local bit32 = require("bit32")
local colorlib = {}

local function isNan(x)
  return x~=x
end

function colorlib.HEXtoRGB(color)
  return bit32.rshift(color, 16), bit32.band(bit32.rshift(color, 8), 0xFF), bit32.band(color, 0xFF)
end

function colorlib.RGBtoHEX(rr, gg, bb)
  return bit32.lshift(rr, 16) + bit32.lshift(gg, 8) + bb
end

--HSB model
function colorlib.RGBtoHSB(rr, gg, bb)
  local max = math.max(rr, math.max(gg, bb))
  local min = math.min(rr, math.min(gg, bb))
  local delta = max - min

  local h = 0
  if ( max == rr and gg >= bb) then h = 60*(gg-bb)/delta end
  if ( max == rr and gg <= bb ) then h = 60*(gg-bb)/delta + 360 end
  if ( max == gg ) then h = 60*(bb-rr)/delta + 120 end
  if ( max == bb ) then h = 60*(rr-gg)/delta + 240 end

  local s = 0
  if ( max ~= 0 ) then s = 1 - (min / max) end

  local b = max * 100 / 255

  if isNan(h) then h = 0 end

  return h, s * 100, b
end

function colorlib.HSBtoRGB(h, s, v)
  if h > 359 then h = 0 end
  local rr, gg, bb = 0, 0, 0
  local const = 255

  s = s/100
  v = v/100
  
  local i = math.floor(h/60)
  local f = h/60 - i
  
  local p = v*(1-s)
  local q = v*(1-s*f)
  local t = v*(1-(1-f)*s)

  if ( i == 0 ) then rr, gg, bb = v, t, p end
  if ( i == 1 ) then rr, gg, bb = q, v, p end
  if ( i == 2 ) then rr, gg, bb = p, v, t end
  if ( i == 3 ) then rr, gg, bb = p, q, v end
  if ( i == 4 ) then rr, gg, bb = t, p, v end
  if ( i == 5 ) then rr, gg, bb = v, p, q end

  return math.floor(rr * const), math.floor(gg * const), math.floor(bb * const)
end

function colorlib.HEXtoHSB(color)
  local rr, gg, bb = colorlib.HEXtoRGB(color)
  local h, s, b = colorlib.RGBtoHSB( rr, gg, bb )
  
  return h, s, b
end

function colorlib.HSBtoHEX(h, s, b)
  local rr, gg, bb = colorlib.HSBtoRGB(h, s, b)
  local color = colorlib.RGBtoHEX(rr, gg, bb)

  return color
end

--Смешивание двух цветов на основе альфа-канала второго
function colorlib.alphaBlend(firstColor, secondColor, alphaChannel)
  local invertedAlphaChannel = 1 - alphaChannel
  
  local firstColorRed, firstColorGreen, firstColorBlue = colorlib.HEXtoRGB(firstColor)
  local secondColorRed, secondColorGreen, secondColorBlue = colorlib.HEXtoRGB(secondColor)

  return colorlib.RGBtoHEX(
    secondColorRed * invertedAlphaChannel + firstColorRed * alphaChannel,
    secondColorGreen * invertedAlphaChannel + firstColorGreen * alphaChannel,
    secondColorBlue * invertedAlphaChannel + firstColorBlue * alphaChannel
  )
end

--Получение среднего цвета между перечисленными. К примеру, между черным и белым выдаст серый.
function colorlib.getAverageColor(colors)
  local sColors = #colors
  local averageRed, averageGreen, averageBlue = 0, 0, 0
  for i = 1, sColors do
    local r, g, b = colorlib.HEXtoRGB(colors[i])
    averageRed, averageGreen, averageBlue = averageRed + r, averageGreen + g, averageBlue + b
  end
  return colorlib.RGBtoHEX(math.floor(averageRed / sColors), math.floor(averageGreen / sColors), math.floor(averageBlue / sColors))
end

-----------------------------------------------------------------------------------------------------------------------

local palette = {
  0x000000, 0x000040, 0x000080, 0x0000BF, 0x0000FF, 0x002400, 0x002440, 0x002480, 0x0024BF, 0x0024FF, 0x004900, 0x004940, 0x004980, 0x0049BF, 0x0049FF, 0x006D00, 
  0x006D40, 0x006D80, 0x006DBF, 0x006DFF, 0x009200, 0x009240, 0x009280, 0x0092BF, 0x0092FF, 0x00B600, 0x00B640, 0x00B680, 0x00B6BF, 0x00B6FF, 0x00DB00, 0x00DB40, 
  0x00DB80, 0x00DBBF, 0x00DBFF, 0x00FF00, 0x00FF40, 0x00FF80, 0x00FFBF, 0x00FFFF, 0x0F0F0F, 0x1E1E1E, 0x2D2D2D, 0x330000, 0x330040, 0x330080, 0x3300BF, 0x3300FF, 
  0x332400, 0x332440, 0x332480, 0x3324BF, 0x3324FF, 0x334900, 0x334940, 0x334980, 0x3349BF, 0x3349FF, 0x336D00, 0x336D40, 0x336D80, 0x336DBF, 0x336DFF, 0x339200, 
  0x339240, 0x339280, 0x3392BF, 0x3392FF, 0x33B600, 0x33B640, 0x33B680, 0x33B6BF, 0x33B6FF, 0x33DB00, 0x33DB40, 0x33DB80, 0x33DBBF, 0x33DBFF, 0x33FF00, 0x33FF40, 
  0x33FF80, 0x33FFBF, 0x33FFFF, 0x3C3C3C, 0x4B4B4B, 0x5A5A5A, 0x660000, 0x660040, 0x660080, 0x6600BF, 0x6600FF, 0x662400, 0x662440, 0x662480, 0x6624BF, 0x6624FF, 
  0x664900, 0x664940, 0x664980, 0x6649BF, 0x6649FF, 0x666D00, 0x666D40, 0x666D80, 0x666DBF, 0x666DFF, 0x669200, 0x669240, 0x669280, 0x6692BF, 0x6692FF, 0x66B600, 
  0x66B640, 0x66B680, 0x66B6BF, 0x66B6FF, 0x66DB00, 0x66DB40, 0x66DB80, 0x66DBBF, 0x66DBFF, 0x66FF00, 0x66FF40, 0x66FF80, 0x66FFBF, 0x66FFFF, 0x696969, 0x787878, 
  0x878787, 0x969696, 0x990000, 0x990040, 0x990080, 0x9900BF, 0x9900FF, 0x992400, 0x992440, 0x992480, 0x9924BF, 0x9924FF, 0x994900, 0x994940, 0x994980, 0x9949BF, 
  0x9949FF, 0x996D00, 0x996D40, 0x996D80, 0x996DBF, 0x996DFF, 0x999200, 0x999240, 0x999280, 0x9992BF, 0x9992FF, 0x99B600, 0x99B640, 0x99B680, 0x99B6BF, 0x99B6FF, 
  0x99DB00, 0x99DB40, 0x99DB80, 0x99DBBF, 0x99DBFF, 0x99FF00, 0x99FF40, 0x99FF80, 0x99FFBF, 0x99FFFF, 0xA5A5A5, 0xB4B4B4, 0xC3C3C3, 0xCC0000, 0xCC0040, 0xCC0080, 
  0xCC00BF, 0xCC00FF, 0xCC2400, 0xCC2440, 0xCC2480, 0xCC24BF, 0xCC24FF, 0xCC4900, 0xCC4940, 0xCC4980, 0xCC49BF, 0xCC49FF, 0xCC6D00, 0xCC6D40, 0xCC6D80, 0xCC6DBF, 
  0xCC6DFF, 0xCC9200, 0xCC9240, 0xCC9280, 0xCC92BF, 0xCC92FF, 0xCCB600, 0xCCB640, 0xCCB680, 0xCCB6BF, 0xCCB6FF, 0xCCDB00, 0xCCDB40, 0xCCDB80, 0xCCDBBF, 0xCCDBFF, 
  0xCCFF00, 0xCCFF40, 0xCCFF80, 0xCCFFBF, 0xCCFFFF, 0xD2D2D2, 0xE1E1E1, 0xF0F0F0, 0xFF0000, 0xFF0040, 0xFF0080, 0xFF00BF, 0xFF00FF, 0xFF2400, 0xFF2440, 0xFF2480, 
  0xFF24BF, 0xFF24FF, 0xFF4900, 0xFF4940, 0xFF4980, 0xFF49BF, 0xFF49FF, 0xFF6D00, 0xFF6D40, 0xFF6D80, 0xFF6DBF, 0xFF6DFF, 0xFF9200, 0xFF9240, 0xFF9280, 0xFF92BF, 
  0xFF92FF, 0xFFB600, 0xFFB640, 0xFFB680, 0xFFB6BF, 0xFFB6FF, 0xFFDB00, 0xFFDB40, 0xFFDB80, 0xFFDBBF, 0xFFDBFF, 0xFFFF00, 0xFFFF40, 0xFFFF80, 0xFFFFBF, 0xFFFFFF, 
}

function colorlib.convert24BitTo8Bit(hex24)
  local encodedIndex = nil
  local colorMatchFactor = nil
  local colorMatchFactor_min = math.huge

  local red24, green24, blue24 = colorlib.HEXtoRGB(hex24)

  for colorIndex, colorPalette in ipairs(palette) do
    local redPalette, greenPalette, bluePalette = colorlib.HEXtoRGB(colorPalette)

    colorMatchFactor = (redPalette-red24)^2 + (greenPalette-green24)^2 + (bluePalette-blue24)^2

    if (colorMatchFactor < colorMatchFactor_min) then
      encodedIndex = colorIndex
      colorMatchFactor_min = colorMatchFactor
    end
  end
    
  return encodedIndex - 1
  -- return searchClosestColor(1, #palette, hex24)
end

function colorlib.convert8BitTo24Bit(hex8)
  return palette[hex8 + 1]
end

function colorlib.debugColorCompression(color)
  local compressedColor = colorlib.convert24BitTo8Bit(color)
  local decompressedColor = colorlib.convert8BitTo24Bit(compressedColor)
  print("Исходный цвет: " .. string.format("0x%06X", color))
  print("Сжатый цвет: " .. string.format("0x%02X", compressedColor))
  print("Расжатый цвет: " .. string.format("0x%06X", decompressedColor))
end


-----------------------------------------------------------------------------------------------------------------------

return colorlib



