/**
 * uix-boot-check — the guard that breaks the build when the compiled boot
 * on disk no longer describes the source it came from.
 *
 * The whole boot axis fails SILENTLY by construction. The tag is wrapped
 * in a mute `try`/`catch` (it runs in `<head>`, before anything can
 * report), a stale artifact stamps values that are merely OLD rather than
 * invalid, and a browser that blocks the script leaves no trace in the
 * page. So the only guard worth having is one that stops the build: a
 * site that edits its preference schema and forgets to recompile must
 * learn it from `vite build`, not from a user in Cairo reading an LTR
 * page. (`createActiveUix`'s dev audit is the other half — it names the
 * axis that moved, in the browser, after the fact.)
 *
 * It lives in `scripts/` and not under `src/uix` on purpose: it imports
 * esbuild and Vite's plugin type, which are the HOST's build tools. The
 * framework does not ship its consumer's bundler.
 *
 * Two shapes, one check:
 *   - `uixBootCheck()` — a Vite plugin. `buildStart` recompiles with the
 *     site's own configuration and fails the build on any difference. In
 *     dev it WARNS instead (a dev server that refuses to start over a
 *     stale cosmetic artifact helps nobody) and registers every input the
 *     compile read, so editing a dimension re-runs the check there and
 *     then instead of waiting for a deploy. That doctrine covers a compile
 *     that FAILS outright too — a half-typed schema module is the most
 *     ordinary state a watched file is ever in, and it must cost a line in
 *     the log, not the session.
 *   - `checkUixBootArtifact()` — the same check as a promise, for a site
 *     with no Vite (or a CI job that prefers a test over a build).
 */
import { readFileSync } from 'node:fs';
import { relative, resolve } from 'node:path';

import type { Plugin } from 'vite';

import { BOOT_OUTPUT, compileBoot, renderBootModule } from './generate-boot.ts';

export interface UixBootCheckOptions {
	/**
	 * The module exporting `bootPrefsSchema` the artifact was compiled
	 * with — the same path passed to `generate-boot --schema`. Omitted,
	 * the framework's default schema.
	 */
	readonly schema?: string;
	/** The artifact on disk. Defaults to the framework's own. */
	readonly out?: string;
}

export interface UixBootCheckResult {
	readonly ok: boolean;
	/** Why it is stale, in the words a site can act on. Absent when `ok`. */
	readonly reason?: string;
	/** Every source file the compile read — what dev watches. */
	readonly inputs: readonly string[];
}

/**
 * Recompile and compare. The comparison is over the artifact's TEXT, not
 * over the hash alone: the hash lives in the same file, and a check that
 * only compared hashes would pass on a file where someone edited the
 * script and left the hash — the exact pair that makes a browser block
 * the tag.
 */
export async function checkUixBootArtifact(
	options: UixBootCheckOptions = {},
	// Filled as the compile reads, and still filled when it throws — see
	// `compileBoot`.
	read = new Set<string>()
): Promise<UixBootCheckResult> {
	const out = options.out === undefined ? BOOT_OUTPUT : resolve(options.out);
	const schema = options.schema === undefined ? undefined : resolve(options.schema);
	const { script, inputs } = await compileBoot({ schema }, read);
	const expected = renderBootModule(script);

	let actual: string;
	try {
		// LF: the artifact is written with LF and a checkout with
		// `core.autocrlf` must not be read as a stale one.
		actual = readFileSync(out, 'utf8').replace(/\r\n/g, '\n');
	} catch {
		return { ok: false, reason: `no compiled boot at ${out} — run the boot compiler`, inputs };
	}

	if (actual === expected) return { ok: true, inputs };
	return {
		ok: false,
		reason: `the compiled boot at ${out} is stale — it no longer matches ${
			schema === undefined ? 'the framework schema' : relative(process.cwd(), schema)
		} and the modules it imports. Recompile it.`,
		inputs
	};
}

/**
 * A compile that never produced a result — almost always a syntax error
 * the site is halfway through typing into its schema module. It is a
 * different event from a stale artifact and gets its own sentence,
 * because the artifact on disk may well be fine.
 */
function compileFailure(error: unknown): string {
	return `could not compile the boot: ${error instanceof Error ? error.message : String(error)}`;
}

export function uixBootCheck(options: UixBootCheckOptions = {}): Plugin {
	let serve = false;
	// The files the last compile READ. A file that is NOT one of them cannot
	// make the artifact stale, and a file that becomes one can only do it
	// through an edit to a file that already is — so membership is enough to
	// decide whether a save is worth a recompile.
	//
	// That holds for a compile that FAILED too, as long as the set is the one
	// it read before it broke: the file that broke it is in there, and so is
	// every file that imports it. Measured, twice: a set kept only from
	// SUCCESSFUL compiles was empty on a dev server that started on a
	// half-typed schema, and never held a module the schema imported broken
	// for the first time — either way the fix was discarded as "not an input"
	// and the guard stayed silent. Checking every save instead while broken
	// was measured too: ten duplicate warnings from a SvelteKit start-up,
	// which writes its own files.
	let inputs = new Set<string>();

	return {
		name: 'uix-boot-check',

		configResolved(config) {
			serve = config.command === 'serve';
		},

		async buildStart() {
			const read = new Set<string>();
			let result: UixBootCheckResult | undefined;
			let failure: unknown;
			try {
				result = await checkUixBootArtifact(options, read);
			} catch (error) {
				// In dev this is a warning like any other: a guard over a
				// cosmetic artifact must never be the reason a dev server
				// refuses to start, and the site is about to see the same
				// syntax error from Vite itself. On a build there is nothing
				// to recover to.
				if (!serve) throw error;
				failure = error;
			}
			inputs = read;
			// In dev the input files are registered so a later edit re-runs
			// the check; on a build there is no "later", so a difference is
			// the end of the build.
			if (serve) for (const input of read) this.addWatchFile(input);
			if (result === undefined) {
				this.warn(compileFailure(failure));
				return;
			}
			if (result.ok) return;
			if (serve) this.warn(result.reason!);
			else this.error(result.reason!);
		},

		configureServer(server) {
			server.watcher.on('change', (file) => {
				if (!inputs.has(resolve(file))) return;
				const read = new Set<string>();
				void checkUixBootArtifact(options, read)
					.then((result) => {
						inputs = new Set(result.inputs);
						if (result.ok) return;
						server.config.logger.warn(`[uix-boot-check] ${result.reason}`);
					})
					// Without this the rejection is unhandled and Node 24 ENDS
					// THE PROCESS: one typo in a schema module and the session
					// is over. (The compile itself no longer throws from
					// outside a promise — see `inputCollector` in
					// `generate-boot.ts` — but a guard that watches a file the
					// user is editing has to survive every state that file
					// passes through.)
					.catch((error: unknown) => {
						inputs = read;
						server.config.logger.warn(`[uix-boot-check] ${compileFailure(error)}`);
					});
			});
		}
	};
}