relative flex items-center"
style={{ height, backgroundColor: tint ? `${tint}1a` : undefined }}
aria-hidden={travels ? undefined : true}
data-line={travels ? line.id : undefined}
>
{showLineNumbers ? (
<span
className={cn(
"shrink-0 border-r border-hairline pr-1.5 text-right font-mono tabular-nums text-ink-mute/70 select-none",
gutter,
compact ? "text-[10px]" : "text-[11px]",
)}
>
{number === "old"
? (line.oldNo ?? "")
: number === "new"
? (line.newNo ?? "")
: (line.newNo ?? line.oldNo ?? "")}
</span>
) : null}
<span
className={cn(
"shrink-0 px-1.5 text-center font-mono select-none",
compact ? "text-[11px]" : "text-[12px]",
)}
style={{ color: tint ?? "var(--sg-ink-mute)" }}
aria-hidden
>
{SIGN[line.kind]}
</span>
{travels ? (
<span className="sr-only">{SPOKEN[line.kind]}</span>
) : null}
{travels ? (
<motion.span
layoutId={`${uid}/${line.id}`}
initial={reveal ? { opacity: 0, x: -6 } : false}
animate={{ opacity: 1, x: 0 }}
transition={reveal ? { ...reveal, layout: spring } : { layout: spring }}
className={cn(
"inline-block pr-4 pl-1 font-mono whitespace-pre text-ink",
compact ? "text-[11px]" : "text-[12px]",
)}
>
{line.text || " "}
</motion.span>
) : (
<span
className={cn(
"inline-block pr-4 pl-1 font-mono whitespace-pre text-ink/70",
compact ? "text-[11px]" : "text-[12px]",
)}
>
{line.text || " "}
</span>
)}
</div>
);
}
export default function DiffReview({
hunks = [],
onAccept,
onReject,
defaultView = "unified",
morphDuration = 380,
stiffness = 420,
damping = 38,
stagger = 14,
density = "comfortable",
showLineNumbers = true,
contextLines = 3,
collapseDecided = true,
addColor = "#4ade80",
delColor = "#f87171",
accentColor = "#a855f7",
reducedMotion = false,
className,
}: DiffReviewProps) {
const uid = useId().replace(/:/g, "");
const [view, setView] = useState<"unified" | "split">(defaultView);
const [verdicts, setVerdicts] = useState<Record<string, HunkVerdict>>({});
const [unfolded, setUnfolded] = useState<Record<string, boolean>>({});
const [lastDefault, setLastDefault] = useState(defaultView);
if (defaultView !== lastDefault) {
setLastDefault(defaultView);
setView(defaultView);
}
const seen = useRef(new Set<string>());
const rootRef = useRef<HTMLDivElement>(null);
useEffect(() => {
const root = rootRef.current;
if (!root) return;
for (const node of root.querySelectorAll<HTMLElement>("[data-line]")) {
if (node.dataset.line) seen.current.add(node.dataset.line);
}
});
const compact = density === "compact";
const spring = reducedMotion
? ({ duration: 0 } as const)
: ({ type: "spring", stiffness, damping } as const);
const ease = reducedMotion
? ({ duration: 0 } as const)
: ({ duration: morphDuration / 1000, ease: EASE } as const);
const segments = useMemo(
() =>
hunks.map((hunk) => ({
hunk,
stats: tally(hunk.lines),
segments: foldContext(hunk.lines, contextLines),
})),
[hunks, contextLines],
);
const totals = useMemo(() => {
let add = 0;
let del = 0;
for (const entry of segments) {
add += entry.stats.add;
del += entry.stats.del;
}
return { add, del };
}, [segments]);
const decided = hunks.filter((h) => (verdicts[h.id] ?? "pending") !== "pending").length;
const rule = (hunk: DiffHunk, verdict: HunkVerdict) => {
setVerdicts((prev) => {
if ((prev[hunk.id] ?? "pending") === verdict) return prev;
return { ...prev, [hunk.id]: verdict };
});
if (verdict === "accepted") onAccept?.(hunk);
if (verdict === "rejected") onReject?.(hunk);
};
const revealFor = (id: string, index: number): Transition | false => {
if (reducedMotion || seen.current.has(id)) return false;
return {
duration: (morphDuration / 1000) * 0.5,
delay: (Math.min(index, STAGGER_CAP) * stagger) / 1000,
ease: EASE,
};
};
return (
<div
ref={rootRef}
className={cn(
"w-full overflow-hidden rounded-lg border border-hairline bg-panel",
className,
)}
>
<div className="flex flex-wrap items-center justify-between gap-3 border-b border-hairline px-3 py-2.5">
<div className="flex items-center gap-3">
<span className="font-display text-[10px] tracking-[0.24em] text-ink-mute uppercase">
Proposed patch
</span>
<span className="font-mono text-[11px] tabular-nums" style={{ color: addColor }}>
+{totals.add}
</span>
<span className="font-mono text-[11px] tabular-nums" style={{ color: delColor }}>
−{totals.del}
</span>
</div>
<div className="flex items-center gap-3">
<span
className="font-mono text-[11px] tabular-nums"
style={{ color: decided === hunks.length ? accentColor : "var(--sg-ink-mute)" }}
aria-live="polite"
>
{decided}/{hunks.length} reviewed
</span>
<div
className="flex overflow-hidden rounded-md border border-hairline"
role="group"
aria-label="Diff layout"
>
{(["unified", "split"] as const).map((mode) => {
const active = view === mode;
return (
<button
key={mode}
type="button"
aria-pressed={active}
onClick={() => setView(mode)}
className={cn(
"px-2.5 py-1 font-display text-[10px] tracking-[0.16em] uppercase transition-colors outline-none focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-inset",
active ? "text-on-accent" : "text-ink-mute hover:bg-raised hover:text-ink",
)}
style={active ? { backgroundColor: accentColor } : undefined}
>
{mode}
</button>
);
})}
</div>
</div>
</div>
<LayoutGroup id={uid}>
<div className="divide-y divide-hairline">
{segments.map(({ hunk, stats, segments: parts }) => {
const verdict = verdicts[hunk.id] ?? "pending";
const open = !(collapseDecided && verdict !== "pending");
const edge =
verdict === "accepted"
? addColor
: verdict === "rejected"
? delColor
: null;
return (
<section key={hunk.id} aria-label={`${hunk.file} ${hunk.header ?? ""}`}>
<div
className="flex flex-wrap items-center justify-between gap-2 px-3 py-2"
style={{
borderLeft: `2px solid ${edge ?? "transparent"}`,
backgroundColor: edge ? `${edge}0f` : undefined,
}}
>
<div className="flex min-w-0 items-baseline gap-2">
<span className="truncate font-mono text-[12px] text-ink">
{hunk.file}
</span>
{hunk.header ? (
<span className="truncate font-mono text-[11px] text-ink-mute">
{hunk.header}
</span>
) : null}
<span
className="font-mono text-[10px] tabular-nums"
style={{ color: addColor }}
>
+{stats.add}
</span>
<span
className="font-mono text-[10px] tabular-nums"
style={{ color: delColor }}
>
−{stats.del}
</span>
</div>
<div className="flex shrink-0 items-center gap-2">
{verdict === "pending" ? (
<>
<button
type="button"
onClick={() => rule(hunk, "rejected")}
className="rounded-md border border-hairline px-2.5 py-1 font-display text-[10px] tracking-[0.16em] text-ink-dim uppercase transition-colors outline-none hover:bg-raised hover:text-ink focus-visible:ring-2 focus-visible:ring-accent"
>
Reject
</button>
<button
type="button"
onClick={() => rule(hunk, "accepted")}
className="rounded-md px-2.5 py-1 font-display text-[10px] tracking-[0.16em] text-on-accent uppercase transition-opacity outline-none hover:opacity-90 focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-offset-2 focus-visible:ring-offset-panel"
style={{ backgroundColor: accentColor }}
>
Accept
</button>
</>
) : (
<>
<span
className="font-display text-[10px] tracking-[0.16em] uppercase"
style={{ color: edge ?? undefined }}
>
{verdict}
</span>
<button
type="button"
onClick={() => rule(hunk, "pending")}
className="rounded-md border border-hairline px-2.5 py-1 font-display text-[10px] tracking-[0.16em] text-ink-dim uppercase transition-colors outline-none hover:bg-raised hover:text-ink focus-visible:ring-2 focus-visible:ring-accent"
>
Undo
</button>
</>
)}
</div>
</div>
<motion.div
initial={false}
animate={{ height: open ? "auto" : 0, opacity: open ? 1 : 0 }}
transition={ease}
className="overflow-hidden"
inert={!open}
>
{view === "unified" ? (
<div className="overflow-x-auto">
<div className="w-max min-w-full">
{parts.map((part) =>
part.kind === "fold" && !unfolded[part.key] ? (
<FoldRow
key={part.key}
count={part.lines.length}
compact={compact}
accentColor={accentColor}
onExpand={() =>
setUnfolded((prev) => ({ ...prev, [part.key]: true }))
}
/>
) : (
part.lines.map((line, i) => (
<LineCell
key={line.id}
line={line}
number="both"
travels
uid={uid}
compact={compact}
showLineNumbers={showLineNumbers}
addColor={addColor}
delColor={delColor}
spring={spring}
reveal={revealFor(line.id, i)}
/>
))
),
)}
</div>
</div>
) : (
<div className="grid grid-cols-2 divide-x divide-hairline">
{(["old", "new"] as const).map((side) => (
<div key={side} className="min-w-0 overflow-x-auto">
<div className="w-max min-w-full">
{parts.map((part) => {
if (part.kind === "fold" && !unfolded[part.key]) {
return (
<FoldRow
key={part.key}
count={part.lines.length}
compact={compact}
accentColor={accentColor}
onExpand={
side === "old"
? () =>
setUnfolded((prev) => ({
...prev,
[part.key]: true,
}))
: undefined
}
/>
);
}
return pairRows(part.lines).map((row, i) => {
const line = side === "old" ? row.left : row.right;
const travels =
line !== null &&
(line.kind !== "context" || side === "old");
return (
<LineCell
key={`${side}:${row.key}`}
line={line}
number={side}
travels={travels}
uid={uid}
compact={compact}
showLineNumbers={showLineNumbers}
addColor={addColor}
delColor={delColor}
spring={spring}
reveal={
line && travels ? revealFor(line.id, i) : false
}
/>
);
});
})}
</div>
</div>
))}
</div>
)}
</motion.div>
</section>
);
})}
</div>
</LayoutGroup>
</div>
);
}
function FoldRow({
count,
compact,
accentColor,
onExpand,
}: {
count: number;
compact: boolean;
accentColor: string;
onExpand?: () => void;
}) {
const height = compact ? ROW.compact : ROW.comfortable;
const label = `Show ${count} unchanged line${count === 1 ? "" : "s"}`;
if (!onExpand) {
return (
<div
style={{ height }}
aria-hidden
className="flex items-center bg-raised/40 px-3 font-mono text-[11px] text-ink-mute/60 select-none"
>
{"⋯"}
</div>
);
}
return (
<button
type="button"
onClick={onExpand}
style={{ height, color: accentColor }}
className="flex w-full items-center gap-2 bg-raised/40 px-3 font-mono text-[11px] transition-colors outline-none hover:bg-raised focus-visible:ring-2 focus-visible:ring-accent focus-visible:ring-inset"
>
<span aria-hidden>{"⋯"}</span>
{label}
</button>
);
}