Browser for GrimShell

--==============================
-- File browser using GrimShell
--
-- Written by PaymentOption
-- 19 November 2012
--==============================

-- Variables --
local scroll = 0 -- The scroll offest of items drawn in the current directory.
local currentDirectory = "" -- The current directory that the interface is in.

local interfaceTitle = "Browser"
local interfaceHeight = 8 -- The amount of options minus the MORE option (if any) allowed to be displayed at any time.
local interfaceWidth = interfaceTitle:len() + 2
local interface_xPos, interface_yPos = 2, 2
local interfaceOptions = {}

local browserInterface = nil
---------------

-- Functions --
-- This function will be assigned to each file so that
-- when they are clicked, nothing will be executed.
function emptyFunction()
end

-- This function will be assigend to each directory so
-- that when they are clicked, they will be entered.
-- Params: optionIndex - The index of this option in the
--                       interface options table.
function enterDirectory(path)
      updateInterfaceData(browserInterface)
      currentDirectory = currentDirectory .. '/' .. path
      local newOptions = setOptionsProperly(getObjectsAsOptions(currentDirectory, scroll))
      browserInterface.setOptions(newOptions)
end

function setOptionsProperly(options)
      for index, option in pairs(options) do
            if option.label == "MORE" and not option.path then
                  option.associatedFunction = function() showMore(); end
            elseif option.path and fs.isDir(currentDirectory .. '/' .. option.path) then
                  option.associatedFunction = function() enterDirectory(option.path); end
            else
                  option.associatedFunction = emptyFunction
            end
      end

      return options
end

-- This function updates the scroll of the displayed files/directories.
function showMore()
      scroll = scroll + interfaceHeight
      updateInterfaceData(browserInterface)
      local newOptions = setOptionsProperly(getObjectsAsOptions(currentDirectory, scroll))
      browserInterface.setOptions(newOptions)
end

-- Returns an options table that contains options which act
-- as the files/directories within the current directory.
-- Only directories will have functions assigned to them that allow
-- them to be entered; files will have empty functions assigned to them.
-- Format for an options table:
--    interfaceOptions[n] = {label = (string), xPos = (number), yPos = (number), associatedFunction = (function),
--                           itemTextColor = (number(color)), itemBackgroundColor = (number(color))}
function getObjectsAsOptions(path, scroll)
      -- Truncates the name of a file/directory in the case that it is too long.
      local function truncateName(name)
            if name:len() > interfaceWidth - 2 then
                  name = name:sub(1, interfaceWidth - 5) .. "..."
            end

            return name
      end

      local files = fs.list(path)
      local areMoreFiles = (#files - scroll > interfaceHeight) -- Whether or not there are more files to be displayed.
      local newOptions = {}

      local breakPoint = (scroll/interfaceHeight == 0) and interfaceHeight or interfaceHeight*(scroll/interfaceHeight)
      local fileIndex = 0
      for fileIndex = scroll + 1, #files do
            if fileIndex == breakPoint then
                  break
            end

            table.insert(newOptions, {label = truncateName(files[fileIndex]), xPos = interface_xPos + 1, yPos = fileIndex + interface_yPos, associatedFunction = (fs.isDir(files[fileIndex])) and (function() enterDirectory(files[fileIndex]); end) or emptyFunction,
                                      itemTextColor = colors.black, itemBackgroundColor = colors.white, path = files[fileIndex]})
      end

      -- Add the 'MORE' option if there is one.
      if areMoreFiles then
            table.insert(newOptions, {label = "MORE", xPos = interface_xPos + 1, yPos = interface_yPos + interfaceHeight + 1, associatedFunction = showMore,
                                      itemTextColor = colors.black, itemBackgroundColor = colors.white})
      end

      return newOptions
end

-- Takes a new path for the interface to enter, then
-- sets the current directory to the given path.
function setDirectory(newDirectory)
      currentDirectory = newDirectory
end

-- Updates all necessary information from the interface to run the program.
function updateInterfaceData(interface)
      interface_xPos, interface_yPos = interface.getPosition()
end
---------------

interfaceOptions = getObjectsAsOptions(currentDirectory, scroll)
browserInterface = interface.Interface.new(interface_xPos, interface_yPos, interfaceOptions, colors.blue, interfaceTitle, "Browser_Interface", true, interfaceWidth)