CC-BMP : An BMP Image Viewer For ComputerCraft

local function readBMP(filename)
  local file = fs.open(filename, "rb")
  if not file then
    return nil, "Failed to open file"
  end

  local header = file.read(54)
  local width = string.byte(header, 19) + string.byte(header, 20) * 256
  local height = string.byte(header, 23) + string.byte(header, 24) * 256

  local pixels = {}
  for y = height, 1, -1 do
    pixels[y] = {}
    for x = 1, width do
      local b = file.read(1)
      local g = file.read(1)
      local r = file.read(1)
      pixels[y][x] = {r = string.byte(r), g = string.byte(g), b = string.byte(b)}
    end
    if y % 10 == 0 then
      os.queueEvent("yield")
      os.pullEvent("yield")
    end
  end

  file.close()
  return {width = width, height = height, pixels = pixels}
end

local function resizeImage(image, newWidth, newHeight)
  local resized = {width = newWidth, height = newHeight, pixels = {}}
  for y = 1, newHeight do
    resized.pixels[y] = {}
    for x = 1, newWidth do
      local srcX = math.floor(x * image.width / newWidth)
      local srcY = math.floor(y * image.height / newHeight)
      resized.pixels[y][x] = image.pixels[srcY][srcX]
    end
    if y % 10 == 0 then
      os.queueEvent("yield")
      os.pullEvent("yield")
    end
  end
  return resized
end

local function rgbToComputerCraftColor(r, g, b)
  local colors = {
    [0x1] = {240, 240, 240}, [0x2] = {242, 178, 51}, [0x4] = {229, 127, 216},
    [0x8] = {153, 178, 242}, [0x10] = {222, 222, 108}, [0x20] = {127, 204, 25},
    [0x40] = {242, 178, 204}, [0x80] = {76, 76, 76}, [0x100] = {153, 153, 153},
    [0x200] = {76, 153, 178}, [0x400] = {178, 102, 229}, [0x800] = {51, 102, 204},
    [0x1000] = {127, 102, 76}, [0x2000] = {87, 166, 78}, [0x4000] = {204, 76, 76},
    [0x8000] = {17, 17, 17}
  }

  local closestColor = 0x1
  local minDifference = math.huge

  for code, rgb in pairs(colors) do
    local difference = math.sqrt((r - rgb[1])^2 + (g - rgb[2])^2 + (b - rgb[3])^2)
    if difference < minDifference then
      minDifference = difference
      closestColor = code
    end
  end

  return closestColor
end

local function displayBMP(image, output)
  local width, height = output.getSize()
  local resizedImage = resizeImage(image, width, height)

  for y = 1, height do
    for x = 1, width do
      local pixel = resizedImage.pixels[y][x]
      local color = rgbToComputerCraftColor(pixel.r, pixel.g, pixel.b)
      output.setCursorPos(x, y)
      output.setBackgroundColor(color)
      output.write(" ")
    end
    if y % 5 == 0 then
      os.queueEvent("yield")
      os.pullEvent("yield")
    end
  end
end

local function displayBMPMode2(image, output)
  local width, height = output.getSize()
  local resizedImage = resizeImage(image, width * 2, height * 2)

  local charSet = {" ", "\131", "\132", "\133", "\135", "\136", "\137", "\138", "\139", "\140"}

  local colors = {
    [0x1] = {240, 240, 240}, [0x2] = {242, 178, 51}, [0x4] = {229, 127, 216},
    [0x8] = {153, 178, 242}, [0x10] = {222, 222, 108}, [0x20] = {127, 204, 25},
    [0x40] = {242, 178, 204}, [0x80] = {76, 76, 76}, [0x100] = {153, 153, 153},
    [0x200] = {76, 153, 178}, [0x400] = {178, 102, 229}, [0x800] = {51, 102, 204},
    [0x1000] = {127, 102, 76}, [0x2000] = {87, 166, 78}, [0x4000] = {204, 76, 76},
    [0x8000] = {17, 17, 17}
  }

  local function getNearestColor(r, g, b)
    local closestColor = 0x1
    local minDifference = math.huge
    for code, rgb in pairs(colors) do
      local difference = math.abs(r - rgb[1]) + math.abs(g - rgb[2]) + math.abs(b - rgb[3])
      if difference < minDifference then
        minDifference = difference
        closestColor = code
      end
    end
    return closestColor
  end

  local function blendColors(c1, c2)
    return {
      r = (c1.r + c2.r) / 2,
      g = (c1.g + c2.g) / 2,
      b = (c1.b + c2.b) / 2
    }
  end

  for y = 1, height do
    for x = 1, width do
      local tl = resizedImage.pixels[y*2-1][x*2-1]
      local tr = resizedImage.pixels[y*2-1][x*2]
      local bl = resizedImage.pixels[y*2][x*2-1]
      local br = resizedImage.pixels[y*2][x*2]

      local avgColor = blendColors(blendColors(tl, tr), blendColors(bl, br))
      local intensity = (avgColor.r + avgColor.g + avgColor.b) / 3
      local pattern = math.floor(intensity / 28.4) + 1

      local bgColor = getNearestColor(tl.r, tl.g, tl.b)
      local fgColor = getNearestColor(br.r, br.g, br.b)

      if bgColor == fgColor then
        if pattern > 5 then
          fgColor = getNearestColor(math.min(br.r + 30, 255), math.min(br.g + 30, 255), math.min(br.b + 30, 255))
        else
          bgColor = getNearestColor(math.max(tl.r - 30, 0), math.max(tl.g - 30, 0), math.max(tl.b - 30, 0))
        end
      end

      output.setCursorPos(x, y)
      output.setBackgroundColor(bgColor)
      output.setTextColor(fgColor)
      output.write(charSet[pattern])
    end
    if y % 5 == 0 then
      os.queueEvent("yield")
      os.pullEvent("yield")
    end
  end
end

local function displayBMPCraftOSPC(image, output, colorMode)
  local screenWidth, screenHeight = output.getSize()
  local imageWidth, imageHeight = image.width, image.height

  local originalPalette = {}
  for i = 0, 255 do
    originalPalette[i] = {term.getPaletteColor(i)}
  end
  local originalGraphicsMode = term.getGraphicsMode()
  local originalBackgroundColor = term.getBackgroundColor()
  local originalTextColor = term.getTextColor()

  term.setGraphicsMode(colorMode)

  if colorMode == 2 then
    local cubeSize = 5  -- Number of steps for each color component (R, G, B)
    for i = 16, 255 do
      local index = i - 16
      local rIndex = math.floor(index / (cubeSize * cubeSize))
      local gIndex = math.floor((index % (cubeSize * cubeSize)) / cubeSize)
      local bIndex = index % cubeSize

      local r = math.floor(rIndex * 255 / (cubeSize - 1))
      local g = math.floor(gIndex * 255 / (cubeSize - 1))
      local b = math.floor(bIndex * 255 / (cubeSize - 1))
      term.setPaletteColor(i, r / 255, g / 255, b / 255)
    end
  end

  local function adjustBrightness(value)
    return math.min(255, math.max(0, math.floor(value * 1.2)))  -- Increase brightness by 20%
  end

  local function mapColor(r, g, b)
    r, g, b = adjustBrightness(r), adjustBrightness(g), adjustBrightness(b)
    if colorMode == 2 then
      -- Map to the custom color cube palette
      local cubeSize = 5
      local rIndex = math.floor(r / (255 / (cubeSize - 1)))
      local gIndex = math.floor(g / (255 / (cubeSize - 1)))
      local bIndex = math.floor(b / (255 / (cubeSize - 1)))

      return 16 + rIndex * cubeSize * cubeSize + gIndex * cubeSize + bIndex
    else
      return rgbToComputerCraftColor(r, g, b)
    end
  end

  for y = 0, screenHeight * 9 - 1 do
    for x = 0, screenWidth * 6 - 1 do
      local sourceX = math.floor(x * imageWidth / (screenWidth * 6))
      local sourceY = math.floor(y * imageHeight / (screenHeight * 9))

      local pixel = image.pixels[sourceY + 1][sourceX + 1]
      local color = mapColor(pixel.r, pixel.g, pixel.b)

      output.setPixel(x, y, color)
    end
    if y % 10 == 0 then
      os.queueEvent("yield")
      os.pullEvent("yield")
    end
  end

  print("Image displayed. Press any key to exit.")
  os.pullEvent("key")

  term.setGraphicsMode(originalGraphicsMode)
  for i = 0, 255 do
    term.setPaletteColor(i, table.unpack(originalPalette[i]))
  end

  term.setBackgroundColor(originalBackgroundColor)
  term.setTextColor(originalTextColor)

  term.setBackgroundColor(colors.black)
  term.setTextColor(colors.white)
  term.clear()
  term.setCursorPos(1, 1)
end

local function downloadBMP(url, filename)
  if not http then
    error("HTTP API is not enabled. Enable it in ComputerCraft.cfg")
  end

  print("Downloading " .. url .. "...")
  local response = http.get(url, nil, true)
  if not response then
    error("Failed to download file")
  end

  local file = fs.open(filename, "wb")
  local content = response.readAll()
  for i = 1, #content, 8192 do
    file.write(content:sub(i, i + 8191))
    os.queueEvent("yield")
    os.pullEvent("yield")
  end
  file.close()
  response.close()
  print("Downloaded as " .. filename)
end

print("CC-BMP : An Enhanced BMP Image Viewer For ComputerCraft Coded By nonogamer9!")
print("Enter a local filename or URL:")
local input = read()

local filename = input
if string.sub(input, 1, 4) == "http" then
  filename = "downloaded.bmp"
  downloadBMP(input, filename)
end

local image, err = readBMP(filename)
if not image then
  print("Error reading BMP file:", err)
  return
end

print("Select display mode:")
print("1. Basic ComputerCraft screen")
print("2. Mode 2 (Just a better resolution.)")
print("3. CraftOS-PC 16-color Graphics Mode")
print("4. CraftOS-PC 256-color Graphics Mode")
print("5. Monitor")

local mode = tonumber(read())

local output
if mode == 5 then
  output = peripheral.find("monitor")
  if not output then
    print("No monitor found")
    return
  end
else
  output = term
end

if mode == 1 then
  displayBMP(image, output)
elseif mode == 2 then
  displayBMPMode2(image, output)
elseif mode == 3 then
  if term.setGraphicsMode then
    displayBMPCraftOSPC(image, output, 1)  -- 16-color mode
  else
    print("CraftOS-PC Graphics Mode not supported")
  end
elseif mode == 4 then
  if term.setGraphicsMode then
    displayBMPCraftOSPC(image, output, 2)  -- 256-color mode
  else
    print("CraftOS-PC Graphics Mode not supported")
  end
elseif mode == 5 then
  displayBMP(image, output)
else
  print("Invalid mode selected")
end

print("Image displayed")