// Copyright 2011 Google Inc. All Rights Reserved.

package gerrit;

import com.google.gerrit.entities.LabelType;
import com.google.gerrit.entities.LabelTypes;
import com.google.gerrit.entities.PatchSetApproval;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.rules.StoredValues;
import com.googlecode.prolog_cafe.exceptions.PrologException;
import com.googlecode.prolog_cafe.lang.IntegerTerm;
import com.googlecode.prolog_cafe.lang.ListTerm;
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.StructureTerm;
import com.googlecode.prolog_cafe.lang.SymbolTerm;
import com.googlecode.prolog_cafe.lang.Term;
import java.util.Optional;

/** Exports list of {@code commit_label( label('Code-Review', 2), user(12345789) )}. */
class PRED__load_commit_labels_1 extends Predicate.P1 {
  private static final SymbolTerm sym_commit_label = SymbolTerm.intern("commit_label", 2);
  private static final SymbolTerm sym_label = SymbolTerm.intern("label", 2);
  private static final SymbolTerm sym_user = SymbolTerm.intern("user", 1);

  PRED__load_commit_labels_1(Term a1, Operation n) {
    arg1 = a1;
    cont = n;
  }

  @Override
  public Operation exec(Prolog engine) throws PrologException {
    engine.setB0();
    Term a1 = arg1.dereference();

    Term listHead = Prolog.Nil;
    ChangeData cd = StoredValues.CHANGE_DATA.get(engine);
    LabelTypes types = cd.getLabelTypes();

    for (PatchSetApproval a : cd.currentApprovals()) {
      Optional<LabelType> t = types.byLabel(a.labelId());
      if (!t.isPresent()) {
        continue;
      }

      StructureTerm labelTerm =
          new StructureTerm(
              sym_label, SymbolTerm.intern(t.get().getName()), new IntegerTerm(a.value()));

      StructureTerm userTerm = new StructureTerm(sym_user, new IntegerTerm(a.accountId().get()));

      listHead = new ListTerm(new StructureTerm(sym_commit_label, labelTerm, userTerm), listHead);
    }

    if (!a1.unify(listHead, engine.trail)) {
      return engine.fail();
    }
    return cont;
  }
}