Framework contract

// The single context object passed to every loader AND action (@nifrajs/web).
interface LoaderContext {
  params:  Record<string, string>  // matched route params (:id, *path)
  request: Request                 // the standard Web Request - read headers/body/URL off it
  api:     unknown                 // the in-process backend client createWebApp was given
  env:     unknown                 // platform bindings forwarded from c.env (Workers KV/D1/…)
  draft:   boolean                 // true only when a valid draft cookie is present (draftSecret set)
}

// api + env are typed per-route via @nifrajs/client's LoaderArgs<Api, Env>; the agnostic core
// keeps them `unknown`. Branch on `draft` to load unpublished content for preview/editors.

// routes/users/[id].tsx - a route module's full contract (every export optional but `default`).
// doc-check: skip - full-contract sketch; ctx.api's routes and meta's loader-data shape come from
// the reader's own backend type, so it can't compile standalone (see the typed examples elsewhere).
import type { LoaderContext } from "@nifrajs/web"

// GET → data for the page. Runs in-process on the server during SSR (no HTTP hop).
export async function loader(ctx: LoaderContext) {
  return { user: await ctx.api.users.get({ id: ctx.params.id }) }
}

// POST → a mutation. Same context. Return a Response (e.g. a redirect - passed straight
// through) OR data, which reaches the component as `actionData`.
export async function action(ctx: LoaderContext) {
  const form = await ctx.request.formData()
  return { ok: true }
}

// Static OR a function of { data, params, origin }. Static meta is serialized once; function meta
// recomputes per request (its content can vary with loader data). `origin` is the request's
// scheme+host (server-resolved, matches the client's location.origin) - use it for ABSOLUTE
// canonical / og:url / og:image URLs without threading siteUrl through loader data.
export const meta = ({ data, params, origin }) => ({
  title: `User ${data.user.name}`,
  meta: [{ name: "description", content: data.user.bio }],
  link: [{ rel: "canonical", href: `${origin}/users/${params.id}` }],
})

export const hydrate = false   // opt out of full-document hydration (static / island pages)
export default function User(props) { /* props.data, props.actionData, props.params */ }

// TWO ways to handle a request - pick by who is calling.
import type { LoaderContext } from "@nifrajs/web"

// (1) A page's own data + mutations → route exports. A PUBLIC POST is a route ACTION
//     (routes/contact.tsx) - the browser POSTs the route's own URL, Nifra runs `action`:
export async function action(ctx: LoaderContext) {
  const form = await ctx.request.formData()        // the browser POSTed this route
  return { ok: true, body: String(form.get("body")) } // → props.actionData on re-render
}

// (2) ctx.api is the IN-PROCESS backend client (the inProcessClient(server) the app was given).
//     It is LOADERS-ONLY: the SSR backend registers GET handlers, so a .post() to ctx.api 405s.
export async function loader(ctx: LoaderContext) {
  // ✅ a GET in-process - no HTTP hop. (A .post() to ctx.api would 405; write an `action` instead.)
  return { id: ctx.params.id }
}

// Rule of thumb: data INTO a page → loader + ctx.api (GET). A mutation FROM the browser
// (a form/fetch POST) → an `action` export on the route. Don't `inProcessClient(api).post()`.

// routes/users/[id].tsx - plain SSR runs the loader for ANY :id value. `fallback: "404"`
// only takes effect under prerender/CDN, so on on-demand SSR you MUST guard and 404 yourself.
import type { LoaderContext } from "@nifrajs/web"

declare function lookupUser(id: string): Promise<{ id: string } | null>

export async function loader(ctx: LoaderContext) {
  // ctx.params.id is `string | undefined` (an optional segment) - default it before the lookup.
  const user = await lookupUser(ctx.params.id ?? "")
  if (!user) {
    // CONTROL FLOW: a thrown Response is an INTENTIONAL HTTP response - it propagates untouched
    // (no _error boundary, no 500). This is how you 404 a missing record.
    throw new Response("Not Found", { status: 404 })
  }
  return { user }
}

declare function lookupUser(id: string): Promise<{ name: string } | null>

// The throw contract, stated once:
//   • throw a Response  → that exact HTTP response is sent (404 / redirect() / 403 / …). Control flow.
//   • throw an Error    → renders the nearest _error boundary if one exists, else a 500. A bug.
// So NEVER `throw new Error("not found")` to mean 404 - that is a 500. Throw a 404 Response.

// routes/_layout.tsx - a layout can export `meta` too. Its tags are SITEWIDE: they land in
// the <head> of every page below it - the home for hreflang / preconnect / a section <title>.
export const meta = {
  link: [
    { rel: "preconnect", href: "https://cdn.example.com", crossorigin: "anonymous" },
    { rel: "alternate", hreflang: "es", href: "https://example.com/es" },
  ],
  title: "Docs",   // section default - a child page's title overrides it
}

// The route's final <head> = its LAYOUT CHAIN's meta merged with the page's:
//   • title (and other scalars): NEAREST-WINS - page overrides inner layout overrides outer.
//     An undefined page title keeps the layout's.
//   • meta / link arrays: CONCATENATED outermost-layout → … → page (so the page's canonical
//     comes after the layout's links).
// <link> attributes are typed (LinkDescriptor: a partial like { rel, href, hreflang } is assignable),
// name-validated (any letter/digit/hyphen name) and value-escaped against XSS - so
// rel/href/hreflang/crossorigin/media/sizes/as/integrity/fetchpriority/… all survive. A boolean
// attribute (e.g. `disabled: true`) renders bare; `false`/`undefined` is omitted.

// routes/articles/[slug].tsx - a complete SEO head: canonical + Open Graph + Twitter + JSON-LD,
// with ABSOLUTE URLs built from `origin`. The three helpers (canonical/openGraph/jsonLd) are public
// exports of @nifrajs/web; `origin` is the third MetaArgs field (after data + params).
import { canonical, jsonLd, openGraph, type MetaArgs } from "@nifrajs/web"

// CAVEAT: meta() runs in BOTH SSR and client navigation, so it has NO server env - never read
// `process.env` or the request here. The framework injects `origin` (the site's scheme+host, e.g.
// "https://news.example.com") server-side from the request AND on the client from location.origin, so
// the two match and an absolute og:url/canonical/og:image never drifts between SSR and a soft-nav. For
// anything else server-only (an API base, a CDN host), thread it through the LOADER, not meta().
export const meta = ({ data, params, origin }: MetaArgs) => {
  const article = data as { title: string; summary: string; image: string; published: string }
  const url = `${origin}/articles/${params.slug}`        // absolute, from the injected origin
  const image = `${origin}${article.image}`              // og:image MUST be absolute for crawlers
  return {
    title: article.title,
    meta: [
      { name: "description", content: article.summary },
      // og:* - openGraph emits only the props you pass (+ og:type, here "article").
      ...openGraph({
        title: article.title,
        description: article.summary,
        url,
        image,
        type: "article",
      }),
      // twitter:* - a large-image summary card sharing the same absolute image.
      { name: "twitter:card", content: "summary_large_image" },
      { name: "twitter:title", content: article.title },
      { name: "twitter:description", content: article.summary },
      { name: "twitter:image", content: image },
    ],
    link: [canonical(url)],                              // <link rel="canonical"> - the authoritative URL
    // JSON-LD structured data - escaped for safe <script> embedding by the head renderer.
    script: [
      jsonLd({
        "@context": "https://schema.org",
        "@type": "NewsArticle",
        headline: article.title,
        image,
        datePublished: article.published,
        mainEntityOfPage: url,
      }),
    ],
  }
}

import { renderPage, unsafeInlineScript } from "@nifrajs/web"

declare const adapter: import("@nifrajs/web").RenderAdapter
declare const nonce: string // one per response, from your CSP middleware

const page = renderPage({
  adapter,
  chain: [null],
  data: null,
  clientEntry: "/assets/client.js",
  nonce, // reaches the hydration bootstrap, the data script and every island tag
  head: {
    script: [{ content: JSON.stringify({ "@type": "Article" }) }], // inert: JSON only
    unsafeScript: [unsafeInlineScript("window.dataLayer = []", { nonce })],
  },
})

// What runs WHERE:
//
//   SERVER (Bun / edge)            CLIENT (browser)
//   ─────────────────────          ──────────────────────────
//   loader / action                event handlers, useState/effects
//   meta / head resolution         soft-nav re-fetch of loader data
//   SSR of the layout chain        hydration + Fast Refresh (dev)
//   backend (api, env, draft)      -
//
// The client gets the loader's RETURN VALUE (serialized into the document), never the loader
// itself, the api, or env. So:
//  1. Never import server-only modules (Bun, a DB client, secrets) at the top level of a route
//     file - the bundler pulls it into the client chunk and it crashes / leaks. (The build now
//     FAILS with a named error if a `node:` built-in reaches a client chunk - see below.)
//  2. A client soft-nav re-runs the loader over the network (X-Nifra-Data) and re-merges the
//     same layout-chain head, so sitewide tags persist across navigation - no page-only flash.

// buildClient() writes a browser bundle + manifest.json for custom build pipelines:
{
  "entry": "/assets/_nifra-entry-HASH.js",        // the bootstrap module script
  "assets": ["/assets/…"],                          // every emitted chunk URL
  "routes": { "users/[id]": ["/assets/_layout-H.js", "/assets/_slug_-H.js"] },
  "css": ["/assets/app-H.css"],                     // aggregate stylesheets (fallback)
  "routeStyles": { "users/[id]": ["/assets/_layout-H.css"] }  // per-route CSS (chain only)
}

// Invariants worth knowing:
//  • Chunk names are URL-PATH-SAFE. A dynamic-route file [slug].tsx would emit `[slug]-H.js`,
//    whose [ ] make a static server 400 the request. The build renames it (`[slug]` → `_slug_`)
//    and rewrites every reference, so the lazy import resolves and the route hydrates.
//  • `process.env` is compiled away. `process.env` → `({})` and `process.env.NODE_ENV` → the
//    build mode; every other `process.env.X` becomes undefined - EXCEPT names you opt in with the
//    PUBLIC_ prefix (Vite/Next convention), which are baked in with their value (see below). No
//    `process is not defined` crash, and no unprefixed (secret) env leaking into the client bundle.
//  • A `node:` built-in in the CLIENT bundle FAILS the build with a named error (move it behind a
//    loader/action - server-only). It builds via a browser polyfill otherwise, then breaks at runtime.
//  • Assets are content-hashed + immutable. Serve /assets/* with a long-lived cache header.

// process.env in the CLIENT bundle is compiled at build time:
//   process.env             → ({})          (a bare read won't crash hydration)
//   process.env.NODE_ENV    → "production"  (the build mode - frameworks' prod/dev branch)
//   process.env.SECRET_KEY  → undefined     (unprefixed → never exposed; no secret leak)
//   process.env.PUBLIC_API_URL → "https://api.example.com"  (PUBLIC_-prefixed → baked in by value)
//
// So to ship a value to the browser, give it a PUBLIC_ prefix in the BUILD environment:
//   PUBLIC_API_URL=https://api.example.com  bun run build
// then read process.env.PUBLIC_API_URL in app code - it becomes a string literal after the build.
import { buildClient } from "@nifrajs/web/build"

// Override the prefix (or disable auto-exposure) via buildClient:
await buildClient({
  routesDir: "./routes",
  outDir: "./dist",
  clientModule: "@nifrajs/web-react/client",
  publicEnvPrefix: "NIFRA_PUBLIC_", // default "PUBLIC_"; "" disables auto-exposure entirely
})

// build.ts - emit static HTML for opted-in routes. prerenderRoutes + cloudflarePagesRoutes
// are PUBLIC (exported from @nifrajs/web/build) - no need to boot a server and curl it.
import { buildClient, prerenderRoutes, cloudflarePagesRoutes } from "@nifrajs/web/build"
import { discoverRoutes } from "@nifrajs/web/fs"

// 1. Build the client bundle first (so the app references the hashed entry).
await buildClient({ routesDir: "./routes", outDir: "./dist", clientModule: "@nifrajs/web-react/client" })

// 2. Drive the app's own fetch to render each opted-in route → dist/<path>/index.html + _data.json.
//    Static routes opt in with `export const prerender = true`; dynamic routes enumerate concrete
//    params with `export const getStaticPaths` (+ a `fallback: "ssr" | "404"`).
const { app } = await import("./server")
const { prerendered } = await prerenderRoutes({
  app,                                       // the built createWebApp (a { fetch } is enough)
  routes: discoverRoutes("./routes").routes,
  outDir: "./dist",
})

// 3. Hybrid deploy: a Cloudflare Pages _routes.json that serves the prerendered HTML + _data.json
//    from the CDN and falls everything else through to the SSR worker.
const paths = prerendered.map((p) => p.path)
await Bun.write("./dist/_routes.json", JSON.stringify(cloudflarePagesRoutes({ prerendered: paths })))

// A PUBLISHABLE router - contract-first, so its types survive `.d.ts` emit for consumers.
import { client } from "@nifrajs/client"
import { defineContract, implement } from "@nifrajs/core/contract"
import { server } from "@nifrajs/core/server"
import { t } from "@nifrajs/schema"

// --- in the package (say @your-org/billing) ---
// 1. The CONTRACT is ONE plain declared object - methods, paths, schemas, no handlers.
//    Export it: it is the single type the package publishes, and a consumer's typed client is
//    built from THIS value (not from `typeof app`), so no internal server type crosses the seam.
export const billingContract = defineContract({
  getPlan:   { method: "GET",  path: "/billing/plan" },
  subscribe: { method: "POST", path: "/billing/subscribe", body: t.object({ plan: t.string() }) },
})

// 2. A FACTORY closes over the host's dependencies and returns a real, mountable router.
//    `implement` binds handlers to the contract; each handler's context is typed from the contract
//    alone (`c.body` is { plan: string } below) - no per-route `AddRoute` inference accreting.
export interface BillingDeps {
  charge(plan: string): Promise<{ id: string }>
}
export function createBillingRouter(deps: BillingDeps) {
  return implement(billingContract, {
    getPlan:   () => ({ plan: "pro" }),
    subscribe: (c) => deps.charge(c.body.plan),
  })
}

// --- in the consuming app ---
// 3. Mount the router with ONE `.merge()` - no per-route `.get()/.post()` chain to re-infer.
const app = server().merge(createBillingRouter({ charge: async (plan) => ({ id: plan }) }))

// 4. Build the client from the EXPORTED contract value - decoupled, no `typeof app` import needed.
const api = client(billingContract, "https://api.example.com")
const { data } = await api.billing.plan.get()          // GET  /billing/plan
// "subscribe" is a reserved client word (the SSE subscriber), so this segment is reached by
// CALLING the parent node with the segment name - same request, same typed body.
await api.billing("subscribe").post({ plan: "pro" })   // POST /billing/subscribe, body typed