import { copyFile, mkdir, readFile, rm, writeFile } from "node:fs/promises";
import path from "node:path";
import { fileURLToPath } from "node:url";
import esbuild from "esbuild";

/**
 * Builds the Ekklesia shell into a static browser application.
 *
 * This is **not** the module UI build pipeline, and the two must not be conflated. ADR 0023's
 * `@ekklesia/module-ui-build` compiles a *module's* `src/ui/index.tsx` into the artifact its
 * manifest declares, is owned by the platform so module authors write no bundler configuration, and
 * runs when a module is packaged. This script builds *this application*, is owned by this package
 * alone, and knows nothing about manifests. They happen to share a bundler; they share no
 * configuration, no contract, and no output.
 *
 * Installed module UIs are deliberately **not** bundled in. The shell has no import of any module,
 * so there is nothing for esbuild to reach: every module artifact is fetched at run time from the
 * URL the inventory returned. That is the property that makes modules independently installable, and
 * bundling one would silently destroy it.
 */
const packageDirectory = path.dirname(path.dirname(fileURLToPath(import.meta.url)));
const outputDirectory = path.join(packageDirectory, "dist", "browser");
const serve = process.argv.includes("--serve");

/**
 * Development only: the API origin the development server writes into its copy of the Dashboard page,
 * exactly as `apps/api` does at startup in production (ADR 0045). Empty means "the API is on this
 * page's own origin". Set it to an absolute origin for split-origin development
 * (`EKKLESIA_API_BASE_URL=http://127.0.0.1:3000`), and add this page's own origin to
 * `EKKLESIA_IDENTITY_TRUSTED_ORIGINS` so the API reflects it for CORS and the session cookie travels.
 * A production build never reads it: the built page always carries an empty value, and the bundle
 * carries no origin at all.
 */
const apiBaseUrl = serve ? (process.env.EKKLESIA_API_BASE_URL ?? "") : "";
const API_ORIGIN_PLACEHOLDER = '<meta content="" name="ekklesia-api-origin" />';

/** @type {import("esbuild").BuildOptions} */
const buildOptions = {
  absWorkingDir: packageDirectory,
  // Everything the shell needs is bundled; a browser resolves nothing at run time except the module
  // artifacts it is told about, which are real URLs rather than bare specifiers.
  bundle: true,
  define: {
    // React reads this at module scope and a browser has no `process`.
    "process.env.NODE_ENV": JSON.stringify(serve ? "development" : "production"),
  },
  entryPoints: {
    // Emitted under the exact path `apps/api` serves it from (ADR 0044), so the development server's
    // `servedir` and production answer the same absolute URL `index.html` names.
    "assets/ekklesia-dashboard/app": path.join(packageDirectory, "src", "browser", "main.tsx"),
    "display/app": path.join(packageDirectory, "src", "display", "main.tsx"),
    // The display service worker (ADR 0043). A separate entry because a worker is a separate
    // realm with its own globals; bundling it into the page would make it unregisterable and its
    // `self` meaningless.
    "display/sw": path.join(packageDirectory, "src", "display", "sw.ts"),
  },
  format: "esm",
  jsx: "automatic",
  logLevel: "info",
  // Unminified, matching the module UI build: an operator is expected to be able to read what their
  // installation actually serves, and nothing else in this repository minifies.
  minify: false,
  outdir: outputDirectory,
  platform: "browser",
  sourcemap: true,
  // Matches `browser.json`'s `target`, so what TypeScript typechecks and what esbuild emits agree.
  target: "es2022",
};

await rm(outputDirectory, { force: true, recursive: true });
await mkdir(outputDirectory, { recursive: true });
await mkdir(path.join(outputDirectory, "display"), { recursive: true });
const dashboardPage = await readFile(path.join(packageDirectory, "index.html"), "utf8");
if (dashboardPage.split(API_ORIGIN_PLACEHOLDER).length !== 2) {
  throw new Error("index.html must contain exactly one empty ekklesia-api-origin meta element.");
}
await writeFile(
  path.join(outputDirectory, "index.html"),
  dashboardPage.replace(
    API_ORIGIN_PLACEHOLDER,
    `<meta content="${apiBaseUrl.replaceAll("&", "&amp;").replaceAll('"', "&quot;")}" name="ekklesia-api-origin" />`,
  ),
);
await copyFile(
  path.join(packageDirectory, "display.html"),
  path.join(outputDirectory, "display", "index.html"),
);

if (serve) {
  const context = await esbuild.context(buildOptions);
  await context.watch();
  const { host, port } = await context.serve({ servedir: outputDirectory });
  console.log(`Ekklesia shell (development) on http://${host}:${port}`);
  console.log(
    apiBaseUrl === ""
      ? "API origin: this page's own origin. Set EKKLESIA_API_BASE_URL for a split-origin API."
      : `API origin: ${apiBaseUrl}`,
  );
} else {
  await esbuild.build(buildOptions);
  console.log(`Built the Ekklesia shell into ${path.relative(packageDirectory, outputDirectory)}`);
}