#!/usr/bin/env node

'use strict'

var fs = require('fs')

var stdin = require('get-stdin')
var eccrypto = require('eccrypto')

var command = process.argv[0]
var script = process.argv[1]
var private_key = process.argv[2]
var iv = process.argv[3]
var ephem = process.argv[4]
var mac = process.argv[5]
var cipher = process.argv[6]

var pk, m

function d(private_key, message) {
  eccrypto.decrypt(private_key, message).then(function(decrypted) {
    process.stdout.write(JSON.stringify({
      decrypted: decrypted.toString('hex')
    }), function() {
      process.exit(0)
    })
  }).catch(function(err) {
    process.stdout.write(JSON.stringify({
      eccrypto_error: JSON.stringify(err)
    }))
    process.exit(1)
  })
}

if (!(private_key && iv && ephem && mac)) {
  process.stdout.write(JSON.stringify({
    error: 'private key, iv, ephem or mac not given'
  }))
  process.exit(1)
}

try {
  pk = Buffer(private_key, 'hex')
  m = {
    iv: Buffer(iv, 'hex'),
    ephemPublicKey: Buffer(ephem, 'hex'),
    mac: Buffer(mac, 'hex')
  }
} catch (err) {
  process.stdout.write(JSON.stringify({
    error: 'private key, iv, ephem, or mac is not hexadecimal'
  }))
  process.exit(1)
}

stdin.buffer().then(function(s) {
  if (s.length) {
    m.ciphertext = Buffer(s.toString().trim(), 'hex')
    d(pk, m)
  } else if (!cipher) {
    process.stdout.write(JSON.stringify({
      error: 'cipher not given'
    }))
    process.exit(1)
  } else {
    fs.readFile(cipher, function(err, buffer) {
      if (buffer && buffer.length) {
        m.ciphertext = Buffer(buffer.toString().trim(), 'hex')
        d(pk, m)
      } else if (err && cipher.length) {
        try {
          m.ciphertext = Buffer(cipher, 'hex')
          d(pk, m)
        } catch (err) {
          process.stdout.write(JSON.stringify({
            error: 'cipher is not hexadecimal'
          }))
          process.exit(1)
        }
      } else {
        process.exit(1)
      }
    })
  }
})