lumeland · oscarotero · Jan 26, 2024 · Dec 21, 2023 · Dec 21, 2023 · Jan 26, 2024
diff --git a/core/utils/lume_config.ts b/core/utils/lume_config.ts
@@ -30,6 +30,7 @@ export const pluginNames = [
   "prism",
   "pug",
   "reading_info",
+  "redirects",
   "relations",
   "relative_urls",
   "remark",

diff --git a/middlewares/redirects.ts b/middlewares/redirects.ts
@@ -6,7 +6,7 @@ export interface Options {
 
 export interface Redirect {
   to: string;
-  code: 301 | 302 | 307 | 308 | 200;
+  code: 301 | 302 | 303 | 307 | 308 | 200;
 }
 
 /** Implements redirects */

diff --git a/plugins/redirects.ts b/plugins/redirects.ts
@@ -0,0 +1,167 @@
+import { merge } from "../core/utils/object.ts";
+import { Page } from "../core/file.ts";
+import { log } from "../core/utils/log.ts";
+
+import type Site from "../core/site.ts";
+
+export interface Options {
+  /** The redirects output format */
+  output?: "html" | "json" | "netlify" | "vercel" | OutputStrategy;
+
+  /** The default status code to use */
+  defaultStatus?: Status;
+}
+
+type Status = 301 | 302 | 307 | 308;
+type Redirect = [string, string, Status];
+type OutputStrategy = (
+  redirects: Redirect[],
+  site: Site,
+) => Promise<void> | void;
+
+export const defaults: Options = {
+  output: "html",
+  defaultStatus: 301,
+};
+
+/** Predefined output strategies */
+const outputs: Record<string, OutputStrategy> = {
+  html,
+  json,
+  netlify,
+  vercel,
+};
+
+export default function (userOptions?: Options) {
+  const options = merge(defaults, userOptions);
+
+  return (site: Site) => {
+    site.process("*", (pages) => {
+      const redirects: Redirect[] = [];
+
+      pages.forEach((page) => {
+        const { url, oldUrl } = page.data;
+
+        if (url && oldUrl) {
+          const oldUrls = Array.isArray(oldUrl) ? oldUrl : [oldUrl];
+
+          for (const old of oldUrls) {
+            const redirect = parseRedirection(url, old, options.defaultStatus);
+            if (redirect) {
+              redirects.push(redirect);
+            }
+          }
+        }
+      });
+
+      if (!redirects.length) {
+        return;
+      }
+
+      const outputFn = typeof options.output === "string"
+        ? outputs[options.output]
+        : options.output;
+
+      if (!outputFn) {
+        log.error(`[redirects] Invalid output format: ${options.output}`);
+        throw new Error(`Invalid output format: ${options.output}`);
+      }
+
+      redirects.sort((a, b) => a[0].localeCompare(b[0]));
+
+      return outputFn(redirects, site);
+    });
+  };
+}
+
+const validStatusCodes = [301, 302, 303, 307, 308];
+
+function parseRedirection(
+  newUrl: string,
+  oldUrl: string,
+  defaultCode: Status,
+): [string, string, Status] | undefined {
+  const [from, code] = oldUrl.split(/\s+/);
+  const parsedCode = code ? parseInt(code) : defaultCode;
+
+  if (!validStatusCodes.includes(parsedCode)) {
+    log.error(
+      `Invalid status code for redirection from ${from} to ${newUrl} (${code}).`,
+    );
+    return;
+  }
+
+  return [from, newUrl, parsedCode as Status];
+}
+
+/** HTML redirect */
+function html(redirects: Redirect[], site: Site): void {
+  for (const [url, to, statusCode] of redirects) {
+    const timeout = (statusCode === 301 || statusCode === 308) ? 0 : 1;
+    const content = `<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>Redirecting…</title>
+  <meta http-equiv="refresh" content="${timeout}; url=${to}">
+</head>
+<body>
+  <h1>Redirecting…</h1>
+  <a href="${to}">Click here if you are not redirected.</a>
+</body>
+</html>`;
+    const page = Page.create({ url, content });
+    site.pages.push(page);
+  }
+}
+
+/** JSON redirect (to use with redirect middleware) */
+function json(redirects: Redirect[], site: Site): void {
+  const obj = Object.fromEntries(
+    redirects.map((
+      [from, to, code],
+    ) => [from, code === 301 ? to : { to, code }]),
+  );
+  const page = Page.create({
+    url: "_redirects.json",
+    content: JSON.stringify(obj, null, 2),
+  });
+  site.pages.push(page);
+}
+
+/** Netlify redirect */
+async function netlify(redirects: Redirect[], site: Site): Promise<void> {
+  const content = redirects.map(([from, to, code]) => `${from} ${to} ${code}`)
+    .join("\n");
+  const page = await site.getOrCreatePage("_redirects");
+  page.content = content;
+}
+
+/** Vercel redirect */
+async function vercel(redirects: Redirect[], site: Site): Promise<void> {
+  const config = {
+    redirects: redirects.map(([source, destination, statusCode]) => ({
+      source,
+      destination,
+      statusCode,
+    })),
+  };
+
+  const page = await site.getOrCreatePage("vercel.json");
+  const content = JSON.parse(page.content as string | undefined || "{}");
+  Object.assign(content, config);
+  page.content = JSON.stringify(content, null, 2);
+}
+
+/** Extends Data interface */
+declare global {
+  namespace Lume {
+    export interface Data {
+      /**
+       * The old url(s) of a page
+       * @see https://lume.land/plugins/redirects/
+       */
+      oldUrl?: string | string[];
+    }
+  }
+}