-- Copyright (C) 2015,2016 Tomoyuki Fujimori <moyu@dromozoa.com>
--
-- This file is part of dromozoa-commons.
--
-- dromozoa-commons is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.
--
-- dromozoa-commons is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with dromozoa-commons.  If not, see <http://www.gnu.org/licenses/>.

local sequence = require "dromozoa.commons.sequence"
local sha = require "dromozoa.commons.sha"
local uint32 = require "dromozoa.commons.uint32"
local word_block = require "dromozoa.commons.word_block"

local add = uint32.add
local bxor = uint32.bxor
local rotl = uint32.rotl

local Ch = sha.Ch
local Parity = sha.Parity
local Maj = sha.Maj

local K1 = 0x5a827999
local K2 = 0x6ed9eba1
local K3 = 0x8f1bbcdc
local K4 = 0xca62c1d6

local class = {
  hex_format = ("%02x"):rep(20);
}

function class.new()
  return class.reset({
    M = word_block(16, ">");
    W = sequence();
    H = sequence();
    L = 0;
  })
end

function class:reset()
  local H = self.H
  H[1] = 0x67452301
  H[2] = 0xefcdab89
  H[3] = 0x98badcfe
  H[4] = 0x10325476
  H[5] = 0xc3d2e1f0
  return self
end

function class:compute()
  local M = self.M
  local W = self.W
  local H = self.H

  for t = 1, 16 do
    W[t] = M[t]
  end
  for t = 17, 80 do
    W[t] = rotl(bxor(W[t - 3], W[t - 8], W[t - 14], W[t - 16]), 1)
  end

  local H1 = H[1]
  local H2 = H[2]
  local H3 = H[3]
  local H4 = H[4]
  local H5 = H[5]

  local a, b, c, d, e = H1, H2, H3, H4, H5

  for t = 1, 20 do
    local T = add(rotl(a, 5), Ch(b, c, d), e, K1, W[t])
    e = d
    d = c
    c = rotl(b, 30)
    b = a
    a = T
  end

  for t = 21, 40 do
    local T = add(rotl(a, 5), Parity(b, c, d), e, K2, W[t])
    e = d
    d = c
    c = rotl(b, 30)
    b = a
    a = T
  end

  for t = 41, 60 do
    local T = add(rotl(a, 5), Maj(b, c, d), e, K3, W[t])
    e = d
    d = c
    c = rotl(b, 30)
    b = a
    a = T
  end

  for t = 61, 80 do
    local T = add(rotl(a, 5), Parity(b, c, d), e, K4, W[t])
    e = d
    d = c
    c = rotl(b, 30)
    b = a
    a = T
  end

  H[1] = add(a, H1)
  H[2] = add(b, H2)
  H[3] = add(c, H3)
  H[4] = add(d, H4)
  H[5] = add(e, H5)
end

function class.bin(message)
  return class():update(message):finalize("bin")
end

function class.hex(message)
  return class():update(message):finalize("hex")
end

function class.hmac(K, text, encode)
  return sha.hmac(class, K, text, encode)
end

local metatable = {
  __index = class;
}

return setmetatable(class, {
  __index = sha;
  __call = function ()
    return setmetatable(class.new(), metatable)
  end;
})