#!/usr/bin/env node

const repl = require('repl');
const crypto = require('crypto');

const replOptions = { prompt: '> ', useColors: true };
const replServer = repl.start(replOptions);


const getSignatureKey = ({
  key,
  secret,
  environment,
}) => {
  const kKey = crypto.createHmac('sha256', key).digest();
  const kSecret = crypto.createHmac('sha256', kKey).update(secret).digest();
  const kSigning = crypto.createHmac('sha256', kSecret).update(environment).digest();

  return kSigning;
};

const generateSignature = ({ key = '', secret = '', environment = '' }) => {
  const signingKey = getSignatureKey({
    key,
    secret,
    environment,
  });

  return crypto.createHmac('sha256', signingKey).digest('hex');
};


function initializeContext (context) {
  context.key = null;
  context.secret = null;
  context.environment = 'dev';
}

initializeContext(replServer.context);

replServer.on('exit', () => {
  console.log('\x1b[33m%s\x1b[0m', 'Received "exit" event from repl!');
  process.exit();
});

replServer.defineCommand('reset', {
  help: 'Reset repl',
  action() {
    initializeContext(this.context);
    this.displayPrompt();
  },
});

replServer.defineCommand('secret', {
  help: 'Type "secret" to set SECRET',
  async action(value) {
    this.context.secret = value;

    this.displayPrompt();
  },
});

replServer.defineCommand('key', {
  help: 'Type "key" to set KEY',
  async action(value) {
    this.context.key = value;

    this.displayPrompt()
  },
});

replServer.defineCommand('env', {
  help: 'Type "env" to set ENVIRONMENT, default "dev"',
  async action(value) {
    this.context.environment = value;

    this.displayPrompt();
  },
});

replServer.defineCommand('generate', {
  help: 'Type "generate" to generate signature by given values',
  action() {
    if (!this.context.secret || !this.context.key) {
      console.log('\x1b[41m%s\x1b[0m', 'key or secret was not set');
    } else {
      const signature = generateSignature(this.context);
      console.log('Signature generated: ', signature);
    }

    this.displayPrompt();
  },
});

replServer.defineCommand('help', {
  help: 'HELP',
  action() {
    console.log('Type .secret to set SECRET. EXAMPLE: .secret SECRET');
    console.log('Type .key to set KEY. EXAMPLE: .key KEY');
    console.log('Type .env to set ENVIRONMENT. EXAMPLE: .env ENVIRONMENT');
    console.log('Type .generate to get signature. EXAMPLE: .generate');
    console.log('Type .reset to reset all values and start again. EXAMPLE: .reset');
    console.log('Type .exit to close prompt. EXAMPLE: .exit');

    this.displayPrompt();
  },
});