import * as fs from 'fs-extra';
import * as path from 'path';

import { IEnvironment } from '../types/environment';
import { IPluginManifest } from './plugin';

import { logger } from '../core';

/**
 * Plugin manifest loader
 */
export class PluginMetaLoader {
  constructor(private env: IEnvironment) {}

  /**
   * Load a plugin manifest by plugin name.
   * @param name Plugin name
   * @returns Plugin manifest
   */
  public async load(name: string): Promise<IPluginManifest> {
    if (name === 'squeebot') {
      throw new Error('Illegal name.');
    }

    const fullpath = path.join(this.env.pluginsPath, name);
    const metapath = path.join(fullpath, 'plugin.json');
    if (!await fs.pathExists(metapath)) {
      throw new Error('Not a plugin directory.');
    }

    // Read the metadata
    const json = await fs.readJson(metapath);

    // Mandatory fields
    if (!json.name) {
      throw new Error('Plugin metadata does not specify a name, for some reason');
    }

    if (json.name === 'squeebot' || !(/^[a-zA-Z0-9_\-]+$/.test(json.name))) {
      throw new Error('Illegal name.');
    }

    if (!json.version) {
      throw new Error('Plugin metadata does not specify a version, for some reason');
    }

    // Ensure main file exists
    if (!json.main) {
      json.main = 'plugin.js';
    }

    const mainfile = path.resolve(fullpath, json.main);
    if (!await fs.pathExists(mainfile)) {
      throw new Error('Plugin does not have a main file or it is misconfigured.');
    }

    json.fullPath = fullpath;
    json.main = mainfile;

    if (!json.dependencies) {
      json.dependencies = [];
    }

    if (!json.npmDependencies) {
      json.npmDependencies = [];
    }

    return json;
  }

  /**
   * Load all plugin manifests from files.
   * @param ignoreErrors Ignore loading errors instead of throwing them
   * @returns List of plugin manifests ready to be loaded
   */
  public async loadAll(ignoreErrors = false): Promise<IPluginManifest[]> {
    const dirlist = await fs.readdir(this.env.pluginsPath);
    const plugins: IPluginManifest[] = [];
    for (const file of dirlist) {
      // Ignore hidden files and non-directories
      const fpath = path.join(this.env.pluginsPath, file);
      if (file.indexOf('.') === 0 ||
        file === 'node_modules' ||
        !(await fs.lstat(fpath)).isDirectory()) {
        continue;
      }

      try {
        const plugin = await this.load(file);
        plugins.push(plugin);
      } catch (e) {
        if (ignoreErrors) {
          continue;
        }
        logger.error(e);
      }
    }
    return plugins;
  }
}