config API

--[[
    This code is licensed with CreativeCommons BY-NC-SA:
    http://creativecommons.org/licenses/by-nc-sa/3.0/
    You are free to change and redistribut this as long as you give credit to me, the author,
    Stiepen/Kilobyte.
    You also need to distribute your code but you have to use the same license
    Exceptions from this rule are parts of the code that are taken from the regular CC files, since i don't own the rights For them
--]]

local function loadImpl(tLines, pos)
  local ret = {}
  while tLines[pos] do
    local l = tLines[pos]
    pos = pos + 1
    if string.sub(l, 1, 1) == "#" then
      --the line is a comment
    elseif string.find(l, "=") then
      local eqpos = string.find(l, "=")
      local key, val
      key = string.sub(l, 1, eqpos-1)
      val = string.sub(l, eqpos + 3)
      sType = string.sub(l, eqpos + 1, eqpos + 1)
      if sType == "s" then
        ret[key] = val
      elseif sType == "n" then
        ret[key] = tonumber(val)
      elseif sType == "b" then
        ret[key] = (val == "true")
      end
    elseif string.sub(l, -2, -1) == "[[" then
      ret[string.sub(l, 1, -3)], pos = loadImpl(tLines, pos)
    elseif l == "]]" then
      break
    elseif l == "" then
    else
      error("Invalid Config File")
    end
  end
  return ret, pos
end

local function readAsTable(_sFile, _fs)
  local f = _fs.open(_sFile, "r")
  local ret = {}
  while true do
    local line = f.readLine()
    if not line then break end
    table.insert(ret, line)
  end
  f.close()
  return ret
end
--[[
    Loads a config file

    @param _sFile The name of the file where the config should be loaded from.
    Optional @param _fs a file system to use. leave empty or set to nil if you don't know what this means

    @returns a table containing the config info
--]]
function load(_sFile, _fs)
  if not _fs then _fs = fs end
  if not _fs.exists(_sFile) and not _fs.isReadOnly(_sFile) then local f = _fs.open(_sFile, "w") print(f) f.close() end
  if not _fs.isDir(_sFile) then
    local lines = readAsTable(_sFile, _fs)
    local ret, pos = loadImpl(lines, 1)
    return ret
  end
  print("Found you!")
  return nil, "couldn't load config"
end

local function saveImpl(tIn)
  local ret = ""
  for i, v in pairs(tIn) do
    if string.find(i, "=") then
      error("config option key must not contain '='")
    end
    if string.sub(i, 1, 1) == "#" then
      error("key must not start with '#'")
    end
    sType = type(v)
    if sType == "string" then
      ret = ret..i.."=s:"..v.."\n"
    elseif sType == "number" then
      ret = ret..i.."=n:"..v.."\n"
    elseif sType == "boolean" then
      local v_ = "false" if v then v_ = "true" end
      ret = ret..i.."=b:"..v_.."\n"
    elseif sType == "table" then
      ret = ret..i.."[[\n"
      ret = ret..saveImpl(v).."]]\n"
    end
  end
  return ret
end

--[[
    Saves config options from a table to a file

    @param _sFile The filename/path
    @param _tCfg The config option table to write
    @_tComments no effect yet, set to nil or leave out
    Optional @param _fs The filesystem to use. see above
--]]
function save(_sFile, _tCfg, _tComments, _fs)
  if not _fs then _fs = fs end
  local data = saveImpl(_tCfg)
  local f = _fs.open(_sFile, "w")
  f.write(data)
  f.close()
end