var crypto = require('crypto')

function sha (key, body, algorithm) {

return crypto.createHmac(algorithm, key).update(body).digest('base64')

}

function rsa (key, body) {

return crypto.createSign('RSA-SHA1').update(body).sign(key, 'base64')

}

function rfc3986 (str) {

return encodeURIComponent(str)
  .replace(/!/g,'%21')
  .replace(/\*/g,'%2A')
  .replace(/\(/g,'%28')
  .replace(/\)/g,'%29')
  .replace(/'/g,'%27')

}

// Maps object to bi-dimensional array // Converts { foo: 'A', bar: [ 'b', 'B' ]} to // [ ['foo', 'A'], ['bar', 'b'], ['bar', 'B'] ] function map (obj) {

var key, val, arr = []
for (key in obj) {
  val = obj[key]
  if (Array.isArray(val))
    for (var i = 0; i < val.length; i++)
      arr.push([key, val[i]])
  else if (typeof val === 'object')
    for (var prop in val)
      arr.push([key + '[' + prop + ']', val[prop]])
  else
    arr.push([key, val])
}
return arr

}

// Compare function for sort function compare (a, b) {

return a > b ? 1 : a < b ? -1 : 0

}

function generateBase (httpMethod, base_uri, params) {

// adapted from https://dev.twitter.com/docs/auth/oauth and 
// https://dev.twitter.com/docs/auth/creating-signature

// Parameter normalization
// http://tools.ietf.org/html/rfc5849#section-3.4.1.3.2
var normalized = map(params)
// 1.  First, the name and value of each parameter are encoded
.map(function (p) {
  return [ rfc3986(p[0]), rfc3986(p[1] || '') ]
})
// 2.  The parameters are sorted by name, using ascending byte value
//     ordering.  If two or more parameters share the same name, they
//     are sorted by their value.
.sort(function (a, b) {
  return compare(a[0], b[0]) || compare(a[1], b[1])
})
// 3.  The name of each parameter is concatenated to its corresponding
//     value using an "=" character (ASCII code 61) as a separator, even
//     if the value is empty.
.map(function (p) { return p.join('=') })
 // 4.  The sorted name/value pairs are concatenated together into a
 //     single string by using an "&" character (ASCII code 38) as
 //     separator.
.join('&')

var base = [
  rfc3986(httpMethod ? httpMethod.toUpperCase() : 'GET'),
  rfc3986(base_uri),
  rfc3986(normalized)
].join('&')

return base

}

function hmacsign (httpMethod, base_uri, params, consumer_secret, token_secret) {

var base = generateBase(httpMethod, base_uri, params)
var key = [
  consumer_secret || '',
  token_secret || ''
].map(rfc3986).join('&')

return sha(key, base, 'sha1')

}

function hmacsign256 (httpMethod, base_uri, params, consumer_secret, token_secret) {

var base = generateBase(httpMethod, base_uri, params)
var key = [
  consumer_secret || '',
  token_secret || ''
].map(rfc3986).join('&')

return sha(key, base, 'sha256')

}

function rsasign (httpMethod, base_uri, params, private_key, token_secret) {

var base = generateBase(httpMethod, base_uri, params)
var key = private_key || ''

return rsa(key, base)

}

function plaintext (consumer_secret, token_secret) {

var key = [
  consumer_secret || '',
  token_secret || ''
].map(rfc3986).join('&')

return key

}

function sign (signMethod, httpMethod, base_uri, params, consumer_secret, token_secret) {

var method
var skipArgs = 1

switch (signMethod) {
  case 'RSA-SHA1':
    method = rsasign
    break
  case 'HMAC-SHA1':
    method = hmacsign
    break
  case 'HMAC-SHA256':
    method = hmacsign256
    break
  case 'PLAINTEXT':
    method = plaintext
    skipArgs = 4
    break
  default:
   throw new Error('Signature method not supported: ' + signMethod)
}

return method.apply(null, [].slice.call(arguments, skipArgs))

}

exports.hmacsign = hmacsign exports.hmacsign256 = hmacsign256 exports.rsasign = rsasign exports.plaintext = plaintext exports.sign = sign exports.rfc3986 = rfc3986 exports.generateBase = generateBase