package tarau.jinni;
import java.util.Date;

/**
  Initializes Jinni. Sets up shared data areas.
  Ensures that lib.class, obtained from lib.pro->lib.java is loaded.
*/
public class Init { 
  public static final int version=84;

  public static final String getInfo() {
     String s=
       "Kernel Prolog "+version/100.0+"\n"+
       "Copyright (c) Paul Tarau && BinNet Corp. 1999\n"+
       "Open Source Edition, under GNU General Public License.\n"+
       "Download latest version from: http://www.binnetcorp.com/kprolog/Main.html\n"+
       "For commercial licensing, related service or support contracts\n"+
       "and commercial extensions in binary form, contact BinNet Corporation at:\n"+
       "binnetcorp@binnetcorp.com, http://www.binnetcorp.com\n";
     return s;
  }

  public static DataBase default_db; 
  public static Builtins builtinDict;

  public  static Clause getGoal(String line) {
    Clause G=Clause.goalFromString(line);
    //IO.mes("getGoal: "+G+" DICT: "+G.dict); //OK
    return G;
  }


   public static void run_query(String query) {
	   Clause Goal=getGoal(query);
     timeGoal(Goal);
  }

  /**
  * reads a query from input strea
  */
  static Clause getGoal() {
    return getGoal(IO.promptln("?- "));
  }

  /**
  * evalutes a query
  */
  public static void evalGoal(Clause Goal) {
    Clause NamedGoal=Goal.cnumbervars(false);
     Term Names=NamedGoal.getHead();
     if(!(Names instanceof Fun)) { // no vars in Goal
       Term Result=Prog.firstSolution(Goal.getHead(),Goal.getBody());
       if(!Const.aNo.eq(Result))
         Result=Const.aYes;
       IO.println(Result.toString());
       return;
     }

     Prog E=new Prog(Goal,null);
   
     for(int i=0;;i++) {
       Term R=Prog.ask_engine(E);
       //IO.mes("GOAL:"+Goal+"\nANSWER: "+R);
       if(R==null) {
         IO.println("no"); 
         break;
       }
       if(Names instanceof Fun) {
         Fun NamedR=(Fun)R.numbervars();
         for(int j=0; j<Names.getArity(); j++) {
           IO.println(((Fun)Names).getArg(j)+
                  "="+NamedR.getArg(j));
         }
         //IO.println(";");
         if(!moreAnswers(i)) {
           E.stop();
           break;
         }
       }
     }
  }

  static boolean moreAnswers(int i) {
    if(IO.maxAnswers==0) { // under user control
      String more=IO.promptln("; for more, <enter> to stop: ");
      return more.equals(";");
    }
    else if(i<IO.maxAnswers || IO.maxAnswers<0) {
      IO.println(";"); // print all remaining
      return true;
    }
    else { // i >= ...}
      IO.println(";");
      IO.println("No more answers computed, max reached! ("+
        IO.maxAnswers+")");
      return false;
    }
  }

  /**
  *  evaluates and times a Goal querying program P
  */

  public static void timeGoal(Clause Goal) {
     long t1 = System.currentTimeMillis();
     try {
       evalGoal(Goal);
     }
     catch(Throwable e) {
       IO.errmes("Execution error in goal:\n  "+Goal.pprint()+".\n",e);
     }
     long t2 = System.currentTimeMillis();
     IO.println("Time: "+(t2-t1)/1000.0+" sec, threads="+
       Thread.activeCount());
  }

  /**
  *  (almost) standard Prolog-like toplevel in Java
  *  (will) print out variables and values
  */
  public static void standardTop() {
	   standardTop("?- ");
  }
	   
  public static void standardTop(String prompt) {
    for(;;) {
       Clause G=getGoal(IO.promptln(prompt));
       if(null==G) {
         continue;
       }
       IO.peer=null;
       timeGoal(G);
    }
  }
  
   /**
    Asks Jinni a query Answer, Goal and returns the
    first solution of the form "the(Answer)" or the constant
    "no" if no solution exists
  */
  public static Term askJinni(Term Answer,Term Body) {
    return Prog.firstSolution(Answer,Body);
  }

  /**
    Asks Jinni a query Goal and returns the
    first solution of the form "the(Answer)" , where
    Answer is an instance of Goal or the constant
    "no" if no solution exists
  */
  public static Term askJinni(Term Goal) {
    return askJinni(Goal,Goal);
  }

  /**
    Asks Jinni a String query and gets back a string Answer
    of the form "the('[]'(VarsOfQuery))" containing a binding
    of the variables or the first solution to the query or "no"
    if no such solution exists
  */
  public static String askJinni(String query) {
    Clause Goal=getGoal(query);
    Term Body=Goal.getBody();
    return askJinni(Body).pprint();
  }

  public static boolean run(String[] args) {
    if(null!=args) {
      for(int i=0; i<args.length; i++) {
        String result=askJinni(args[i]);
        IO.trace(result);
        if("no".equals(result.intern())) {
          IO.errmes("failing cmd line argument: "+args[i]);
          return false;
        }
      }
    }
    return true;
  }

  /**
     Initialises key data areas. Runs a first query, which,
     if suceeeds a true, otherwise false is returned
  */
  public static final boolean startJinni() {  
    // should be final for expiration mechanism (it should avoid overriding!)
    IO.println(getInfo());
    default_db=new DataBase(); 
    return true;
  }

}