-- This is released into the public domain.
-- No warranty is provided, implied or otherwise.

-- metamachine-vgpu.lua : Virtual GPU library
-- Authors: 20kdc

return {
 -- Creates a new virtual GPU.
 -- 'screens' is the component mapping, and thus:
 -- [id] = <glacier GPU function: gpu, rebound = f()>
 newGPU = function (screens)
  local boundScreen
  local backgroundRGB, foregroundRGB = 0, 0xFFFFFF
  local function bound()
   if not screens[boundScreen] then return end
   local gpu, rebound = screens[boundScreen]()
   if not gpu then screens[boundScreen] = nil return end
   if rebound then
    gpu.setBackground(backgroundRGB)
    gpu.setForeground(foregroundRGB)
   end
   return gpu
  end
  return {
   -- Virtual GPU proxy
   type = "gpu",
   -- == getAspectRatio more or less
   getSize = function ()
    local gpu = bound()
    if not gpu then
     return 1, 1
    else
     return gpu.getSize()
    end
   end,
   bind = function (adr, rst)
    boundScreen = adr
    local gpu = bound()
    if gpu then
     if rst then
      gpu.setResolution(gpu.maxResolution())
     end
     return true
    end
    boundScreen = nil
    -- :(
    return false, "No such virtual screen"
   end,
   getScreen = function ()
    return boundScreen
   end,
   maxResolution = function ()
    local gpu = bound()
    if gpu then
     return gpu.maxResolution()
    end
    error("unbound")
   end,
   getResolution = function ()
    local gpu = bound()
    if gpu then
     return gpu.getResolution()
    end
    error("unbound")
   end,
   getViewport = function ()
    -- annoyingly undocumented so we'll pretend it's this, as OCEmu does
    local gpu = bound()
    if gpu then
     return gpu.getResolution()
    end
    error("unbound")
   end,
   setResolution = function (...)
    local gpu = bound()
    if gpu then
     return gpu.setResolution(...)
    end
    error("unbound")
   end,
   setViewport = function (...)
    -- annoyingly undocumented so we'll pretend it's this, as OCEmu does
    local gpu = bound()
    if gpu then
     return gpu.setResolution(...)
    end
    error("unbound")
   end,
   maxDepth = function ()
    local gpu = bound()
    if gpu then
     return gpu.maxDepth()
    end
    error("unbound")
   end,
   getDepth = function ()
    local gpu = bound()
    if gpu then
     return gpu.getDepth()
    end
    error("unbound")
   end,
   setDepth = function (...)
    local gpu = bound()
    if gpu then
     return gpu.setDepth(...)
    end
    error("unbound")
   end,
   get = function (...)
    local gpu = bound()
    if gpu then
     return gpu.get(...)
    end
    error("unbound")
   end,
   set = function (...)
    local gpu = bound()
    if gpu then
     return gpu.set(...)
    end
    error("unbound")
   end,
   copy = function (...)
    local gpu = bound()
    if gpu then
     return gpu.copy(...)
    end
    error("unbound")
   end,
   fill = function (...)
    local gpu = bound()
    if gpu then
     return gpu.fill(...)
    end
    error("unbound")
   end,
   getPaletteColor = function ()
    return 0
   end,
   setPaletteColor = function ()
    -- Fail
   end,
   setForeground = function (rgb)
    checkArg(1, rgb, "number")
    local old = foregroundRGB
    foregroundRGB = rgb
    local gpu = bound()
    if gpu then
     gpu.setForeground(foregroundRGB)
    end
    return old
   end,
   setBackground = function (rgb)
    checkArg(1, rgb, "number")
    local old = backgroundRGB
    backgroundRGB = rgb
    local gpu = bound()
    if gpu then
     gpu.setBackground(backgroundRGB)
    end
    return old
   end,
   getForeground = function ()
    return foregroundRGB
   end,
   getBackground = function ()
    return backgroundRGB
   end
  }
 end,
 -- 'window' is used for span and setSize.
 -- emitResize(w, h) is used for screen_resized events.
 -- queueLine(y) is used for line queuing.
 newBuffer = function (window, keyboards, maxW, maxH, emitResize, queueLine)
  local screenW, screenH
  local screenText = ""
  local screenFR = ""
  local screenFG = ""
  local screenFB = ""
  local screenBR = ""
  local screenBG = ""
  local screenBB = ""
  -- Gets characters for R, G and B
  local function decodeRGB(rgb)
   return
    string.char(math.floor(rgb / 65536) % 256),
    string.char(math.floor(rgb / 256) % 256),
    string.char(rgb % 256)
  end
  -- Returns the width, or nothing if totally out of bounds.
  local function put(x, y, ch, fg, bg)
   if x < 1 or x > screenW then return end
   if y < 1 or y > screenH then return end
   local fr, fg, fb = decodeRGB(fg)
   local br, bg, bb = decodeRGB(bg)
   ch = unicode.safeTextFormat(ch)
   local chw = unicode.len(ch)
   -- Crop
   ch = unicode.sub(ch, 1, (screenW - x) + 1)
   chw = unicode.len(ch)

   local index = x + ((y - 1) * screenW)
   screenText = unicode.sub(screenText, 1, index - 1) .. ch .. unicode.sub(screenText, index + chw)
   screenFR = screenFR:sub(1, index - 1) .. fr:rep(chw) .. screenFR:sub(index + chw)
   screenFG = screenFG:sub(1, index - 1) .. fg:rep(chw) .. screenFG:sub(index + chw)
   screenFB = screenFB:sub(1, index - 1) .. fb:rep(chw) .. screenFB:sub(index + chw)
   screenBR = screenBR:sub(1, index - 1) .. br:rep(chw) .. screenBR:sub(index + chw)
   screenBG = screenBG:sub(1, index - 1) .. bg:rep(chw) .. screenBG:sub(index + chw)
   screenBB = screenBB:sub(1, index - 1) .. bb:rep(chw) .. screenBB:sub(index + chw)
   return chw
  end
  local function getCh(x, y)
   x, y = math.floor(x), math.floor(y)
   if x < 1 or x > screenW then return " ", 0, 0 end
   if y < 1 or y > screenH then return " ", 0, 0 end
   local index = x + ((y - 1) * screenW)
   local fg = (screenFR:byte(index) * 65536) + (screenFG:byte(index) * 256) + screenFB:byte(index)
   local bg = (screenBR:byte(index) * 65536) + (screenBG:byte(index) * 256) + screenBB:byte(index)
   return unicode.sub(screenText, index, index), fg, bg
  end
  --
  -- Directly exposed to userspace
  local function setSize(w, h, first)
   w = math.min(math.max(math.floor(w), 1), maxW)
   h = math.min(math.max(math.floor(h), 1), maxH)
   screenW, screenH = w, h
   screenText = (" "):rep(w * h)
   screenFR = ("\xFF"):rep(w * h)
   screenFG = screenFR
   screenFB = screenFG
   screenBR = ("\x00"):rep(w * h)
   screenBG = screenBR
   screenBB = screenBG
   if not first then emitResize(w, h) end
   window.setSize(w, h)
  end
  local function rectOOB(x, y, w, h)
   if x < 1 or x > screenW - (w - 1) then return true end
   if y < 1 or y > screenH - (h - 1) then return true end
  end
  local function redrawLine(x, y, w)
   x, y, w = math.floor(x), math.floor(y), math.floor(w)
   w = math.min(w, screenW - (x - 1))
   if w < 1 then return end
   if x < 1 or x > screenW then return end
   if y < 1 or y > screenH then return end
   local index = x + ((y - 1) * screenW)
   local currentSegmentI
   local currentSegment
   local currentSegmentR2
   local function flushSegment()
    if not currentSegment then return end
    local tx = unicode.undoSafeTextFormat(currentSegment)
    local fg = (currentSegmentR2:byte(1) * 65536) + (currentSegmentR2:byte(2) * 256) + currentSegmentR2:byte(3)
    local bg = (currentSegmentR2:byte(4) * 65536) + (currentSegmentR2:byte(5) * 256) + currentSegmentR2:byte(6)
    -- Span format is bg, fg, not fg, bg
    window.span(x + currentSegmentI - 1, y, tx, bg, fg)
    currentSegment = nil
    currentSegmentI = nil
    currentSegmentR2 = nil
   end
   for i = 1, w do
    local idx = index + i - 1
    local p = unicode.sub(screenText, idx, idx)
    local s =
     screenFR:sub(idx, idx) .. screenFG:sub(idx, idx) .. screenFB:sub(idx, idx) ..
     screenBR:sub(idx, idx) .. screenBG:sub(idx, idx) .. screenBB:sub(idx, idx)
    if currentSegmentR2 ~= s then
     flushSegment()
     currentSegmentI = i
     currentSegmentR2 = s
     currentSegment = p
    else
     currentSegment = currentSegment .. p
    end
   end
   flushSegment()
  end
  local function queueRedraw(x, y, w, h)
   for i = 1, h do
    queueLine(y + i - 1)
   end
  end
  setSize(maxW, maxH, true)
  local fgRGB, bgRGB = 0xFFFFFF, 0
  local videoInterfaceChipset = {
   getSize = function ()
    return 1, 1
   end,
   maxResolution = function ()
    return maxW, maxH
   end,
   getResolution = function ()
    return screenW, screenH
   end,
   setResolution = setSize,
   maxDepth = function ()
    return 8
   end,
   getDepth = function ()
    return 8
   end,
   setDepth = function (d)
   end,
   get = getCh,
   set = function (x, y, str, v)
    x, y = math.floor(x), math.floor(y)
    if v then
     for i = 1, unicode.len(str) do
      put(x, y + i - 1, unicode.sub(str, i, i), fgRGB, bgRGB)
     end
     return true
    end
    local chw = put(x, y, str, fgRGB, bgRGB)
    if chw then
     queueLine(y)
    else
     return false, "Out of bounds."
    end
    return true
   end,
   copy = function (x, y, w, h, ox, oy)
    x, y, w, h, ox, oy = math.floor(x), math.floor(y), math.floor(w), math.floor(h), math.floor(ox), math.floor(oy)
    if rectOOB(x, y, w, h) then return false, "out of bounds. s" end
    if rectOOB(x + ox, y + oy, w, h) then return false, "out of bounds. t" end
    local collation = {}
    for iy = 1, h do
     collation[iy] = {}
     for ix = 1, w do
      collation[iy][ix] = {getCh(ix + x - 1, iy + y - 1)}
     end
    end
    for iy = 1, h do
     for ix = 1, w do
      local cc = collation[iy][ix]
      if ix + unicode.charWidth(cc[1]) - 1 <= w then
       put(ix + ox + x - 1, iy + oy + y - 1, cc[1], cc[2], cc[3])
      end
     end
    end
    queueRedraw(x + ox, y + oy, w, h)
    return true
   end,
   fill = function (x, y, w, h, str)
    x, y, w, h = math.floor(x), math.floor(y), math.floor(w), math.floor(h)
    if rectOOB(x, y, w, h) then return false, "out of bounds" end
    str = unicode.sub(str, 1, 1)
    str = str:rep(math.floor(w / unicode.charWidth(str)))
    for i = 1, h do
     put(x, y + i - 1, str, fgRGB, bgRGB)
    end
    queueRedraw(x, y, w, h)
    return true
   end,
   setForeground = function (rgb)
    fgRGB = rgb
   end,
   setBackground = function (rgb)
    bgRGB = rgb
   end,
  }
  -- Various interfaces
  local int = {
   -- Internal interface
   line = function (y)
    redrawLine(1, y, screenW)
   end,
   precise = false
  }
  return function ()
   return videoInterfaceChipset, false
  end, int, {
   type = "screen",
   isOn = function ()
    return true
   end,
   turnOn = function ()
    return true
   end,
   turnOff = function ()
    return true
   end,
   getAspectRatio = function ()
    return 1, 1
   end,
   getKeyboards = function ()
    local kbs = {}
    for k, v in ipairs(keyboards) do
     kbs[k] = v
    end
    return kbs
   end,
   setPrecise = function (p)
    int.precise = p
   end,
   isPrecise = function ()
    return int.precise
   end,
   setTouchModeInverted = function (p)
    return false
   end,
   isTouchModeInverted = function ()
    return false
   end,
  }
 end
}