#424

frontend/src/lib/help.ts

@@ -18,6 +18,18 @@ export type HelpSearchEntry = HelpEditionText & {
     identifier: string
     edition:    string }
 
+export type HelpEditionContent = HelpEditionText & { content: ComponentType }
+
+export type HelpEditionSource = HelpEditionText & { source: string }
+export type HelpChange = HelpSearchEntry & { pred: string | null }
+export type HelpDiffLine = {
+    type: 'added' | 'removed' | 'unchanged'
+    content: string }
+export type HelpDiff = {
+    from: HelpEditionSource
+    to: HelpEditionSource
+    lines: HelpDiffLine[] }
+
 const articleFiles = import.meta.glob<string> ('../../help/*/article.yml',
 					       { query: '?raw',
 						 import: 'default',
@@ -72,6 +84,18 @@ export const getHelpEditions = (
 }
 
 
+export const getHelpPublishedEditions = (
+    identifier: string,
+    language: string,
+): string[] => {
+  const currentEdition = getHelpArticle (identifier)?.languages[language]?.currentEdition
+  return currentEdition == null
+      ? []
+      : getHelpEditions (identifier, language)
+	  .filter (edition => compareEditions (edition, currentEdition) <= 0)
+}
+
+
 export const getHelpEdition = async (
     identifier: string,
     language: string,
@@ -87,28 +111,40 @@ export const getHelpEdition = async (
 }
 
 
-export const getHelpEditionText = async (
+export const getHelpEditionSource = async (
     identifier: string,
     language: string,
     edition: string,
-): Promise<HelpEditionText | null> => {
+): Promise<HelpEditionSource | null> => {
   const path = `../../help/${ identifier }/editions/${ language }/${ edition }.mdx`
   const loader = rawEditionFiles[path]
 
   if (!(loader))
     return null
 
-  const mdx = (await loader ()).replace (/^\uFEFF/, '')
+  const source = await loader ()
+  const mdx = source.replace (/^\uFEFF/, '')
   const heading = mdx.match (/^# +([^\r\n]+)(?:\r?\n|$)/)
 
   if (!(heading))
     throw new Error (`Help MDX の先頭に H1 がありません: ${ path }`)
 
-  return { title: heading[1].trim (),
+  return { source,
+	   title: heading[1].trim (),
 	   body:  mdx.slice (heading[0].length) }
 }
 
 
+export const getHelpEditionText = async (
+    identifier: string,
+    language: string,
+    edition: string,
+): Promise<HelpEditionText | null> => {
+  const content = await getHelpEditionSource (identifier, language, edition)
+  return content == null ? null : { title: content.title, body: content.body }
+}
+
+
 export const getHelpSearchEntries = async (
     language: string,
 ): Promise<HelpSearchEntry[]> => {
@@ -130,3 +166,101 @@ export const getHelpSearchEntries = async (
 
   return entries.filter ((entry): entry is HelpSearchEntry => entry != null)
 }
+
+
+export const getHelpEditionContent = async (
+    identifier: string,
+    language: string,
+    edition: string,
+): Promise<HelpEditionContent | null> => {
+  const [content, text] = await Promise.all ([
+      getHelpEdition (identifier, language, edition),
+      getHelpEditionText (identifier, language, edition)])
+
+  return content != null && text != null ? { content, ...text } : null
+}
+
+
+export const getHelpChanges = async (language: string): Promise<HelpChange[]> => {
+  const articles = Object.values (articleFiles).map (source =>
+      cameliseArticle (parseYAML (source)))
+  const changes = await Promise.all (articles.flatMap (article => {
+    const editions = getHelpPublishedEditions (article.identifier, language)
+    return editions.map (async (edition, index) => {
+      const text = await getHelpEditionText (article.identifier, language, edition)
+      if (text == null)
+	throw new Error (`Help edition が見つかりません: ${ article.identifier }/${ edition }`)
+
+      return { identifier: article.identifier,
+	  edition, pred: editions[index - 1] ?? null, ...text }
+    })
+  }))
+
+  return changes.sort ((a, b) =>
+      compareEditions (b.edition, a.edition)
+      || a.identifier.localeCompare (b.identifier))
+}
+
+
+const diffHelpLines = (from: string, to: string): HelpDiffLine[] => {
+  const before = from.match (/[^\n]*\n|[^\n]+$/g) ?? []
+  const after = to.match (/[^\n]*\n|[^\n]+$/g) ?? []
+  const lengths = Array.from ({ length: before.length + 1 },
+      () => new Uint32Array (after.length + 1))
+
+  for (let i = before.length - 1; i >= 0; --i)
+  {
+    for (let j = after.length - 1; j >= 0; --j)
+    {
+      lengths[i][j] =
+	  before[i] === after[j]
+	  ? lengths[i + 1][j + 1] + 1
+	  : Math.max (lengths[i + 1][j], lengths[i][j + 1])
+    }
+  }
+
+  const lines: HelpDiffLine[] = []
+  let i = 0
+  let j = 0
+  while (i < before.length || j < after.length)
+  {
+    if (i < before.length && j < after.length && before[i] === after[j])
+    {
+      lines.push ({ type: 'unchanged', content: before[i] })
+      ++i
+      ++j
+    }
+    else if (i < before.length
+	     && (j === after.length || lengths[i + 1][j] >= lengths[i][j + 1]))
+    {
+      lines.push ({ type: 'removed', content: before[i] })
+      ++i
+    }
+    else
+    {
+      lines.push ({ type: 'added', content: after[j] })
+      ++j
+    }
+  }
+  return lines
+}
+
+
+export const getHelpDiff = async (
+    identifier: string,
+    language: string,
+    from: string,
+    to: string,
+): Promise<HelpDiff | null> => {
+  const editions = getHelpPublishedEditions (identifier, language)
+  if (!(editions.includes (from)) || !(editions.includes (to)))
+    return null
+
+  const [before, after] = await Promise.all ([
+      getHelpEditionSource (identifier, language, from),
+      getHelpEditionSource (identifier, language, to)])
+  if (before == null || after == null)
+    return null
+
+  return { from: before, to: after, lines: diffHelpLines (before.source, after.source) }
+}