namespace Eva {
  public class List : Object, Term {
    private Term? _tail;
    
    public Gee.List<Term?> list {get; construct;}
    public Term? tail {
      get {
        return _tail;
      }
      set {
        if(value is List) {
          List l = value as List;
          
          list.add_all(l.list);
          _tail = l._tail;
        }
        else {
          _tail = value;
        }
      }
    }
    
    public List() {
      Gee.List<Term?> list0 = new Gee.LinkedList<Term?>();
      Object(list: list0);
      tail = null;
    }
    
    protected bool do_match(Term o, Gee.Map<string, Term> vars, Gee.Map<string, string> aliases) {
      if(o is Var) {
        return o.do_match(this, vars, aliases);
      }
      
      if(o is List) {
        List l = o as List;
        
        if(list.size != l.list.size)
          return false;
        if((tail == null) != (l.tail == null))
          return false;
        if(tail != null && !tail.do_match(l.tail, vars, aliases))
          return false;
        
        Gee.Iterator<Term> lt = l.list.iterator();
        lt.first();
        foreach(Term t in list) {
          if(!t.do_match(lt.get(), vars, aliases))
            return false;
          
          lt.next();
        }
        
        return true;
      }
      else if(o is String) {
        if(tail != null)
          return false;
        
        string s = "";
        
        foreach(Term t in list) {
          unichar c;
          
          if(t is Int) {
            Int i = t as Int;
            if(i.value < 0 || i.value > 255)
              return false;
            
            c = (unichar)i.value;
          }
          else if(t is UInt) {
            UInt i = t as UInt;
            if(i.value > 255)
              return false;
            
            c = (unichar)i.value;
          }
          else {
            return false;
          }
          
          string buf = string.nfill(6, 0);
          c.to_utf8(buf);
          
          s += buf;
        }
        
        return (s == (o as String).value);
      }
      else {
        return false;
      }
    }
    
    public string to_string() {
      string ret = "[";
      bool first = true;
      
      foreach(Term term in list) {
        if(first) {
          first = false;
          ret += term.to_string();
        }
        else {
          ret += "," + term.to_string();
        }
      }
      
      if(tail != null)
        ret += "|" + tail.to_string();
      
      return ret + "]";
    }
    
    public void encode(Erl.Buffer buffer) {
      if(!list.is_empty) {
        buffer.encode_list_header(list.size);
      
        foreach(Term term in list) {
          term.encode(buffer);
        }
      }
      
      if(tail == null)
        buffer.encode_empty_list();
      else
        tail.encode(buffer);
    }
  }
}