text: """
  Barter system
  
  Evennia contribution - Griatch 2012
  
  
  This implements a full barter system - a way for players to safely
  trade items between each other using code rather than simple free-form
  talking.  The advantage of this is increased buy/sell safety but it
  also streamlines the process and makes it faster when doing many
  transactions (since goods are automatically exchanged once both
  agree).
  
  This system is primarily intended for a barter economy, but can easily
  be used in a monetary economy as well -- just let the "goods" on one
  side be coin objects (this is more flexible than a simple "buy"
  command since you can mix coins and goods in your trade).
  
  In this module, a "barter" is generally referred to as a "trade".
  
  
  - Trade example
  
  A trade (barter) action works like this: A and B are the parties.
  
  1) opening a trade
  
  A: trade B: Hi, I have a nice extra sword. You wanna trade?
  B sees: A says: "Hi, I have a nice extra sword. You wanna trade?"
     A wants to trade with you. Enter 'trade A <emote>' to accept.
  B: trade A: Hm, I could use a good sword ...
  A sees: B says: "Hm, I could use a good sword ...
     B accepts the trade. Use 'trade help' for aid.
  B sees: You are now trading with A. Use 'trade help' for aid.
  
  2) negotiating
  
  A: offer sword: This is a nice sword. I would need some rations in trade.
  B sees: A says: "This is a nice sword. I would need some rations in trade."
     [A offers Sword of might.]
  B evalute sword
  B sees: <Sword's description and possibly stats>
  B: offer ration: This is a prime ration.
  A sees: B says: "These is a prime ration."
    [B offers iron ration]
  A: say Hey, this is a nice sword, I need something more for it.
  B sees: A says: "Hey this is a nice sword, I need something more for it."
  B: offer sword,apple: Alright. I will also include a magic apple. That's my last offer.
  A sees: B says: "Alright, I will also include a magic apple. That's my last offer."
    [B offers iron ration and magic apple]
  A accept: You are killing me here, but alright.
  B sees: A says: "You are killing me here, but alright."
    [A accepts your offer. You must now also accept.]
  B accept: Good, nice making business with you.
    You accept the deal. Deal is made and goods changed hands.
  A sees: B says: "Good, nice making business with you."
    B accepts the deal. Deal is made and goods changed hands.
  
  At this point the trading system is exited and the negotiated items
  are automatically exchanged between the parties. In this example B was
  the only one changing their offer, but also A could have changed their
  offer until the two parties found something they could agree on. The
  emotes are optional but useful for RP-heavy worlds.
  
  - Technical info
  
  The trade is implemented by use of a TradeHandler. This object is a
  common place for storing the current status of negotiations. It is
  created on the object initiating the trade, and also stored on the
  other party once that party agrees to trade. The trade request times
  out after a certain time - this is handled by a Script. Once trade
  starts, the CmdsetTrade cmdset is initiated on both parties along with
  the commands relevant for the trading.
  
  - Ideas for NPC bartering:
  
  This module is primarily intended for trade between two players. But
  it can also in principle be used for a player negotiating with an
  AI-controlled NPC. If the NPC uses normal commands they can use it
  directly -- but more efficient is to have the NPC object send its
  replies directly through the tradehandler to the player. One may want
  to add some functionality to the decline command, so players can
  decline specific objects in the NPC offer (decline <object>) and allow
  the AI to maybe offer something else and make it into a proper
  barter.  Along with an AI that "needs" things or has some sort of
  personality in the trading, this can make bartering with NPCs at least
  moderately more interesting than just plain 'buy'.
  
  - Installation:
  
  Just import the CmdTrade command into (for example) the default
  cmdset. This will make the trade (or barter) command available
  in-game.
  
  """
  from __future__ import print_function
  from builtins import object
  
  from evennia import Command, DefaultScript, CmdSet
  
  TRADE_TIMEOUT = 60  # timeout for B to accept trade
  
  
  class TradeTimeout(DefaultScript):
      """
      This times out the trade request, in case player B did not reply in time.
      """
      def at_script_creation(self):
          """
          Called when script is first created
          """
          self.key = "trade_request_timeout"
          self.desc = "times out trade requests"
          self.interval = TRADE_TIMEOUT
          self.start_delay = True
          self.repeats = 1
          self.persistent = False
  
      def at_repeat(self):
          """
          called once
          """
          if self.ndb.tradeevent:
              self.obj.ndb.tradeevent.finish(force=True)
          self.obj.msg("Trade request timed out.")
  
      def is_valid(self):
          """
          Only valid if the trade has not yet started
          """
          return self.obj.ndb.tradeevent and not self.obj.ndb.tradeevent.trade_started
  
  
  class TradeHandler(object):
      """
      Objects of this class handles the ongoing trade, notably storing the current
      offers from each side and wether both have accepted or not.
      """
      def __init__(self, partA, partB):
          """
          Initializes the trade. This is called when part A tries to
          initiate a trade with part B. The trade will not start until
          part B repeats this command (B will then call the self.join()
          command)
  
          Args:
              partA (object): The party trying to start barter.
              partB (object): The party asked to barter.
  
          Notes:
              We also store the back-reference from the respective party
              to this object.
  
          """
          # parties
          self.partA = partA
          self.partB = partB
  
          self.partA.cmdset.add(CmdsetTrade())
          self.trade_started = False
          self.partA.ndb.tradehandler = self
          # trade variables
          self.partA_offers = []
          self.partB_offers = []
          self.partA_accepted = False
          self.partB_accepted = False
  
      def msg(self, party, string):
          """
          Relay a message to the other party. This allows the calling
          command to not have to worry about which party they are in the
          handler.
  
          Args:
              party (object): One of partA or B. The method will figure
                  out which is which.
              string (str): Text to send.
          """
          if self.partA == party:
              self.partB.msg(string)
          elif self.partB == party:
              self.partA.msg(string)
          else:
              # no match, relay to oneself
              self.party.msg(string)
  
      def get_other(self, party):
          """
          Returns the other party of the trade
  
          Args:
              partyX (object): One of the parties of the negotiation
  
          Returns:
              partyY (object): The other party, not partyX.
  
          """
          if self.partA == party:
              return self.partB
          if self.partB == party:
              return self.partA
          return None
  
      def join(self, partB):
          """
          This is used once B decides to join the trade
  
          Args:
              partB (object): The party accepting the barter.
  
          """
          if self.partB == partB:
              self.partB.ndb.tradehandler = self
              self.partB.cmdset.add(CmdsetTrade())
              self.trade_started = True
              return True
          return False
  
      def unjoin(self, partB):
          """
          This is used if B decides not to join the trade.
  
          Args:
              partB (object): The party leaving the barter.
  
          """
          if self.partB == partB:
              self.finish()
              return True
          return False
  
      def offer(self, party, *args):
          """
          Change the current standing offer. We leave it up to the
          command to do the actual checks that the offer consists
          of real, valid, objects.
  
          Args:
              party (object): Who is making the offer
              args (objects or str): Offerings.
  
          """
          if self.trade_started:
              # reset accept statements whenever an offer changes
              self.partA_accepted = False
              self.partB_accepted = False
              if party == self.partA:
                  self.partA_offers = list(args)
              elif party == self.partB:
                  self.partB_offers = list(args)
              else:
                  raise ValueError
  
      def list(self):
          """
          List current offers.
  
          Returns:
              offers (tuple): A tuple with two lists, (A_offers, B_offers).
  
          """
          return self.partA_offers, self.partB_offers
  
      def search(self, offername):
          """
          Search current offers.
  
          Args:
              offername (str or int): Object to search for, or its index in
                  the list of offered items.
  
          Returns:
              offer (object): An object on offer, based on the search criterion.
  
          """
          all_offers = self.partA_offers + self.partB_offers
          if isinstance(offername, int):
              # an index to return
              if 0 <= offername < len(all_offers):
                  return all_offers[offername]
  
          all_keys = [offer.key for offer in all_offers]
          try:
              imatch = all_keys.index(offername)
              return all_offers[imatch]
          except ValueError:
              for offer in all_offers:
                  if offername in offer.aliases:
                      return offer
          return None
  
      def accept(self, party):
          """
          Accept the current offer.
  
          Args:
              party (object): The party accepting the deal.
  
          Returns:
              result (object): `True` if this closes the deal, `False`
                  otherwise
  
          Notes:
              This will only close the deal if both parties have
              accepted independently. This is done by calling the
              `finish()` method.
  
          """
          if self.trade_started:
              if party == self.partA:
                  self.partA_accepted = True
              elif party == self.partB:
                  self.partB_accepted = True
              else:
                  raise ValueError
              return self.finish()  # try to close the deal
  
      def decline(self, party):
          """
          Decline the offer (or change one's mind).
  
          Args:
              party (object): Party declining the deal.
  
          Returns:
              did_decline (bool): `True` if there was really an
                  `accepted` status to change, `False` otherwise.
  
          Notes:
              If previously having used the `accept` command, this
              function will only work as long as the other party has not
              yet accepted.
  
          """
          if self.trade_started:
              if party == self.partA:
                  if self.partA_accepted:
                      self.partA_accepted = False
                      return True
                  return False
              elif party == self.partB:
                  if self.partB_accepted:
                      self.partB_accepted = False
                      return True
                  return False
              else:
                  raise ValueError
  
      def finish(self, force=False):
          """
          Conclude trade - move all offers and clean up
  
          Args:
              force (bool, optional): Force cleanup regardless of if the
                  trade was accepted or not (if not, no goods will change
                  hands but trading will stop anyway)
  
          """
          fin = False
          if self.trade_started and self.partA_accepted and self.partB_accepted:
              # both accepted - move objects before cleanup
              for obj in self.partA_offers:
                  obj.location = self.partB
              for obj in self.partB_offers:
                  obj.location = self.partA
              fin = True
          if fin or force:
              # cleanup
              self.partA.cmdset.delete("cmdset_trade")
              self.partB.cmdset.delete("cmdset_trade")
              self.partA_offers = None
              self.partB_offers = None
              # this will kill it also from partB
              del self.partA.ndb.tradehandler
              if self.partB.ndb.tradehandler:
                  del self.partB.ndb.tradehandler
              return True
  
  
  # trading commands (will go into CmdsetTrade, initialized by the
  # CmdTrade command further down).
  
  class CmdTradeBase(Command):
      """
      Base command for Trade commands to inherit from. Implements the
      custom parsing.
      """
      def parse(self):
          """
          Parse the relevant parts and make it easily
          available to the command
          """
          self.args = self.args.strip()
          self.tradehandler = self.caller.ndb.tradehandler
          self.partA = self.tradehandler.partA
          self.partB = self.tradehandler.partB
  
          self.other = self.tradehandler.get_other(self.caller)
          self.msg_other = self.tradehandler.msg
  
          self.trade_started = self.tradehandler.trade_started
          self.emote = ""
          self.str_caller = "Your trade action: %s"
          self.str_other = "%s:s trade action: " % self.caller.key + "%s"
          if ':' in self.args:
              self.args, self.emote = [part.strip() for part in self.args.rsplit(":", 1)]
              self.str_caller = 'You say, "' + self.emote + '"\n  [%s]'
              if self.caller.has_player:
                  self.str_other = '{c%s{n says, "' % self.caller.key + self.emote + '"\n  [%s]'
              else:
                  self.str_other = '%s says, "' % self.caller.key + self.emote + '"\n  [%s]'
  
  
  # trade help
  
  class CmdTradeHelp(CmdTradeBase):
      """
      help command for the trade system.
  
      Usage:
          trade help
  
      Displays help for the trade commands.
      """
      key = "trade help"
      #aliases = ["trade help"]
      locks = "cmd:all()"
      help_category = "Trade"
  
      def func(self):
          "Show the help"
          string = """
          Trading commands
  
          {woffer <objects> [:emote]{n
              offer one or more objects for trade. The emote can be used for
              RP/arguments. A new offer will require both parties to re-accept
              it again.
          {waccept [:emote]{n
              accept the currently standing offer from both sides. Also 'agree'
              works. Once both have accepted, the deal is finished and goods
              will change hands.
          {wdecline [:emote]{n
              change your mind and remove a previous accept (until other
              has also accepted)
          {wstatus{n
              show the current offers on each side of the deal. Also 'offers'
              and 'deal' works.
          {wevaluate <nr> or <offer>{n
              examine any offer in the deal. List them with the 'status' command.
          {wend trade{n
              end the negotiations prematurely. No trade will take place.
  
          You can also use {wemote{n, {wsay{n etc to discuss
          without making a decision or offer.
          """
          self.caller.msg(string)
  
  
  # offer
  
  class CmdOffer(CmdTradeBase):
      """
      offer one or more items in trade.
  
      Usage:
        offer <object> [, object2, ...][:emote]
  
      Offer objects in trade. This will replace the currently
      standing offer.
      """
      key = "offer"
      locks = "cmd:all()"
      help_category = "Trading"
  
      def func(self):
          "implement the offer"
  
          caller = self.caller
          if not self.args:
              caller.msg("Usage: offer <object> [, object2, ...] [:emote]")
              return
          if not self.trade_started:
              caller.msg("Wait until the other party has accepted to trade with you.")
              return
  
          # gather all offers
          offers = [part.strip() for part in self.args.split(',')]
          offerobjs = []
          for offername in offers:
              obj = caller.search(offername)
              if not obj:
                  return
              offerobjs.append(obj)
          self.tradehandler.offer(self.caller, *offerobjs)
  
          # output
          if len(offerobjs) > 1:
              objnames = ", ".join("{w%s{n" % obj.key for obj in offerobjs[:-1]) + " and {w%s{n" % offerobjs[-1].key
          else:
              objnames = "{w%s{n" % offerobjs[0].key
  
          caller.msg(self.str_caller % ("You offer %s" % objnames))
          self.msg_other(caller, self.str_other % ("They offer %s" % objnames))
  
  
  # accept
  
  class CmdAccept(CmdTradeBase):
      """
      accept the standing offer
  
      Usage:
        accept [:emote]
        agreee [:emote]
  
      This will accept the current offer. The other party must also accept
      for the deal to go through. You can use the 'decline' command to change
      your mind as long as the other party has not yet accepted. You can inspect
      the current offer using the 'offers' command.
      """
      key = "accept"
      aliases = ["agree"]
      locks = "cmd:all()"
      help_category = "Trading"
  
      def func(self):
          "accept the offer"
          caller = self.caller
          if not self.trade_started:
              caller.msg("Wait until the other party has accepted to trade with you.")
              return
          if self.tradehandler.accept(self.caller):
              # deal finished. Trade ended and cleaned.
              caller.msg(self.str_caller % "You {gaccept{n the deal. {gDeal is made and goods changed hands.{n")
              self.msg_other(caller, self.str_other % "%s {gaccepts{n the deal. {gDeal is made and goods changed hands.{n" % caller.key)
          else:
              # a one-sided accept.
              caller.msg(self.str_caller % "You {Gaccept{n the offer. %s must now also accept." % self.other.key)
              self.msg_other(caller, self.str_other % "%s {Gaccepts{n the offer. You must now also accept." % caller.key)
  
  
  # decline
  
  class CmdDecline(CmdTradeBase):
      """
      decline the standing offer
  
      Usage:
        decline [:emote]
  
      This will decline a previously 'accept'ed offer (so this allows you to
      change your mind). You can only use this as long as the other party
      has not yet accepted the deal. Also, changing the offer will automatically
      decline the old offer.
      """
      key = "decline"
      locks = "cmd:all()"
      help_category = "Trading"
  
      def func(self):
          "decline the offer"
          caller = self.caller
          if not self.trade_started:
              caller.msg("Wait until the other party has accepted to trade with you.")
              return
          offerA, offerB = self.tradehandler.list()
          if not offerA or not offerB:
              caller.msg("Noone has offered anything (yet) so there is nothing to decline.")
              return
          if self.tradehandler.decline(self.caller):
              # changed a previous accept
              caller.msg(self.str_caller % "You change your mind, {Rdeclining{n the current offer.")
              self.msg_other(caller, self.str_other % "%s changes their mind, {Rdeclining{n the current offer." % caller.key)
          else:
              # no acceptance to change
              caller.msg(self.str_caller % "You {Rdecline{n the current offer.")
              self.msg_other(caller, self.str_other % "%s declines the current offer." % caller.key)
  
  
  # evaluate
  
  # Note: This version only shows the description. If your particular game
  # lists other important properties of objects (such as weapon damage, weight,
  # magical properties, ammo requirements or whatnot), then you need to add this
  # here.
  
  class CmdEvaluate(CmdTradeBase):
      """
      evaluate objects on offer
  
      Usage:
        evaluate <offered object>
  
      This allows you to examine any object currently on offer, to
      determine if it's worth your while.
      """
      key = "evaluate"
      aliases = ["eval"]
      locks = "cmd:all()"
      help_category = "Trading"
  
      def func(self):
          "evaluate an object"
          caller = self.caller
          if not self.args:
              caller.msg("Usage: evaluate <offered object>")
              return
          # we also accept indices
          try:
              ind = int(self.args)
              self.args = ind - 1
          except Exception:
              pass
  
          offer = self.tradehandler.search(self.args)
          if not offer:
              caller.msg("No offer matching '%s' was found." % self.args)
              return
          # show the description
          caller.msg(offer.db.desc)
  
  
  # status
  
  class CmdStatus(CmdTradeBase):
      """
      show a list of the current deal
  
      Usage:
        status
        deal
        offers
  
      Shows the currently suggested offers on each sides of the deal. To
      accept the current deal, use the 'accept' command. Use 'offer' to
      change your deal. You might also want to use 'say', 'emote' etc to
      try to influence the other part in the deal.
      """
      key = "status"
      aliases = ["offers", "deal"]
      locks = "cmd:all()"
      help_category = "Trading"
  
      def func(self):
          "Show the current deal"
          caller = self.caller
          partA_offers, partB_offers = self.tradehandler.list()
          count = 1
          partA_offerlist = ""
          for offer in partA_offers:
              partA_offerlist += "\n {w%i{n %s" % (count, offer.key)
              count += 1
          if not partA_offerlist:
              partA_offerlist = "\n <nothing>"
          partB_offerlist = ""
          for offer in partB_offers:
              partB_offerlist += "\n {w%i{n %s" % (count, offer.key)
              count += 1
          if not partB_offerlist:
              partB_offerlist = "\n <nothing>"
  
          string = "{gOffered by %s:{n%s\n{yOffered by %s:{n%s" % (self.partA.key,
                                                                   partA_offerlist,
                                                                   self.partB.key,
                                                                   partB_offerlist)
          acceptA = self.tradehandler.partA_accepted and "{gYes{n" or "{rNo{n"
          acceptB = self.tradehandler.partB_accepted and "{gYes{n" or "{rNo{n"
          string += "\n\n%s agreed: %s, %s agreed: %s" % \
                                            (self.partA.key, acceptA, self.partB.key, acceptB)
          string += "\n Use 'offer', 'eval' and 'accept'/'decline' to trade. See also 'trade help'."
          caller.msg(string)
  
  
  # finish
  
  class CmdFinish(CmdTradeBase):
      """
      end the trade prematurely
  
      Usage:
        end trade [:say]
        finish trade [:say]
  
      This ends the trade prematurely. No trade will take place.
  
      """
      key = "end trade"
      aliases = "finish trade"
      locks = "cmd:all()"
      help_category = "Trading"
  
      def func(self):
          "end trade"
          caller = self.caller
          self.tradehandler.finish(force=True)
          caller.msg(self.str_caller % "You {raborted{n trade. No deal was made.")
          self.msg_other(caller, self.str_other % "%s {raborted{n trade. No deal was made." % caller.key)
  
  
  # custom Trading cmdset
  
  class CmdsetTrade(CmdSet):
      """
      This cmdset is added when trade is initated. It is handled by the
      trade event handler.
      """
      key = "cmdset_trade"
  
      def at_cmdset_creation(self):
          "Called when cmdset is created"
          self.add(CmdTradeHelp())
          self.add(CmdOffer())
          self.add(CmdAccept())
          self.add(CmdDecline())
          self.add(CmdEvaluate())
          self.add(CmdStatus())
          self.add(CmdFinish())
  
  
  # access command - once both have given this, this will create the
  # trading cmdset to start trade.
  
  class CmdTrade(Command):
      """
      Initiate trade with another party
  
      Usage:
        trade <other party> [:say]
        trade <other party> accept [:say]
        trade <other party> decline [:say]
  
      Initiate trade with another party. The other party needs to repeat
      this command with trade accept/decline within a minute in order to
      properly initiate the trade action. You can use the decline option
      yourself if you want to retract an already suggested trade. The
      optional say part works like the say command and allows you to add
      info to your choice.
      """
      key = "trade"
      aliases = ["barter"]
      locks = "cmd:all()"
      help_category = "General"
  
      def func(self):
          "Initiate trade"
  
          if not self.args:
              if self.caller.ndb.tradehandler and self.caller.ndb.tradeevent.trade_started:
                  self.caller.msg("You are already in a trade. Use 'end trade' to abort it.")
              else:
                  self.caller.msg("Usage: trade <other party> [accept|decline] [:emote]")
              return
          self.args = self.args.strip()
  
          # handle the emote manually here
          selfemote = ""
          theiremote = ""
          if ':' in self.args:
              self.args, emote = [part.strip() for part in self.args.rsplit(":", 1)]
              selfemote = 'You say, "%s"\n  ' % emote
              if self.caller.has_player:
                  theiremote = '{c%s{n says, "%s"\n  ' % (self.caller.key, emote)
              else:
                  theiremote = '%s says, "%s"\n  ' % (self.caller.key, emote)
  
          # for the sake of this command, the caller is always partA; this
          # might not match the actual name in tradehandler (in the case of
          # using this command to accept/decline a trade invitation).
          partA = self.caller
          accept = 'accept' in self.args
          decline = 'decline' in self.args
          if accept:
              partB = self.args.rstrip('accept').strip()
          elif decline:
              partB = self.args.rstrip('decline').strip()
          else:
              partB = self.args
          partB = self.caller.search(partB)
          if not partB:
              return
          if partA == partB:
              partA.msg("You play trader with yourself.")
              return
  
          # messages
          str_initA = "You ask to trade with %s. They need to accept within %s secs."
          str_initB = "%s wants to trade with you. Use {wtrade %s accept/decline [:emote]{n to answer (within %s secs)."
          str_noinitA = "%s declines the trade"
          str_noinitB = "You decline trade with %s."
          str_startA = "%s starts to trade with you. See {wtrade help{n for aid."
          str_startB = "You start to trade with %s. See {wtrade help{n for aid."
  
          if not (accept or decline):
              # initialization of trade
              if self.caller.ndb.tradehandler:
                  # trying to start trade without stopping a previous one
                  if self.caller.ndb.tradehandler.trade_started:
                      string = "You are already in trade with %s. You need to end trade first."
                  else:
                      string = "You are already trying to initiate trade with %s. You need to decline that trade first."
                  self.caller.msg(string % partB.key)
              elif partB.ndb.tradehandler and partB.ndb.tradehandler.partB == partA:
                  # this is equivalent to partA accepting a trade from partB (so roles are reversed)
                  partB.ndb.tradehandler.join(partA)
                  partB.msg(theiremote + str_startA % partA.key)
                  partA.msg(selfemote + str_startB % (partB.key))
              else:
                  # initiate a new trade
                  TradeHandler(partA, partB)
                  partA.msg(selfemote + str_initA % (partB.key, TRADE_TIMEOUT))
                  partB.msg(theiremote + str_initB % (partA.key, partA.key, TRADE_TIMEOUT))
                  partA.scripts.add(TradeTimeout)
              return
          elif accept:
              # accept a trade proposal from partB (so roles are reversed)
              if partA.ndb.tradehandler:
                  # already in a trade
                  partA.msg("You are already in trade with %s. You need to end that first." % partB.key)
                  return
              if partB.ndb.tradehandler.join(partA):
                  partB.msg(theiremote + str_startA % partA.key)
                  partA.msg(selfemote + str_startB % partB.key)
              else:
                  partA.msg("No trade proposal to accept.")
              return
          else:
              # decline trade proposal from partB (so roles are reversed)
              if partA.ndb.tradehandler and partA.ndb.tradehandler.partB == partA:
                  # stopping an invite
                  partA.ndb.tradehandler.finish(force=True)
                  partB.msg(theiremote + "%s aborted trade attempt with you." % partA)
                  partA.msg(selfemote + "You aborted the trade attempt with %s." % partB)
              elif partB.ndb.tradehandler and partB.ndb.tradehandler.unjoin(partA):
                  partB.msg(theiremote + str_noinitA % partA.key)
                  partA.msg(selfemote + str_noinitB % partB.key)
              else:
                  partA.msg("No trade proposal to decline.")
              return
  
  