-- Copyright (C) 2018-2021 by KittenOS NEO contributors
--
-- Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
-- THIS SOFTWARE.

-- knbs.lua : Partial .nbs (Note Block Studio) R/W library
-- Does not support custom instruments!
-- Authors: 20kdc

local function dsu16(str)
 return
  str:byte(1) +
  (str:byte(2) * 256),
  str:sub(3)
end
local function dsu32(str)
 local a, str = dsu16(str)
 local b, str = dsu16(str)
 return a + (b * 0x10000), str
end
local function dsstr(str)
 local a, str = dsu32(str)
 return str:sub(1, a), str:sub(a + 1)
end
local function su16(i, wr)
 wr(string.char(i % 0x100, math.floor(i / 0x100)))
end
local function su32(i, wr)
 su16(i % 0x10000, wr)
 su16(math.floor(i / 0x10000), wr)
end
local function sstr(str, wr)
 su32(#str, wr)
 wr(str)
end

return {
 new = function ()
  return {
   length = 1,
   height = 1,
   name = "New Song",
   transcriptor = "Mr.Anderson",
   songwriter = "Morpheus",
   description = "A blank song.",
   tempo = 200,
   autosave = 0,
   autosaveMin = 60,
   timeSignature = 4,
   usageMin = 0, usageLeft = 0, usageRight = 0, usageAdd = 0, usageRm = 0,
   importName = "",
   ci = "",
   ticks = {
    [0] = {
     [0] = {0, 33}
    }
   },
   layers = {
    [0] = {"L0", 100}
   }
  }
 end,
 deserialize = function (str)
  local nbs = {}
  nbs.length, str = dsu16(str)
  nbs.length = nbs.length + 1 -- hmph!
  nbs.height, str = dsu16(str)
  nbs.name, str = dsstr(str)
  nbs.transcriptor, str = dsstr(str)
  nbs.songwriter, str = dsstr(str)
  nbs.description, str = dsstr(str)
  nbs.tempo, str = dsu16(str)
  nbs.autosave, str = str:byte(), str:sub(2)
  nbs.autosaveMin, str = str:byte(), str:sub(2)
  nbs.timeSignature, str = str:byte(), str:sub(2)
  nbs.usageMin, str = dsu32(str)
  nbs.usageLeft, str = dsu32(str)
  nbs.usageRight, str = dsu32(str)
  nbs.usageAdd, str = dsu32(str)
  nbs.usageRm, str = dsu32(str)
  nbs.importName, str = dsstr(str)
  -- ticks[tick][layer] = key
  nbs.ticks = {}
  local tick = -1
  while true do
   local ntJ
   ntJ, str = dsu16(str)
   if ntJ == 0 then break end
   tick = tick + ntJ
   local tickData = {}
   nbs.ticks[tick] = tickData
   local layer = -1
   while true do
    local lJ
    lJ, str = dsu16(str)
    if lJ == 0 then break end
    layer = layer + lJ
    local ins = str:byte(1)
    local key = str:byte(2)
    str = str:sub(3)
    local layerData = {ins, key}
    if layer < nbs.height then
     tickData[layer] = layerData
     -- else: drop the invalid note
    end
   end
  end
  -- nbs.layers[layer] = {name, volume}
  nbs.layers = {}
  if str ~= "" then
   for i = 0, nbs.height - 1 do
    nbs.layers[i] = {}
    nbs.layers[i][1], str = dsstr(str)
    nbs.layers[i][2], str = str:byte(), str:sub(2)
   end
  else
   for i = 0, nbs.height - 1 do
    nbs.layers[i] = {"L" .. i, 100}
   end
  end
  nbs.ci = str
  return nbs
 end,
 resizeLayers = function (nbs, layers)
  -- make all layers after target layer go away
  for i = layers, nbs.height - 1 do
   nbs.layers[i] = nil
  end
  -- add layers up to target
  for i = nbs.height, layers - 1 do
   nbs.layers[i] = {"L" .. i, 100}
  end
  -- clean up song
  for k, v in pairs(nbs.ticks) do
   for lk, lv in pairs(v) do
    if lk >= layers then
     v[lk] = nil
    end
   end
  end
  nbs.height = layers
 end,
 -- Corrects length, height (should not be necessary in correct applications!), and clears out unused tick columns.
 -- Returns the actual effective height, which can be passed to resizeLayers to remove dead weight.
 correctSongLH = function (nbs)
  nbs.length = 1
  nbs.height = 0
  for k, v in pairs(nbs.layers) do
   nbs.height = math.max(nbs.height, k + 1)
  end
  local eH = 0
  for k, v in pairs(nbs.ticks) do
   local ok = false
   for lk, lv in pairs(v) do
    ok = true
    eH = math.max(eH, lk + 1)
   end
   if not ok then
    nbs.ticks[k] = nil
   else
    nbs.length = math.max(nbs.length, k + 1)
   end
  end
  return eH
 end,
 serialize = function (nbs, wr)
  su16(math.max(0, nbs.length - 1), wr)
  su16(nbs.height, wr)
  sstr(nbs.name, wr)
  sstr(nbs.transcriptor, wr)
  sstr(nbs.songwriter, wr)
  sstr(nbs.description, wr)
  su16(nbs.tempo, wr)
  wr(string.char(nbs.autosave, nbs.autosaveMin, nbs.timeSignature))
  su32(nbs.usageMin, wr)
  su32(nbs.usageLeft, wr)
  su32(nbs.usageRight, wr)
  su32(nbs.usageAdd, wr)
  su32(nbs.usageRm, wr)
  sstr(nbs.importName, wr)
  local ptr = -1
  for i = 0, nbs.length - 1 do
   if nbs.ticks[i] then
    su16(i - ptr, wr)
    ptr = i
    local lp = -1
    for j = 0, nbs.height - 1 do
     local id = nbs.ticks[i][j]
     if id then
      su16(j - lp, wr)
      lp = j
      wr(string.char(id[1], id[2]))
     end
    end
    su16(0, wr)
   end
  end
  su16(0, wr)
  for i = 0, nbs.height - 1 do
   sstr(nbs.layers[i][1], wr)
   wr(string.char(nbs.layers[i][2]))
  end
  wr(nbs.ci)
 end
}