const fs = require("node:fs");
const path = require("node:path");
const http = require("node:http");
const { spawn } = require("node:child_process");

// Pins on the CI workflow and on what the boot check assumes of the Dockerfile.
// The runtime stays 0-dependency and vitest ships no YAML parser, so these read
// the files with narrow regexes: each one looks at a single key, never at the
// YAML structure as a whole.

const ROOT = path.join(__dirname, "..");
const CI_PATH = path.join(ROOT, ".forgejo", "workflows", "ci.yml");
const ci = fs.readFileSync(CI_PATH, "utf-8");
const dockerfile = fs.readFileSync(path.join(ROOT, "Dockerfile"), "utf-8");

// Comment lines stripped, so an explanation that quotes a key cannot satisfy
// (or break) a pin.
const ciCode = ci
  .split("\n")
  .filter((line) => !/^\s*#/.test(line))
  .join("\n");

// Lines of a top-level-indented block (`  pull_request:`), up to the next key at
// the same or a lower indentation.
function block(text, key) {
  const lines = text.split("\n");
  const start = lines.findIndex((l) => new RegExp(`^(\\s*)${key}:`).test(l));
  if (start === -1) return null;
  const indent = lines[start].match(/^(\s*)/)[1].length;
  const out = [lines[start]];
  for (const line of lines.slice(start + 1)) {
    if (line.trim() === "") continue;
    if (line.match(/^(\s*)/)[1].length <= indent) break;
    out.push(line);
  }
  return out.join("\n");
}

describe("CI workflow", () => {
  test("runs in the Dockerfile's own base image", () => {
    const from = dockerfile.match(/^\s*FROM\s+(\S+)/m);
    const container = ciCode.match(/^\s*container:\s*["']?([^"'\s]+)["']?\s*$/m);

    expect(from).not.toBeNull();
    expect(container).not.toBeNull();
    expect(container[1]).toBe(from[1]);
  });

  test("runs the unit tests, the socket pass and the boot check", () => {
    expect(ciCode).toMatch(/^\s*run:\s*npm ci\s*$/m);
    expect(ciCode).toMatch(/^\s*run:\s*npm test\s*$/m);
    expect(ciCode).toMatch(/^\s*run:\s*bash test-curl\.sh\s*$/m);
    expect(ciCode).toMatch(/^\s*run:\s*sh scripts\/boot-from-copy\.sh\s*$/m);
  });

  test("builds every pull request, whatever branch it targets", () => {
    // A `branches: [main]` here would leave the intermediate links of a stack
    // without any status.
    const pr = block(ciCode, "pull_request");

    expect(pr).not.toBeNull();
    expect(pr).not.toMatch(/branches(-ignore)?:/);
  });

  test("builds pushes to main", () => {
    const push = block(ciCode, "push");

    expect(push).not.toBeNull();
    expect(push).toMatch(/branches:\s*\[\s*main\s*\]/);
  });

  test("avoids the two forms the runner rejects before the first command", () => {
    // `defaults:` anywhere, and `working-directory` on a `uses:` step.
    expect(ciCode).not.toMatch(/^\s*defaults:/m);
    const steps = ciCode.split(/^\s*- (?=name:|uses:|run:)/m);
    for (const step of steps) {
      if (/^\s*uses:|\n\s*uses:/.test(step)) expect(step).not.toMatch(/working-directory:/);
    }
  });
  test("never lets a failing step pass", () => {
    // `continue-on-error: true` turns a red step green without a trace in the
    // commit status. Anchored on the key position, so only a real key counts.
    expect(ciCode).not.toMatch(/^\s*(- )?continue-on-error\s*:/m);
  });
});

describe("what the boot check assumes of the Dockerfile", () => {
  test("the image still drops to the node user, as the script does", () => {
    expect(dockerfile).toMatch(/^\s*USER\s+node\s*$/m);
  });

  test("CMD is in exec form, the only one the script parses", () => {
    const cmd = dockerfile.match(/^\s*CMD\s+(.+)$/m);

    expect(cmd).not.toBeNull();
    const argv = JSON.parse(cmd[1]);
    expect(Array.isArray(argv)).toBe(true);
    expect(argv.length).toBeGreaterThan(0);
  });
});

// Spawns a command from the repository root with `env` over the test's own
// environment; a key set to undefined is dropped (spawn ignores undefined
// values). Async, so a listener in this process keeps answering meanwhile.
function run(command, args, env) {
  return new Promise((resolve, reject) => {
    const child = spawn(command, args, { cwd: ROOT, env: { ...process.env, ...env } });
    let stderr = "";
    child.stderr.on("data", (d) => (stderr += d));
    child.on("error", reject);
    child.on("close", (code) => resolve({ code, stderr }));
  });
}

const runBootScript = (env) => run("sh", ["scripts/boot-from-copy.sh"], env);

// A port nothing listens on. The probe closes before the script starts: should
// something take the port in between, the script's own check refuses it and
// the test fails loudly.
async function freePort() {
  const probe = http.createServer();
  await new Promise((resolve) => probe.listen(0, "127.0.0.1", resolve));
  const { port } = probe.address();
  await new Promise((resolve) => probe.close(resolve));
  return port;
}

describe("boot-from-copy.sh", () => {
  // A listener already on the port: without the pre-check, the wait loop could
  // reach this neighbour and assert on a server it never started.
  test("refuses a port something else already holds", async () => {
    const neighbour = http.createServer((req, res) => res.end("not the API"));
    await new Promise((resolve) => neighbour.listen(0, "127.0.0.1", resolve));
    try {
      const { port } = neighbour.address();
      const { code, stderr } = await runBootScript({ BOOT_PORT: String(port) });

      expect(code).toBe(1);
      expect(stderr).toMatch(new RegExp(`port ${port} is already taken`));
    } finally {
      await new Promise((resolve) => neighbour.close(resolve));
    }
  }, 15000);

  // Every curl of the script targets the loopback, and a proxy from the
  // environment would answer in the server's place. Before #35 only the port
  // check had --noproxy: the wait loop and the assertions reached the proxy.
  test("never sends a request through a proxy from the environment", async () => {
    // Answers everything, as a real proxy would, and records what reaches it.
    const proxied = [];
    const proxy = http.createServer((req, res) => {
      proxied.push(`${req.method} ${req.url}`);
      res.end("answered by the proxy");
    });
    await new Promise((resolve) => proxy.listen(0, "127.0.0.1", resolve));
    try {
      const proxyUrl = `http://127.0.0.1:${proxy.address().port}`;
      // ALL_PROXY as well, so that unsetting http_proxy alone would not pass.
      // An inherited NO_PROXY would hide the defect, hence dropped.
      const env = { http_proxy: proxyUrl, ALL_PROXY: proxyUrl, NO_PROXY: undefined, no_proxy: undefined };
      const port = await freePort();

      // The proxy is live: a bare curl with the same environment reaches it.
      // Without this, "nothing reached the proxy" could pass for nothing.
      await run("curl", ["-s", "-o", "/dev/null", "--max-time", "5", `http://127.0.0.1:${port}/`], env);
      expect(proxied).toEqual([`GET http://127.0.0.1:${port}/`]);
      proxied.length = 0;

      const { code, stderr } = await runBootScript({ ...env, BOOT_PORT: String(port) });

      expect(proxied).toEqual([]);
      expect(code, stderr).toBe(0);
    } finally {
      await new Promise((resolve) => proxy.close(resolve));
    }
  }, 20000);
});

// The boot check only calls /health, so it proves the existence of the modules
// loaded at startup, nothing more. A require inside a route handler would load
// only when that route runs and escape it. Heuristic stand-in for "loaded at
// startup": every require starts at column 0 (a top-level statement), and there
// is no dynamic import. Comment lines are skipped, so an explanation quoting
// require( cannot break the pin.
describe("runtime modules are all loaded at startup", () => {
  const copyLine = dockerfile.match(/^\s*COPY\s+(.+)$/m);
  const sources = copyLine ? copyLine[1].trim().split(/\s+/).slice(0, -1) : [];
  const runtimeJs = sources.filter((f) => f.endsWith(".js"));

  test("the COPY line lists runtime modules", () => {
    expect(runtimeJs.length).toBeGreaterThan(0);
  });

  test.each(runtimeJs)("%s requires only at module level", (file) => {
    const lines = fs.readFileSync(path.join(ROOT, file), "utf-8").split("\n");
    const offenders = [];
    lines.forEach((line, i) => {
      if (/^\s*(\/\/|\/?\*)/.test(line)) return;
      if (/\brequire\(/.test(line) && /^\s/.test(line)) offenders.push(`${file}:${i + 1}: ${line.trim()}`);
      if (/\bimport\(/.test(line)) offenders.push(`${file}:${i + 1}: ${line.trim()}`);
    });

    expect(offenders).toEqual([]);
  });
});