salet-module/lib/salet.coffee

markdown = require('./markdown.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;
String.prototype.fcall = function() { return this; }

# Utility functions

parseFn = (str) ->
  unless str?
    return str
    
  fstr = """
(function(character, system, situation) {
#{str}
#})
"""
  return eval(fstr)

# Scrolls the top of the screen to the specified point
scrollTopTo = (value) ->
  $('html,body').animate({scrollTop: value}, 500)

# Scrolls the bottom of the screen to the specified point
scrollBottomTo = (value) ->
  scrollTopTo(value - $(window).height())

# Scrolls all the way to the bottom of the screen
scrollToBottom = () ->
  scrollTopTo($('html').height() - $(window).height());

# 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_-]+))?$/

# Returns HTML from the given content with the non-raw links wired up.
augmentLinks = (content) ->
  output = $(content)

  # Wire up the links for regular <a> tags.
  output.find("a").each((index, element) ->
    a = $(element)
    href = a.attr('href')
    if (!a.hasClass("raw")|| href.match(/[?&]raw[=&]?/))
      if (href.match(linkRe))
        a.click((event) ->
          event.preventDefault()

          # If we're a once-click, remove all matching links.
          if (a.hasClass("once") || href.match(/[?&]once[=&]?/))
            system.clearLinks(href)

          processClick(href)
          return false
        )
      else
        a.addClass("raw")
  )
  return output

###
This is the control structure, it has minimal amount of data and
this data is volatile anyway (as in, it won't get saved).
###
Salet = {
  rnd: null
  time: 0

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

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

  # --- Hooks ---

  ###
  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. If this function is given it should have
  the signature function(character, system).
  ###
  init: null

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

  ###
  Hook for when the situation has already been carried out
  and printed.
  ### 
  afterEnter: (character, system, 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: (character, system, 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: (character, system, situationId, actionId) ->

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

  ###
  Removes all content from the page, clearing the main content area.

  If an elementSelector is given, then only that selector will be
  cleared. Note that all content from the cleared element is removed,
  but the element itself remains, ready to be filled again using
  System.write.
  ###
  clearContent: (elementSelector) ->
    document.querySelector(elementSelector).innerHTML = ""

  # jQuery was confused by this point where's the context so I did it vanilla-way
  write: (content, elementSelector) ->
    if content == ""
      return
    if typeof content == "function"
      content = content()
    block = document.getElementById("current-situation")
    if block
      block.innerHTML = block.innerHTML + markdown(content)
    else
      console.error("No current situation found.")

  ###
  Turns any links that target the given href into plain
  text. This can be used to remove action options when an action
  is no longer available. It is used automatically when you give
  a link the 'once' class.
  ###
  clearLinks: (code) ->
    $("a[href='" + code + "']").each((index, element) ->
        a = $(element)
        a.replaceWith($("<span>").addClass("ex_link").html(a.html()))
    )

  ###
  Given a list of situation ids, this outputs a standard option
  block with the situation choices in the given order.
  
  The contents of each choice will be a link to the situation,
  the text of the link will be given by the situation's
  outputText property. Note that the canChoose function is
  called, and if it returns false, then the text will appear, but
  the link will not be clickable.
 
  Although canChoose is honored, canView and displayOrder are
  not. If you need to honor these, you should either do so
  manually, ot else use the `getSituationIdChoices` method to
  return an ordered list of valid viewable situation ids.
  ###
  writeChoices: (listOfIds, elementSelector) ->
    if (listOfIds.length == 0)
      return

    currentSituation = getCurrentSituation();
    $options = $("<ul>").addClass("options");
    for (i = 0; i < listOfIds.length; ++i) {
        situationId = listOfIds[i]
        situation = game.situations[situationId]
        assert(situation, "unknown_situation".l({id:situationId}))
        if (situation == currentSituation) {
            continue
        }

        optionText = situation.optionText.fcall(this, character, this, currentSituation)
        if (!optionText)
          optionText = "choice".l({number:i+1})
        $option = $("<li>")
        $a = $("<span>")
        if (situation.canChoose(character, this, currentSituation)) {
            $a = $("<a>").attr({href: situationId})
        }
        $a.html(optionText)
        $option.html($a)
        $options.append($option)
    }
    @write($options, elementSelector)

  ###
  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 minChoices value is given, then the function will attempt
  to return at least that many results. If not enough results are
  available at the highest priority, then lower priorities will
  be considered in turn, until enough situations are found. In
  the example above, if we had a minChoices of three, then all
  three situations would be returned, even though they have
  different priorities. If you need to return all valid
  situations, regardless of their priorities, set minChoices to a
  large number, such as `Number.MAX_VALUE`, and leave maxChoices
  undefined.
 
  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, minChoices, maxChoices) ->
    datum = null
    i = 0

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

    # First we build a list of all candidate ids.
    allIds = {}
    for (i = 0; i < listOfOrOneIdsOrTags.length; ++i)
        tagOrId = listOfOrOneIdsOrTags[i]
        if (tagOrId.substr(0, 1) == '#')
            ids = getSituationIdsWithTag(tagOrId.substr(1))
            for (j = 0; j < ids.length; ++j)
              allIds[ids[j]] = true
        else
          allIds[tagOrId] = true

    #Filter out anything that can't be viewed right now.
    currentSituation = getCurrentSituation()
    viewableSituationData = []
    for (situationId in allIds)
        situation = game.situations[situationId]
        assert(situation, "unknown_situation".l({id:situationId}))

        if (situation.canView(character, system, currentSituation))
          #While we're here, get the selection data.
          viewableSituationDatum = situation.choiceData(character, system, currentSituation)
          viewableSituationDatum.id = situationId
          viewableSituationData.push(viewableSituationDatum)

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

    committed = []
    candidatesAtLastPriority = []
    lastPriority
    # In descending priority order.
    for (i = 0; i < viewableSituationData.length; ++i)
        datum = viewableSituationData[i];
        if (datum.priority != lastPriority)
            if (lastPriority !== undefined)
              # We've dropped a priority group, see if we have enough
              # situations so far, and stop if we do.
              if (minChoices === undefined || i >= minChoices)
                break
            # Continue to acccumulate more options.
            committed.push.apply(committed, candidatesAtLastPriority);
            candidatesAtLastPriority = [];
            lastPriority = datum.priority;
        candidatesAtLastPriority.push(datum);

    # So the values in committed we're committed to, because without
    # them we wouldn't hit our minimum. But those in
    # candidatesAtLastPriority might take us over our maximum, so
    # figure out how many we should choose.
    totalChoices = committed.length + candidatesAtLastPriority.length
    if (maxChoices === undefined || maxChoices >= totalChoices)
      # We can use all the choices.
      committed.push.apply(committed, candidatesAtLastPriority)
    else if (maxChoices >= committed.length)
      # We can only use the commited ones.
      # NO-OP
    else
      # We have to sample the candidates, using their relative frequency.
      candidatesToInclude = maxChoices - committed.length;
      for (i = 0; i < candidatesAtLastPriority.length; ++i)
        datum = candidatesAtLastPriority[i];
        datum._frequencyValue = this.rnd.random() / datum.frequency;
      candidatesToInclude.sort((a, b) ->
        return a.frequencyValue - b.frequencyValue;
      )
      chosen = candidatesToInclude.slice(0, candidatesToInclude)
      committed.push.apply(committed, chosen)

    # 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 = 0; i < committed.length; ++i)
      result.push(committed[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;

  # This is the current character. It should be reconstructable
  # from the above progress data.
  character: {};

  # 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

  getCurrentSituation: () =>
    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;

  # At last, we scroll the view so that .new objects are in view.
  endOutputTransaction: () =>
    if (!@interactive) return; # We're loading a save; do nothing at all.
    $new = $('.new')
    viewHeight = $(window).height()
    newTop, newBottom, newHeight, optionHeight = 0

    if ($new.length === 0) return; # Somehow, there's nothing new.

    newTop = $new.first().offset().top,
    newBottom = $new.last().offset().top + $new.last().height(),
    newHeight = newBottom - newTop;

    # We take the options list into account, because we don't want the new
    # content to scroll offscreen when the list disappears. So we calculate
    # scroll points as though the option list was already gone.
    if ($('.options').not('.new').length)
      optionHeight = $('.options').not('new').height()

    if (newHeight > (viewHeight - optionHeight - 50))
      # The new content is too long for our viewport, so we scroll the
      # top of the new content to roughly 75% of the way up the viewport's
      # height.
      scrollTopTo(newTop-(viewHeight*0.25) - optionHeight);
    else
      if (newTop > $('body').height() - viewHeight)
        # If we scroll right to the bottom, the new content will be in
        # view. So we do that.
        scrollToBottom();
      else
        # Our new content is too far up the page. So we scroll to place
        # it somewhere near the bottom.
        scrollBottomTo(newBottom+100 - optionHeight);

  # 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

    $('.new').removeClass('new')

    # 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.
    @endOutputTransaction()

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

  disableSaving: () ->
    $("#save").addClass('disabled');
  enableSaving: () ->
    $("#save").removeClass('disabled');

  ###
  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 !== '.')
      if (situation !== current)
        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)
      situation = getCurrentSituation()
      if (situation)
        if (game.beforeAction)
          # Try the global act handler, and see if we need
          # to notify the situation.
          consumed = game.beforeAction(
            character, system, current, action
          )
          if (consumed != true)
            situation.act(character, system, action)
          else
            # We have no global act handler, always notify the situation.
            situation.act(character, system, action)
          
          if (game.afterAction)
            game.afterAction(character, system, current, action)

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

  # Transitions between situations.
  doTransitionTo: (newSituationId) ->
    oldSituationId = current
    oldSituation = getCurrentSituation()
    newSituation = game.situations[newSituationId]

    assert(newSituation, "unknown_situation".l({id:newSituationId}))

    # We might not have an old situation if this is the start of the game.
    if (oldSituation)
      if (game.exit)
        game.exit(character, system, oldSituationId, newSituationId);

    # Remove links and transient sections.
    $('#content a').each((index, element) ->
      a = $(element);
      if (a.hasClass('sticky') || a.attr("href").match(/[?&]sticky[=&]?/))
        return;
      a.replaceWith($("<span>").addClass("ex_link").html(a.html()))
    )
    contentToHide = $('#content .transient, #content ul.options')
    contentToHide.add($("#content a").filter(() ->
      return $(this).attr("href").match(/[?&]transient[=&]?/)
    ))
    if (interactive)
      contentToHide.animate({opacity: 0}, 350).
        slideUp(500, () ->
          $(this).remove()
        )
    else
      contentToHide.remove()

    # Move the character.
    current = newSituationId

    # Notify the incoming situation.
    if (game.enter)
      game.enter(character, system, oldSituationId, newSituationId)
    newSituation.entering(character, system, oldSituationId)

    # additional hook for when the situation text has already been printed
    if (game.afterEnter)
      game.afterEnter(character, system, oldSituationId, newSituationId)

  ###
  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. */
  ###
  erase_save: (force = false) =>
    save_id = @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.
  getSituationIdsWithTag: (tag) =>
    result = []
    for (situationId, situation of @situations)
      for (i = 0; i < situation.tags.length; ++i)
        if (situation.tags[i] == tag)
          result.push(situationId)
          break
    return result

  # Saves the character 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.
    localStorage.setItem(getSaveId(), JSON.stringify(progress))

    # Switch the button highlights.
    $("#erase").removeClass('disabled')
    $("#load").removeClass('disabled')
    @disableSaving()

  # Loads the game from the given data
  loadGame = (characterData) ->
    progress = characterData

    character = new Character()
    system.rnd = new Random(progress.seed)

    # Empty the display
    $("#content").empty()
    $("#intro").empty()

    # Now play through the actions so far:
    if (game.init)
      game.init(character, system)

    # Run through all the player's history.
    interactive = false
    for (i = 0; i < progress.sequence.length; i++)
      step = progress.sequence[i]
      # The action must be done at the recorded time.
      system.time = step.when
      processLink(step.link)
    interactive = true

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

  game_begin: () ->
    # Handle storage.
    storedCharacter = false
    if (@hasLocalStorage())
      storedCharacter = localStorage.getItem(@getSaveId())

    if (storedCharacter)
      try
        @loadGame(JSON.parse(storedCharacter))
        @disableSaving()
        $("#erase").removeClass('disabled')
      catch(err)
        @erase_save(true)
    else
      progress.seed = new Date().toString()

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

      # Empty the display
      $("#content").empty()

      # Start the game
      startTime = new Date().getTime() * 0.001
      system.time = 0
      if (game.init)
        game.init(character, system)

      # Do the first state.
      doTransitionTo(game.start);

    # Any point that an option list appears, its options are its first links.
    $("body").on('click', "ul.options li, #menu li", (event) ->
      # Make option clicks pass through to their first link.
      link = $("a", this)
      if (link.length > 0)
        $(link.get(0)).click()
    );

}

# Set up the game when everything is loaded.
$(document).ready(() ->
  salet = new Salet
  if (salet.hasLocalStorage())
    $("#erase").click(salet.erase_save) # is Salet defined here?
    $("#save").click(salet.saveGame)

  salet.game_begin()
)