local fs = require("filesystem")
local keyboard = require("keyboard")
local shell = require("shell")
local term = require("term") -- TODO use tty and cursor position instead of global area and gpu
local text = require("text")
local unicode = require("unicode")

-- Monokai color scheme
local bgColor = 0x272822
local lineColor = 0x39392F
local textColor = 0xF8F8F2
local keywordColor = 0xF92672
local commentColor = 0x75715E
local stringColor = 0xE6DB74
local valueColor = 0xAE81FF
local builtinColor = 0x66D9EF
local lineNrColor = 0x90908A

local keywords = {
  ['break'] = true,
  ['do'] = true,
  ['else'] = true,
  ['for'] = true,
  ['if'] = true,
  ['elseif'] = true,
  ['return'] = true,
  ['then'] = true,
  ['repeat'] = true,
  ['while'] = true,
  ['until'] = true,
  ['end'] = true,
  ['function'] = true,
  ['local'] = true,
  ['in'] = true,
  ['and'] = true,
  ['or'] = true,
  ['not'] = true,

  ['+'] = true,
  ['-'] = true,
  ['%'] = true,
  ['#'] = true,
  ['*'] = true,
  ['/'] = true,
  ['^'] = true,
  ['='] = true,
  ['=='] = true,
  ['~='] = true,
  ['<'] = true,
  ['<='] = true,
  ['>'] = true,
  ['>='] = true,
  ['..'] = true
}

local builtins = {
  ['assert'] = true,
  ['collectgarbage'] = true,
  ['dofile'] = true,
  ['error'] = true,
  ['getfenv'] = true,
  ['getmetatable'] = true,
  ['ipairs'] = true,
  ['loadfile'] = true,
  ['loadstring'] = true,
  ['module'] = true,
  ['next'] = true,
  ['pairs'] = true,
  ['pcall'] = true,
  ['print'] = true,
  ['rawequal'] = true,
  ['rawget'] = true,
  ['rawset'] = true,
  ['require'] = true,
  ['select'] = true,
  ['setfenv'] = true,
  ['setmetatable'] = true,
  ['tonumber'] = true,
  ['tostring'] = true,
  ['type'] = true,
  ['unpack'] = true,
  ['xpcall'] = true
}

local values = {
  ['false'] = true,
  ['nil'] = true,
  ['true'] = true,
  ['_G'] = true,
  ['_VERSION'] = true
}

local patterns = {
  {"^%-%-%[%[.-%]%]", commentColor},
  {"^%-%-.*", commentColor},
  {"^\"\"", stringColor},
  {"^\".-[^\\]\"", stringColor},
  {"^\'\'", stringColor},
  {"^\'.-[^\\]\'", stringColor},
  {"^%[%[.-%]%]", stringColor},
  {"^[%w_%+%-%%%#%*%/%^%=%~%<%>%.]+", function(text)
    if values[text] or tonumber(text) then
      local match = text:find('^0x%x%x%x%x%x%x$')

      if match then
        local luminosity = 0.2126 * tonumber('0x' .. text:sub(3, 4)) + 0.7152 * tonumber('0x' .. text:sub(5, 6)) + 0.0722 * tonumber('0x' .. text:sub(7, 8))

        if luminosity > 20 then
          return 0x000000, tonumber(text)
        else
          return 0xffffff, tonumber(text)
        end
      else
        return valueColor
      end
    elseif keywords[text] then
      return keywordColor
    elseif builtins[text] then
      return builtinColor
    end

    return textColor
  end}
}

local cache = {}
local currentMargin = 7

if not term.isAvailable() then
  return
end
local gpu = term.gpu()

local originalFg = gpu.setForeground(textColor)
local originalBg = gpu.setBackground(bgColor)

local function resetColors()
  gpu.setForeground(originalFg)
  gpu.setBackground(originalBg)
end

local args, options = shell.parse(...)
if #args == 0 then
  resetColors()
  io.write("Usage: edit <filename>")
  return
end

local filename = shell.resolve(args[1])
local file_parentpath = fs.path(filename)

if fs.exists(file_parentpath) and not fs.isDirectory(file_parentpath) then
  resetColors()
  io.stderr:write(string.format("Not a directory: %s\n", file_parentpath))
  return 1
end

local readonly = options.r or fs.get(filename) == nil or fs.get(filename).isReadOnly()

if fs.isDirectory(filename) then
  resetColors()
  io.stderr:write("file is a directory\n")
  return 1
elseif not fs.exists(filename) and readonly then
  resetColors()
  io.stderr:write("file system is read only\n")
  return 1
end

local function loadConfig()
  local env = {}
  local config = loadfile("/etc/edit.cfg", nil, env)
  if config then
    pcall(config)
  end
  env.keybinds = env.keybinds or {
    left = {{"left"}},
    right = {{"right"}},
    up = {{"up"}},
    down = {{"down"}},
    home = {{"home"}},
    eol = {{"end"}},
    pageUp = {{"pageUp"}},
    pageDown = {{"pageDown"}},

    backspace = {{"back"}},
    delete = {{"delete"}},
    deleteLine = {{"control", "delete"}, {"shift", "delete"}},
    newline = {{"enter"}},

    save = {{"control", "s"}},
    close = {{"control", "w"}},
    find = {{"control", "f"}},
    findnext = {{"control", "g"}, {"control", "n"}, {"f3"}},

    jump = {{'control', 'j'}}
  }

  if not config then
    local root = fs.get("/")
    if root and not root.isReadOnly() then
      fs.makeDirectory("/etc")
      local f = io.open("/etc/edit.cfg", "w")
      if f then
        local serialization = require("serialization")
        for k, v in pairs(env) do
          f:write(k.."="..tostring(serialization.serialize(v, math.huge)).."\n")
        end
        f:close()
      end
    end
  end
  return env
end

term.clear()
term.setCursorBlink(true)

local running = true
local buffer = {}
local scrollX, scrollY = 0, 0
local config = loadConfig()

local getKeyBindHandler

local function helpStatusText()
  local function prettifyKeybind(label, command)
    local keybind = type(config.keybinds) == "table" and config.keybinds[command]
    if type(keybind) ~= "table" or type(keybind[1]) ~= "table" then return "" end
    local alt, control, shift, key
    for _, value in ipairs(keybind[1]) do
      if value == "alt" then alt = true
      elseif value == "control" then control = true
      elseif value == "shift" then shift = true
      else key = value end
    end
    if not key then return "" end
    return label .. ": [" ..
           (control and "Ctrl+" or "") ..
           (alt and "Alt+" or "") ..
           (shift and "Shift+" or "") ..
           unicode.upper(key) ..
           "] "
  end
  return prettifyKeybind("Save", "save") ..
         prettifyKeybind("Close", "close") ..
         prettifyKeybind("Find", "find") ..
         prettifyKeybind('Jump to line', 'jump')
end

local currentStatus = ''

local function setStatus(value)
  local x, y, w, h = term.getGlobalArea()
  value = unicode.wlen(value) > w - 10 and unicode.wtrunc(value, w - 9) or value
  value = text.padRight(value, w - 10)
  gpu.set(x, y + h - 1, value)

  currentStatus = value
end

local function getArea()
  local x, y, w, h = term.getGlobalArea()
  return x + currentMargin, y, w - currentMargin, h - 1
end

local function removePrefix(line, length)
  if length >= unicode.wlen(line) then
    return ""
  else
    local prefix = unicode.wtrunc(line, length + 1)
    local suffix = unicode.sub(line, unicode.len(prefix) + 1)
    length = length - unicode.wlen(prefix)
    if length > 0 then
      suffix = (" "):rep(unicode.charWidth(suffix) - length) .. unicode.sub(suffix, 2)
    end
    return suffix
  end
end

local function lengthToChars(line, length)
  if length > unicode.wlen(line) then
    return unicode.len(line) + 1
  else
    local prefix = unicode.wtrunc(line, length)
    return unicode.len(prefix) + 1
  end
end

local function isWideAtPosition(line, x)
  local index = lengthToChars(line, x)
  if index > unicode.len(line) then
    return false, false
  end
  local prefix = unicode.sub(line, 1, index)
  local char = unicode.sub(line, index, index)
  return unicode.isWide(char), unicode.wlen(prefix) == x
end

local function drawLine(x, y, w, h, lineNr)
  local yLocal = lineNr - scrollY
  local drawY = y - 1 + lineNr - scrollY

  if yLocal > 0 and yLocal <= h then
    local colors = {}
    local line = buffer[lineNr] or ""

    if cache[lineNr] and cache[lineNr][1] == line then
      colors = cache[lineNr][2]
    else
      local function appendTextInColor(text, color, bgcolor)
        local data = colors[#colors]

        if data ~= nil then
          if data[2] == color and data[3] == bgcolor then
            data[1] = data[1] .. text
          else
            colors[#colors + 1] = {text, color, bgcolor}
          end
        else
          colors[#colors + 1] = {text, color, bgcolor}
        end
      end

      local len = 0

      for char = 1, line:len() do
        if char > len then
          local patternFound = false

          for pat = 1, #patterns do
            local data = patterns[pat]
            local foundb, founde = line:find(data[1], char)

            if foundb ~= nil then
              local text = line:sub(foundb, founde)
              local color = data[2]
              local bgcolor = data[3]

              if type(color) == 'function' then
                color, bgcolor = color(text)
              end

              appendTextInColor(text, color, bgcolor)
              len = len + (founde - foundb + 1)

              patternFound = true
              break
            end
          end

          if not patternFound then
            appendTextInColor(line:sub(char, char), textColor)
            len = len + 1
          end
        end
      end

      cache[lineNr] = {line, colors}
    end

    local i = 0
    local cx, cy = term.getCursor()
    local lineBg = bgColor

    if cy + scrollY == lineNr then
      lineBg = lineColor
    end

    gpu.setBackground(lineBg)
    gpu.fill(1, y - 1 + lineNr - scrollY, 7, 1, ' ')
    gpu.fill(x, drawY, w + currentMargin, 1, ' ')

    if lineNr <= #buffer then
      for l = 1, #colors do
        local data = colors[l]
        local text = data[1]
        local color = data[2]
        local bg = data[3]
        local drawAt = i - scrollX + x

        if drawAt + text:len() > 0 then
          local currentColor = gpu.setForeground(color)
          local currentBg = gpu.setBackground(bg or lineBg)
          gpu.set(drawAt, drawY, text)
          gpu.setForeground(currentColor)
          gpu.setBackground(currentBg)
        end

        i = i + text:len()
      end

      local currentColor = gpu.setForeground(lineNrColor)
      local number = tostring(math.floor(lineNr))

      gpu.fill(1, y - 1 + lineNr - scrollY, 7, 1, ' ')
      gpu.set(2 + (5 - number:len()), y - 1 + lineNr - scrollY, number)
      gpu.setForeground(currentColor)
      gpu.setBackground(bgColor)
    end
  end
end

local function getCursor()
  local cx, cy = term.getCursor()
  return cx + scrollX - currentMargin, cy + scrollY
end

local function line()
  local cbx, cby = getCursor()
  return buffer[cby]
end

local function getNormalizedCursor()
  local cbx, cby = getCursor()
  local wide, right = isWideAtPosition(buffer[cby], cbx)
  if wide and right then
    cbx = cbx - 1
  end
  return cbx, cby
end

local function setCursor(nbx, nby)
  local x, y, w, h = getArea()
  nby = math.max(1, math.min(#buffer, nby))

  local ncy = nby - scrollY
  if ncy > h then
    term.setCursorBlink(false)
    local sy = nby - h
    local dy = math.abs(scrollY - sy)
    scrollY = sy
    if h > dy then
      gpu.copy(x - currentMargin, y + dy, w + currentMargin, h - dy, 0, -dy)
    end
    for lineNr = nby - (math.min(dy, h) - 1), nby do
      drawLine(x, y, w, h, lineNr)
    end
  elseif ncy < 1 then
    term.setCursorBlink(false)
    local sy = nby - 1
    local dy = math.abs(scrollY - sy)
    scrollY = sy
    if h > dy then
      gpu.copy(x - currentMargin, y, w + currentMargin, h - dy, 0, dy)
    end
    for lineNr = nby, nby + (math.min(dy, h) - 1) do
      drawLine(x, y, w, h, lineNr)
    end
  end
  term.setCursor(term.getCursor(), nby - scrollY)

  nbx = math.max(1, math.min(unicode.wlen(line()) + 1, nbx))
  local wide, right = isWideAtPosition(line(), nbx)
  local ncx = nbx - scrollX
  if ncx > w or (ncx + 1 > w and wide and not right) then
    term.setCursorBlink(false)
    scrollX = nbx - w + ((wide and not right) and 1 or 0)
    for lineNr = 1 + scrollY, math.min(h + scrollY, #buffer) do
      drawLine(x, y, w, h, lineNr)
    end
  elseif ncx < 1 or (ncx - 1 < 1 and wide and right) then
    term.setCursorBlink(false)
    scrollX = nbx - 1 - ((wide and right) and 1 or 0)
    for lineNr = 1 + scrollY, math.min(h + scrollY, #buffer) do
      drawLine(x, y, w, h, lineNr)
    end
  end
  term.setCursor(nbx - scrollX + currentMargin, nby - scrollY)
  nbx, nby = getCursor()
  gpu.set(x + w - 10, y + h, text.padLeft(string.format("%d,%d", nby, nbx), 10))
end

local function highlight(bx, by, length, enabled)
  local x, y, w, h = getArea()
  local cx, cy = bx - scrollX, by - scrollY
  cx = math.max(1, math.min(w, cx))
  cy = math.max(1, math.min(h, cy))
  length = math.max(1, math.min(w - cx, length))

  local fg, fgp = gpu.getForeground()
  local bg, bgp = gpu.getBackground()
  if enabled then
    gpu.setForeground(bg, bgp)
    gpu.setBackground(fg, fgp)
  end
  local indexFrom = lengthToChars(buffer[by], bx)
  local value = unicode.sub(buffer[by], indexFrom)
  if unicode.wlen(value) > length then
    value = unicode.wtrunc(value, length + 1)
  end
  gpu.set(x - 1 + cx, y - 1 + cy, value)
  if enabled then
    gpu.setForeground(fg, fgp)
    gpu.setBackground(bg, bgp)
  end
end

local function home()
  local cbx, cby = getCursor()
  setCursor(1, cby)
end

local function ende()
  local cbx, cby = getCursor()
  setCursor(unicode.wlen(line()) + 1, cby)
end

local function left()
  local cbx, cby = getNormalizedCursor()
  if cbx > 1 then
    local wideTarget, rightTarget = isWideAtPosition(line(), cbx - 1)
    if wideTarget and rightTarget then
      setCursor(cbx - 2, cby)
    else
      setCursor(cbx - 1, cby)
    end
    return true
  elseif cby > 1 then
    setCursor(cbx, cby - 1)
    ende()
    return true
  end
end

local function right(n)
  n = n or 1
  local cbx, cby = getNormalizedCursor()
  local be = unicode.wlen(line()) + 1
  local wide, right = isWideAtPosition(line(), cbx + n)
  if wide and right then
    n = n + 1
  end
  if cbx + n <= be then
    setCursor(cbx + n, cby)
  elseif cby < #buffer then
    setCursor(1, cby + 1)
  end
end

local function up(n)
  n = n or 1
  local cbx, cby = getCursor()
  if cby > 1 then
    setCursor(cbx, cby - n)
  end
end

local function down(n)
  n = n or 1
  local cbx, cby = getCursor()
  if cby < #buffer then
    setCursor(cbx, cby + n)
  end
end

local function delete(fullRow)
  local cx, cy = term.getCursor()
  local cbx, cby = getCursor()
  local x, y, w, h = getArea()
  local function deleteRow(row)
    local content = table.remove(buffer, row)
    local rcy = cy + (row - cby)
    if rcy <= h then
      gpu.copy(x, y + rcy, w, h - rcy, 0, -1)
      drawLine(x, y, w, h, row + (h - rcy))
    end
    return content
  end
  if fullRow then
    term.setCursorBlink(false)
    if #buffer > 1 then
      deleteRow(cby)
    else
      buffer[cby] = ""
      gpu.fill(x, y - 1 + cy, w, 1, " ")
    end
    setCursor(1, cby)
  elseif cbx <= unicode.wlen(line()) then
    term.setCursorBlink(false)
    local index = lengthToChars(line(), cbx)
    buffer[cby] = unicode.sub(line(), 1, index - 1) ..
                  unicode.sub(line(), index + 1)
    drawLine(x, y, w, h, cby)
  elseif cby < #buffer then
    term.setCursorBlink(false)
    local append = deleteRow(cby + 1)
    buffer[cby] = buffer[cby] .. append
    drawLine(x, y, w, h, cby)
  else
    return
  end
  setStatus(helpStatusText())
end

-- enter() jetzt mit Schalter für Auto-Indent
local function enter(autoIndent)
  if autoIndent == nil then autoIndent = true end

  term.setCursorBlink(false)
  local cx, cy = term.getCursor()
  local cbx, cby = getCursor()
  local x, y, w, h = getArea()
  local index = lengthToChars(line(), cbx)
  table.insert(buffer, cby + 1, unicode.sub(buffer[cby], index))
  buffer[cby] = unicode.sub(buffer[cby], 1, index - 1)
  drawLine(x, y, w, h, cby)
  if cy < h then
    if cy < h - 1 then
      gpu.copy(x, y + cy, w, h - (cy + 1), 0, 1)
    end
    drawLine(x, y, w, h, cby + 1)
  end

  if autoIndent then
    local whitespace = buffer[cby]:match('^[%s]+') or ""
    buffer[cby + 1] = whitespace .. buffer[cby + 1]
    setCursor(1 + whitespace:len(), cby + 1)
  else
    setCursor(1, cby + 1)
  end

  setStatus(helpStatusText())
end

local findText = ""

local function find()
  local x, y, w, h = getArea()
  local cx, cy = term.getCursor()
  local cbx, cby = getCursor()
  local ibx, iby = cbx, cby
  while running do
    if unicode.len(findText) > 0 then
      local sx, sy
      for syo = 1, #buffer do
        sy = (iby + syo - 1 + #buffer - 1) % #buffer + 1
        sx = string.find(buffer[sy], findText, syo == 1 and ibx or 1, true)
        if sx and (sx >= ibx or syo > 1) then
          break
        end
      end
      if not sx then
        sy = iby
        sx = string.find(buffer[sy], findText, nil, true)
      end
      if sx then
        sx = unicode.wlen(string.sub(buffer[sy], 1, sx - 1)) + 1
        cbx, cby = sx, sy
        setCursor(cbx, cby)
        highlight(cbx, cby, unicode.wlen(findText), true)
      end
    end
    term.setCursor(7 + unicode.wlen(findText), h + 1)
    setStatus("Find: " .. findText)

    local _, address, char, code = term.pull("key_down")
    if address == term.keyboard() then
      local handler, name = getKeyBindHandler(code)
      highlight(cbx, cby, unicode.wlen(findText), false)
      if name == "newline" then
        break
      elseif name == "close" then
        handler()
      elseif name == "backspace" then
        findText = unicode.sub(findText, 1, -2)
      elseif name == "find" or name == "findnext" then
        ibx = cbx + 1
        iby = cby
      elseif not keyboard.isControl(char) then
        findText = findText .. unicode.char(char)
      end
    end
  end
  setCursor(cbx, cby)
  setStatus(helpStatusText())
end

local function fix()
  local x, y, w, h = getArea()

  gpu.fill(x, y, w, h, ' ')

  for i = 1, #buffer do
    if i > scrollY and i <= (scrollY + h) then
      drawLine(x, y, w, h, i)
    end
  end
end

local function jump()
  local x, y, w, h = getArea()
  local cx, cy = term.getCursor()
  local currentStatus = currentStatus

  setStatus('Jump to line #')

  local current = ''

  while true do
    local _, address, char, code = term.pull('key_down')

    char = math.floor(char)

    if address == term.keyboard() then
      if char == 13 then
        break
      elseif char >= string.byte('0') and char <= string.byte('9') then
        if current:len() < 5 then
          current = current .. string.char(char)
        end
      elseif char == 127 then
        if current:len() > 0 then
          current = current:sub(1, -1)
        end
      end

      term.setCursor(15, h + 1)
      gpu.set(15, h + 1, '     ')
      term.write(current)
    end
  end

  term.setCursor(cx, cy)

  current = tonumber(current)

  if current then
    if current <= #buffer then
      setCursor(1, current)
      setStatus('Jumped to line ' .. tostring(current))
    else
      setStatus('Line ' .. tostring(current) .. ' does not exist')
    end
  else
    setStatus(currentStatus)
  end
end

local keyBindHandlers = {
  left = left,
  right = right,
  up = up,
  down = down,
  home = home,
  eol = ende,
  pageUp = function()
    local x, y, w, h = getArea()
    up(h - 1)
  end,
  pageDown = function()
    local x, y, w, h = getArea()
    down(h - 1)
  end,

  backspace = function()
    if not readonly and left() then
      delete()
    end
  end,
  delete = function()
    if not readonly then
      delete()
    end
  end,
  deleteLine = function()
    if not readonly then
      delete(true)
    end
  end,
  newline = function()
    if not readonly then
      enter()
    end
  end,

  save = function()
    if readonly then return end
    local new = not fs.exists(filename)
    local backup
    if not new then
      backup = filename .. "~"
      for i = 1, math.huge do
        if not fs.exists(backup) then
          break
        end
        backup = filename .. "~" .. i
      end
      fs.copy(filename, backup)
    end
    if not fs.exists(file_parentpath) then
      fs.makeDirectory(file_parentpath)
    end
    local f, reason = io.open(filename, "w")
    if f then
      local chars, firstLine = 0, true
      for _, line in ipairs(buffer) do
        if not firstLine then
          line = "\n" .. line
        end
        firstLine = false
        f:write(line)
        chars = chars + unicode.len(line)
      end
      f:close()
      local format
      if new then
        format = [["%s" [New] %dL,%dC written]]
      else
        format = [["%s" %dL,%dC written]]
      end
      setStatus(string.format(format, fs.name(filename), #buffer, chars))
    else
      setStatus(reason)
    end
    if not new then
      fs.remove(backup)
    end
  end,
  close = function()
    running = false
  end,
  find = function()
    findText = ""
    find()
  end,
  findnext = find,

  jump = jump
}

getKeyBindHandler = function(code)
  if type(config.keybinds) ~= "table" then return end
  local result, resultName, resultWeight = nil, nil, 0
  for command, keybinds in pairs(config.keybinds) do
    if type(keybinds) == "table" and keyBindHandlers[command] then
      for _, keybind in ipairs(keybinds) do
        if type(keybind) == "table" then
          local alt, control, shift, key
          for _, value in ipairs(keybind) do
            if value == "alt" then alt = true
            elseif value == "control" then control = true
            elseif value == "shift" then shift = true
            else key = value end
          end
          local keyboardAddress = term.keyboard()
          if (not alt or keyboard.isAltDown(keyboardAddress)) and
             (not control or keyboard.isControlDown(keyboardAddress)) and
             (not shift or keyboard.isShiftDown(keyboardAddress)) and
             code == keyboard.keys[key] and
             #keybind > resultWeight
          then
            resultWeight = #keybind
            resultName = command
            result = keyBindHandlers[command]
          end
        end
      end
    end
  end
  return result, resultName
end

local function insert(value)
  if not value or unicode.len(value) < 1 then
    return
  end
  term.setCursorBlink(false)
  local cx, cy = term.getCursor()
  local cbx, cby = getCursor()
  local x, y, w, h = getArea()
  local index = lengthToChars(line(), cbx)
  buffer[cby] = unicode.sub(line(), 1, index - 1) ..
                value ..
                unicode.sub(line(), index)
  drawLine(x, y, w, h, cby)
  right(unicode.wlen(value))
  setStatus(helpStatusText())
end

local function onKeyDown(char, code)
  local handler = getKeyBindHandler(code)
  if handler then
    handler()
  elseif readonly and code == keyboard.keys.q then
    running = false
  elseif not readonly then
    if not keyboard.isControl(char) then
      insert(unicode.char(char))
    elseif unicode.char(char) == "\t" then
      insert("  ")
    end
  end
end

-- WICHTIG: hier das Einfügen fixen
local function onClipboard(value)
  value = value:gsub("\r\n", "\n")
  local cbx, cby = getCursor()
  local start = 1
  local l = value:find("\n", 1, true)
  if l then
    repeat
      local line = string.sub(value, start, l - 1)
      line = text.detab(line, 2)
      insert(line)
      -- beim Einfügen KEIN Auto-Indent
      enter(false)
      start = l + 1
      l = value:find("\n", start, true)
    until not l
  end
  insert(string.sub(value, start))
end

local function onClick(x, y)
  setCursor(x + scrollX, y + scrollY)
end

local function onScroll(direction)
  local cbx, cby = getCursor()
  setCursor(cbx, cby - direction * 12)
end

do
  local f = io.open(filename)
  if f then
    local x, y, w, h = getArea()
    local chars = 0
    for line in f:lines() do
      table.insert(buffer, line)
      chars = chars + unicode.len(line)
      if #buffer <= h then
        drawLine(x, y, w, h, #buffer)
      end
    end
    f:close()
    if #buffer == 0 then
      table.insert(buffer, "")
    end
    local format
    if readonly then
      format = [["%s" [readonly] %dL,%dC]]
    else
      format = [["%s" %dL,%dC]]
    end
    setStatus(string.format(format, fs.name(filename), #buffer, chars))
  else
    table.insert(buffer, "")
    setStatus(string.format([["%s" [New File] ]], fs.name(filename)))
  end
  setCursor(1, 1)
end

while running do
  local startX = scrollX
  local startY = scrollY
  local _, startC = getCursor()

  local event, address, arg1, arg2, arg3 = term.pull()
  if address == term.keyboard() or address == term.screen() then
    local blink = true
    if event == "key_down" then
      onKeyDown(arg1, arg2)
    elseif event == "clipboard" and not readonly then
      onClipboard(arg1)
    elseif event == "touch" or event == "drag" then
      local x, y, w, h = getArea()
      arg1 = arg1 - x + 1
      arg2 = arg2 - y + 1
      if arg1 >= 1 and arg2 >= 1 and arg1 <= w and arg2 <= h then
        onClick(arg1, arg2)
      end
    elseif event == "scroll" then
      onScroll(arg3)
    else
      blink = false
    end
    if blink then
      term.setCursorBlink(true)
    end

    local _, endC = getCursor()
    local x, y, w, h = getArea()

    if startC ~= endC then
      drawLine(x, y, w, h, startC)
    end

    drawLine(x, y, w, h, endC)
  end
end

resetColors()
term.clear()
term.setCursorBlink(true)