// Test runner. Every `tests/*_test.js` file is discovered automatically and run
// as a suite. By default the files are farmed out across a pool of worker
// processes, so the whole run is bounded by the slowest file rather than their
// sum. A single file can be run in-process for debugging.
//
//     node tests/run_tests.js             # all files, parallel
//     node tests/run_tests.js --jobs 4    # cap the worker pool
//     node tests/run_tests.js --file map_view_test.js
//
// In worker mode (`--file`) the file's exported TestCase classes are run and a
// single machine-readable result line is printed for the parent to collect.

import { readdirSync } from "node:fs";
import { spawn } from "node:child_process";
import { fileURLToPath } from "node:url";
import { dirname } from "node:path";
import { cpus } from "node:os";

const HERE = dirname(fileURLToPath(import.meta.url));
const SELF = fileURLToPath(import.meta.url);
const RESULT_MARKER = "__TEST_RESULT__";
const MAX_JOBS = 8;

function flagValue(args, flag) {
  const inline = args.find((arg) => arg.startsWith(`${flag}=`));
  if (inline) return inline.slice(flag.length + 1);
  const index = args.indexOf(flag);
  return index >= 0 ? args[index + 1] : null;
}

// Every test file in this directory, in a stable order.
function discoverFiles() {
  return readdirSync(HERE)
    .filter((name) => name.endsWith("_test.js"))
    .sort();
}

// The TestCase classes a module exports, with their sorted test methods. Using
// the exports rather than a hand-written list means a new test file is picked
// up with no runner edit.
function testClasses(module) {
  const classes = [];
  for (const value of Object.values(module)) {
    if (typeof value !== "function" || !value.prototype) continue;
    const methods = Object.getOwnPropertyNames(value.prototype)
      .filter((name) => name.startsWith("test_") && name !== "constructor")
      .sort();
    if (methods.length > 0) classes.push({ ctor: value, methods });
  }
  return classes;
}

async function runFile(file) {
  const started = Date.now();
  const module = await import(new URL(file, import.meta.url));
  let passed = 0;
  const failures = [];
  for (const { ctor, methods } of testClasses(module)) {
    for (const method of methods) {
      const instance = new ctor();
      try {
        await instance[method]();
        passed += 1;
      } catch (error) {
        failures.push(`${ctor.name}::${method}: ${error.message}`);
      }
    }
  }
  return { file, passed, failures, ms: Date.now() - started };
}

// Worker mode: run one file, then exit. When spawned by the parent it prints a
// machine-readable marker; run by hand it prints the usual summary. The write
// callback guarantees output reaches the parent before the process ends.
async function runWorker(file) {
  const result = await runFile(file);
  const code = result.failures.length === 0 ? 0 : 1;
  if (process.env.TISMO_WORKER === "1") {
    const line = `\n${RESULT_MARKER}${JSON.stringify(result)}\n`;
    process.stdout.write(line, () => process.exit(code));
    return;
  }
  console.log("");
  if (result.failures.length === 0) console.log(`PASS: ${result.passed} test(s) passed.`);
  else {
    console.log(`FAIL: ${result.passed} passed, ${result.failures.length} failed.`);
    for (const failure of result.failures) console.log(`  - ${failure}`);
  }
  process.exit(code);
}

function runChild(file) {
  return new Promise((resolve) => {
    const started = Date.now();
    const child = spawn(process.execPath, [SELF, "--file", file], {
      stdio: ["ignore", "pipe", "pipe"],
      env: { ...process.env, TISMO_WORKER: "1" },
    });
    let out = "";
    let err = "";
    child.stdout.on("data", (chunk) => (out += chunk));
    child.stderr.on("data", (chunk) => (err += chunk));
    child.on("close", (code) => {
      const index = out.lastIndexOf(RESULT_MARKER);
      if (index >= 0) {
        const line = out.slice(index + RESULT_MARKER.length).split("\n")[0];
        try {
          resolve(JSON.parse(line));
          return;
        } catch {
          // fall through to the failure record below
        }
      }
      resolve({
        file,
        passed: 0,
        failures: [`${file}: worker produced no result (exit ${code}) ${err.trim()}`],
        ms: Date.now() - started,
      });
    });
  });
}

// Runs `worker` over `items`, never more than `jobs` at a time. Results keep
// their input order so the summary is deterministic.
async function pool(items, jobs, worker) {
  const results = new Array(items.length);
  let next = 0;
  const run = async () => {
    while (next < items.length) {
      const index = next;
      next += 1;
      results[index] = await worker(items[index]);
    }
  };
  await Promise.all(Array.from({ length: Math.min(jobs, items.length) }, run));
  return results;
}

async function main() {
  const args = process.argv.slice(2);
  const fileArg = flagValue(args, "--file");
  if (fileArg) {
    await runWorker(fileArg);
    return;
  }

  const requested = Number(flagValue(args, "--jobs")) || cpus().length;
  const jobs = Math.max(1, Math.min(requested, MAX_JOBS));
  const files = discoverFiles();
  const results = await pool(files, jobs, runChild);

  let passed = 0;
  const failures = [];
  for (const result of results) {
    passed += result.passed;
    failures.push(...result.failures);
  }

  console.log("");
  for (const result of results.slice().sort((a, b) => b.ms - a.ms)) {
    const seconds = (result.ms / 1000).toFixed(1).padStart(5);
    const status = result.failures.length === 0 ? "ok  " : "FAIL";
    console.log(`${status} ${seconds}s  ${result.file}`);
  }
  console.log("");
  if (failures.length === 0) {
    console.log(`PASS: ${passed} test(s) passed.`);
    process.exit(0);
  }
  console.log(`FAIL: ${passed} passed, ${failures.length} failed.`);
  for (const failure of failures) console.log(`  - ${failure}`);
  process.exit(1);
}

main();