/**
 * blocks-check — the mechanical guard of the blocks tier's B contract
 * (docs/architecture/blocks.md). Small on purpose: blocks are exempt from the
 * acceptance matrix, NOT from discipline.
 *
 * Checks:
 *   B-2      no raw interactive natives (`<button/input/select/textarea/a>`)
 *            in block `.svelte` files — every interactive element is a canon
 *            eidos component.
 *   B-4/B-1  import direction: blocks never import `$packs` or `$uix/sema`;
 *            nothing in the canon (`src/uix/{morfo,soma,sema,eidos,
 *            active-uix,langs}`) nor in `src/{arts,libs,packs}` imports the
 *            blocks tier.
 *   B-10     a block never imports another block (declared exception: the
 *            shells allowlist).
 *   D-BLK.2  no `.css` files under the tier; a scoped `<style>` requires a
 *            `justified:` comment marker (layout-components-first).
 *   B-9      every block folder ships `README.md` and a demo route at
 *            `web/routes/blocks/{kebab}/+page.svelte`.
 *
 * Self-testing: the detectors are asserted against inline fixtures on every
 * run (a raw `<button>` fixture MUST be flagged, a `<Button>` fixture must
 * not, …), so a silently-broken regex fails the guard itself.
 */

import { existsSync, readdirSync, readFileSync, statSync } from 'node:fs';
import { dirname, join, relative, resolve } from 'node:path';

const REPO = process.cwd();
const BLOCKS_DIR = join(REPO, 'src', 'uix', 'blocks');
const DEMO_DIR = join(REPO, 'web', 'routes', 'blocks');

// B-10 declared exception: the shells compose F1 pieces and blocks by design.
const SHELL_ALLOWLIST = new Set(['app-shell', 'docs-shell']);

// Trees that must never import the blocks tier (B-4).
const OUTSIDE_ROOTS = [
	join(REPO, 'src', 'arts'),
	join(REPO, 'src', 'libs'),
	join(REPO, 'src', 'packs'),
	join(REPO, 'src', 'uix', 'morfo'),
	join(REPO, 'src', 'uix', 'soma'),
	join(REPO, 'src', 'uix', 'sema'),
	join(REPO, 'src', 'uix', 'eidos'),
	join(REPO, 'src', 'uix', 'active-uix'),
	join(REPO, 'src', 'uix', 'langs')
];

interface Violation {
	rule: string;
	file: string;
	line: number;
	detail: string;
}

const RAW_NATIVE_RE = /<(button|input|select|textarea|a)\b/;
const IMPORT_RE = /(?:from|import)\s*['"]([^'"]+)['"]/g;

function norm(path: string): string {
	return path.replace(/\\/g, '/');
}

function isUnder(abs: string, root: string): boolean {
	return norm(abs).startsWith(norm(root) + '/');
}

/** Resolve an import specifier to an absolute path when it targets the repo. */
function resolveSpec(fileAbs: string, spec: string): string | null {
	if (spec.startsWith('./') || spec.startsWith('../')) return resolve(dirname(fileAbs), spec);
	if (spec === '$blocks' || spec.startsWith('$blocks/'))
		return join(BLOCKS_DIR, spec.slice('$blocks'.length + 1));
	if (spec === '$packs' || spec.startsWith('$packs/'))
		return join(REPO, 'src', 'packs', spec.slice('$packs'.length + 1));
	if (spec.startsWith('$uix/')) return join(REPO, 'src', 'uix', spec.slice('$uix/'.length));
	if (spec.startsWith('@/')) return join(REPO, 'src', spec.slice(2));
	return null;
}

/** The block folder a path belongs to, or null. */
function blockOf(abs: string): string | null {
	if (!isUnder(abs, BLOCKS_DIR)) return null;
	return norm(relative(BLOCKS_DIR, abs)).split('/')[0] ?? null;
}

/** Scan one file INSIDE the tier. Pure — safe for self-test fixtures. */
export function scanBlockFile(fileAbs: string, rel: string, src: string): Violation[] {
	const out: Violation[] = [];
	const ownBlock = blockOf(fileAbs);
	const lines = src.split('\n');

	if (fileAbs.endsWith('.svelte')) {
		lines.forEach((line, i) => {
			const code = line.replace(/<!--.*?-->/g, '');
			if (RAW_NATIVE_RE.test(code)) {
				out.push({
					rule: 'B-2',
					file: rel,
					line: i + 1,
					detail: `raw interactive native — compose the canon component (${code.trim().slice(0, 60)}…)`
				});
			}
		});
		if (/<style\b/.test(src) && !/justified:/.test(src)) {
			out.push({
				rule: 'D-BLK.2',
				file: rel,
				line: lines.findIndex((l) => /<style\b/.test(l)) + 1,
				detail: 'scoped <style> without a `/* justified: … */` marker — layout-components-first'
			});
		}
	}

	for (const match of src.matchAll(IMPORT_RE)) {
		const spec = match[1];
		const line = src.slice(0, match.index).split('\n').length;
		const target = resolveSpec(fileAbs, spec);
		if (spec.startsWith('$packs') || (target && isUnder(target, join(REPO, 'src', 'packs')))) {
			out.push({ rule: 'B-4', file: rel, line, detail: `a block must not import the packs tier (${spec})` });
			continue;
		}
		if (
			spec.startsWith('$uix/sema') ||
			(target && isUnder(target, join(REPO, 'src', 'uix', 'sema')))
		) {
			out.push({
				rule: 'B-1',
				file: rel,
				line,
				detail: `a block must not import sema — perception belongs to the canon (${spec})`
			});
			continue;
		}
		if (target) {
			const targetBlock = blockOf(target);
			if (targetBlock && ownBlock && targetBlock !== ownBlock && !SHELL_ALLOWLIST.has(ownBlock)) {
				out.push({
					rule: 'B-10',
					file: rel,
					line,
					detail: `block "${ownBlock}" imports block "${targetBlock}" — share via canon or duplicate consciously`
				});
			}
		}
	}
	return out;
}

/** Scan one file OUTSIDE the tier for imports INTO it. Pure. */
export function scanOutsideFile(fileAbs: string, rel: string, src: string): Violation[] {
	const out: Violation[] = [];
	for (const match of src.matchAll(IMPORT_RE)) {
		const spec = match[1];
		const target = resolveSpec(fileAbs, spec);
		if (
			spec === '$blocks' ||
			spec.startsWith('$blocks/') ||
			(target && (target === BLOCKS_DIR || isUnder(target, BLOCKS_DIR)))
		) {
			out.push({
				rule: 'B-4',
				file: rel,
				line: src.slice(0, match.index).split('\n').length,
				detail: `the canon must not import the blocks tier (${spec})`
			});
		}
	}
	return out;
}

function walk(dir: string, exts: RegExp, out: string[] = []): string[] {
	for (const entry of readdirSync(dir)) {
		const path = join(dir, entry);
		if (statSync(path).isDirectory()) walk(path, exts, out);
		else if (exts.test(entry)) out.push(path);
	}
	return out;
}

/** Assert the detectors against inline fixtures — the permanent negative test. */
function selfTest(): string[] {
	const failures: string[] = [];
	const inHero = join(BLOCKS_DIR, 'hero', 'hero.svelte');
	const inShell = join(BLOCKS_DIR, 'app-shell', 'app-shell.svelte');
	const expectRules = (name: string, got: Violation[], want: string[]) => {
		const gotRules = got.map((v) => v.rule).sort();
		if (JSON.stringify(gotRules) !== JSON.stringify([...want].sort()))
			failures.push(`${name}: expected [${want}], got [${gotRules}]`);
	};

	expectRules(
		'raw <button> flagged',
		scanBlockFile(inHero, 'fixture', '<button onclick={x}>go</button>'),
		['B-2']
	);
	expectRules(
		'canon <Button> + <aside> clean',
		scanBlockFile(inHero, 'fixture', '<aside>\n<Button onclick={x}>go</Button>\n</aside>'),
		[]
	);
	expectRules(
		'packs import flagged',
		scanBlockFile(inHero, 'fixture', "import { mesh } from '$packs/ambient';"),
		['B-4']
	);
	expectRules(
		'sema import flagged',
		scanBlockFile(inHero, 'fixture', "import { pack } from '$uix/sema/components/dialog';"),
		['B-1']
	);
	expectRules(
		'unjustified <style> flagged',
		scanBlockFile(inHero, 'fixture', '<div />\n<style>.x{color:red}</style>'),
		['D-BLK.2']
	);
	expectRules(
		'justified <style> clean',
		scanBlockFile(inHero, 'fixture', '<div />\n<style>/* justified: demo glue */ .x{}</style>'),
		[]
	);
	expectRules(
		'cross-block import flagged',
		scanBlockFile(inHero, 'fixture', "import Pricing from '$blocks/pricing';"),
		['B-10']
	);
	expectRules(
		'shell composing a block allowed',
		scanBlockFile(inShell, 'fixture', "import Hero from '../hero/index.ts';"),
		[]
	);
	expectRules(
		'canon importing $blocks flagged',
		scanOutsideFile(join(REPO, 'src', 'uix', 'eidos', 'x.ts'), 'fixture', "import H from '$blocks/hero';"),
		['B-4']
	);
	expectRules(
		'canon relative import into blocks flagged',
		scanOutsideFile(
			join(REPO, 'src', 'uix', 'eidos', 'x.ts'),
			'fixture',
			"import H from '../blocks/hero/index.ts';"
		),
		['B-4']
	);
	return failures;
}

function main(): void {
	const selfFailures = selfTest();
	if (selfFailures.length > 0) {
		for (const f of selfFailures) console.error(`SELF-TEST FAIL — ${f}`);
		console.error(`\nblocks-check: the guard's own detectors are broken (${selfFailures.length})`);
		process.exit(1);
	}

	const violations: Violation[] = [];
	let blockFiles: string[] = [];
	let blockDirs: string[] = [];
	if (existsSync(BLOCKS_DIR)) {
		blockFiles = walk(BLOCKS_DIR, /\.(ts|svelte|css)$/);
		blockDirs = readdirSync(BLOCKS_DIR).filter((e) =>
			statSync(join(BLOCKS_DIR, e)).isDirectory()
		);
	}

	for (const file of blockFiles) {
		const rel = relative(REPO, file);
		if (file.endsWith('.css')) {
			violations.push({
				rule: 'D-BLK.2',
				file: rel,
				line: 1,
				detail: 'a block ships no .css file — layout-components-first'
			});
			continue;
		}
		if (/\.test\./.test(file)) continue;
		violations.push(...scanBlockFile(file, rel, readFileSync(file, 'utf8')));
	}

	for (const dir of blockDirs) {
		const hasCode = walk(join(BLOCKS_DIR, dir), /\.(ts|svelte)$/).length > 0;
		if (!hasCode) continue;
		if (!existsSync(join(BLOCKS_DIR, dir, 'README.md'))) {
			violations.push({
				rule: 'B-9',
				file: `src/uix/blocks/${dir}`,
				line: 1,
				detail: 'block folder without README.md (Function · Composition map · Decisions · Gaps)'
			});
		}
		if (!existsSync(join(DEMO_DIR, dir, '+page.svelte'))) {
			violations.push({
				rule: 'B-9',
				file: `src/uix/blocks/${dir}`,
				line: 1,
				detail: `block without a demo route (web/routes/blocks/${dir}/+page.svelte)`
			});
		}
	}

	let outsideCount = 0;
	for (const root of OUTSIDE_ROOTS) {
		if (!existsSync(root)) continue;
		for (const file of walk(root, /\.(ts|svelte)$/)) {
			outsideCount++;
			violations.push(...scanOutsideFile(file, relative(REPO, file), readFileSync(file, 'utf8')));
		}
	}

	if (violations.length > 0) {
		for (const v of violations) {
			console.error(`ERROR [${v.rule}] ${v.file}:${v.line} — ${v.detail}`);
		}
		console.error(`\nblocks-check: ${violations.length} error(s) across ${blockDirs.length} block(s)`);
		process.exit(1);
	}
	console.log(
		`blocks-check: self-test OK · 0 error(s) across ${blockDirs.length} block(s) (${blockFiles.length} files; ${outsideCount} canon/arts/libs/packs files scanned for direction)`
	);
}

main();