💄 diff view for revisions

src/renderer/components/Revisions/RevisionPanel.css

@@ -188,3 +188,144 @@
 .revision-restore-btn:hover {
   background: var(--accent-hover);
 }
+
+/* ─── View mode toggle (Diff | Preview) ─────────────────────────────────── */
+.revision-view-toggle {
+  display: flex;
+  flex-shrink: 0;
+  border-bottom: 1px solid var(--border);
+  background: var(--toolbar-bg);
+  padding: 0 16px;
+  gap: 2px;
+}
+
+.revision-view-btn {
+  background: none;
+  border: none;
+  border-bottom: 2px solid transparent;
+  color: var(--text-muted);
+  font-family: var(--font-sans);
+  font-size: 11px;
+  font-weight: 600;
+  letter-spacing: 0.05em;
+  text-transform: uppercase;
+  padding: 8px 10px 6px;
+  cursor: pointer;
+  margin-bottom: -1px;
+  transition: color 0.15s, border-color 0.15s;
+}
+
+.revision-view-btn:hover {
+  color: var(--text-secondary);
+}
+
+.revision-view-btn.active {
+  color: var(--accent);
+  border-bottom-color: var(--accent);
+}
+
+/* ─── Shared scroll container ────────────────────────────────────────────── */
+.revision-preview-scroll {
+  flex: 1;
+  overflow-y: auto;
+  min-height: 0;
+}
+
+/* ─── Diff renderer ──────────────────────────────────────────────────────── */
+.rdiff-root {
+  font-family: var(--font-serif);
+  font-size: 13px;
+  line-height: 1.75;
+  padding: 12px 0;
+}
+
+.rdiff-line {
+  display: flex;
+  align-items: baseline;
+  min-height: 1.75em;
+  padding-right: 16px;
+  word-break: break-word;
+}
+
+.rdiff-gutter {
+  flex-shrink: 0;
+  width: 24px;
+  text-align: center;
+  font-family: var(--font-sans);
+  font-size: 11px;
+  font-weight: 700;
+  user-select: none;
+  padding-top: 2px;
+}
+
+.rdiff-text {
+  flex: 1;
+  min-width: 0;
+}
+
+/* Added lines (in current, not in revision) */
+.rdiff-line--added {
+  background: rgba(80, 160, 80, 0.13);
+}
+
+.rdiff-line--added .rdiff-gutter {
+  color: #6abf6a;
+}
+
+.rdiff-line--added .rdiff-text {
+  color: var(--text-primary);
+}
+
+/* Removed lines (in revision, not in current) */
+.rdiff-line--removed {
+  background: rgba(180, 60, 60, 0.12);
+}
+
+.rdiff-line--removed .rdiff-gutter {
+  color: #c07070;
+}
+
+.rdiff-line--removed .rdiff-text {
+  color: var(--text-muted);
+  text-decoration: line-through;
+  text-decoration-color: rgba(180, 60, 60, 0.45);
+}
+
+/* Unchanged context lines */
+.rdiff-line--context .rdiff-gutter {
+  color: transparent;
+}
+
+.rdiff-line--context .rdiff-text {
+  color: var(--text-muted);
+}
+
+/* Changed hunk group */
+.rdiff-hunk {
+  border-top: 1px solid var(--border);
+  border-bottom: 1px solid var(--border);
+  margin: 1px 0;
+}
+
+/* Expand collapsed context */
+.rdiff-collapse-btn {
+  display: block;
+  width: 100%;
+  background: none;
+  border: none;
+  border-top: 1px dashed var(--border);
+  border-bottom: 1px dashed var(--border);
+  color: var(--text-muted);
+  font-family: var(--font-sans);
+  font-size: 11px;
+  text-align: center;
+  padding: 5px 0;
+  cursor: pointer;
+  letter-spacing: 0.03em;
+  transition: color 0.15s, background 0.15s;
+}
+
+.rdiff-collapse-btn:hover {
+  color: var(--text-secondary);
+  background: var(--hover-bg);
+}

src/renderer/components/Revisions/RevisionPanel.tsx

@@ -1,4 +1,6 @@
 import { useEffect, useState } from 'react'
+import { diffLines } from 'diff'
+import type { Change } from 'diff'
 import { marked } from 'marked'
 import DOMPurify from 'dompurify'
 import { useEditorStore } from '../../store/editorStore'
@@ -6,6 +8,126 @@ import { currentEditorView } from '../Editor/MarkdownEditor'
 import type { RevisionMeta } from '../../types/editor'
 import './RevisionPanel.css'
 
+// ─── Diff view ────────────────────────────────────────────────────────────────
+
+const CONTEXT_LINES = 3
+
+type Segment =
+  | { kind: 'changed'; changes: Change[] }
+  | { kind: 'context'; lines: string[]; segIndex: number }
+
+interface DiffViewProps {
+  oldText: string
+  newText: string
+  expandedSegments: Set<number>
+  onExpand: (segIndex: number) => void
+}
+
+function DiffView({ oldText, newText, expandedSegments, onExpand }: DiffViewProps): JSX.Element {
+  const changes = diffLines(oldText, newText)
+
+  // Build flat list of segments: changed hunks and unchanged context runs
+  const segments: Segment[] = []
+  let pendingLines: string[] = []
+  let segCounter = 0
+
+  const flushContext = (): void => {
+    if (pendingLines.length > 0) {
+      segments.push({ kind: 'context', lines: pendingLines, segIndex: segCounter++ })
+      pendingLines = []
+    }
+  }
+
+  for (const change of changes) {
+    if (change.added || change.removed) {
+      flushContext()
+      const last = segments[segments.length - 1]
+      if (last?.kind === 'changed') {
+        last.changes.push(change)
+      } else {
+        segments.push({ kind: 'changed', changes: [change] })
+      }
+    } else {
+      const lines = change.value.split('\n')
+      if (lines[lines.length - 1] === '') lines.pop()
+      pendingLines.push(...lines)
+    }
+  }
+  flushContext()
+
+  if (segments.length === 0 || !changes.some((c) => c.added || c.removed)) {
+    return <p className="revision-preview-empty">No changes — this revision matches the current content.</p>
+  }
+
+  return (
+    <div className="rdiff-root">
+      {segments.map((seg, i) => {
+        if (seg.kind === 'changed') {
+          return (
+            <div key={i} className="rdiff-hunk">
+              {seg.changes.flatMap((ch, j) => {
+                const prefix = ch.added ? '+' : '-'
+                const cls = ch.added ? 'rdiff-line--added' : 'rdiff-line--removed'
+                const lines = ch.value.split('\n')
+                if (lines[lines.length - 1] === '') lines.pop()
+                return lines.map((line, k) => (
+                  <div key={`${j}-${k}`} className={`rdiff-line ${cls}`}>
+                    <span className="rdiff-gutter">{prefix}</span>
+                    <span className="rdiff-text">{line || '\u00A0'}</span>
+                  </div>
+                ))
+              })}
+            </div>
+          )
+        }
+
+        const { lines, segIndex } = seg
+        const total = lines.length
+        const isExpanded = expandedSegments.has(segIndex)
+
+        if (total <= CONTEXT_LINES * 2 || isExpanded) {
+          return (
+            <div key={i} className="rdiff-context">
+              {lines.map((line, k) => (
+                <div key={k} className="rdiff-line rdiff-line--context">
+                  <span className="rdiff-gutter"> </span>
+                  <span className="rdiff-text">{line || '\u00A0'}</span>
+                </div>
+              ))}
+            </div>
+          )
+        }
+
+        const topLines = lines.slice(0, CONTEXT_LINES)
+        const bottomLines = lines.slice(total - CONTEXT_LINES)
+        const hiddenCount = total - CONTEXT_LINES * 2
+
+        return (
+          <div key={i} className="rdiff-context">
+            {topLines.map((line, k) => (
+              <div key={`t${k}`} className="rdiff-line rdiff-line--context">
+                <span className="rdiff-gutter"> </span>
+                <span className="rdiff-text">{line || '\u00A0'}</span>
+              </div>
+            ))}
+            <button className="rdiff-collapse-btn" onClick={() => onExpand(segIndex)}>
+              ··· {hiddenCount} unchanged line{hiddenCount !== 1 ? 's' : ''} ···
+            </button>
+            {bottomLines.map((line, k) => (
+              <div key={`b${k}`} className="rdiff-line rdiff-line--context">
+                <span className="rdiff-gutter"> </span>
+                <span className="rdiff-text">{line || '\u00A0'}</span>
+              </div>
+            ))}
+          </div>
+        )
+      })}
+    </div>
+  )
+}
+
+// ─── Helpers ──────────────────────────────────────────────────────────────────
+
 function formatDate(ts: number): string {
   const d = new Date(ts)
   const now = new Date()
@@ -17,12 +139,19 @@ function formatDate(ts: number): string {
   return d.toLocaleDateString([], { month: 'short', day: 'numeric' }) + ' · ' + time
 }
 
+// ─── RevisionPanel ────────────────────────────────────────────────────────────
+
+type ViewMode = 'diff' | 'preview'
+
 export function RevisionPanel(): JSX.Element {
-  const { activeFilePath, toggleRevisionPanel, revisions, setRevisions } = useEditorStore()
+  const { activeFilePath, activeFileContent, toggleRevisionPanel, revisions, setRevisions } =
+    useEditorStore()
   const [selected, setSelected] = useState<RevisionMeta | null>(null)
   const [previewHtml, setPreviewHtml] = useState<string | null>(null)
   const [previewRaw, setPreviewRaw] = useState<string | null>(null)
   const [loading, setLoading] = useState(false)
+  const [viewMode, setViewMode] = useState<ViewMode>('diff')
+  const [expandedSegments, setExpandedSegments] = useState<Set<number>>(new Set())
 
   useEffect(() => {
     if (!activeFilePath) return
@@ -37,6 +166,8 @@ export function RevisionPanel(): JSX.Element {
     setSelected(rev)
     setPreviewHtml(null)
     setPreviewRaw(null)
+    setViewMode('diff')
+    setExpandedSegments(new Set())
     if (!activeFilePath) return
     setLoading(true)
     try {
@@ -82,6 +213,8 @@ export function RevisionPanel(): JSX.Element {
         <span className="revision-panel-title">Revision History</span>
       </div>
       <div className="revision-panel-body">
+
+        {/* ── Left: revision list ── */}
         <div className="revision-list">
           {revisions.length === 0 ? (
             <p className="revision-empty">No revisions yet.<br />Save with ⌘S to create one.</p>
@@ -106,17 +239,47 @@ export function RevisionPanel(): JSX.Element {
           )}
         </div>
 
+        {/* ── Right: preview / diff ── */}
         <div className="revision-preview">
           {selected === null ? (
             <p className="revision-preview-empty">Select a revision to preview</p>
           ) : loading ? (
             <p className="revision-preview-empty">Loading…</p>
-          ) : previewHtml !== null ? (
+          ) : previewRaw !== null ? (
             <>
-              <div
-                className="revision-preview-content"
-                dangerouslySetInnerHTML={{ __html: previewHtml }}
-              />
+              <div className="revision-view-toggle">
+                <button
+                  className={`revision-view-btn${viewMode === 'diff' ? ' active' : ''}`}
+                  onClick={() => setViewMode('diff')}
+                >
+                  Diff
+                </button>
+                <button
+                  className={`revision-view-btn${viewMode === 'preview' ? ' active' : ''}`}
+                  onClick={() => setViewMode('preview')}
+                >
+                  Preview
+                </button>
+              </div>
+
+              <div className="revision-preview-scroll">
+                {viewMode === 'diff' ? (
+                  <DiffView
+                    oldText={previewRaw}
+                    newText={activeFileContent}
+                    expandedSegments={expandedSegments}
+                    onExpand={(idx) =>
+                      setExpandedSegments((prev) => new Set([...prev, idx]))
+                    }
+                  />
+                ) : (
+                  <div
+                    className="revision-preview-content"
+                    dangerouslySetInnerHTML={{ __html: previewHtml ?? '' }}
+                  />
+                )}
+              </div>
+
               <div className="revision-preview-footer">
                 <button className="revision-restore-btn" onClick={restore}>
                   Restore this version
@@ -125,6 +288,7 @@ export function RevisionPanel(): JSX.Element {
             </>
           ) : null}
         </div>
+
       </div>
     </div>
   )