#!/usr/bin/env node
// Test harness for newOS4 core FileSystemModule commands (tail, sed, cat/head regression).
// Loads module-fs.js in a vm sandbox with stub terminal/fs — no browser needed.
// Run: node scripts/test-fs-commands.mjs   (exit 1 on failure)

import { readFileSync } from 'node:fs';
import vm from 'node:vm';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const SRC = readFileSync(path.join(ROOT, 'modules/core/module-fs.js'), 'utf8');

function makeCtx() {
    const ctx = {
        setInterval, clearInterval, setTimeout, clearTimeout, console,
        __test: { files: new Map(), writes: [] },
    };
    vm.createContext(ctx);
    vm.runInContext(SRC + '\n;globalThis.FileSystemModule = FileSystemModule;', ctx, { filename: 'module-fs.js' });
    return ctx;
}

function makeMod(ctx) {
    const out = [];
    const files = ctx.__test.files;
    const terminal = {
        print: (text, type) => out.push({ text: String(text), type: type || '' }),
        fs: {
            readFile: (p) => (files.has(p) ? files.get(p) : null),
            writeFile: (p, c) => { files.set(p, String(c)); ctx.__test.writes.push([p, String(c)]); },
        },
        _pipeInput: null,
        _activeFollow: null,
        stopFollow(msg) {
            if (!this._activeFollow) return false;
            clearInterval(this._activeFollow.interval);
            this._activeFollow = null;
            this.print(msg || '^C — stopped following', 'warning');
            return true;
        },
    };
    const mod = new ctx.FileSystemModule();
    mod.terminal = terminal;
    mod.registerCommands();
    return { mod, terminal, out };
}

function scenario(filesInit) {
    const ctx = makeCtx();
    for (const [k, v] of Object.entries(filesInit || {})) ctx.__test.files.set(k, v);
    const s = makeMod(ctx);
    s.ctx = ctx;
    return s;
}

function runCmd(mod, name, args) {
    if (typeof mod.commands[name] !== 'function') {
        mod.terminal.print(name + ': command not defined', 'error');
        return;
    }
    mod.commands[name](args);
}

let pass = 0, fail = 0;
const check = (name, cond, got) => {
    if (cond) { pass++; console.log('  ok   ' + name); }
    else { fail++; console.log('  FAIL ' + name + (got !== undefined ? '  — got: ' + JSON.stringify(got) : '')); }
};
const text = (out) => out.map(o => o.text).join('\n');
const sleep = (ms) => new Promise(r => setTimeout(r, ms));

const L12 = ['l1','l2','l3','l4','l5','l6','l7','l8','l9','l10','l11','l12'].join('\n');

// ─── regression: cat / head unchanged ───
{
    const { mod, out } = scenario({ 'a.txt': 'hello' });
    runCmd(mod, 'cat', ['a.txt']);
    check('cat regression', text(out) === 'hello', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': '1\n2\n3' });
    runCmd(mod, 'head', ['a.txt', '2']);
    check('head regression', text(out) === '1\n2', text(out));
}

// ─── tail ───
{
    const { mod, out } = scenario({ 'log.txt': L12 });
    runCmd(mod, 'tail', ['log.txt']);
    check('tail default last 10', text(out) === 'l3\nl4\nl5\nl6\nl7\nl8\nl9\nl10\nl11\nl12', text(out));
}
{
    const { mod, out } = scenario({ 'log.txt': L12 });
    runCmd(mod, 'tail', ['log.txt', '2']);
    check('tail legacy count arg', text(out) === 'l11\nl12', text(out));
}
{
    const { mod, out } = scenario({ 'log.txt': L12 });
    runCmd(mod, 'tail', ['-n', '3', 'log.txt']);
    check('tail -n 3', text(out) === 'l10\nl11\nl12', text(out));
}
{
    const { mod, out } = scenario({ 'log.txt': L12 });
    runCmd(mod, 'tail', ['-4', 'log.txt']);
    check('tail -4 attached flag', text(out) === 'l9\nl10\nl11\nl12', text(out));
}
{
    const { mod, out } = scenario({ 'log.txt': L12 });
    runCmd(mod, 'tail', ['-n', 'abc', 'log.txt']);
    check('tail -n abc errors', out[0].type === 'error', out);
}
{
    const { mod, out } = scenario({});
    runCmd(mod, 'tail', ['nope.txt']);
    check('tail missing file errors', out[0].type === 'error' && text(out).includes('No such file'), text(out));
}
{
    const { mod, out } = scenario({});
    runCmd(mod, 'tail', []);
    check('tail no args usage', out[0].type === 'warning', out);
}
{
    const { mod, terminal, out, ctx } = scenario({ 'log.txt': 'a\nb' });
    runCmd(mod, 'tail', ['-f', 'log.txt']);
    check('tail -f prints initial content', out.some(o => o.text === 'a\nb'), out.map(o => o.text));
    check('tail -f registers follow timer', !!(terminal._activeFollow && terminal._activeFollow.file === 'log.txt'), terminal._activeFollow);
    ctx.__test.files.set('log.txt', 'a\nb\nc');
    await sleep(1700);
    check('tail -f prints appended line', out.some(o => o.text === '\nc'), out.map(o => o.text));
    check('tail -f stopFollow clears', terminal.stopFollow() === true && terminal._activeFollow === null);
    ctx.__test.files.set('log.txt', 'a\nb\nc\nd');
    await sleep(1700);
    check('no output after stopFollow', !out.some(o => o.text.includes('d')), out.map(o => o.text));
}
{
    const { mod, terminal, out, ctx } = scenario({ 'log.txt': 'aaaa' });
    runCmd(mod, 'tail', ['-f', 'log.txt']);
    ctx.__test.files.set('log.txt', 'xy');
    await sleep(1700);
    check('tail -f detects truncation', out.some(o => o.text === 'xy') && out.some(o => o.text.includes('truncated')), out.map(o => o.text));
    terminal.stopFollow();
}

// ─── sed ───
{
    const { mod, out } = scenario({ 'a.txt': 'foo bar\nfoo baz' });
    runCmd(mod, 'sed', ['s/foo/X/', 'a.txt']);
    check('sed s/foo/X/ first per line', text(out) === 'X bar\nfoo baz', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'foo bar foo' });
    runCmd(mod, 'sed', ['s/foo/X/g', 'a.txt']);
    check('sed global flag', text(out) === 'X bar X', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'Hello HELLO' });
    runCmd(mod, 'sed', ['s/hello/hey/i', 'a.txt']);
    check('sed case-insensitive', text(out) === 'hey HELLO', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'ab' });
    runCmd(mod, 'sed', ['s/a/$&/', 'a.txt']);
    check('sed $& replacement', text(out) === 'ab', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'a/b path' });
    runCmd(mod, 'sed', ['s/a\\/b/X/', 'a.txt']);
    check('sed escaped slash', text(out) === 'X path', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'keep\ndelete me\nkeep2' });
    runCmd(mod, 'sed', ['/delete/d', 'a.txt']);
    check('sed /pat/d', text(out) === 'keep\nkeep2', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': '1\n2\n3' });
    runCmd(mod, 'sed', ['2d', 'a.txt']);
    check('sed 2d', text(out) === '1\n3', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': '1\n2\n3' });
    runCmd(mod, 'sed', ['$d', 'a.txt']);
    check('sed $d', text(out) === '1\n2', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'foo\nbar\nfoo' });
    runCmd(mod, 'sed', ['-n', 's/foo/X/p', 'a.txt']);
    check('sed -n s///p prints only changed', text(out) === 'X\nX', text(out));
}
{
    const { mod, out, ctx } = scenario({ 'a.txt': 'old line' });
    runCmd(mod, 'sed', ['-i', 's/old/new/', 'a.txt']);
    check('sed -i writes file', ctx.__test.files.get('a.txt') === 'new line', ctx.__test.files.get('a.txt'));
    check('sed -i success msg', out.some(o => o.type === 'success'), out);
}
{
    const { mod, ctx } = scenario({ 'a.txt': '1\n2\n' });
    runCmd(mod, 'sed', ['-i', '2d', 'a.txt']);
    check('sed -i keeps trailing newline', ctx.__test.files.get('a.txt') === '1\n', JSON.stringify(ctx.__test.files.get('a.txt')));
}
{
    const { mod, out, terminal } = scenario({});
    terminal._pipeInput = 'x1\nx2';
    runCmd(mod, 'sed', ['s/x/y/']);
    check('sed reads pipe input', text(out) === 'y1\nx2', text(out));
}
{
    const { mod, out } = scenario({});
    runCmd(mod, 'sed', []);
    check('sed no args usage', out[0].type === 'warning', out);
}
{
    const { mod, out } = scenario({ 'a.txt': 'x' });
    runCmd(mod, 'sed', ['s/a', 'a.txt']);
    check('sed malformed expr errors', out[0].type === 'error', text(out));
}
{
    const { mod, out } = scenario({ 'a.txt': 'x' });
    runCmd(mod, 'sed', ['s/[/y/', 'a.txt']);
    check('sed invalid regex errors', out[0].type === 'error', text(out));
}
{
    const { mod, out } = scenario({});
    runCmd(mod, 'sed', ['s/a/b/', 'missing.txt']);
    check('sed missing file errors', out[0].type === 'error', text(out));
}
{
    const { mod, out } = scenario({});
    runCmd(mod, 'sed', ['s/a/b/']);
    check('sed no operand errors', out[0].type === 'error', text(out));
}

console.log('');
console.log(`${pass} passed, ${fail} failed`);
process.exit(fail ? 1 : 0);