feature: sk-react-toolkit holds the server helpers, web components and Vite font plugin shared by manage-ui and sql-query-webui.

server/http.ts

@@ -0,0 +1,66 @@
+import type {} from '@fastify/static'
+import type { FastifyError, FastifyReply, FastifyRequest } from 'fastify'
+import { existsSync } from 'node:fs'
+import { join } from 'node:path'
+import type { Log } from './log.ts'
+
+/**
+ * An error answered with its status code and message as { error }. A refused write also carries the problems by
+ * field and a message about what it would break elsewhere, answered as { error, problems, message }.
+ */
+export class HttpError extends Error {
+  statusCode: number
+  problems?: Record<string, string>
+  detail?: string
+
+  constructor(statusCode: number, message: string, problems?: Record<string, string>, detail?: string) {
+    super(message)
+    this.statusCode = statusCode
+    this.problems = problems
+    this.detail = detail
+  }
+}
+
+/**
+ * A JSON schema of an object with exactly the properties given, all required. With Fastify's removeAdditional off, a
+ * body with another property is refused with 400.
+ */
+export function strict(properties: Record<string, unknown>) {
+  return { type: 'object', required: Object.keys(properties), additionalProperties: false, properties }
+}
+
+/**
+ * The error handler of setErrorHandler: the status of the error, 500 when it has none, with { error }, and the
+ * problems and message of an HttpError that has problems. An error of 500 or more that is not an HttpError is logged
+ * with its stack. A request that fails its schema is answered with "The request is not valid".
+ */
+export function errorHandler(log: Log) {
+  return (error: FastifyError, request: FastifyRequest, reply: FastifyReply) => {
+    const status = error.statusCode ?? 500
+    if (status >= 500 && !(error instanceof HttpError)) {
+      log.error(`${request.method} ${request.url}: ${error.stack ?? error.message}`)
+    }
+    const message = error.validation ? `The request is not valid (${error.message}).` : error.message
+    if (error instanceof HttpError && error.problems !== undefined) {
+      return reply.code(status).send({ error: message, problems: error.problems, message: error.detail ?? '' })
+    }
+    return reply.code(status).send({ error: message })
+  }
+}
+
+/**
+ * The not-found handler of setNotFoundHandler for an application of webDir, the built frontend served by
+ * @fastify/static: a path under /api is 404 with { error }; any other path answers index.html, so the frontend's
+ * routes work on a reload, or 503 with buildHint while the frontend is not built.
+ */
+export function notFoundHandler(webDir: string, buildHint: string) {
+  return (request: FastifyRequest, reply: FastifyReply) => {
+    if (request.url === '/api' || request.url.startsWith('/api/')) {
+      return reply.code(404).send({ error: `'${request.method} ${request.url.split('?')[0]}' is not an endpoint of this tool.` })
+    }
+    if (!existsSync(join(webDir, 'index.html'))) {
+      return reply.code(503).type('text/plain; charset=utf-8').send(`${buildHint}\n`)
+    }
+    return reply.type('text/html; charset=utf-8').sendFile('index.html')
+  }
+}