// Copyright (C) 2011 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package gerrit;

import com.google.gerrit.common.data.Permission;
import com.google.gerrit.common.data.PermissionRange;
import com.google.gerrit.rules.StoredValues;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.project.ChangeControl;

import com.googlecode.prolog_cafe.exceptions.IllegalTypeException;
import com.googlecode.prolog_cafe.exceptions.PInstantiationException;
import com.googlecode.prolog_cafe.exceptions.PrologException;
import com.googlecode.prolog_cafe.lang.IntegerTerm;
import com.googlecode.prolog_cafe.lang.JavaObjectTerm;
import com.googlecode.prolog_cafe.lang.Operation;
import com.googlecode.prolog_cafe.lang.Predicate;
import com.googlecode.prolog_cafe.lang.Prolog;
import com.googlecode.prolog_cafe.lang.SymbolTerm;
import com.googlecode.prolog_cafe.lang.Term;
import com.googlecode.prolog_cafe.lang.VariableTerm;

/**
 * Resolves the valid range for a label on a CurrentUser.
 *
 * <pre>
 *   '$user_label_range'(+Label, +CurrentUser, -Min, -Max)
 * </pre>
 */
class PRED__user_label_range_4 extends Predicate.P4 {
  PRED__user_label_range_4(Term a1, Term a2, Term a3, Term a4, Operation n) {
    arg1 = a1;
    arg2 = a2;
    arg3 = a3;
    arg4 = a4;
    cont = n;
  }

  @Override
  public Operation exec(Prolog engine) throws PrologException {
    engine.setB0();
    Term a1 = arg1.dereference();
    Term a2 = arg2.dereference();
    Term a3 = arg3.dereference();
    Term a4 = arg4.dereference();

    if (a1 instanceof VariableTerm) {
      throw new PInstantiationException(this, 1);
    }
    if (!(a1 instanceof SymbolTerm)) {
      throw new IllegalTypeException(this, 1, "atom", a1);
    }
    String label = a1.name();

    if (a2 instanceof VariableTerm) {
      throw new PInstantiationException(this, 2);
    }
    if (!(a2 instanceof JavaObjectTerm) || !a2.convertible(CurrentUser.class)) {
      throw new IllegalTypeException(this, 2, "CurrentUser)", a2);
    }
    CurrentUser user = (CurrentUser) ((JavaObjectTerm) a2).object();

    ChangeControl ctl = StoredValues.CHANGE_CONTROL.get(engine).forUser(user);
    PermissionRange range = ctl.getRange(Permission.LABEL + label);
    if (range == null) {
      return engine.fail();
    }

    IntegerTerm min = new IntegerTerm(range.getMin());
    IntegerTerm max = new IntegerTerm(range.getMax());

    if (!a3.unify(min, engine.trail)) {
      return engine.fail();
    }

    if (!a4.unify(max, engine.trail)) {
      return engine.fail();
    }

    return cont;
  }
}