infra(docs): add docs diff script (#1755)

6 files changed, 204 insertions, 15 deletions

diff --git a/scripts/apidoc/apiDocsWriter.ts b/scripts/apidoc/apiDocsWriter.ts
index f18b7cd9..d40dec34 100644
--- a/scripts/apidoc/apiDocsWriter.ts
+++ b/scripts/apidoc/apiDocsWriter.ts
@@ -9,8 +9,8 @@ import {
   selectApiMethods,
   selectApiModules,
 } from './typedoc';
-import type { PageIndex } from './utils';
-import { pathDocsDir, pathOutputDir } from './utils';
+import type { DocsApiDiffIndex, PageIndex } from './utils';
+import { pathDocsDiffIndexFile, pathDocsDir, pathOutputDir } from './utils';
 
 const pathDocsApiPages = resolve(pathDocsDir, '.vitepress', 'api-pages.ts');
 const pathDocsApiSearchIndex = resolve(
@@ -120,6 +120,10 @@ export function writeApiPagesIndex(pages: PageIndex): void {
   writeFileSync(pathDocsApiPages, apiPagesContent);
 }
 
+export function writeApiDiffIndex(diffIndex: DocsApiDiffIndex): void {
+  writeFileSync(pathDocsDiffIndexFile, JSON.stringify(diffIndex));
+}
+
 export function writeApiSearchIndex(project: ProjectReflection): void {
   const apiIndex: APIGroup[] = [];
 
diff --git a/scripts/apidoc/diff.ts b/scripts/apidoc/diff.ts
new file mode 100644
index 00000000..913062c8
--- /dev/null
+++ b/scripts/apidoc/diff.ts
@@ -0,0 +1,98 @@
+import type { DocsApiDiffIndex } from './utils';
+import { nameDocsDiffIndexFile, pathDocsDiffIndexFile } from './utils';
+
+/**
+ * Loads the diff index from the given source url.
+ *
+ * @param url The url to load the diff index from.
+ */
+async function loadRemote(url: string): Promise<DocsApiDiffIndex> {
+  return fetch(url).then((res) => {
+    if (!res.ok) {
+      throw new Error(
+        `Failed to load remote diff index from ${url}: ${res.statusText}`
+      );
+    } else {
+      return res.json() as Promise<DocsApiDiffIndex>;
+    }
+  });
+}
+
+/**
+ * Loads the diff index from the given local path.
+ *
+ * @param path The path to load the diff index from. Should start with `file://` for cross platform compatibility.
+ */
+async function loadLocal(path: string): Promise<DocsApiDiffIndex> {
+  return import(path).then((imp) => imp.default as DocsApiDiffIndex);
+}
+
+/**
+ * Loads the diff index from the given source.
+ * If the source starts with `https://` it will be loaded from the remote url.
+ * Otherwise it will be loaded from the local path.
+ *
+ * @param source The source to load the diff index from.
+ */
+async function load(source: string): Promise<DocsApiDiffIndex> {
+  if (source.startsWith('https://')) {
+    return loadRemote(source);
+  } else {
+    return loadLocal(source);
+  }
+}
+
+/**
+ * Returns a set of all keys from the given entries.
+ *
+ * @param entries The entries to get the keys from.
+ */
+function allKeys(
+  ...entries: ReadonlyArray<Record<string, unknown>>
+): Set<string> {
+  return new Set(entries.map(Object.keys).flat());
+}
+
+/**
+ * Compares the target (reference) and source (changed) diff index and returns the differences.
+ * The returned object contains the module names as keys and the method names as values.
+ * If the module name is `ADDED` or `REMOVED` it means that the module was added or removed in the local diff index.
+ *
+ * @param targetDiffIndex The url to the target (reference) diff index. Defaults to the next.fakerjs.dev diff index.
+ * @param sourceDiffIndex The path to the source (changed) index. Defaults to the local diff index.
+ */
+export async function diff(
+  targetDiffIndex = `https://next.fakerjs.dev/${nameDocsDiffIndexFile}`,
+  sourceDiffIndex = `file://${pathDocsDiffIndexFile}`
+): Promise<Record<string, ['ADDED'] | ['REMOVED'] | string[]>> {
+  const target = await load(targetDiffIndex);
+  const source = await load(sourceDiffIndex);
+
+  const diff: Record<string, string[]> = {};
+
+  for (const moduleName of allKeys(target, source)) {
+    const remoteModule = target[moduleName];
+    const localModule = source[moduleName];
+
+    if (!remoteModule) {
+      diff[moduleName] = ['ADDED'];
+      continue;
+    }
+
+    if (!localModule) {
+      diff[moduleName] = ['REMOVED'];
+      continue;
+    }
+
+    for (const methodName of allKeys(remoteModule, localModule)) {
+      const remoteMethod = remoteModule[methodName];
+      const localMethod = localModule[methodName];
+
+      if (remoteMethod !== localMethod) {
+        (diff[moduleName] ??= []).push(methodName);
+      }
+    }
+  }
+
+  return diff;
+}
diff --git a/scripts/apidoc/generate.ts b/scripts/apidoc/generate.ts
index 1f7c0016..6aa3ae0c 100644
--- a/scripts/apidoc/generate.ts
+++ b/scripts/apidoc/generate.ts
@@ -1,5 +1,9 @@
 import { resolve } from 'path';
-import { writeApiPagesIndex, writeApiSearchIndex } from './apiDocsWriter';
+import {
+  writeApiDiffIndex,
+  writeApiPagesIndex,
+  writeApiSearchIndex,
+} from './apiDocsWriter';
 import { processModuleMethods } from './moduleMethods';
 import { loadProject } from './typedoc';
 import { pathOutputDir } from './utils';
@@ -16,7 +20,10 @@ export async function generate(): Promise<void> {
   await app.generateJson(project, pathOutputJson);
 
   const modules = processModuleMethods(project);
-  writeApiPagesIndex(modules);
+  writeApiPagesIndex(modules.map(({ text, link }) => ({ text, link })));
+  writeApiDiffIndex(
+    modules.reduce((data, { text, diff }) => ({ ...data, [text]: diff }), {})
+  );
 
   writeApiSearchIndex(project);
 }
diff --git a/scripts/apidoc/moduleMethods.ts b/scripts/apidoc/moduleMethods.ts
index b52d4780..bf7b93f9 100644
--- a/scripts/apidoc/moduleMethods.ts
+++ b/scripts/apidoc/moduleMethods.ts
@@ -8,7 +8,8 @@ import {
   selectApiMethodSignatures,
   selectApiModules,
 } from './typedoc';
-import type { PageIndex } from './utils';
+import type { PageAndDiffIndex } from './utils';
+import { diffHash } from './utils';
 
 /**
  * Analyzes and writes the documentation for modules and their methods such as `faker.animal.cat()`.
@@ -16,8 +17,10 @@ import type { PageIndex } from './utils';
  * @param project The project used to extract the modules.
  * @returns The generated pages.
  */
-export function processModuleMethods(project: ProjectReflection): PageIndex {
-  const pages: PageIndex = [];
+export function processModuleMethods(
+  project: ProjectReflection
+): PageAndDiffIndex {
+  const pages: PageAndDiffIndex = [];
 
   // Generate module files
   for (const module of selectApiModules(project)) {
@@ -33,10 +36,11 @@ export function processModuleMethods(project: ProjectReflection): PageIndex {
  * @param module The module to process.
  * @returns The generated pages.
  */
-function processModuleMethod(module: DeclarationReflection): PageIndex {
+function processModuleMethod(module: DeclarationReflection): PageAndDiffIndex {
   const moduleName = extractModuleName(module);
   const moduleFieldName = extractModuleFieldName(module);
   console.log(`Processing Module ${moduleName}`);
+  const comment = toBlock(module.comment);
 
   const methods: Method[] = [];
 
@@ -45,22 +49,29 @@ function processModuleMethod(module: DeclarationReflection): PageIndex {
     selectApiMethodSignatures(module)
   )) {
     console.debug(`- ${methodName}`);
-
     methods.push(analyzeSignature(signature, moduleFieldName, methodName));
   }
 
-  writeApiDocsModulePage(
-    moduleName,
-    moduleFieldName,
-    toBlock(module.comment),
-    methods
-  );
+  writeApiDocsModulePage(moduleName, moduleFieldName, comment, methods);
   writeApiDocsData(moduleFieldName, methods);
 
   return [
     {
       text: moduleName,
       link: `/api/${moduleFieldName}.html`,
+      diff: methods.reduce(
+        (data, method) => ({
+          ...data,
+          [method.name]: diffHash(method),
+        }),
+        {
+          moduleHash: diffHash({
+            name: moduleName,
+            field: moduleFieldName,
+            comment,
+          }),
+        }
+      ),
     },
   ];
 }
diff --git a/scripts/apidoc/utils.ts b/scripts/apidoc/utils.ts
index f480c0b1..5de80cc3 100644
--- a/scripts/apidoc/utils.ts
+++ b/scripts/apidoc/utils.ts
@@ -1,3 +1,4 @@
+import { createHash } from 'node:crypto';
 import { resolve } from 'node:path';
 
 // Types
@@ -5,10 +6,39 @@ import { resolve } from 'node:path';
 export type Page = { text: string; link: string };
 export type PageIndex = Page[];
 
+export type PageAndDiff = Page & {
+  diff: DocsApiDiff;
+};
+export type PageAndDiffIndex = PageAndDiff[];
+
+export interface DocsApiDiffIndex {
+  /**
+   * The methods in the module by name.
+   */
+  [module: string]: DocsApiDiff;
+}
+
+export interface DocsApiDiff {
+  /**
+   * The checksum of the entire module.
+   */
+  moduleHash: string;
+  /**
+   * The checksum of the method by name.
+   */
+  [method: string]: string;
+}
+
 // Paths
 
 const pathRoot = resolve(__dirname, '..', '..');
 export const pathDocsDir = resolve(pathRoot, 'docs');
+const pathPublicDir = resolve(pathDocsDir, 'public');
+export const nameDocsDiffIndexFile = 'api-diff-index.json';
+export const pathDocsDiffIndexFile = resolve(
+  pathPublicDir,
+  nameDocsDiffIndexFile
+);
 export const pathOutputDir = resolve(pathDocsDir, 'api');
 
 // Functions
@@ -22,3 +52,12 @@ export function mapByName<T extends { name: string }, V>(
     {}
   );
 }
+
+/**
+ * Creates a diff hash for the given object.
+ *
+ * @param object The object to create a hash for.
+ */
+export function diffHash(object: unknown): string {
+  return createHash('md5').update(JSON.stringify(object)).digest('hex');
+}
diff --git a/scripts/diff.ts b/scripts/diff.ts
new file mode 100644
index 00000000..09a07046
--- /dev/null
+++ b/scripts/diff.ts
@@ -0,0 +1,30 @@
+import { existsSync } from 'node:fs';
+import { argv } from 'node:process';
+import { diff } from './apidoc/diff';
+import { pathDocsDiffIndexFile } from './apidoc/utils';
+
+const [target, source] = argv.slice(2);
+
+if (!source && !existsSync(pathDocsDiffIndexFile)) {
+  throw new Error(
+    `Unable to find local diff index file at: ${pathDocsDiffIndexFile}\n
+    You can run \`pnpm run generate:api-docs\` to generate it.`
+  );
+}
+
+diff(target, source)
+  .then((delta) => {
+    if (Object.keys(delta).length === 0) {
+      console.log('No documentation changes detected');
+      return;
+    }
+
+    console.log('Documentation changes detected:');
+    for (const [module, methods] of Object.entries(delta)) {
+      console.log(`- ${module}`);
+      for (const method of methods) {
+        console.log(`  - ${method}`);
+      }
+    }
+  })
+  .catch(console.error);