/**
 * Architectural layer guard. Asserts dependencies point inward only:
 *
 *   domain/  → no imports from storage/app/ui/pi (pure, only node: + relative)
 *   ui/      → may import domain + pi-tui (NO node:fs — view must not persist)
 *   storage/ → may import domain (implements the ports)
 *   root     → pi-tracker.ts + index.ts: the only place wiring pi-coding-agent
 *
 * Run: npm run check:layers   (node --import tsx ./check-layers.ts)
 * Exits non-zero on any violation.
 */
import { readdirSync, readFileSync, statSync } from "node:fs";
import { extname, relative, resolve } from "node:path";

const ROOT = import.meta.dirname;

function walk(dir: string): string[] {
	const out: string[] = [];
	let entries: string[];
	try {
		entries = readdirSync(dir);
	} catch {
		return [];
	}
	for (const e of entries) {
		const full = resolve(dir, e);
		if (statSync(full).isDirectory()) {
			out.push(...walk(full));
		} else if (extname(e) === ".ts") {
			out.push(full);
		}
	}
	return out;
}

const files = [
	...walk(resolve(ROOT, "src/domain")),
	...walk(resolve(ROOT, "src/app")),
	...walk(resolve(ROOT, "src/ui")),
	...walk(resolve(ROOT, "src/storage")),
	resolve(ROOT, "pi-tracker.ts"),
	resolve(ROOT, "index.ts"),
];

const layer = (p: string): "domain" | "app" | "ui" | "storage" | "root" => {
	const r = relative(ROOT, p);
	if (r.startsWith("src/domain/")) return "domain";
	if (r.startsWith("src/app/")) return "app";
	if (r.startsWith("src/ui/")) return "ui";
	if (r.startsWith("src/storage/")) return "storage";
	return "root";
};

const IMPORT_RE = /(?:import|export)\s[^;]*?from\s+["']([^"']+)["']/g;

let violations = 0;

for (const file of files) {
	const src = readFileSync(file, "utf8");
	const L = layer(file);
	IMPORT_RE.lastIndex = 0;
	let m: RegExpExecArray | null;
	while ((m = IMPORT_RE.exec(src))) {
		const spec = m[1];
		const errs: string[] = [];

		// domain must be pure: no fs, no pi, no upper layers
		if (L === "domain") {
			if (spec.startsWith("node:fs")) errs.push("imports node:fs (must stay pure)");
			if (spec.includes("pi-coding-agent") || spec.includes("pi-tui")) errs.push("imports pi (must stay pure)");
			if (spec.includes("/storage") || spec.includes("/app") || spec.includes("/ui"))
				errs.push("imports an outer layer");
		}
		// ui must not persist: no direct node:fs
		if (L === "ui") {
			if (spec.startsWith("node:fs")) errs.push("imports node:fs (view must not persist)");
		}

		if (errs.length) {
			console.error(`✗ ${relative(ROOT, file)}: "${spec}" → ${errs.join(", ")}`);
			violations++;
		}
	}
}

if (violations > 0) {
	console.error(`\n${violations} layer violation(s)`);
	process.exit(1);
}
console.log(`✓ layer dependencies point inward (${files.length} files checked, no violations)`);