--    OBJ model library 1.0
--    ---------------------
-- by Totoro (computercraft.ru)
-- ---
-- texture support by Xytabich

local png = require("PNGImage")

tobj = {}

local vertex = {}
local faces = {}

local image
local texCoords = {}
local palette = {}

local color = {r = 1, g = 0, b = 0, a = 1}
local position = {x = 0, y = 0, z = 0}
local scale = 1.0

local paletteColors = true

local function getVT(data)
  local v, t = data:match("(-?%d+)/(-?%d+)")
  return tonumber(v), tonumber(t) or nil
end

local function round(v)
  local r = math.floor(v)
  if v-0.5 > r then return math.ceil(v)
  else return r end
end

local function inBounds(u, v) -- trim the number to the borders of 0-1
  if u > 1 then
    local a, b = math.modf(u)
    u = b
  elseif u < 0 then
    local a, b = math.modf(u)
    u = 1+b
  end
  if v > 1 then
    local a, b = math.modf(v)
    v = b
  elseif v < 0 then
    local a, b = math.modf(v)
    v = 1+b
  end
  return u, v
end

local function getFaceColor(t1, t2, t3)
  if (image == nil) or (t1 > #texCoords) or
    (t2 > #texCoords) or (t3 > #texCoords) then return nil
  else
    local u,v = table.unpack(texCoords[t1])
    local w,h = image:getSize()
    w=w-1 h=h-1
    if paletteColors then
      local r,g,b,a = image:getPixel(round(u*w), round((1-v)*h))
      if r == nil then return nil end
      return r/255, g/255, b/255, a/255
    else -- average color of 3 points - алгоритм для ленивых
      local r1,g1,b1,a1 = image:getPixel(round(u*w), round((1-v)*h))
      if r1 == nil then return nil end
      u,v = table.unpack(texCoords[t2])
      local r2,g2,b2,a2 = image:getPixel(round(u*w), round((1-v)*h))
      if r2 == nil then return nil end
      u,v = table.unpack(texCoords[t3])
      local r3,g3,b3,a3 = image:getPixel(round(u*w), round((1-v)*h))
      if r3 == nil then return nil end
      return ((r1+r2+r3)/3)/255, ((g1+g2+g3)/3)/255, ((b1+b2+b3)/3)/255, ((a1+a2+a3)/3)/255
    end
  end
end

local function getPaletteIndex(r,g,b,a)
  for i=1, #palette do
    local pr,pg,pb,pa = table.unpack(palette[i])
    if (r==pr) and (g==pg) and (b==pb) and (a==pa) then
      return i
    end
  end
  
  table.insert(palette, {r,g,b,a})
  return #palette
end

local function getPaletteColor(i)
  if (i < 1) or (i > #palette) then return 1,1,1,1
  else return table.unpack(palette[i]) end
end

tobj.loadTexture = function(filename)
  image = png.newFromFile(filename);
end

tobj.load = function(filename)
  file = io.open(filename, "r")
  if file ~= nil then
    vertex = {}
    
    for line in file:lines() do
      if line ~= nil and line ~= '' then
        local key, a, b, c, d = line:match("(%S+)%s+(%S+)%s+(%S+)%s+(%S+)%s*(%S*)")
        
        -- load vertex data / skip normals
        if key == 'v' then
          local x, y, z = tonumber(a), tonumber(b), tonumber(c)
          table.insert(vertex, {x,y,z})
        
        -- load texture data
        elseif key == "vt" then
          local u, v = tonumber(a), tonumber(b)
          table.insert(texCoords, table.pack(inBounds(u, v)))
        
        -- load faces data
        elseif key == 'f' then
          local v1, t1 = getVT(a)
          local v2, t2 = getVT(b)
          local v3, t3 = getVT(c)
          if v1 < 0 then
            local len = #vertex + 1
            v1, v2, v3 = len + v1, len + v2, len + v3
          end
          local p = 0
          if t1 ~= nil then
            r,g,b,a = getFaceColor(t1, t2, t3)
            if r ~= nil then
              p = getPaletteIndex(r,g,b,a)
            end
          end
          table.insert(faces, {vertex[v1], vertex[v2], vertex[v3], p})
        end
      end
    end
    file:close()
  else
    error("[OBJ.load] File not found!")
  end
end

tobj.setColor = function(r, g, b, a)
  color.r = r; color.g = g; color.b = b; color.a = a or 1;
end
tobj.setPosition = function(x, y, z)
  position.x = x; position.y = y; position.z = z
end
tobj.setScale = function(s)
  scale = s
end

tobj.getColor = function()
  return {color.r, color.g, color.b, color.a}
end
tobj.getPosition = function()
  return {position.x, position.y, position.z}
end
tobj.getScale = function()
  return scale
end

tobj.usePalette = function(use)
  if use ~= nil then paletteColors = use
  else return paletteColors end
end

tobj.draw = function(glasses)
  local count = 0
  for n, face in pairs(faces) do
    local triangle = glasses.addTriangle3D()
    triangle.setVertex(1, face[1][1]*scale + position.x, face[1][2]*scale + position.y, face[1][3]*scale + position.z)
    triangle.setVertex(2, face[2][1]*scale + position.x, face[2][2]*scale + position.y, face[2][3]*scale + position.z)
    triangle.setVertex(3, face[3][1]*scale + position.x, face[3][2]*scale + position.y, face[3][3]*scale + position.z)
    r,g,b,a = getPaletteColor(face[4])
    triangle.setColor(color.r*r, color.g*g, color.b*b)
    triangle.setAlpha(color.a*a)
    triangle.setVisibleThroughObjects(false)
    ---
    count = count + 1
    if count > 20 then count = 0; os.sleep(0.1) end
  end
end

tobj.getVertexNum = function()
  return #vertex
end
tobj.getPolyNum = function()
  return #faces
end

return tobj