feat: stage edits to published articles as drafts (#14842)

2026-07-16 12:44:10 +05:30
parent f1a07657e9
commit 0fccb7dacd
21 changed files with 1280 additions and 59 deletions
@@ -0,0 +1,172 @@
+// Powers the "unpublished changes" preview: marks what changed between the live
+// article and the draft — word by word in the title, block by block in the body.
+
+import MarkdownIt from 'markdown-it';
+
+// Matches the public renderer (CommonMark, no typographer). True when two
+// markdown strings render the same — so blank-line/spacing-only edits don't count,
+// but real changes (code indentation, smart quotes, width markers) do.
+const commonmark = MarkdownIt('commonmark');
+export const rendersIdentically = (a, b) =>
+  commonmark.render(a ?? '') === commonmark.render(b ?? '');
+
+const INS_CLASS = '!bg-n-teal-5 !text-n-teal-12 !no-underline rounded px-0.5';
+const DEL_CLASS = '!bg-n-ruby-5 !text-n-ruby-12 !line-through rounded px-0.5';
+
+// Detailed compare gets slow on huge texts; past this, show all old as removed
+// and all new as added.
+const MAX_DIFF_TOKENS = 2000;
+
+const tokenizeWords = value => (value || '').match(/\S+/g) || [];
+
+const escapeHtml = value =>
+  value.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
+
+// Compares two lists in order and reports what's the same (`equal`), removed
+// (`del`) or added (`ins`), keeping as much unchanged as possible. `keyOf` says
+// how to compare items (title passes words, body passes blocks).
+const diffSequence = (a, b, keyOf = item => item) => {
+  const n = a.length;
+  const m = b.length;
+  if (n > MAX_DIFF_TOKENS || m > MAX_DIFF_TOKENS) {
+    return [
+      ...a.map(item => ({ type: 'del', item })),
+      ...b.map(item => ({ type: 'ins', item })),
+    ];
+  }
+
+  const dp = Array.from({ length: n + 1 }, () => new Array(m + 1).fill(0));
+  for (let i = n - 1; i >= 0; i -= 1) {
+    for (let j = m - 1; j >= 0; j -= 1) {
+      dp[i][j] =
+        keyOf(a[i]) === keyOf(b[j])
+          ? dp[i + 1][j + 1] + 1
+          : Math.max(dp[i + 1][j], dp[i][j + 1]);
+    }
+  }
+
+  const ops = [];
+  let i = 0;
+  let j = 0;
+  while (i < n && j < m) {
+    if (keyOf(a[i]) === keyOf(b[j])) {
+      ops.push({ type: 'equal', item: a[i] });
+      i += 1;
+      j += 1;
+    } else if (dp[i + 1][j] >= dp[i][j + 1]) {
+      ops.push({ type: 'del', item: a[i] });
+      i += 1;
+    } else {
+      ops.push({ type: 'ins', item: b[j] });
+      j += 1;
+    }
+  }
+  while (i < n) {
+    ops.push({ type: 'del', item: a[i] });
+    i += 1;
+  }
+  while (j < m) {
+    ops.push({ type: 'ins', item: b[j] });
+    j += 1;
+  }
+  return ops;
+};
+
+const wrapDiff = {
+  ins: text => `<ins class="${INS_CLASS}">${text}</ins>`,
+  del: text => `<del class="${DEL_CLASS}">${text}</del>`,
+};
+
+// Builds the highlighted title. Compares whole words (not single spaces) so
+// repeated words/spaces don't make the highlights jump around, then rejoins
+// with single spaces — a run of added/removed words shares one <ins>/<del> tag.
+export const renderInlineDiff = (oldValue, newValue) => {
+  const ops = diffSequence(tokenizeWords(oldValue), tokenizeWords(newValue));
+
+  const segments = [];
+  let run = [];
+  let runType = null;
+  const flushRun = () => {
+    if (!run.length) return;
+    const text = run.map(escapeHtml).join(' ');
+    segments.push(wrapDiff[runType] ? wrapDiff[runType](text) : text);
+    run = [];
+  };
+
+  ops.forEach(({ type, item }) => {
+    if (type !== runType) flushRun();
+    runType = type;
+    run.push(item);
+  });
+  flushRun();
+
+  return segments.join(' ');
+};
+
+// A fenced code block opener: ``` or ~~~, indented up to 3 spaces (CommonMark).
+const FENCE_RE = /^ {0,3}(```|~~~)/;
+// A list item marker: -, *, + or "1." / "1)", indented up to 3 spaces.
+const LIST_ITEM_RE = /^ {0,3}(?:[-*+]|\d{1,9}[.)])(?:\s|$)/;
+
+// Split on blank lines so each paragraph, heading or list compares as one piece.
+// Blank lines inside a fenced code block, or between items of the same list, are
+// content — splitting there would tear a code block or list apart and render it
+// with broken structure (orphaned <li>/<p>), so we keep those together.
+const splitBlocks = text => {
+  const lines = (text || '').split('\n');
+  const blocks = [];
+  let buffer = [];
+  let fence = null;
+  let inList = false;
+
+  const flush = () => {
+    const block = buffer.join('\n');
+    if (block.trim()) blocks.push(block);
+    buffer = [];
+    inList = false;
+  };
+
+  lines.forEach((line, index) => {
+    const marker = line.match(FENCE_RE)?.[1];
+    if (marker && !fence) fence = marker;
+    else if (fence && line.trimStart().startsWith(fence)) fence = null;
+
+    if (fence) {
+      buffer.push(line);
+      return;
+    }
+
+    if (LIST_ITEM_RE.test(line)) inList = true;
+
+    if (line.trim() !== '') {
+      buffer.push(line);
+      return;
+    }
+
+    // Blank line: keep it when the current list continues on the next non-blank
+    // line (another item or an indented continuation); otherwise end the block.
+    const next = lines.slice(index + 1).find(other => other.trim() !== '');
+    if (inList && next && (LIST_ITEM_RE.test(next) || /^\s/.test(next))) {
+      buffer.push(line);
+    } else {
+      flush();
+    }
+  });
+
+  flush();
+  return blocks;
+};
+
+const BLOCK_TYPE = { equal: 'equal', del: 'removed', ins: 'added' };
+
+// Diffs the body block by block. Blocks match when they render to the same HTML
+// (the check staging uses), so only edits that change the page show as a diff.
+export const buildDiffBlocks = (oldText, newText) => {
+  const toBlocks = text =>
+    splitBlocks(text).map(md => ({ md, key: commonmark.render(md) }));
+  const ops = diffSequence(toBlocks(oldText), toBlocks(newText), b => b.key);
+  return ops.map(op => ({ type: BLOCK_TYPE[op.type], md: op.item.md }));
+};
+
+export const hasPendingChanges = article =>
+  article?.draftTitle != null || article?.draftContent != null;
@@ -0,0 +1,170 @@
+import {
+  renderInlineDiff,
+  buildDiffBlocks,
+  hasPendingChanges,
+  rendersIdentically,
+} from '../articleDiffHelper';
+
+describe('articleDiffHelper', () => {
+  describe('renderInlineDiff', () => {
+    it('returns the text unchanged when there is no difference', () => {
+      const result = renderInlineDiff('hello world', 'hello world');
+      expect(result).toBe('hello world');
+      expect(result).not.toContain('<ins');
+      expect(result).not.toContain('<del');
+    });
+
+    it('wraps inserted words in <ins>', () => {
+      const result = renderInlineDiff('hello', 'hello there');
+      expect(result).toContain('hello');
+      expect(result).toContain('<ins');
+      expect(result).toContain('there');
+    });
+
+    it('wraps removed words in <del>', () => {
+      const result = renderInlineDiff('hello there', 'hello');
+      expect(result).toContain('<del');
+      expect(result).toContain('there');
+    });
+
+    it('keeps a single removal contiguous when a word repeats', () => {
+      const result = renderInlineDiff(
+        'How to use Agent bots?',
+        'How How to Agent bots?'
+      );
+      expect(result).toBe(
+        'How <ins class="!bg-n-teal-5 !text-n-teal-12 !no-underline rounded px-0.5">How</ins> to <del class="!bg-n-ruby-5 !text-n-ruby-12 !line-through rounded px-0.5">use</del> Agent bots?'
+      );
+    });
+
+    it('escapes markup when diffing plain text', () => {
+      const result = renderInlineDiff('a', 'a <b>');
+      expect(result).toContain('&lt;b&gt;');
+      expect(result).not.toContain('<b>');
+    });
+
+    it('treats a cleared empty string as a full deletion', () => {
+      const result = renderInlineDiff('gone', '');
+      expect(result).toContain('<del');
+      expect(result).toContain('gone');
+    });
+  });
+
+  describe('buildDiffBlocks', () => {
+    it('passes an unchanged block through as equal', () => {
+      const blocks = buildDiffBlocks('same para', 'same para');
+      expect(blocks).toEqual([{ type: 'equal', md: 'same para' }]);
+    });
+
+    it('marks an appended block as added', () => {
+      const blocks = buildDiffBlocks('a', 'a\n\nb');
+      expect(blocks).toContainEqual({ type: 'equal', md: 'a' });
+      expect(blocks).toContainEqual({ type: 'added', md: 'b' });
+    });
+
+    it('marks a deleted block as removed', () => {
+      const blocks = buildDiffBlocks('a\n\nb', 'a');
+      expect(blocks).toContainEqual({ type: 'removed', md: 'b' });
+    });
+
+    it('emits the old block then the new block for a reworded section', () => {
+      const blocks = buildDiffBlocks('hello world', 'hello there');
+      expect(blocks).toEqual([
+        { type: 'removed', md: 'hello world' },
+        { type: 'added', md: 'hello there' },
+      ]);
+    });
+
+    it('keeps a fenced code block whole when it contains blank lines', () => {
+      const code = '```\nline one\n\nline two\n```';
+      const blocks = buildDiffBlocks(code, code);
+      expect(blocks).toEqual([{ type: 'equal', md: code }]);
+    });
+
+    it('diffs an edited code block as one whole removed + added block', () => {
+      const live = '```\ncode line\n```';
+      const draft = '```\ncode line\n\nsd\n```';
+      const blocks = buildDiffBlocks(live, draft);
+      expect(blocks).toContainEqual({ type: 'removed', md: live });
+      expect(blocks).toContainEqual({ type: 'added', md: draft });
+    });
+
+    it('surfaces whitespace edits that change the rendered output', () => {
+      expect(
+        buildDiffBlocks('```\nx\n```', '```\n  x\n```').some(
+          block => block.type !== 'equal'
+        )
+      ).toBe(true);
+      expect(
+        buildDiffBlocks('line one\nline two', 'line one  \nline two').some(
+          block => block.type !== 'equal'
+        )
+      ).toBe(true);
+    });
+
+    it('surfaces an indented code block turning into a paragraph', () => {
+      const blocks = buildDiffBlocks(
+        '    curl example.com',
+        'curl example.com'
+      );
+      expect(blocks).toContainEqual({
+        type: 'removed',
+        md: '    curl example.com',
+      });
+      expect(blocks).toContainEqual({ type: 'added', md: 'curl example.com' });
+    });
+
+    it('keeps spacing the renderer ignores as equal', () => {
+      const blocks = buildDiffBlocks('a\nb', 'a \nb');
+      expect(blocks.every(block => block.type === 'equal')).toBe(true);
+    });
+
+    it('keeps a loose list with item descriptions as one block', () => {
+      const list =
+        '1. **One**\n\n   First item.\n\n2. **Two**\n\n   Second item.';
+      const blocks = buildDiffBlocks(list, list);
+      expect(blocks).toEqual([{ type: 'equal', md: list }]);
+    });
+  });
+
+  describe('rendersIdentically', () => {
+    it('ignores blank-line / empty-paragraph differences', () => {
+      expect(rendersIdentically('a\n\nb', 'a\n\n\nb')).toBe(true);
+      expect(rendersIdentically('hello', 'hello\n\n')).toBe(true);
+    });
+
+    it('counts code-block indentation changes', () => {
+      expect(rendersIdentically('```\n  x\n```', '```\nx\n```')).toBe(false);
+    });
+
+    it('counts smart vs straight quotes (no typographer)', () => {
+      expect(rendersIdentically('"hi"', '“hi”')).toBe(false);
+    });
+
+    it('counts real text changes', () => {
+      expect(rendersIdentically('hello world', 'hello there')).toBe(false);
+    });
+
+    it('treats nullish input as empty', () => {
+      expect(rendersIdentically(null, '')).toBe(true);
+      expect(rendersIdentically(undefined, 'x')).toBe(false);
+    });
+  });
+
+  describe('hasPendingChanges', () => {
+    it('is true when a draft title or content is staged', () => {
+      expect(hasPendingChanges({ draftContent: 'edit' })).toBe(true);
+      expect(hasPendingChanges({ draftTitle: 'edit' })).toBe(true);
+    });
+
+    it('treats a cleared empty-string draft as a pending change', () => {
+      expect(hasPendingChanges({ draftTitle: '' })).toBe(true);
+    });
+
+    it('is false with no draft columns', () => {
+      expect(hasPendingChanges({ title: 'live' })).toBe(false);
+      expect(hasPendingChanges({})).toBe(false);
+      expect(hasPendingChanges(null)).toBe(false);
+    });
+  });
+});