--[[ Copyright (c) 2009 Peter "Corsix" Cawley

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE. --]]

local pathsep = package.config:sub(1, 1)
local rnc = require "rnc"
local lfs = require "lfs"
local TH = require "TH"
local SDL = require "sdl"
local assert, io, type, dofile, loadfile, pcall, tonumber, print
    = assert, io, type, dofile, loadfile, pcall, tonumber, print

-- Increment each time a savegame break would occur
-- and add compatibility code in afterLoad functions
local SAVEGAME_VERSION = 16

class "App"

function App:App()
  self.command_line = {}
  self.config = {}
  self.runtime_config = {}
  self.running = false
  self.gfx = {}
  self.last_dispatch_type = ""
  self.eventHandlers = {
    frame = self.drawFrame,
    timer = self.onTick,
    keydown = self.onKeyDown,
    keyup = self.onKeyUp,
    buttonup = self.onMouseUp,
    buttondown = self.onMouseDown,
    motion = self.onMouseMove,
    music_over = self.onMusicOver,
  }
  self.strings = {}
  self.savegame_version = SAVEGAME_VERSION
end

function App:setCommandLine(...)
  self.command_line = {...}
  for i, arg in ipairs(self.command_line) do
    local setting, value = arg:match"^%-%-([^=]*)=(.*)$" --setting=value
    if value then
      self.command_line[setting] = value
    end
  end
end

function App:init()
  -- App initialisation 1st goal: Get the loading screen up
  
  -- Prereq 1: Config file (for screen width / height / TH folder)
  -- Note: These errors cannot be translated, as the config file specifies the language
  local conf_path = self.command_line["config-file"] or "config.txt"
  local conf_chunk, conf_err = loadfile_envcall(conf_path)
  if not conf_chunk then
    error("Unable to load the config file. Please ensure that CorsixTH "..
    "has permission to read/write ".. conf_path ..", or use the "..
    "--config-file=filename command line option to specify a writable file. "..
    "For reference, the error loading the config file was: " .. conf_err)
  else
    conf_chunk(self.config)
  end
  self:fixConfig()
  dofile "filesystem"
  local good_install_folder = self:checkInstallFolder()
  -- self:checkLanguageFile()
  self.savegame_dir = self.config.savegames or conf_path:match("^(.-)[^".. pathsep .. "]*$") .. "Saves"
  if self.savegame_dir:sub(-1, -1) == pathsep then
    self.savegame_dir = self.savegame_dir:sub(1, -2)
  end
  if lfs.attributes(self.savegame_dir, "mode") ~= "directory" then
    if not lfs.mkdir(self.savegame_dir) then
       print "Notice: Savegame directory does not exist and could not be created."
    end
  end
  if self.savegame_dir:sub(-1, -1) ~= pathsep then
    self.savegame_dir = self.savegame_dir .. pathsep
  end
  
  -- Create the window
  if not SDL.init("audio", "video", "timer") then
    return false, "Cannot initialise SDL"
  end
  local compile_opts = TH.GetCompileOptions()
  local api_version = dofile "api_version"
  if api_version ~= compile_opts.api_version then
    api_version = api_version or 0
    compile_opts.api_version = compile_opts.api_version or 0
    if api_version < compile_opts.api_version then
      print "Notice: Compiled binary is more recent than Lua scripts."
    elseif api_version > compile_opts.api_version then
      print("Warning: Compiled binary is out of date. CorsixTH will likely"..
      " fail to run until you recompile the binary.")
    end
  end
  local caption_descs = {compile_opts.renderer}
  if compile_opts.jit then
    caption_descs[#caption_descs + 1] = compile_opts.jit
  end
  if compile_opts.arch_64 then
    caption_descs[#caption_descs + 1] = "64 bit"
  end
  self.caption = "CorsixTH (" .. table.concat(caption_descs, ", ") .. ")"
  SDL.wm.setCaption(self.caption)
  local modes = {"hardware", "doublebuf"}
  self.fullscreen = false
  if _MAP_EDITOR then
    modes[#modes + 1] = "reuse context"
    self.config.width = 640
    self.config.height = 480
  elseif self.config.fullscreen then
    self.fullscreen = true
    modes[#modes + 1] = "fullscreen"
  end
  if self.config.track_fps then
    modes[#modes + 1] = "present immediate"
  end
  self.modes = modes
  self.video = assert(TH.surface(self.config.width, self.config.height, unpack(modes)))
  SDL.wm.setIconWin32()
  
  
  -- Prereq 2: Load and initialise the graphics subsystem
  dofile "persistance"
  dofile "graphics"
  self.gfx = Graphics(self)
  
  -- Put up the loading screen
  if good_install_folder then
    self.video:startFrame()
    self.gfx:loadRaw("Load01V", 640, 480):draw(self.video,
      (self.config.width - 640) / 2, (self.config.height - 480) / 2)
    self.video:endFrame()
  end
  
  -- App initialisation 2nd goal: Load remaining systems and data in an appropriate order
  
  math.randomseed(os.time() + SDL.getTicks())
  
  -- Load audio
  dofile "audio"
  self.audio = Audio(self)
  self.audio:init()
  
  -- Load strings before UI and before additional Lua
  dofile "strings"
  self.strings = Strings(self)
  self.strings:init()
  self:initLanguage()
  if (self.command_line.dump or ""):match"strings" then
    -- Specify --dump=strings on the command line to dump strings
    -- (or insert "true or" after the "if" in the above)
    self:dumpStrings()
  end
  
  -- Load map before world
  dofile "map"
  
  -- Load additional Lua before world
  if good_install_folder then
    self.anims = self.gfx:loadAnimations("Data", "V")
    self.animation_manager = AnimationManager(self.anims)
    self.walls = self:loadLuaFolder"walls"
    dofile "entities/object"
    dofile "entities/machine"

    local objects = self:loadLuaFolder"objects"
    self.objects = self:loadLuaFolder("objects/machines", nil, objects)
    -- Doors are in their own folder to ensure that the swing doors (which 
    -- depend on the door) are loaded after the door object.
    self.objects = self:loadLuaFolder("objects/doors", nil, objects)
    for _, v in ipairs(self.objects) do
      if v.slave_id then
        v.slave_type = self.objects[v.slave_id]
        v.slave_type.master_type = v
      end
      Object.processTypeDefinition(v)
    end
    dofile "room"
    self.rooms = self:loadLuaFolder"rooms"
    self.humanoid_actions = self:loadLuaFolder"humanoid_actions"
    local diseases = self:loadLuaFolder"diseases"
    self.diseases = self:loadLuaFolder("diagnosis", nil, diseases)
    -- Load world before UI
    dofile "world"
  end
  
  -- Load UI
  dofile "ui"
  if good_install_folder then
    dofile "game_ui"
  else
    self.ui = UI(self, true)
    self.ui:setMenuBackground()
    self.ui:addWindow(UIDirBrowser(self.ui))
    return true
  end
  
  -- Load main menu (which creates UI)
  self:loadMainMenu()
  -- If a savegame was specified, load it
  if self.command_line.load then
    local status, err = pcall(self.load, self, self.command_line.load)
    if not status then
      err = _S.errors.load_prefix .. err
      print(err)
      self.ui:addWindow(UIInformation(self.ui, {err}))
    end
  end
  return true
end

function App:initLanguage()
  local strings, speech_file = self.strings:load(self.config.language)
  strict_declare_global "_S"
  local old_S = _S
  _S = strings
  -- For immediate compatibility:
  getmetatable(_S).__call = function(_, sec, str, ...)
    assert(_S.deprecated[sec] and _S.deprecated[sec][str], "_S(".. sec ..", ".. str ..") does not exist!")
    
    str = _S.deprecated[sec][str]
    if ... then
      str = str:format(...)
    end
    return str
  end
  if old_S then
    unpermanent "_S"
  end
  _S = permanent("_S", TH.stringProxy(_S))
  if old_S then
    TH.stringProxy.reload(old_S, _S)
  end
  if self.ui then
    self.ui:onChangeLanguage()
  end
  self.audio:initSpeech(speech_file)
end

function App:loadMainMenu(message)
  -- Unload ui, world and map
  self.ui = nil
  self.world = nil
  self.map = nil

  self.ui = UI(self)
  self.ui:setMenuBackground()
  self.ui:addWindow(UIMainMenu(self.ui))
  self.ui:addWindow(UITipOfTheDay(self.ui))
  
  -- If a message was supplied, show it
  if message then
    self.ui:addWindow(UIInformation(self.ui, {message}))
  end
end

-- Loads the specified level. If a string is passed it looks for the file with the same name
-- in the "Levels" folder of CorsixTH, if it is a number it tries to load that level from
-- the original game.
function App:loadLevel(level, ...)
  -- Check that we can load the data before unloading current map
  local new_map = Map(self)
  local map_objects, errors = new_map:load(level, ...)
  if not map_objects then
    error(errors)
  end
  -- Unload ui, world and map
  self.ui = nil
  self.world = nil
  self.map = nil
  
  -- Load map
  self.map = new_map
  self.map:setBlocks(self.gfx:loadSpriteTable("Data", "VBlk-0"))
  self.map:setDebugFont(self.gfx:loadFont("QData", "Font01V"))
  
  -- Load world
  self.world = World(self)
  self.world:createMapObjects(map_objects)
  
  -- Load UI
  self.ui = GameUI(self, self.world:getLocalPlayerHospital())
  self.world:setUI(self.ui) -- Function call allows world to set up its keyHandlers
end

-- This is a useful debug and development aid
function App:dumpStrings()
  -- Accessors to reach through the userdata proxies on strings
  local LUT = debug.getregistry().StringProxyValues
  local function val(o)
    if type(o) == "userdata" then
      return LUT[o]
    else
      return o
    end
  end
  local function is_table(o)
    return type(val(o)) == "table"
  end
  
  local fi = assert(io.open("debug-strings-orig.txt", "wt"))
  for i, sec in ipairs(_S.deprecated) do
    for j, str in ipairs(sec) do
      fi:write("[" .. i .. "," .. j .. "] " .. ("%q\n"):format(val(str)))
    end
    fi:write"\n"
  end
  fi:close()
  
  local function dump_by_line(file, obj, prefix)
    for n, o in pairs(obj) do
      if n ~= "deprecated" then
        local new_prefix
        if type(n) == "number" then
          new_prefix = prefix .. "[" .. n .. "]"
        else
          new_prefix = (prefix == "") and n or (prefix .. "." .. n)
        end
        if is_table(o) then
          dump_by_line(file, o, new_prefix)
        else
          file:write(new_prefix .. " = " .. "\"" .. val(o) .. "\"\n")
        end
      end
    end
  end
  
  local function dump_grouped(file, obj, prefix)
    for n, o in pairs(obj) do
      if n ~= "deprecated" then
        if type(n) == "number" then
          n = "[" .. n .. "]"
        end
        if is_table(o) then
          file:write(prefix .. n .. " = {\n")
          dump_grouped(file, o, prefix .. "  ")
          file:write(prefix .. "}")
        else
          file:write(prefix .. n .. " = " .. "\"" .. val(o) .. "\"")
        end
        if prefix ~= "" then
          file:write(",")
        end
        file:write("\n")
      end
    end
  end
  
  fi = assert(io.open("debug-strings-new-lines.txt", "wt"))
  dump_by_line(fi, _S, "")
  fi:close()

  fi = assert(io.open("debug-strings-new-grouped.txt", "wt"))
  dump_grouped(fi, _S, "")
  fi:close()
end

function App:fixConfig()
  -- Fill in default values for things which dont exist
  local _, config_defaults = dofile "config_finder"
  for k, v in pairs(config_defaults) do
    if self.config[k] == nil then
      self.config[k] = v
    end
  end
  
  for key, value in pairs(self.config) do
    -- Trim whitespace from beginning and end string values - it shouldn't be
    -- there (at least in any current configuration options).
    if type(value) == "string" then
      if value:match"^[%s]" or value:match"[%s]$" then
        self.config[key] = value:match"^[%s]*(.-)[%s]*$"
      end
    end
    
    -- For language, make language name lower case
    if key == "language" and type(value) == "string" then
      self.config[key] = value:lower()
    end
    
    -- For resolution, check that resolution is at least 640x480
    if key == "width" and type(value) == "number" and value < 640 then
      self.config[key] = 640
    end
    
    if key == "height" and type(value) == "number" and value < 480 then
      self.config[key] = 480
    end
  end
end

function App:saveConfig()
  -- Load lines from config file
  local fi = io.open(self.command_line["config-file"] or "config.txt", "r")
  local lines = {}
  local handled_ids = {}
  if fi then
    for line in fi:lines() do
      lines[#lines + 1] = line
      if not (string.find(line, "^%s*$") or string.find(line, "^%s*%-%-")) then -- empty lines or comments
        -- Look for identifiers we want to save
        local _, _, identifier, value = string.find(line, "^%s*([_%a][_%w]*)%s*=%s*(.-)%s*$")
        if identifier then
          -- Trim possible trailing comment from value
          local _, _, temp = string.find(value, "^(.-)%s*%-%-.*")
          value = temp or value
          -- Remove enclosing [[]], if necessary
          local _, _, temp = string.find(value, "^%[%[(.*)%]%]$")
          value = temp or value
          
          -- If identifier also exists in runtime options, compare their values and
          -- replace the line, if needed
          if self.config[identifier] ~= nil then
            handled_ids[identifier] = true
            if value ~= tostring(self.config[identifier]) then
              local new_value = self.config[identifier]
              if type(new_value) == "string" then
                new_value = string.format("[[%s]]", new_value)
              else
                new_value = tostring(new_value)
              end
              lines[#lines] = string.format("%s = %s", identifier, new_value)
            end
          end
        end
      end
    end
    fi:close()
  end
  -- Append options that were not found
  for identifier, value in pairs(self.config) do
    if not handled_ids[identifier] then
      if type(value) == "string" then
        value = string.format("[[%s]]", value)
      else
        value = tostring(value)
      end
      lines[#lines + 1] = string.format("%s = %s", identifier, value)
    end
  end
  -- Trim trailing newlines
  while lines[#lines] == "" do
    lines[#lines] = nil
  end

  fi = io.open(self.command_line["config-file"] or "config.txt", "w")
  for _, line in ipairs(lines) do
    fi:write(line .. "\n")
  end
  fi:close()
end

function App:run()
  -- The application "main loop" is an SDL event loop written in C, which calls
  -- a coroutine whenver an event occurs. Initially it may seem odd to involve
  -- coroutines, but it does give a few advantages:
  --  1) Lua can signal the main loop to exit by finishing the coroutine
  --  2) If an error occurs, the call stack is preserved in the coroutine, so
  --     Lua can query or print the call stack as required, rather than
  --     hardcoding error behaviour in C.
  local co = coroutine.create(function(self)
    local yield = coroutine.yield
    local dispatch = self.dispatch
    local repaint = true
    while self.running do
      repaint = dispatch(self, yield(repaint))
    end
  end)
  
  if self.config.track_fps then
    SDL.trackFPS(true)
    SDL.limitFPS(false)
  end
  
  self.running = true
  do
    local num_iterations = 0
    self.resetInfiniteLoopChecker = function()
      num_iterations = 0
    end
    debug.sethook(co, function()
      num_iterations = num_iterations + 1
      if num_iterations == 100 then
        error("Suspected infinite loop", 2)
      end
    end, "", 1e7)
  end
  coroutine.resume(co, self)
  local e, where = SDL.mainloop(co)
  debug.sethook(co, nil)
  self.running = false
  if e ~= nil then
    if where then
      -- Errors from an asynchronous callback done on the dispatcher coroutine
      -- will end up here. As the error didn't originate from a dispatched
      -- event, self.last_dispatch_type is wrong. Therefore, an extra value is
      -- returned from mainloop(), meaning that where == "callback".
      self.last_dispatch_type = where
    end
    print("An error has occured while running the " .. self.last_dispatch_type .. " handler.")
    print "A stack trace is included below, and the handler has been disconnected."
    print(debug.traceback(co, e, 0))
    print ""
    if self.world then
      self.world:gameLog("Error in " .. self.last_dispatch_type .. " handler: ")
      self.world:gameLog(debug.traceback(co, e, 0))
      self.world:dumpGameLog()
    end
    if self.world and self.last_dispatch_type == "timer" and self.world.current_tick_entity then
      -- Disconnecting the tick handler is quite a drastic measure, so give
      -- the option of just disconnecting the offending entity and attemping
      -- to continue.
      local handler = self.eventHandlers[self.last_dispatch_type]
      local entity = self.world.current_tick_entity
      self.world.current_tick_entity = nil
      if class.is(entity, Patient) then
        self.ui:addWindow(UIPatient(self.ui, entity))
      elseif class.is(entity, Staff) then
        self.ui:addWindow(UIStaff(self.ui, entity))
      end
      self.ui:addWindow(UIConfirmDialog(self.ui,
        "An error has occured while running the timer handler - see the log "..
        "window for details. Would you like to attempt a recovery?",
        --[[persistable:app_attempt_recovery]] function()
          self.world:gameLog("Recovering from error in timer handler...")
          entity.ticks = false
          self.eventHandlers.timer = handler
        end
      ))
    end
    self.eventHandlers[self.last_dispatch_type] = nil
    if self.last_dispatch_type ~= "frame" then
      -- If it wasn't the drawing code which failed, then it would be useful
      -- to ensure that a draw happens, as with events disconnected, a frame
      -- might not otherwise be drawn for a while.
      pcall(self.drawFrame, self)
    end
    return self:run()
  end
end

local done_no_handler_warning = {}

function App:dispatch(evt_type, ...)
  local handler = self.eventHandlers[evt_type]
  if handler then
    self:resetInfiniteLoopChecker()
    self.last_dispatch_type = evt_type
    return handler(self, ...)
  else
    if not done_no_handler_warning[evt_type] then
      print("Warning: No event handler for " .. evt_type)
      done_no_handler_warning[evt_type] = true
    end
    return false
  end
end

function App:onTick(...)
  if self.world then
    self.world:onTick(...)
  end
  self.ui:onTick(...)
  return true -- tick events always result in a repaint
end

local fps_history = {} -- Used to average FPS over the last thirty frames
for i = 1, 30 do fps_history[i] = 0 end
local fps_sum = 0 -- Sum of fps_history array
local fps_next = 1 -- Used to loop through fps_history when [over]writing

function App:drawFrame()
  self.video:startFrame()
  self.ui:draw(self.video)
  self.video:endFrame()
  
  if self.config.track_fps then
    fps_sum = fps_sum - fps_history[fps_next]
    fps_history[fps_next] = SDL.getFPS()
    fps_sum = fps_sum + fps_history[fps_next]
    fps_next = (fps_next % #fps_history) + 1
  end
end

function App:getFPS()
  if self.config.track_fps then
    return fps_sum / #fps_history
  end
end

function App:onKeyDown(...)
  return self.ui:onKeyDown(...)
end

function App:onKeyUp(...)
  return self.ui:onKeyUp(...)
end

function App:onMouseUp(...)
  return self.ui:onMouseUp(...)
end

function App:onMouseDown(...)
  return self.ui:onMouseDown(...)
end

function App:onMouseMove(...)
  return self.ui:onMouseMove(...)
end

function App:onMusicOver(...)
  return self.audio:onMusicOver(...)
end

function App:checkInstallFolder()
  self.fs = FileSystem()
  local status, err
  if self.config.theme_hospital_install then
    status, err = self.fs:setRoot(self.config.theme_hospital_install)
  end
  local message = "Please ensure that the theme_hospital_install setting in"..
    " config.txt points to a copy of the data files from the original game,"..
    " as said files are required for graphics and sounds."
  if not status then
    -- If the given directory didn't exist, then likely the config file hasn't
    -- been changed at all from the default, so we continue to initialise the
    -- app, and give the user a dialog asking for the correct directory.
    return false
  end
  
  -- Check that a few core files are present
  local missing = {}
  local function check(path)
    if not self.fs:readContents(path) then
      missing[#missing + 1] = path
    end
  end
  check("Data".. pathsep .."VBlk-0.tab")
  check("Levels".. pathsep .."Level.L1")
  check("QData".. pathsep .."SPointer.dat")
  if #missing ~= 0 then
    missing = table.concat(missing, ", ")
    error("Invalid Theme Hospital install folder specified in config file, "..
          "as at least the following files are missing: ".. missing ..".\n"..
          message)
  end
    
  -- Check for demo version
  if self.fs:readContents("DataM", "Demo.dat") then
    print "Notice: Using data files from demo version of Theme Hospital."
    print "Consider purchasing a full copy of the game to support EA."
  end
  return true
end

-- TODO: is it okay to remove this without replacement?
--[[
function App:checkLanguageFile()
  -- Some TH installs are trimmed down to a single language file, rather than
  -- providing every language file. If the user has selected a language which
  -- isn't present, then we should detect this and inform the user of their
  -- options.
  
  local filename = self:getDataFilename("Lang-" .. self.config.language .. ".dat")
  local file, err = io.open(filename, "rb")
  if file then
    -- Everything is fine
    file:close()
    return
  end
  
  print "Theme Hospital install seems to be missing the language file for the language which you requested."
  print "The following language files are present:"
  local none = true
  local is_win32 = not not package.cpath:lower():find(".dll", 1, true)
  for item in lfs.dir(self.config.theme_hospital_install .. self.data_dir_map.DATA) do
    local n = item:upper():match"^LANG%-([0-9]+)%.DAT$"
    if n then
      local name = languages_by_num[tonumber(n)] or "??"
      local warning = ""
      if not is_win32 and item ~= item:upper() then
        warning = " (Needs to be renamed to " .. item:upper() .. ")"
      end
      print(" " .. item .. " (" .. name .. ")" .. warning)
      none = false
    end
  end
  if none then
    print " (none)"
  end
  error(err)
end]]

function App:readBitmapDataFile(filename)
  filename = (self.command_line["bitmap-dir"] or "Bitmap") .. pathsep .. filename
  local file = assert(io.open(filename, "rb"))
  local data = file:read"*a"
  file:close()
  if data:sub(1, 3) == "RNC" then
    data = assert(rnc.decompress(data))
  end
  return data
end

function App:readDataFile(dir, filename)
  if dir == "Bitmap" then
    return self:readBitmapDataFile(filename)
  elseif dir == "Levels" then
    return self:readLevelDataFile(filename)
  end
  if filename == nil then
    dir, filename = "Data", dir
  end
  local data = assert(self.fs:readContents(dir .. pathsep .. filename))
  if data:sub(1, 3) == "RNC" then
    data = assert(rnc.decompress(data))
  end
  return data
end

function App:readLevelDataFile(filename)
  local dir = "Levels" .. pathsep .. filename
  -- First look in the original install directory, if not found there
  -- look in the CorsixTH directory "Levels".
  local data = self.fs:readContents(dir)
  if not data then
    local file = io.open(debug.getinfo(1, "S").source:sub(2, -12) .. dir, "rb")
    if file then
      data = file:read"*a"
      file:close()
    end
  end
  if data then
    if data:sub(1, 3) == "RNC" then
      data = assert(rnc.decompress(data))
    end
  else
    -- Could not find the file
    return nil, _S.errors.map_file_missing:format(filename)
  end
  return data
end

function App:loadLuaFolder(dir, no_results, append_to)
  local ourpath = debug.getinfo(1, "S").source:sub(2, -8)
  dir = dir .. pathsep
  local path = ourpath .. dir
  local results = no_results and "" or (append_to or {})
  for file in lfs.dir(path) do
    if file:match"%.lua$" then
      local status, result = pcall(dofile, dir .. file:sub(1, -5))
      if not status then
        print("Error loading " .. dir ..  file .. ":\n" .. tostring(result))
      else
        if result == nil then
          if not no_results then
            print("Warning: " .. dir .. file .. " returned no value")
          end
        else
          if no_results then
            print("Warning: " .. dir .. file .. " returned a value:", result)
          else
            if type(result) == "table" and result.id then
              results[result.id] = result
            elseif type(result) == "function" then
              results[file:match"(.*)%."] = result
            end
            results[#results + 1] = result
          end
        end
      end
    end
  end
  if no_results then
    return
  else
    return results
  end
end

function App:scanSavegames()
  local saves = {}
  for file in lfs.dir(self.savegame_dir) do
    if file:match"%.sav$" then
      saves[#saves + 1] = file:sub(1, -5)
    end
  end
  return saves
end

function App:save(filename)
  return SaveGameFile(self.savegame_dir .. filename)
end

function App:load(filename)
  return LoadGameFile(self.savegame_dir .. filename)
end

--! Quits the running game and returns to main menu (offers confirmation window first)
function App:quit()
  self.ui:addWindow(UIConfirmDialog(self.ui, _S.confirmation.quit, --[[persistable:app_confirm_quit]] function()
    self:loadMainMenu()
  end))
end

--! Exits the game completely (no confirmation window)
function App:exit()
  -- Save config before exiting
  self:saveConfig()
  self.running = false
end

--! This function is automatically called after loading a game and serves for compatibility.
function App:afterLoad()
  local old = self.world.savegame_version or 0
  local new = self.savegame_version
  
  if old == 0 then
    -- Game log was not present before introduction of savegame versions, so create it now.
    self.world.game_log = {}
    self.world:gameLog("Created Gamelog on load of old (pre-versioning) savegame.")
  end
  
  if new == old then
    return
  elseif new > old then
    self.world:gameLog("Savegame version changed from " .. old .. " to " .. new .. ".")
  else
    -- TODO: This should maybe be forbidden completely.
    self.world:gameLog("Warning: loaded savegame version " .. old .. " in older version " .. new .. ".")
  end
  self.world.savegame_version = new
  
  self.map:afterLoad(old, new)
  self.world:afterLoad(old, new)
  self.ui:afterLoad(old, new)
end