// Guards the one architectural rule the type system cannot express: the game
// logic must not depend on the engine. See docs/TECHNICAL.md.
//
//   core/     never imports `cc`, at all.
//   modules/  is engine-aware, but only through the adapters listed below —
//             everything else in it stays testable headlessly.
//
// A new file that needs `cc` under modules/ is a deliberate decision, so it has
// to be added here on purpose rather than slipping in unnoticed.
import { readdirSync, readFileSync, statSync } from 'node:fs';
import { join, relative, sep } from 'node:path';

const PURE_ROOT = 'assets/scripts/core';
const MODULES_ROOT = 'assets/scripts/modules';
const ENGINE_ADAPTERS = new Set([
    'save/CocosStorage.ts',
]);

const ENGINE_IMPORT = /\bfrom\s+['"](cc|cc\/env)['"]/;

const offenders = [];

function walk(dir, onFile) {
    for (const entry of readdirSync(dir)) {
        const path = join(dir, entry);
        if (statSync(path).isDirectory()) walk(path, onFile);
        else if (path.endsWith('.ts')) onFile(path);
    }
}

function engineImports(path) {
    return readFileSync(path, 'utf8')
        .split('\n')
        .map((line, i) => ({ line: line.trim(), number: i + 1 }))
        .filter((entry) => ENGINE_IMPORT.test(entry.line));
}

walk(PURE_ROOT, (path) => {
    for (const hit of engineImports(path)) {
        offenders.push(`${path}:${hit.number}  ${hit.line}   (core/ must never import the engine)`);
    }
});

walk(MODULES_ROOT, (path) => {
    const key = relative(MODULES_ROOT, path).split(sep).join('/');
    if (ENGINE_ADAPTERS.has(key)) return;
    for (const hit of engineImports(path)) {
        offenders.push(
            `${path}:${hit.number}  ${hit.line}   (add '${key}' to ENGINE_ADAPTERS if this is intended)`,
        );
    }
});

if (offenders.length > 0) {
    console.error(`Engine dependency in code that must stay pure:\n${offenders.join('\n')}`);
    process.exit(1);
}

console.log('core purity OK');