import * as vm from 'vm';
import * as fs from 'fs';
import * as _ from 'lodash';
import {SystemConfig} from './models';

export function readConfig(cfgCode: string[]) {
  let cfg: any = {};
  let configFunc = (systemCfg: any) => {
    _.merge(cfg, systemCfg);
  };

  let sandbox = {
    System: {
      config: configFunc
    },
    SystemJS: {
      config: configFunc
    }
  };
  vm.createContext(sandbox);
  cfgCode.forEach(c => {
    vm.runInContext(c, sandbox);
  });

  return cfg as SystemConfig;
}

export function isSystemJS(cfgCode: string) {
  let res = false;
  let sandbox = {
    SystemJS: {
      config: () => {
        res = true;
      }
    },
    System: {
      config: () => {
        res = false;
      }
    }
  };
  vm.createContext(sandbox);
  vm.runInContext(cfgCode, sandbox);
  return res;
}

export function isSystem(cfgCode: string) {
  let res = false;
  let sandbox = {
    System: {
      config: () => {
        res = true;
      }
    },
    SystemJS: {
      config: () => {
        res = false;
      }
    }
  };
  vm.createContext(sandbox);
  vm.runInContext(cfgCode, sandbox);

  return res;
}

export function serializeConfig(config: SystemConfig, isSystemJS: boolean = false) {
  let tab = '  ';
  let json = JSON.stringify(config, null, 2)
    .replace(new RegExp('^' + tab + '"(\\w+)"', 'mg'), tab + '$1');

  if (isSystemJS) {
    return `SystemJS.config(${json});`;
  }
  return `System.config(${json});`;
}

export function getAppConfig(configPath: string | string[]) {
  let configCode: string[] = [];

  if (typeof configPath === 'string') {
    configCode.push(fs.readFileSync(configPath, 'utf8'));
  }

  if (Array.isArray(configPath)) {
    configPath.forEach(cp => {
      configCode.push(fs.readFileSync(cp, 'utf8'));
    });
  }

  let appCfg = readConfig(configCode);

  if (!appCfg.map) {
    appCfg.map = {};
  }
  return appCfg;
}

export function saveAppConfig(configPath: string, config: SystemConfig) {
  fs.writeFileSync(configPath, serializeConfig(config, isSystemJS(fs.readFileSync(configPath, 'utf8'))));
}