/**
 * Copyright 2018-present Facebook.
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 * @format
 */

const path = require('path');
const fs = require('fs');
const Metro = require('metro');
const util = require('util');
const recursiveReaddir = require('recursive-readdir');
const HOME_DIR = require('os').homedir();

module.exports = async (reloadCallback, pluginPaths, pluginCache) => {
  const plugins = pluginEntryPoints(pluginPaths);
  if (!fs.existsSync(pluginCache)) {
    fs.mkdirSync(pluginCache);
  }
  watchChanges(plugins, reloadCallback, pluginCache);
  const dynamicPlugins = [];
  for (let plugin of Object.values(plugins)) {
    const compiledPlugin = await compilePlugin(plugin, false, pluginCache);
    if (compiledPlugin) {
      dynamicPlugins.push(compiledPlugin);
    }
  }
  console.log('✅  Compiled all plugins.');
  return dynamicPlugins;
};

function watchChanges(plugins, reloadCallback, pluginCache) {
  // eslint-disable-next-line no-console
  console.log('🕵️‍  Watching for plugin changes');

  Object.values(plugins).map(plugin =>
    fs.watch(plugin.rootDir, (eventType, filename) => {
      // eslint-disable-next-line no-console
      console.log(`🕵️‍  Detected changes in ${plugin.name}`);
      compilePlugin(plugin, true, pluginCache).then(reloadCallback);
    }),
  );
}
function hash(string) {
  let hash = 0;
  if (string.length === 0) {
    return hash;
  }
  let chr;
  for (let i = 0; i < string.length; i++) {
    chr = string.charCodeAt(i);
    hash = (hash << 5) - hash + chr;
    hash |= 0;
  }
  return hash;
}
const fileToIdMap = new Map();
const createModuleIdFactory = () => filePath => {
  if (filePath === '__prelude__') {
    return 0;
  }
  let id = fileToIdMap.get(filePath);
  if (typeof id !== 'number') {
    id = hash(filePath);
    fileToIdMap.set(filePath, id);
  }
  return id;
};
function pluginEntryPoints(additionalPaths = []) {
  const defaultPluginPath = path.join(HOME_DIR, '.flipper', 'node_modules');
  const entryPoints = entryPointForPluginFolder(defaultPluginPath);
  if (typeof additionalPaths === 'string') {
    additionalPaths = [additionalPaths];
  }
  additionalPaths.forEach(additionalPath => {
    const additionalPlugins = entryPointForPluginFolder(additionalPath);
    Object.keys(additionalPlugins).forEach(key => {
      entryPoints[key] = additionalPlugins[key];
    });
  });
  return entryPoints;
}
function entryPointForPluginFolder(pluginPath) {
  pluginPath = pluginPath.replace('~', HOME_DIR);
  if (!fs.existsSync(pluginPath)) {
    return {};
  }
  return fs
    .readdirSync(pluginPath)
    .filter(name =>
      /*name.startsWith('flipper-plugin') && */ fs
        .lstatSync(path.join(pluginPath, name))
        .isDirectory(),
    )
    .filter(Boolean)
    .map(name => {
      let packageJSON;
      try {
        packageJSON = fs
          .readFileSync(path.join(pluginPath, name, 'package.json'))
          .toString();
      } catch (e) {}
      if (packageJSON) {
        try {
          const pkg = JSON.parse(packageJSON);
          return {
            packageJSON: pkg,
            name: pkg.name,
            entry: path.join(pluginPath, name, pkg.main || 'index.js'),
            rootDir: path.join(pluginPath, name),
          };
        } catch (e) {
          console.error(
            `Could not load plugin "${pluginPath}", because package.json is invalid.`,
          );
          console.error(e);
          return null;
        }
      }
    })
    .filter(Boolean)
    .reduce((acc, cv) => {
      acc[cv.name] = cv;
      return acc;
    }, {});
}
function mostRecentlyChanged(dir) {
  return util
    .promisify(recursiveReaddir)(dir)
    .then(files =>
      files
        .map(f => fs.lstatSync(f).ctime)
        .reduce((a, b) => (a > b ? a : b), new Date(0)),
    );
}
async function compilePlugin(
  {rootDir, name, entry, packageJSON},
  force,
  pluginCache,
) {
  const fileName = `${name}@${packageJSON.version || '0.0.0'}.js`;
  const out = path.join(pluginCache, fileName);
  const result = Object.assign({}, packageJSON, {rootDir, name, entry, out});
  // check if plugin needs to be compiled
  const rootDirCtime = await mostRecentlyChanged(rootDir);
  if (!force && fs.existsSync(out) && rootDirCtime < fs.lstatSync(out).ctime) {
    // eslint-disable-next-line no-console
    console.log(`🥫  Using cached version of ${name}...`);
    return result;
  } else {
    console.log(`⚙️  Compiling ${name}...`); // eslint-disable-line no-console
    try {
      await Metro.runBuild(
        {
          reporter: {update: () => {}},
          projectRoot: rootDir,
          watchFolders: [__dirname, rootDir],
          serializer: {
            getRunModuleStatement: moduleID =>
              `module.exports = global.__r(${moduleID}).default;`,
            createModuleIdFactory,
          },
          transformer: {
            babelTransformerPath: path.join(
              __dirname,
              'transforms',
              'index.js',
            ),
          },
        },
        {
          entry: entry.replace(rootDir, '.'),
          out,
          dev: false,
          sourceMap: true,
          // due to a bug in metro inline source maps are only created when
          // sourceMapUrl is truthy: https://github.com/facebook/metro/pull/260
          sourceMapUrl: 'inline',
        },
      );
    } catch (e) {
      console.error(
        `❌  Plugin ${name} is ignored, because it could not be compiled.`,
      );
      console.error(e);
      return null;
    }
    return result;
  }
}