import * as fs from 'fs';
import ConfigFileMissingError from '../errors/config_file_missing.error';
import ConfigProfileError from '../errors/config_profile_missing.error';
import ConfigFileFormatError from '../errors/config_file_format.error';
import Config004 from './config.0.0.4';

const HOME = require('os').homedir();
const CONFIG_FILE_NAME = '.telmeconfig';
const FILEPATH = `${HOME}/${CONFIG_FILE_NAME}`;

let singleton = null;

export enum EConfigVersions {
  V004 = '0.0.4',
  V010 = '0.1.0'
}

const CURRENT_CONFIG_VERSION = EConfigVersions.V010;

export default class Config {
  static APP_NAME = 'telme';
  static CURRENT_CONFIG_VERSION = CURRENT_CONFIG_VERSION;
  static DEFAULT_TASK_MESSAGE_TEMPLATE = '*Task:*\n\n```sh\n%cmd%\n```\nHas finished.\n*Errors*:\n %errors%';
  private config: IConfig;
  static cliInit() {
    singleton = new Config();
  }
  constructor() {
    const file = this.readConfigFile();
    const parsed = this.parseConfig(file);
    if (parsed.originalConfigVersion != CURRENT_CONFIG_VERSION) {
      this.writeConfigToFile(parsed.config);
    }
    this.config = parsed.config;
  }
  static getConfig(profile: string = 'default'): ITaskConfig {
    return singleton.getConfig(profile);
  }

  static generateProfileTemplate(): ITaskConfig {
    return {
      chat_id: null,
      task_message_template: Config.DEFAULT_TASK_MESSAGE_TEMPLATE,
      bot_token: null
    }
  }

  static getFullConfig(): IConfig {
    return singleton.config;
  }

  static async writeConfigToFile(config: IConfig) {
    return singleton.writeConfigToFile(config);
  }

  private getConfig(profile: string): ITaskConfig {
    if (!this.config.profiles[profile]) {
      throw new ConfigProfileError(`No profile named ${profile} found.`);
    }
    return this.config.profiles[profile];
  }

  private readConfigFile(): Buffer {
    try {
      const file = fs.readFileSync(FILEPATH);
      return file;
    } catch (e) {
      return Buffer.from(JSON.stringify(EMPTY_CONFIG));
    }
  }

  private parseConfig(file: Buffer): { config: IConfig, originalConfigVersion: EConfigVersions } {
    try {
      const config = JSON.parse(file.toString());
      const confVersion: EConfigVersions = config.version || EConfigVersions.V004;
      switch (confVersion) {
        case EConfigVersions.V004:
          return { config: Config004.parse(config), originalConfigVersion: EConfigVersions.V004 };
        // Using switch to easily add more config version. If needed...
        default:
          return { config, originalConfigVersion: config.version };
      }
    } catch (e) {
      throw new ConfigFileFormatError('Invalid JSON format in config file. If you modified the file yourself, please double check your modifications');
    }
  }

  private writeConfigToFile(config: IConfig): boolean {
    try {
      fs.writeFileSync(FILEPATH, JSON.stringify(config, null, 2));
      console.log(`✅ created config file at ${FILEPATH}`);
      return true;
    } catch (e) {
      return false;
    }
  }
}

const EMPTY_CONFIG: IConfig = {
  version: CURRENT_CONFIG_VERSION,
  profiles: {}
}
export interface IMessageConfig {
  chat_id: string;
  bot_token: string;
}
export interface ITaskConfig extends IMessageConfig {
  task_message_template: string;
}

export interface IConfig {
  version: EConfigVersions,
  profiles: {
    [key: string]: ITaskConfig;
  }
}