--
-- melisma - extensible and scriptable audio engine
-- Copyright (C) 2026  Ludvig Gunne Lindström
--
-- This program 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.
--
-- This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
--

local M = {}

function M.decode(data)
  local addr,ttag,offset = string.unpack('!4 z Xs4 z Xs4',data)
  if offset == nil then error('invalid osc message') end

  ttag = string.sub(ttag,2)
  data = string.sub(data,offset)

  local args = {}
  for i = 1,#ttag do
    local format
    local c = string.sub(ttag,i,i)

    if c == 's' then format = '!4 z Xs4'
    elseif c == 'i' then format = '>i4'
    elseif c == 'f' then format = '>f'
    else error('invalid osc message') end

    local arg,offset = string.unpack(format,data)
    if offset == nil then error('invalid osc message') end

    table.insert(args,arg)
    data = string.sub(data,offset)
  end

  return {addr=addr, args=args}
end

function M.encode(msg)
  local addr = msg.addr
  local args = msg.args
  local data = ''
  local ttag = ','

  for _,arg in pairs(args) do
    if type(arg) == 'string' then
      ttag = ttag..'s'
      data = data..string.pack('!4 z Xs4',arg)
    elseif type(arg) == 'number' then
      if math.type(arg) == 'integer' then
        ttag = ttag..'i'
        data = data..string.pack('>i4',arg)
      elseif math.type(arg) == 'float' then
        ttag = ttag..'f'
        data = data..string.pack('>f',arg)
      else
        error('unsupported argument type '..math.type(arg))
      end
    else
      error('unsupported argument type '..type(arg))
    end
  end

  return string.pack('!4 z Xs4',addr)..string.pack('!4 z Xs4',ttag)..data
end

return M