import {
  isDepExists,
  createDebugger,
  compatRequire,
  INTERNAL_PLUGINS,
} from '@modern-js/utils';

const debug = createDebugger('load-plugins');

export interface PluginConfigItem {
  cli?: string;
  server?: string;
}

export type PluginConfig = Array<PluginConfigItem>;

/**
 * Try to resolve plugin entry file path.
 * @param appDirectory - Application root directory.
 * @param plugin - Plugin name or plugin name with options.
 * @returns Resolved file path.
 */
const resolvePlugin = (appDirectory: string, plugin: PluginConfigItem) => {
  const tryResolve = (name: string) => {
    let filePath = '';
    try {
      filePath = require.resolve(name, { paths: [appDirectory] });
      delete require.cache[filePath];
    } catch (err) {
      if ((err as any).code === 'MODULE_NOT_FOUND') {
        throw new Error(`Can not find plugin ${name}.`);
      }
      throw err;
    }
    return filePath;
  };

  const resolved: PluginConfigItem = {};

  if (typeof plugin === 'string' || plugin.cli) {
    resolved.cli =
      typeof plugin === 'string' ? tryResolve(plugin) : tryResolve(plugin.cli!);
  }

  if (plugin.server) {
    resolved.server = tryResolve(plugin.server);
  }

  return resolved;
};

/**
 * Load internal plugins which in @modern-js scope and user's custom plugins.
 * @param appDirectory - Application root directory.
 * @param pluginsConfig - Plugins declared in the user configuration.
 * @returns Plugin Objects has been required.
 */
export const loadPlugins = (
  appDirectory: string,
  pluginConfig: PluginConfig,
  internalPlugins?: typeof INTERNAL_PLUGINS,
) => {
  const plugins = [
    ...Object.keys(internalPlugins || INTERNAL_PLUGINS)
      .filter(name => isDepExists(appDirectory, name))
      .map(name => (internalPlugins || INTERNAL_PLUGINS)[name]),
    ...pluginConfig,
  ];

  return plugins.map(plugin => {
    const { cli, server } = resolvePlugin(appDirectory, plugin);

    debug(`resolve plugin %s: %s`, plugin, {
      cli,
      server,
    });

    return {
      cli: cli && compatRequire(cli),
      server: server && compatRequire(server),
    };
  });
};