salet/lib/salet.coffee

markdown = require('./markdown.coffee')
SaletView = require('./view.coffee')
Random = require('./random.js')
languages = require('./localize.coffee')

###
fcall() (by analogy with fmap) is added to the prototypes of both String and
Function. When called on a Function, it's an alias for Function#call();
when called on a String, it only returns the string itself, discarding any input.
###

Function.prototype.fcall = Function.prototype.call;
Boolean.prototype.fcall = () ->
  return this
String.prototype.fcall = () ->
  return this

assert = (msg, assertion) -> console.assert assertion, msg

class Character
  inventory: []

###
This is the control structure, it has minimal amount of data and
this data is volatile anyway (as in, it won't get saved).

There is only one instance of this class.
###
class Salet
  # REDEFINE THIS IN YOUR GAME
  game_id: null
  game_version: "1.0"
  autosave: true

  rnd: null
  time: 0

  # Corresponding room names to room objects.
  rooms: {}

  # The unique id of the starting room.
  start: "start"

  # Regular expression to catch every link action.
  # Salet's default is a general URL-safe expression.
  linkRe: /^([0-9A-Za-z_-]+|\.)(\/([0-9A-Za-z_-]+))?$/

  character: new Character

  ###
  This function is called at the start of the game. It is
  normally overridden to provide initial character creation
  (setting initial quality values, setting the
  character-text. This is optional, however, as set-up
  processing could also be done by the first situation's
  enter function.
  ###
  init: () ->

  ###
  This function is called before entering any new
  situation. It is called before the corresponding situation
  has its `enter` method called.
  ###
  enter: (oldSituationId, newSituationId) ->

  ###
  Hook for when the situation has already been carried out
  and printed.
  ###
  afterEnter: (oldSituationId, newSituationId) ->

  ###
  This function is called before carrying out any action in
  any situation. It is called before the corresponding
  situation has its `act` method called.

  If the function returns true, then it is indicating that it
  has consumed the action, and the action will not be passed
  on to the situation. Note that this is the only one of
  these global handlers that can consume the event.
  ###
  beforeAction: (situationId, actionId) ->

  ###
  This function is called after carrying out any action in
  any situation. It is called after the corresponding
  situation has its `act` method called.
  ###
  afterAction: (situationId, actionId) ->

  ###
  This function is called after leaving any situation. It is
  called after the corresponding situation has its `exit`
  method called.
  ###
  exit: (oldSituationId, newSituationId) ->

  ###
  Returns a list of situation ids to choose from, given a set of
  specifications.

  This function is a complex and powerful way of compiling
  implicit situation choices. You give it a list of situation ids
  and situation tags (if a single id or tag is needed just that
  string can be given, it doesn't need to be wrapped in a
  list). Tags should be prefixed with a hash # to differentiate
  them from situation ids. The function then considers all
  matching situations in descending priority order, calling their
  canView functions and filtering out any that should not be
  shown, given the current state. Without additional parameters
  the function returns a list of the situation ids at the highest
  level of priority that has any valid results. So, for example,
  if a tag #places matches three situations, one with priority 2,
  and two with priority 3, and all of them can be viewed in the
  current context, then only the two with priority 3 will be
  returned. This allows you to have high-priority situations that
  trump any lower situations when they are valid, such as
  situations that force the player to go to one destination if
  the player is out of money, for example.

  If a maxChoices value is given, then the function will not
  return any more than the given number of results. If there are
  more than this number of results possible, then the highest
  priority resuls will be guaranteed to be returned, but the
  lowest priority group will have to fight it out for the
  remaining places. In this case, a random sample is chosen,
  taking into account the frequency of each situation. So a
  situation with a frequency of 100 will be chosen 100 times more
  often than a situation with a frequency of 1, if there is one
  space available. Often these frequencies have to be taken as a
  guideline, and the actual probabilities will only be
  approximate. Consider three situations with frequencies of 1,
  1, 100, competing for two spaces. The 100-frequency situation
  will be chosen almost every time, but for the other space, one
  of the 1-frequency situations must be chosen. So the actual
  probabilities will be roughly 50%, 50%, 100%. When selecting
  more than one result, frequencies can only be a guide.

  Before this function returns its result, it sorts the
  situations in increasing order of their displayOrder values.
  ###
  getSituationIdChoices: (listOfOrOneIdsOrTags, maxChoices) =>
    datum = null
    i = 0

    # First check if we have a single string for the id or tag.
    if (typeof(listOfOrOneIdsOrTags) == 'string')
      listOfOrOneIdsOrTags = [listOfOrOneIdsOrTags]

    # First we build a list of all candidate ids.
    allIds = []
    for tagOrId in listOfOrOneIdsOrTags
      if (tagOrId.substr(0, 1) == '#')
        ids = @getRoomsTagged(tagOrId.substr(1))
        for id in ids
          allIds.push(id)
      else #it's an id, not a tag
        allIds.push(tagOrId)

    #Filter out anything that can't be viewed right now.
    currentRoom = @getCurrentRoom()
    viewableRoomData = []
    for roomId in allIds
      room = @rooms[roomId]
      assert(room, "unknown_situation".l({id:roomId}))

      if (room.canView.fcall(this, currentRoom))
        viewableRoomData.push({
          priority: room.priority
          id: roomId
          displayOrder: room.displayOrder
        })

    # Then we sort in descending priority order.
    viewableRoomData.sort((a, b) ->
      return b.priority - a.priority
    )

    committed = []

    # if we need to filter out the results
    if (maxChoices? && viewableRoomData.length > maxChoices)
      viewableRoomData = viewableRoomData[-maxChoices..]

    for candidateRoom in viewableRoomData
      committed.push({
        id: candidateRoom.id
        displayOrder: candidateRoom.displayOrder
      })

    # Now sort in ascending display order.
    committed.sort((a, b) ->
      return a.displayOrder - b.displayOrder
    )

    # And return as a list of ids only.
    result = []
    for i in committed
      result.push(i.id)

    return result

  # This is the data on the player's progress that gets saved.
  progress: {
    # A random seed string, used internally to make random
    # sequences predictable.
    seed: null
    # Keeps track of the links clicked, and when.
    sequence: [],
    # The time when the progress was saved.
    saveTime: null
  }

  # The Id of the current situation the player is in.
  current: null;

  # Tracks whether we're in interactive mode or batch mode.
  interactive: true

  # The system time when the game was initialized.
  startTime: null

  # The stack of links, resulting from the last action, still be to resolved.
  linkStack: null

  getCurrentRoom: () =>
    if (@current)
      return @rooms[@current]
    return null

  # Gets the unique id used to identify saved games.
  getSaveId: (slot = "") =>
    return 'salet_'+@game_id+'_'+@game_version#+'_'+slot

  # This gets called when a link needs to be followed, regardless
  # of whether it was user action that initiated it.
  processLink: (code) =>
    # Check if we should do this now, or if processing is already underway.
    if @linkStack != null
      @linkStack.push(code)
      return

    @view.mark_all_links_old

    # We're processing, so make the stack available.
    @linkStack = []

    # Handle each link in turn.
    @processOneLink(code);
    while (@linkStack.length > 0)
      code = @linkStack.shift()
      @processOneLink(code)

    # We're done, so remove the stack to prevent future pushes.
    @linkStack = null;

    # Scroll to the top of the new content.
    @view.endOutputTransaction()

    # We're able to save, if we weren't already.
    @view.enableSaving()

  goTo: (roomId) =>
    return @processLink(roomId)

  ###
  This gets called to actually do the work of processing a code.
  When one doLink is called (or a link is clicked), this may set call
  code that further calls doLink, and so on. This method processes
  each one, and processLink manages this.
  ###
  processOneLink: (code) =>
    match = code.match(@linkRe)
    assert(match, "link_not_valid".l({link:code}))

    situation = match[1]
    action = match[3]

    # Change the situation
    if situation != '.' and situation != @current_room
      @doTransitionTo(situation)
    else
      # We should have an action if we have no situation change.
      assert(action, "link_no_action".l())

    # Carry out the action
    if (action)
      room = @getCurrentRoom()
      if (room and @beforeAction)
        # Try the global act handler
        consumed = @beforeAction(room, action)
        if (consumed != true)
          room.act(this, action)

      if (@afterAction)
        @afterAction(this, room, action)

  # This gets called when the user clicks a link to carry out an action.
  processClick: (code) =>
    now = (new Date()).getTime() * 0.001
    @time = now - @startTime
    @progress.sequence.push({link:code, when:@time})
    @processLink(code)

  # Transitions between situations.
  doTransitionTo: (newRoomId) =>
    oldRoomId = @current
    oldRoom = @getCurrentRoom()
    newRoom = @rooms[newRoomId]

    assert(newRoom, "unknown_situation".l({id:newRoomId}))

    # We might not have an old situation if this is the start of the game.
    if (oldRoom and @exit)
      @exit(oldRoomId, newRoomId)

    @current = newRoomId

    # Remove links and transient sections.
    @view.removeTransient(@interactive)

    # Notify the incoming situation.
    if (@enter)
      @enter(oldRoomId, newRoomId)
    newRoom.entering(this, oldRoomId)

    # additional hook for when the situation text has already been printed
    if (@afterEnter)
      @afterEnter(oldRoomId, newRoomId)

  ###
  Erases the character in local storage. This is permanent!
  To restart the game afterwards, we perform a simple page refresh.
  This guarantees authors don't have to care about "tainting" the
  game state across save/erase cycles, meaning that character.sandbox
  no longer has to be the end-all be-all repository of game state.
  ###
  eraseSave: (force = false) =>
    saveId = @getSaveId() # save slot
    if (localStorage.getItem(saveId) and (force or confirm("erase_message".l())))
      localStorage.removeItem(saveId)
      window.location.reload()

  # Find and return a list of ids for all situations with the given tag.
  getRoomsTagged: (tag) =>
    result = []
    for id, room of @rooms
      for i in room.tags
        if (i == tag)
          result.push(id)
          break
    return result

  # Saves the character and the walking history to local storage.
  saveGame: () =>
    # Store when we're saving the game, to avoid exploits where a
    # player loads their file to gain extra time.
    now = (new Date()).getTime() * 0.001
    @progress.saveTime = now - @startTime

    # Save the game.
    window.localStorage.setItem(@getSaveId(), JSON.stringify({
      progress: @progress,
      character: @character
    }))

    # Switch the button highlights.
    @view.disableSaving()
    @view.enableErasing()
    @view.enableLoading()

  # Loads the game from the given data
  loadGame: (saveFile) =>
    @progress = saveFile.progress
    @character = saveFile.character

    @rnd = new Random(@progress.seed)

    # Don't load the save if it's an autosave at the first room (start).
    # We don't need to clear the screen.
    if saveFile.progress? and saveFile.progress.sequence.length > 1
      @view.clearContent()

    # Now play through the actions so far:
    if (@init)
      @init()

    # Run through all the player's history.
    interactive = false
    for step in @progress.sequence
      # The action must be done at the recorded time.
      @time = step.when
      @processLink(step.link)
    interactive = true

    # Reverse engineer the start time.
    now = new Date().getTime() * 0.001
    startTime = now - @progress.saveTime

  view: new SaletView

  beginGame: () =>
    @view.fixClicks()

    # Handle storage.
    saveFile = false
    if (@view.hasLocalStorage())
      saveFile = localStorage.getItem(@getSaveId())

    if (saveFile)
      try
        @loadGame(JSON.parse(saveFile))
        @view.disableSaving()
        @view.enableErasing()
      catch err
        console.log "There was an error loading your save. The save is deleted."
        console.error err
        @eraseSave(true)
    else
      @progress.seed = new Date().toString()

      character = new Character()
      @rnd = new Random(@progress.seed)
      @progress.sequence = [{link:@start, when:0}]

      # Start the game
      @startTime = new Date().getTime() * 0.001
      if (@init)
        @init(character)

      # Do the first state.
      @doTransitionTo(@start)

  getRoom: (name) =>
    return @rooms[name]

  # Just an alias for getCurrentRoom
  here: () => @getCurrentRoom()

  isVisited: (name) =>
    place = @getRoom(name)
    if place
      return Boolean place.visited
    return 0

module.exports = Salet