docs: add static website and docs

vite.config.ts

@@ -1,10 +1,93 @@
+import { createReadStream } from "node:fs";
+import { stat } from "node:fs/promises";
+import type { IncomingMessage, ServerResponse } from "node:http";
+import { extname, join, resolve, sep } from "node:path";
+import type { Plugin } from "vite";
 import { defineConfig } from "vite";
 import { effectivePiWebConfig } from "./src/config";
 
 const { config } = effectivePiWebConfig();
 const apiPort = config.port ?? 8504;
+const docsRoot = resolve("docs");
+const docsPrefix = "/site";
+
+const contentTypes: Record<string, string> = {
+  ".css": "text/css; charset=utf-8",
+  ".gif": "image/gif",
+  ".html": "text/html; charset=utf-8",
+  ".js": "text/javascript; charset=utf-8",
+  ".md": "text/markdown; charset=utf-8",
+  ".png": "image/png",
+  ".svg": "image/svg+xml",
+  ".webm": "video/webm",
+};
+
+type MiddlewareNext = (error?: unknown) => void;
+
+async function serveDevDocs(request: IncomingMessage, response: ServerResponse, next: MiddlewareNext): Promise<void> {
+  const requestUrl = request.url;
+  if (requestUrl === undefined) {
+    next();
+    return;
+  }
+
+  const url = new URL(requestUrl, "http://localhost");
+  if (url.pathname === docsPrefix) {
+    response.statusCode = 302;
+    response.setHeader("Location", `${docsPrefix}/`);
+    response.end();
+    return;
+  }
+  if (!url.pathname.startsWith(`${docsPrefix}/`)) {
+    next();
+    return;
+  }
+
+  const relativePath = decodeURIComponent(url.pathname.slice(docsPrefix.length + 1)) || "index.html";
+  const requestedPath = relativePath.endsWith("/") ? join(relativePath, "index.html") : relativePath;
+  const filePath = resolve(docsRoot, requestedPath);
+  if (filePath !== docsRoot && !filePath.startsWith(`${docsRoot}${sep}`)) {
+    response.statusCode = 403;
+    response.end("Forbidden");
+    return;
+  }
+
+  try {
+    const fileStat = await stat(filePath);
+    if (!fileStat.isFile()) {
+      response.statusCode = 404;
+      response.end("Not found");
+      return;
+    }
+    response.statusCode = 200;
+    response.setHeader("Content-Type", contentTypes[extname(filePath)] ?? "application/octet-stream");
+    response.setHeader("Cache-Control", "no-store");
+    createReadStream(filePath).pipe(response);
+  } catch (error) {
+    const code = error instanceof Error && "code" in error ? error.code : undefined;
+    if (code === "ENOENT") {
+      response.statusCode = 404;
+      response.end("Not found");
+      return;
+    }
+    next(error);
+  }
+}
+
+function devDocsPlugin(): Plugin {
+  return {
+    name: "pi-web-dev-docs",
+    apply: "serve",
+    configureServer(server) {
+      server.middlewares.use((request, response, next) => {
+        void serveDevDocs(request, response, next);
+      });
+    },
+  };
+}
 
 export default defineConfig({
+  plugins: [devDocsPlugin()],
   root: "src/client",
   build: {
     outDir: "../../dist/client",