// Structure check, run before every commit: node tools/check_structure.mjs
// Fails when a source file is missing from the architecture map, a web module is
// no longer imported from an entry, a new file starts over the size threshold, a
// file already over it grew since the last commit (AGENTS.md section 2), or a web file
// does not parse as the ES module the browser loads.
import fs from 'node:fs';
import path from 'node:path';
import { execFileSync } from 'node:child_process';
import { fileURLToPath } from 'node:url';

const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const read = (rel) => fs.readFileSync(path.join(ROOT, rel), 'utf8');
const list = (dir, ext) => fs.readdirSync(path.join(ROOT, dir))
    .filter((f) => f.endsWith(ext))
    .map((f) => path.posix.join(dir, f));

const ENTRIES = ['web/main.js', 'web/hash_resolver.js'];
// Language catalogs and data tables are exempt from the size threshold (AGENTS.md section 2).
const SIZE_EXEMPT = new Set(['web/modules/locales.js']);
const SIZE_LIMIT = 600;

const pythonFiles = [...list('.', '.py'), ...list('api', '.py')].filter((f) => !f.endsWith('__init__.py'));
const webFiles = [...list('web', '.js'), ...list('web/modules', '.js')];
const failures = [];

// 1. Every source file has a line in ARCHITECTURE.md or docs/architecture/.
const docs = ['ARCHITECTURE.md', ...list('docs/architecture', '.md')].map(read).join('\n');
for (const file of [...pythonFiles, ...webFiles]) {
    if (!docs.includes(path.posix.basename(file))) failures.push(`${file}: no line in the architecture map`);
}

// 2. Every web module is reachable by imports from an entry.
const IMPORT = /(?:\bfrom\s*|\bimport\s*\(\s*|\bimport\s+)['"](\.{1,2}\/[^'"]+\.js)['"]/g;
const reached = new Set();
const walk = (file) => {
    if (reached.has(file) || !fs.existsSync(path.join(ROOT, file))) return;
    reached.add(file);
    for (const [, spec] of read(file).matchAll(IMPORT)) walk(path.posix.join(path.posix.dirname(file), spec));
};
ENTRIES.forEach(walk);
for (const file of webFiles) {
    if (!reached.has(file)) failures.push(`${file}: not imported from ${ENTRIES.join(' or ')}; remove it or wire it in`);
}

// 3. Size threshold: files over it are listed; a new file may not start over it, and a
// file already over it may only shrink or stay the same (compared with the last commit).
const lineCount = (text) => text.replace(/\r\n/g, '\n').split('\n').length;
const committedLines = (file) => {
    try {
        return lineCount(execFileSync('git', ['show', `HEAD:${file}`], { cwd: ROOT, encoding: 'utf8', stdio: ['ignore', 'pipe', 'ignore'] }));
    } catch (_) {
        return null; // not committed yet (a new file), or no git here
    }
};
const large = [...pythonFiles, ...webFiles]
    .filter((f) => !SIZE_EXEMPT.has(f))
    .map((f) => [f, lineCount(read(f))])
    .filter(([, lines]) => lines > SIZE_LIMIT)
    .sort((a, b) => b[1] - a[1]);

if (large.length) {
    console.log(`Over ${SIZE_LIMIT} lines (may only shrink, AGENTS.md section 2):`);
    for (const [file, lines] of large) {
        const before = committedLines(file);
        const note = before === null ? '  NEW' : lines > before ? `  grew from ${before}` : '';
        console.log(`  ${lines}\t${file}${note}`);
        if (before === null) failures.push(`${file}: new file over ${SIZE_LIMIT} lines; split it by responsibility`);
        else if (lines > before) failures.push(`${file}: over ${SIZE_LIMIT} lines and grew from ${before} to ${lines}; move a responsibility out first`);
    }
}
// 4. Syntax: every web file must parse as an ES module. `node --check` on a .js file can
// pass what the browser rejects (a raw line break inside a string did), so compile them
// the way the browser does, in one child process.
const PARSE = "const vm = require('node:vm'); const fs = require('node:fs');"
    + " for (const f of process.argv.slice(1)) { try { new vm.SourceTextModule(fs.readFileSync(f, 'utf8')); }"
    + " catch (e) { console.log(f + ' | ' + e.message); } }";
const syntax = execFileSync(process.execPath, ['--experimental-vm-modules', '--no-warnings', '-e', PARSE,
    ...webFiles.map((file) => path.join(ROOT, file))], { encoding: 'utf8' });
for (const line of syntax.split(/\r?\n/).filter(Boolean)) {
    const [file, message] = line.split(' | ');
    failures.push(`${path.relative(ROOT, file).split(path.sep).join('/')}: does not parse (${message})`);
}

if (failures.length) {
    console.error(`\nStructure check failed:\n  ${failures.join('\n  ')}`);
    process.exit(1);
}
console.log(`\nStructure check passed: ${pythonFiles.length + webFiles.length} source files mapped, ${reached.size} web modules reachable.`);