/**
 * __theming-diff — compares two `__theming-probe` captures (PLAN-theming §7.4).
 *
 *   node scripts/__theming-diff.ts before.json after.json
 *
 * The gate is EMPTY: one differing computed value means the default moved, and
 * that is a stop-and-explain, not a warning. Temporary instrument (`__` prefix).
 */

import { readFileSync } from 'node:fs';

type Rows = Record<string, Record<string, string>>;

const [a, b] = process.argv.slice(2);
const A = JSON.parse(readFileSync(a, 'utf8')) as Record<string, Rows>;
const B = JSON.parse(readFileSync(b, 'utf8')) as Record<string, Rows>;

let diffs = 0;
let compared = 0;
const missing: string[] = [];

for (const state of Object.keys(A)) {
	const ra = A[state];
	const rb = B[state] ?? {};
	for (const node of Object.keys(ra)) {
		const na = ra[node];
		const nb = rb[node];
		if (!nb) {
			missing.push(`${state} :: ${node}`);
			continue;
		}
		for (const prop of Object.keys(na)) {
			if (prop === '__key') continue;
			compared++;
			if (na[prop] !== nb[prop]) {
				diffs++;
				console.log(
					`DIFF ${state} :: ${node} :: ${prop}\n  before: ${na[prop]}\n  after:  ${nb[prop]}`
				);
			}
		}
	}
}

for (const m of missing) console.log(`MISSING NODE ${m}`);
console.log(
	`\ncompared ${compared} computed values across ${Object.keys(A).length} states — ${diffs} diff(s), ${missing.length} missing node(s)`
);
process.exit(diffs === 0 && missing.length === 0 ? 0 : 1);