""" goal.py
 Copyright (C) 1998 Aloril
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 Goal is to make prolog like language at higher level.

 Now: goal has function that checks whether goal is fulfilled.
 If it's not fullfilled, then do this and this and ... to fulfill it.
 'This' can be function or subgoal.

 Things to add in near future: 'real' prolog style variables and 'or' metarule.
"""

from types import *
from event import *

class goal:
    def __init__(self,desc="some goal",fulfilled=None,subgoals=[],
                 time=None, debug=0):
        self.desc=desc
        #mind sets these:
        #self.str
        #self.key
        if fulfilled: self.fulfilled=fulfilled
        else: self.fulfilled=lambda :0 #false
        self.subgoals=subgoals[:]
        self.time=time
        self.debug=debug
        self.vars=[]
    def info(self):
        name=self.__class__.__name__
        if name=="goal":
            return name+"("+`self.desc`+")"
        var=""
        for v in self.vars:
            if var: var=var+","
            var=var+`getattr(self,v)`
        return name+"("+var+")"
    def check_goal(self, me, time):
        "executes goal, see top of file"
        res,deb=self.check_goal_rec(me,time,0)
        if res!=None:
            return res+[event("goal",what=res,what_desc=self.info()+"."+deb)]
    def check_goal_rec(self, me, time, depth):
        res,deb=None,""
        #is it right time range?
        if self.time and self.time!=time: return res,deb
        if self.debug:
            print "\t"*depth+"GOAL: bef fulfilled:",self.desc,self.fulfilled
        if self.fulfilled(me): return res,deb
        for sg in self.subgoals:
            if type(sg)==FunctionType or type(sg)==MethodType:
                res=sg(me)
                if res!=None:
                    deb=sg.__name__+"()"
                    return res,deb
                if self.debug: print "\t"*depth+"GOAL: function:",sg,res
            else:
                if self.debug: print "\t"*depth+"GOAL: bef sg:",sg.desc
                res,deb=sg.check_goal_rec(me,time,depth+1)
                if self.debug: print "\t"*depth+"GOAL: aft sg:",sg.desc,res
                if res!=None:
                    deb=sg.info()+"."+deb
                    return res,deb
        return res,deb