#gamethings.py
"""Standard thing classes.

Classes:
  - ThingGraphic:   Represents how thing is to be visualized.
  - Thing:          The abstract base class for every thing.
  - Observer:       The abstract base class for things that listen to events.
  - Item:           A thing that can exist in a character's inventory.
  - Useable:        A thing that can be used by a character.
  - Character:      A thing that represents a character.
  - NPC:            A character that is not controlled by the player.
  - Door:           A thing that sometimes blocks paths.
  - MapExit:        A technical thing that marks a map transition.
"""

import ruamel.yaml
from ruamel.yaml.comments import CommentedMap

class ThingGraphic(object):
    """Represent how a thing is to be visualized.
    
    Background color, foreground color, and shape are represented.
    This could hypothetically be extended to hold sprites, textures or models."""
    
    def __init__(self, background: str, foreground: str, shape: str):
        """Create a graphic for a thing.
        
        The background and foregrond must be strings with color hex representations.
        For instance: '#00FF00' means bright green.
        The shape must be a string containing exactly one of the following shapes:
        o: circle
        x: cross
        -: horizontal line
        |: vertical line
        #: square
        ^: triangle
        A graphic may be invalid.
        """
        if not isinstance(background, str):
            raise TypeError("Background must be a string of form '#[0-9A-Fa-f]{6}'.")
        if not isinstance(foreground, str):
            raise TypeError("Foreground must be a string of form '#[0-9A-Fa-f]{6}'.")
        if not isinstance(shape, str):
            raise TypeError("Shape must be a string of form '[-|ox#^]'.")
        self.background = background
        self.foreground = foreground
        self.shape = shape

class Thing(object):
    
    def __init__(self, thingType: str, name: str, x: int, y: int, description: str, flags: int, playerx = None, playery = None, **kwargs):
        self.thingType = thingType
        self.name = name
        self.description = description
        self.x = x
        self.y = y
        self.playerx = x
        self.playery = y
        self.prevx = x # if an area gets double-occupied, a thing can get pushed back.
        self.prevy = y
        if playerx:
            self.playerx = playerx
        if playery:
            self.playery = playery
        self.flags = flags
        self.graphic = ThingGraphic('clear', '#7F7F7F', ' ')
        self.thingID = -1 # ID not assigned
        
    def __str__(self):
        """__str__ is used for look."""
        return self.description
        
    def __eq__(self, other):
        if not isinstance(other, Thing):
            return False
        return self.name == other.name

    @property
    def passable(self):
        return bool(self.flags & 1)
    
    @property
    def talkable(self):
        return bool(self.flags & 2)
        
    @property
    def lookable(self):
        return bool(self.flags & 4)
    
    @property
    def takeable(self):
        return bool(self.flags & 8)
    
    @property
    def useable(self):
        return bool(self.flags & 16)
        
    def fromPrefab(self, prefab):
        """This only exists as a catch-all in case an unsupported thing type is prefabed."""
        parts = prefab.details
        # set default values for optional arguments
        name = self.name
        description = self.description
        playerx = prefab.x + (self.playerx - self.x)
        playery = prefab.y + (self.playery - self.y)
        bgc = self.graphic.background
        fgc = self.graphic.foreground
        shape = self.graphic.shape
        if parts != None:
            if 'name' in parts:
                name = parts['name']
            if 'description' in parts:
                description = parts['description']
            # load graphic
            if 'graphic' in parts:
                if 'bgc' in parts['graphic']:
                    bgc = parts['graphic']['bgc']
                if 'fgc' in parts['graphic']:
                    fgc = parts['graphic']['fgc']
                if 'shape' in parts['graphic']:
                    shape = parts['graphic']['shape']
            if 'useLocation' in parts:
                playerx, playery = parts['useLocation']
        graphic = ThingGraphic(bgc, fgc, shape)
        return Thing(self.thingType, name, prefab.x, prefab.y, description, self.flags, playerx, playery)
        
class Prefab(Thing):
    """Basically a placeholder for a predefined prefab. This is for reading in YAML."""
    yaml_flag = u'!Prefab'
    defaultGraphic = ThingGraphic('clear', 'clear', 'x')
    
    def __init__(self, name: str, x: int, y: int, **kwargs):
        super(Prefab, self).__init__('z', name, x, y, '', 1) # 'p' is already taken by the player.
        self.details = None # This is so that custom overrides can be made for specific instances.
        if "details" in kwargs:
            self.details = kwargs["details"]
    
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'name': node.name, 'location': (node.x, node.y), 'details': self.details}
        return representer.represent_mapping(cls.yaml_flag, ret)
    
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        mdetails = None
        if 'details' in parts:
            mdetails = dict(parts['details'])
        return cls(parts['name'], parts['location'][0], parts['location'][1], details = mdetails)

class Observer(Thing):
    """ABC for things that have a dict of events that they should listen to."""
    
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.behaviors = {} # {the name of the event : (behaviorQueue priority, the name of the behavior)}
        self.busy = False # Prevents a new behavior until the current one is finished
        self.behaviorQueue = [] # If you can't make it perfect, then make it adjustable.
        # The behavior queue is for behaviors that need to execute once the current action is finished.
        # If it's not considered important enough (behaviors[event][0] < 0), it's dropped.
        
class Item(Thing):
    yaml_flag = u'!Item'
    defaultGraphic = ThingGraphic('clear', '#00BF00', '^')
    
    def __init__(self, name, x: int, y: int, description: str, useFunc: str, useOnFunc: str, customValues: dict, ranged: bool, graphic = defaultGraphic):
        super(Item, self).__init__('i', name, x, y, description, 13)
        self.useFunc = useFunc
        self.useOnFunc = useOnFunc
        self.customValues = customValues
        self.ranged = ranged
        self.graphic = graphic
        
    def use(self):
        pass
        
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'name': node.name, 'location': (node.x, node.y), 'description': node.description}
        # save graphic
        graphic = {}
        if node.graphic.background != Item.defaultGraphic.background:
            graphic['bgc'] = node.graphic.background
        if node.graphic.foreground != Item.defaultGraphic.forground:
            graphic['fgc'] = node.graphic.foreground
        if node.graphic.shape != Item.defaultGraphic.shape:
            graphic['shape'] = node.graphicshape
        if len(graphic) > 0:
            ret['graphic'] = graphic
        # save use functions
        if node.useFunc != '':
            ret['useFunc'] = node.useFunc
        if node.useOnFunc != '':
            ret['useOnFunc'] = node.useOnFunc
        if len(node.customValues) > 0:
            ret['customValues'] = node.customValues
        if node.ranged:
            ret['ranged'] = node.ranged
        return representer.represent_mapping(cls.yaml_flag, ret)
        
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        useFunc = ''
        useOnFunc = ''
        customValues = {}
        ranged = False
        bgc = Item.defaultGraphic.background
        fgc = Item.defaultGraphic.foreground
        shape = Item.defaultGraphic.shape
        # load graphic
        if 'graphic' in parts:
            if 'bgc' in parts['graphic']:
                bgc = parts['graphic']['bgc']
            if 'fgc' in parts['graphic']:
                fgc = parts['graphic']['fgc']
            if 'shape' in parts['graphic']:
                shape = parts['graphic']['shape']
        graphic = ThingGraphic(bgc, fgc, shape)
        # load use functions
        if 'useFunc' in parts:
            useFunc = parts['useFunc']
        if 'useOnFunc' in parts:
            useOnFunc = parts['useOnFunc']
        if 'customValues' in parts:
            customValues = dict(parts['customValues'])
            for v in customValues:
                if isinstance(customValues[v], tuple):
                    customValues[v] = list(customValues[v])
        if 'ranged' in parts:
            ranged = parts['ranged']
        return cls(parts['name'], parts['location'][0], parts['location'][1],
            parts['description'], useFunc, useOnFunc, customValues, ranged, graphic)
    
    def use(self, user, gameBase, args) -> float:
        pass
        
    def useOn(self, user, gameBase, thing, args) -> float:
        pass
    
    def fromPrefab(self, prefab):
        parts = prefab.details
        # set default values for optional arguments
        name = self.name
        useFunc = self.useFunc
        useOnFunc = self.useOnFunc
        customValues = dict(self.customValues)
        ranged = self.ranged
        bgc = self.graphic.background
        fgc = self.graphic.foreground
        shape = self.graphic.shape
        description = self.description
        if parts:
            if 'name' in parts:
                name = parts['name']
            if 'description' in parts:
                description = parts['description']
            # load graphic
            if 'graphic' in parts:
                if 'bgc' in parts['graphic']:
                    bgc = parts['graphic']['bgc']
                if 'fgc' in parts['graphic']:
                    fgc = parts['graphic']['fgc']
                if 'shape' in parts['graphic']:
                    shape = parts['graphic']['shape']
            # load use functions
            if 'useFunc' in parts:
                useFunc = parts['useFunc']
            if 'useOnFunc' in parts:
                useOnFunc = parts['useOnFunc']
            if 'customValues' in parts:
                customValues = dict(parts['customValues'])
                for v in customValues:
                    if isinstance(customValues[v], tuple):
                        customValues[v] = list(customValues[v])
            if 'ranged' in parts:
                ranged = parts['ranged']
        graphic = ThingGraphic(bgc, fgc, shape)
        return Item(name, prefab.x, prefab.y, description, useFunc, useOnFunc, customValues, ranged, graphic)
        
class Useable(Thing):
    yaml_flag = u'!Useable'
    defaultGraphic = ThingGraphic('clear', '#0000FF', '#')
    
    def __init__(self, name, x: int, y: int, description: str, useFunc: str, customValues: dict, playerx = None, playery = None, graphic = defaultGraphic):
        super(Useable, self).__init__('u', name, x, y, description, 16, playerx, playery)
        self.useFunc = useFunc
        self.customValues = customValues
        self.graphic = graphic
    
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'name': node.name, 'location': (node.x, node.y), 'description': node.description}
        # save graphic
        graphic = {}
        if node.graphic.background != Useable.defaultGraphic.background:
            graphic['bgc'] = node.graphic.background
        if node.graphic.foreground != Useable.defaultGraphic.foreground:
            graphic['fgc'] = node.graphic.foreground
        if node.graphic.shape != Useable.defaultGraphic.shape:
            graphic['shape'] = node.graphic.shape
        if len(graphic) > 0:
            ret['graphic'] = graphic
        # save use functions
        if node.useFunc != '':
            ret['useFunc'] = node.useFunc
        if len(node.customValues) > 0:
            ret['customValues'] = node.customValues
        if node.x != node.playerx or node.y != node.playery:
            ret['useLocation'] = (node.playerx, node.playery)
        return representer.represent_mapping(cls.yaml_flag, ret)
    
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        useFunc = ''
        customValues = {}
        playerx, playery = parts['location']
        bgc = Useable.defaultGraphic.background
        fgc = Useable.defaultGraphic.foreground
        shape = Useable.defaultGraphic.shape
        # load graphic
        if 'graphic' in parts:
            if 'bgc' in parts['graphic']:
                bgc = parts['graphic']['bgc']
            if 'fgc' in parts['graphic']:
                fgc = parts['graphic']['fgc']
            if 'shape' in parts['graphic']:
                shape = parts['graphic']['shape']
        graphic = ThingGraphic(bgc, fgc, shape)
        # load use functions
        if 'useFunc' in parts:
            useFunc = parts['useFunc']
        if 'customValues' in parts:
            customValues = dict(parts['customValues'])
            for v in customValues:
                if isinstance(customValues[v], tuple):
                    customValues[v] = list(customValues[v])
        if 'useLocation' in parts:
            playerx, playery = parts['useLocation']
        return cls(parts['name'], parts['location'][0], parts['location'][1],
            parts['description'], useFunc, customValues, playerx, playery, graphic)
            
    def use(self, user, gameBase, args) -> float:
        pass
        
    def fromPrefab(self, prefab):
        parts = prefab.details
        # set default values for optional arguments
        name = self.name
        description = self.description
        useFunc = self.useFunc
        customValues = dict(self.customValues)
        playerx = prefab.x + (self.playerx - self.x)
        playery = prefab.y + (self.playery - self.y)
        bgc = self.graphic.background
        fgc = self.graphic.foreground
        shape = self.graphic.shape
        if parts != None:
            if 'name' in parts:
                name = parts['name']
            if 'description' in parts:
                description = parts['description']
            # load graphic
            if 'graphic' in parts:
                if 'bgc' in parts['graphic']:
                    bgc = parts['graphic']['bgc']
                if 'fgc' in parts['graphic']:
                    fgc = parts['graphic']['fgc']
                if 'shape' in parts['graphic']:
                    shape = parts['graphic']['shape']
            # load use functions
            if 'useFunc' in parts:
                useFunc = parts['useFunc']
            if 'customValues' in parts:
                customValues = dict(parts['customValues'])
                for v in customValues:
                    if isinstance(customValues[v], tuple):
                        customValues[v] = list(customValues[v])
            if 'useLocation' in parts:
                playerx, playery = parts['useLocation']
        graphic = ThingGraphic(bgc, fgc, shape)
        return Useable(name, prefab.x, prefab.y, description, useFunc, customValues, playerx, playery, graphic)

class Character(Thing):
    defaultGraphic = ThingGraphic('clear', '#000000', 'o')
    
    def __init__(self, inventory: dict, customValues: dict, graphic = defaultGraphic, **kwargs):
        super(Character, self).__init__(**kwargs)
        if inventory == None:
            inventory = {} # create a new dict for the inventory.
                           # This couldn't be in the NPC constructor because
                           # then all characters would share a reference to
                           # the same empty inventory.
        self.__inventory = inventory
        self.customValues = customValues
        self.graphic = graphic
        self.thingNames = {} #{str: int}
        # set up inventory shtuff
        for i in self.__inventory:
            if self.__inventory[i].name in self.thingNames:
                self.thingNames[self.__inventory[i].name].append(i)
            else:
                self.thingNames[self.__inventory[i].name] = [i]
    
    def addThing(self, thing):
        if not isinstance(thing, Item):
            raise TypeError("Only items can be added to a character's inventory.")
        self.__inventory[thing.thingID] = thing
        if thing.name in self.thingNames:
            self.thingNames[thing.name].append(thing.thingID)
        else:
            self.thingNames[thing.name] = [thing.thingID]
        
    def getThingByID(self, thingID):
        if thingID in self.__inventory:
            return self.__inventory[thingID]
        else:
            return None
        
    def getThingByName(self, name):
        if name in self.thingNames:
            return self.__inventory[self.thingNames[name][0]]
        else:
            return None
    
    def removeThingByID(self, thingID):
        ret = self.__inventory[thingID]
        self.thingNames[ret.name].remove(thingID)
        if len(self.thingNames[ret.name]) == 0:
            del self.thingNames[ret.name]
        del self.__inventory[thingID]
        return ret
        
    def removeThingByName(self, name):
        ret = self.getThingByName(name)
        self.thingNames[ret.name].remove(ret.thingID)
        if len(self.thingNames[ret.name]) == 0:
            del self.thingNames[ret.name]
        del self.__inventory[ret.thingID]
        return ret
    
    def removeThing(self, ret):
        self.thingNames[ret.name].remove(ret.thingID)
        if len(self.thingNames[ret.name]) == 0:
            del self.thingNames[ret.name]
        del self.__inventory[ret.thingID]
        return ret
    
    @property
    def inventory(self):
        """Get the inventory as a list."""
        return list(self.__inventory.values())

class NPC(Character, Observer):
    yaml_flag = u'!NPC'
    defaultGraphic = ThingGraphic('clear', '#000000', 'o')
    
    def __init__(self, behaviors: dict, tempInventory: list, **kwargs):
        if 'graphic' not in kwargs:
            kwargs['graphic'] = PlayerCharacter.defaultGraphic
        super(NPC, self).__init__(thingType = 'n', inventory = {}, flags = 6, **kwargs)
        self.behaviors = behaviors
        self.behaveEvent = None
        self.tempInventory = tempInventory # should be deleted once NPC is loaded
        
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'name': node.name, 'location': (node.x, node.y),
            'description': node.description, 'behaviors': node.behaviors}
        # save graphic
        graphic = {}
        if node.graphic.background != Useable.defaultGraphic.background:
            graphic['bgc'] = node.graphic.background
        if node.graphic.foreground != Useable.defaultGraphic.foreground:
            graphic['fgc'] = node.graphic.foreground
        if node.graphic.shape != Useable.defaultGraphic.shape:
            graphic['shape'] = node.graphic.shape
        if len(graphic) > 0:
            ret['graphic'] = graphic
        # save use functions
        if len(node.inventory) > 0:
            ret['inventory'] = node.inventory
        if len(node.customValues) > 0:
            ret['customValues'] = node.customValues
        if node.x != node.playerx or node.y != node.playery:
            ret['useLocation'] = (node.playerx, node.playery)
        return representer.represent_mapping(cls.yaml_flag, ret)
    
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        minventory = []
        mcustomValues = {}
        mplayerx, mplayery = parts['location']
        bgc = NPC.defaultGraphic.background
        fgc = NPC.defaultGraphic.foreground
        shape = NPC.defaultGraphic.shape
        # load graphic
        if 'graphic' in parts:
            if 'bgc' in parts['graphic']:
                bgc = parts['graphic']['bgc']
            if 'fgc' in parts['graphic']:
                fgc = parts['graphic']['fgc']
            if 'shape' in parts['graphic']:
                shape = parts['graphic']['shape']
        mgraphic = ThingGraphic(bgc, fgc, shape)
        # load use functions
        if 'inventory' in parts:
            inventory = parts['inventory']
        if 'customValues' in parts:
            mcustomValues = dict(parts['customValues'])
            for v in mcustomValues:
                if isinstance(mcustomValues[v], tuple):
                    mcustomValues[v] = list(mcustomValues[v])
        if 'useLocation' in parts:
            playerx, playery = parts['useLocation']
        return cls(name = parts['name'], x = parts['location'][0], y = parts['location'][1],
            description = parts['description'], behaviors = parts['behaviors'], tempInventory = minventory, customValues = mcustomValues,
            playerx = mplayerx, plyery = mplayery, graphic = mgraphic)
    
    def fromPrefab(self, prefab):
        parts = prefab.details
        # set default values for optional arguments
        mname = self.name
        mdescription = self.description
        minventory = list(self.tempInventory)
        mcustomValues = dict(self.customValues)
        mbehaviors = dict(self.behaviors)
        mplayerx = prefab.x + (self.playerx - self.x)
        mplayery = prefab.y + (self.playery - self.y)
        bgc = self.graphic.background
        fgc = self.graphic.foreground
        shape = self.graphic.shape
        if prefab != None:
            if 'name' in parts:
                mname = parts['name']
            if 'description' in parts:
                mdescription = parts['description']
            # load graphic
            if 'graphic' in parts:
                if 'bgc' in parts['graphic']:
                    bgc = parts['graphic']['bgc']
                if 'fgc' in parts['graphic']:
                    fgc = parts['graphic']['fgc']
                if 'shape' in parts['graphic']:
                    shape = parts['graphic']['shape']
            # load use functions
            if 'inventory' in parts:
                inventory = parts['inventory']
            if 'customValues' in parts:
                mcustomValues = dict(parts['customValues'])
                for v in mcustomValues:
                    if isinstance(mcustomValues[v], tuple):
                        mcustomValues[v] = list(mcustomValues[v])
            if 'useLocation' in parts:
                playerx, playery = parts['useLocation']
            if 'behaviors' in parts:
                mbehaviors = dict(parts['behaviors'])
        mgraphic = ThingGraphic(bgc, fgc, shape)
        return NPC(name = mname, x = prefab.x, y = prefab.y, description = mdescription, behaviors = mbehaviors, tempInventory = minventory, customValues = mcustomValues,
            playerx = mplayerx, plyery = mplayery, graphic = mgraphic)

class Door(Thing):
    yaml_flag = u'!Door'
    defaultGraphic = ThingGraphic('clear', '#7F3F00', '#')
    
    def __init__(self, name, x: int, y: int, locked: bool, description = None, key = None, graphic = defaultGraphic):
        self.descBase = description
        if description == None:
            if locked:
                description = "The {0} is locked.".format(name)
            else:
                description = "The {0} is unlocked.".format(name)
        else:
            if locked:
                description += " It is locked.".format(name)
            else:
                description += " It is unlocked.".format(name)
        super(Door, self).__init__('d', name, x, y, description, 1)
        self.passable = not locked
        self.key = key
        self.graphic = graphic
            
    def lock(self, key = None):
        if key == self.key:
            self.passable = not self.passable
            if self.descBase == None:
                if self.passable:
                    self.description = "The {0} is unlocked.".format(self.name)
                else:
                    self.description = "The {0} is locked.".format(self.name)
            else:
                if self.passable:
                    self.description += " It is unlocked.".format(self.name)
                else:
                    self.description += " It is locked.".format(self.name)
            return True
        return False
        
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'name': node.name, 'location': (node.x, node.y)}
        # save graphic
        graphic = {}
        if node.graphic.background != Useable.defaultGraphic.background:
            graphic['bgc'] = node.graphic.background
        if node.graphic.foreground != Useable.defaultGraphic.foreground:
            graphic['fgc'] = node.graphic.foreground
        if node.graphic.shape != Useable.defaultGraphic.shape:
            graphic['shape'] = node.graphic.shape
        if len(graphic) > 0:
            ret['graphic'] = graphic
        # save door state
        if node.passable:
            ret['locked'] = not node.passable
        if node.descBase != None:
            ret['description'] = node.descBase
        if node.key != None:
            ret['key'] = node.key
        return representer.represent_mapping(cls.yaml_flag, ret)
    
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        description = None
        locked = False
        key = None
        bgc = Door.defaultGraphic.background
        fgc = Door.defaultGraphic.foreground
        shape = Door.defaultGraphic.shape
        # load graphic
        if 'graphic' in parts:
            if 'bgc' in parts['graphic']:
                bgc = parts['graphic']['bgc']
            if 'fgc' in parts['graphic']:
                fgc = parts['graphic']['fgc']
            if 'shape' in parts['graphic']:
                shape = parts['graphic']['shape']
        graphic = ThingGraphic(bgc, fgc, shape)
        # load door state
        if 'description' in parts:
            description = parts['description']
        if 'locked' in parts:
            locked = parts['locked']
        if 'key' in parts:
            key = parts['key']
        return cls(parts['name'], parts['location'][0], parts['location'][1],
            locked, description, key, graphic)
            
class MapExit(Thing):
    yaml_flag = u'!MapExit'
    defaultGraphic = ThingGraphic('clear', '#FF0000', 'x')
    
    def __init__(self, name, x: int, y: int, exitid: int, destination: str, prefix = None, onUse = '', key = True, graphic = defaultGraphic):
        description = name
        if prefix:
            description = "{0} {1}".format(prefix, name)
        super(MapExit, self).__init__('x', name, x, y, description, 5)
        self.exitid = exitid
        self.destination = destination
        self.prefix = prefix
        self.onUse = onUse
        self.key = key
        self.graphic = graphic
    
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'name': node.name, 'location': (node.x, node.y), 'id': node.exitid, 'destination': node.destination}
        # save graphic
        graphic = {}
        if node.graphic.background != Useable.defaultGraphic.background:
            graphic['bgc'] = node.graphic.background
        if node.graphic.foreground != Useable.defaultGraphic.foreground:
            graphic['fgc'] = node.graphic.foreground
        if node.graphic.shape != Useable.defaultGraphic.shape:
            graphic['shape'] = node.graphic.shape
        if len(graphic) > 0:
            ret['graphic'] = graphic
        if node.prefix != None:
            ret['prefix'] = node.prefix
        if node.onUse != '':
            ret['onUse'] = node.onUse
        if node.key != True:
            ret['key'] = node.key
        return representer.represent_mapping(cls.yaml_flag, ret)
    
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        prefix = None
        onUse = ''
        key = True
        bgc = MapExit.defaultGraphic.background
        fgc = MapExit.defaultGraphic.foreground
        shape = MapExit.defaultGraphic.shape
        # load graphic
        if 'graphic' in parts:
            if 'bgc' in parts['graphic']:
                bgc = parts['graphic']['bgc']
            if 'fgc' in parts['graphic']:
                fgc = parts['graphic']['fgc']
            if 'shape' in parts['graphic']:
                shape = parts['graphic']['shape']
        graphic = ThingGraphic(bgc, fgc, shape)
        if 'prefix' in parts:
            prefix = parts['prefix']
        if 'onUse' in parts:
            onUse = parts['onUse']
        if 'key' in parts:
            key = parts['key']
        return cls(parts['name'], parts['location'][0], parts['location'][1],
            parts['id'], parts['destination'], prefix, onUse, key, graphic)
            
class MapEntrance(Thing):
    yaml_flag = u'!MapEntrance'
    defaultGraphic = ThingGraphic('clear', 'clear', 'x')
    # no graphic - should not be drawn
    
    def __init__(self, x: int, y: int, exitid: int, name = None):
        if name == None:
            name = 'entrance {}'.format(exitid)
        super(MapEntrance, self).__init__('a', name, x, y, '', 1)
        self.exitid = exitid
        #self.graphic = MapEntrance.defaultGraphic
    
    @classmethod
    def to_yaml(cls, representer, node):
        # save usual things
        ret = {'location': (node.x, node.y), 'id': node.exitid}
        return representer.represent_mapping(cls.yaml_flag, ret)
    
    @classmethod
    def from_yaml(cls, constructor, node):
        parts = CommentedMap()
        constructor.construct_mapping(node, parts, True)
        # set default values for optional arguments
        return cls(parts['location'][0], parts['location'][1], parts['id'])

class PlayerCharacter(Character):
    """Player object. Cannot be created with yaml."""
    defaultGraphic = ThingGraphic('clear', '#0000FF', 'o')
    
    def __init__(self, **kwargs):
        if 'name' not in kwargs:
            kwargs['name'] == 'You'
        if 'graphic' not in kwargs:
            kwargs['graphic'] = PlayerCharacter.defaultGraphic
        super(PlayerCharacter, self).__init__(thingType = 'p', flags = 5, **kwargs)