/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 */

import Watchman from './watchman';
import {getPluginSourceFolders, isPluginDir} from 'flipper-plugin-lib';
import path from 'path';
import chalk from 'chalk';
import {rebuildPlugin} from './build-utils';

export default async function startWatchPlugins(
  onChanged?: () => void | Promise<void>,
) {
  // eslint-disable-next-line no-console
  console.log('🕵️‍  Watching for plugin changes');

  let delayedCompilation: NodeJS.Timeout | undefined;
  const kCompilationDelayMillis = 1000;
  const onPluginChangeDetected = (root: string, files: string[]) => {
    if (!delayedCompilation) {
      delayedCompilation = setTimeout(async () => {
        delayedCompilation = undefined;
        // eslint-disable-next-line no-console
        console.log(`🕵️‍  Detected plugin change`);
        await Promise.all(
          // https://facebook.github.io/watchman/docs/nodejs.html#subscribing-to-changes
          files.map(async (file: string) => {
            const filePathAbs = path.resolve(root, file);
            let dirPath = path.dirname(filePathAbs);
            while (
              // Stop when we reach plugin root
              !(await isPluginDir(dirPath))
            ) {
              const relative = path.relative(root, dirPath);
              // Stop when we reach desktop/plugins folder
              if (!relative || relative.startsWith('..')) {
                console.warn(
                  chalk.yellow('Failed to find a plugin root for path'),
                  filePathAbs,
                );
                return;
              }
              dirPath = path.resolve(dirPath, '..');
            }
            await rebuildPlugin(dirPath);
          }),
        );
        onChanged?.();
      }, kCompilationDelayMillis);
    }
  };
  try {
    await startWatchingPluginsUsingWatchman(onPluginChangeDetected);
  } catch (err) {
    console.error(
      'Failed to start watching plugin files using Watchman, continue without hot reloading',
      err,
    );
  }
}

async function startWatchingPluginsUsingWatchman(
  onChange: (root: string, files: string[]) => void,
) {
  const pluginFolders = await getPluginSourceFolders();
  await Promise.all(
    pluginFolders.map(async (pluginFolder) => {
      const watchman = new Watchman(pluginFolder);
      await watchman.initialize();
      await watchman.startWatchFiles(
        '.',
        ({files}) => onChange(pluginFolder, files),
        {
          excludes: [
            '**/__tests__/**/*',
            '**/node_modules/**/*',
            '**/dist/*',
            '**/.*',
          ],
        },
      );
    }),
  );
}