// Copyright (C) 2013 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 com.google.gerrit.server.index;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.base.CharMatcher;
import com.google.common.base.Preconditions;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.config.TrackingFooters;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;

import org.eclipse.jgit.lib.Config;

/**
 * Definition of a field stored in the secondary index.
 *
 * @param <I> input type from which documents are created and search results are
 *     returned.
 * @param <T> type that should be extracted from the input object when converting
 *     to an index document.
 */
public abstract class FieldDef<I, T> {
  /** Definition of a single (non-repeatable) field. */
  public abstract static class Single<I, T> extends FieldDef<I, T> {
    Single(String name, FieldType<T> type, boolean stored) {
      super(name, type, stored);
    }

    @Override
    public final boolean isRepeatable() {
      return false;
    }
  }

  /** Definition of a repeatable field. */
  public abstract static class Repeatable<I, T>
      extends FieldDef<I, Iterable<T>> {
    Repeatable(String name, FieldType<T> type, boolean stored) {
      super(name, type, stored);
      Preconditions.checkArgument(type != FieldType.INTEGER_RANGE,
          "Range queries against repeated fields are unsupported");
    }

    @Override
    public final boolean isRepeatable() {
      return true;
    }
  }

  /** Arguments needed to fill in missing data in the input object. */
  public static class FillArgs {
    final TrackingFooters trackingFooters;
    final boolean allowsDrafts;

    @Inject
    FillArgs(TrackingFooters trackingFooters,
        @GerritServerConfig Config cfg) {
      this.trackingFooters = trackingFooters;
      this.allowsDrafts = cfg == null
          ? true
          : cfg.getBoolean("change", "allowDrafts", true);
    }
  }

  private final String name;
  private final FieldType<?> type;
  private final boolean stored;

  private FieldDef(String name, FieldType<?> type, boolean stored) {
    this.name = checkName(name);
    this.type = type;
    this.stored = stored;
  }

  private static String checkName(String name) {
    CharMatcher m = CharMatcher.anyOf("abcdefghijklmnopqrstuvwxyz0123456789_");
    checkArgument(m.matchesAllOf(name), "illegal field name: %s", name);
    return name;
  }

  /** @return name of the field. */
  public final String getName() {
    return name;
  }

  /**
   * @return type of the field; for repeatable fields, the inner type, not the
   *     iterable type.
   */
  public final FieldType<?> getType() {
    return type;
  }

  /** @return whether the field should be stored in the index. */
  public final boolean isStored() {
    return stored;
  }

  /**
   * Get the field contents from the input object.
   *
   * @param input input object.
   * @param args arbitrary arguments needed to fill in indexable fields of the
   *     input object.
   * @return the field value(s) to index.
   *
   * @throws OrmException
   */
  public abstract T get(I input, FillArgs args) throws OrmException;

  /** @return whether the field is repeatable. */
  public abstract boolean isRepeatable();
}