// Record an aggregation corpus by asking a real mongod what the answer is.
//
// `mongodb/specifications` has no aggregation suite (see PLAN amendment A6), so
// M2.5 has to bring its own. The one thing a corpus we author must not do is
// encode our own bugs as expectations -- so the *inputs* are authored here and
// the *expectations* are measured, the same discipline that corrected three
// assumptions in M1's session work and every error code in M2.
//
//   1. author `sources/<name>.json`: documents, and a list of pipelines
//   2. run this against a real mongod
//   3. it writes `<name>.json` in the unified format, expectations filled in
//   4. `node tests/spec/run.js --suite-dir tests/spec/aggregate` runs it
//
// Generated files are committed: they are the corpus, and regenerating them is
// how a disagreement with mongod gets re-measured rather than argued about.
//
//   node tests/spec/aggregate/record.js --mongod-port 27099
//
// Options:
//   --mongod-port <n>  a running mongod to measure against (default 27099)
//   --only <name>      record just one source file
const fs = require('fs');
const path = require('path');
// The same pinned driver `run.js` uses, resolved the same way: there is one
// lockfile in this repo and it lives with the e2e suites.
const { MongoClient } = require(path.join(__dirname, '..', '..', 'e2e', 'node_modules', 'mongodb'));

const argv = process.argv.slice(2);
function opt(name, dflt) {
    const i = argv.indexOf('--' + name);
    if (i < 0) return dflt;
    const v = argv[i + 1];
    return v === undefined || v.startsWith('--') ? true : v;
}

const PORT = parseInt(opt('mongod-port', '27099'), 10);
const ONLY = opt('only', null);
const SRC_DIR = path.join(__dirname, 'sources');
const DB_NAME = 'aggregate-corpus';

// The corpus is run against a server that reports 4.4.0, so a case whose answer
// depends on a later server would be recorded from mongod 8.x and then judged
// against a 4.4 answer. Pinned here rather than per file: every case in this
// corpus is expected to be version-independent, and one that is not should be
// left out rather than annotated.
const SCHEMA_VERSION = '1.4';

async function main() {
    if (!fs.existsSync(SRC_DIR)) {
        console.error(`missing ${SRC_DIR}`);
        process.exit(2);
    }
    const client = new MongoClient(`mongodb://127.0.0.1:${PORT}`, { serverSelectionTimeoutMS: 3000 });
    try {
        await client.connect();
    } catch (e) {
        console.error(`no mongod on :${PORT} -- start one first:\n` +
            `  mongod --port ${PORT} --dbpath <dir>\n${e.message}`);
        process.exit(2);
    }
    const build = await client.db('admin').command({ buildInfo: 1 });
    console.log(`recording against mongod ${build.version} on :${PORT}`);

    const sources = fs.readdirSync(SRC_DIR).filter((f) => f.endsWith('.json'))
        .filter((f) => !ONLY || f === ONLY || f === ONLY + '.json')
        .sort();
    if (!sources.length) {
        console.error('no source files');
        process.exit(2);
    }

    for (const file of sources) {
        const src = JSON.parse(fs.readFileSync(path.join(SRC_DIR, file), 'utf8'));
        const name = path.basename(file, '.json');
        const out = await record(client, name, src);
        const target = path.join(__dirname, `${name}.json`);
        fs.writeFileSync(target, JSON.stringify(out, null, 2) + '\n');
        const errs = out.tests.filter((t) => t.operations[0].expectError).length;
        console.log(`  ${name}: ${out.tests.length} cases, ${errs} of them errors`);
    }
    await client.close();
    console.log('RECORDED');
}

async function record(client, name, src) {
    const db = client.db(DB_NAME);
    const coll = db.collection('coll');
    const tests = [];

    for (const c of src.cases) {
        await coll.drop().catch(() => {});
        await coll.insertMany(structuredClone(src.documents));

        const op = { object: 'collection0', name: 'aggregate', arguments: { pipeline: c.pipeline } };
        try {
            const got = await coll.aggregate(structuredClone(c.pipeline)).toArray();
            op.expectResult = got;
        } catch (e) {
            // The code, not the message: message text is mongod's to change
            // between releases, and a corpus that pins it would fail for the
            // wrong reason. `isError` plus the code is what the unified format
            // asserts anyway.
            op.expectError = { isError: true, errorCode: e.code };
        }
        tests.push({ description: c.description, operations: [op] });
    }
    await coll.drop().catch(() => {});

    return {
        description: name,
        schemaVersion: SCHEMA_VERSION,
        // Recorded, not authored. Regenerate with tests/spec/aggregate/record.js.
        createEntities: [
            { client: { id: 'client0' } },
            { database: { id: 'database0', client: 'client0', databaseName: DB_NAME } },
            { collection: { id: 'collection0', database: 'database0', collectionName: 'coll' } },
        ],
        initialData: [
            { collectionName: 'coll', databaseName: DB_NAME, documents: src.documents },
        ],
        tests,
    };
}

main().catch((e) => {
    console.error('RECORD_FAIL', e);
    process.exit(1);
});