import { spawn } from "child_process";
import path from "path";
import { setTimeout as sleep } from "timers/promises";

// Root `pnpm run dev` starts eager generators and package watch builds in
// parallel. `generate-openapi-docs:watch` intentionally runs `codegen-docs`
// once before starting chokidar, because chokidar only responds to future file
// changes. Without that initial run, dev docs could serve stale OpenAPI JSON
// from a previous branch, or no generated JSON at all after a clean checkout,
// until someone edits an API route.
//
// That eager OpenAPI generation imports backend modules, and some of those
// backend modules resolve workspace packages through their built `dist`
// entrypoints. Package watch scripts update those entrypoints with
// `tsdown --watch`, but on a cold checkout, after `pnpm clean`, or during the
// first package watcher build, the entrypoints may not exist yet even though
// `tsdown --watch` is about to create them.
//
// We keep this wait scoped to the eager generator rather than putting it in
// front of backend `dev`: the long-running Next dev server can tolerate package
// watchers warming up, while a one-shot generator exits immediately on a missing
// import and `concurrently -k` then tears down the whole dev command. Package
// watch scripts also avoid deleting `dist` in dev mode, which removes the
// common restart race; this probe covers the remaining cold-start case.
//
// This probe waits only for the package imports that the backend-side generator
// needs. It does not hide real runtime errors: we retry missing-module failures
// while package builds warm up, and fail immediately for other import failures.
//
// In addition to workspace packages, the probe checks that the generated Prisma
// client exists. When `turbo run dev` starts the backend, `codegen-prisma:watch`
// (`prisma generate --watch`) performs an initial generation that briefly removes
// and recreates `src/generated/prisma/`. If `codegen-docs` runs during that
// window it fails with ERR_MODULE_NOT_FOUND for `@/generated/prisma/client`.
const repoRoot = path.resolve(__dirname, "..");
const backendDir = path.join(repoRoot, "apps/backend");
const timeoutMs = 60_000;
const retryDelayMs = 1_000;

const probeScript = `
(async () => {
  await import('@hexclave/next');
  await import('@hexclave/shared/dist/utils/env');
  const { existsSync, readdirSync } = await import('node:fs');
  const { join } = await import('node:path');
  const generatedDir = join(process.cwd(), 'src', 'generated', 'prisma');
  if (!existsSync(generatedDir) || readdirSync(generatedDir).length === 0) {
    const err = new Error('ERR_MODULE_NOT_FOUND: Generated Prisma client not yet available at ' + generatedDir);
    throw err;
  }
})().then(
  () => undefined,
  (error) => {
    console.error(error);
    process.exit(1);
  },
);
`;

type ProbeResult = {
  exitCode: number | null,
  output: string,
};

function runProbe(): Promise<ProbeResult> {
  return new Promise((resolve, reject) => {
    const child = spawn("pnpm", ["exec", "tsx", "-e", probeScript], {
      cwd: backendDir,
      env: process.env,
      stdio: ["ignore", "pipe", "pipe"],
    });

    let output = "";

    child.stdout.setEncoding("utf8");
    child.stderr.setEncoding("utf8");
    child.stdout.on("data", (chunk: string) => {
      output += chunk;
    });
    child.stderr.on("data", (chunk: string) => {
      output += chunk;
    });

    child.on("error", reject);
    child.on("close", (exitCode) => {
      resolve({ exitCode, output });
    });
  });
}

function isMissingModuleError(output: string) {
  return output.includes("ERR_MODULE_NOT_FOUND") || output.includes("MODULE_NOT_FOUND");
}

async function main() {
  const start = performance.now();
  let lastOutput = "";
  let hasLoggedWait = false;
  let isReady = false;

  while (performance.now() - start < timeoutMs) {
    const result = await runProbe();
    if (result.exitCode === 0) {
      isReady = true;
      break;
    }

    lastOutput = result.output;
    if (!isMissingModuleError(result.output)) {
      throw new Error(`Dev package import probe failed with a non-retryable error:\n${result.output}`);
    }

    if (!hasLoggedWait) {
      console.log("Waiting for dev package entrypoints to be generated...");
      hasLoggedWait = true;
    }
    await sleep(retryDelayMs);
  }

  if (!isReady) {
    throw new Error(`Timed out waiting for dev package imports to become available. Last probe output:\n${lastOutput}`);
  }
}

main().then(
  () => undefined,
  (error) => {
    console.error(error);
    process.exit(1);
  },
);