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/*
 * Copyright 2015 Objectos, Fábrica de Software LTDA.
 *
 * 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 br.com.objectos.db;

import java.util.Objects;

/**
 * @author [email protected] (Marcio Endo)
 */
public abstract class AbstractSqlBuilder implements SqlBuilder {

  protected final Name name;
  protected final Space space;
  protected final StringBuilder sql;

  protected AbstractSqlBuilder(Name name, Space space, StringBuilder sql) {
    this.name = name;
    this.space = space;
    this.sql = sql;
  }

  @Override
  public final SqlBuilder accept(SqlElement element) {
    return element.accept(this);
  }

  @Override
  public final SqlBuilder add(char character) {
    write(character);
    return self();
  }

  @Override
  public final SqlBuilder add(String string) {
    Objects.requireNonNull(string);
    write(string);
    return self();
  }

  @Override
  public final SqlBuilder autoSpaceOff() {
    return factory(name, Space.OFF, sql);
  }

  @Override
  public final SqlBuilder autoSpaceOn() {
    return factory(name, Space.ON, sql);
  }

  @Override
  public SqlBuilder autoSpaceOnNext() {
    return factoryDelayed(name, sql);
  }

  @Override
  public final SqlBuilder identifier(String identifier) {
    Objects.requireNonNull(identifier);
    identifier0(identifier);
    return self();
  }

  @Override
  public final SqlBuilder identifier(String id0, String id1) {
    Objects.requireNonNull(id0);
    Objects.requireNonNull(id1);
    qualifiedName(id0, id1);
    return self();
  }

  @Override
  public final SqlBuilder identifier(String id0, String id1, String id2) {
    Objects.requireNonNull(id0);
    Objects.requireNonNull(id1);
    Objects.requireNonNull(id2);
    qualifiedName(id0, id1, id2);
    return self();
  }

  @Override
  public final SqlBuilder identifier(String id0, String id1, String id2, String id3) {
    Objects.requireNonNull(id0);
    Objects.requireNonNull(id1);
    Objects.requireNonNull(id2);
    Objects.requireNonNull(id3);
    qualifiedName(id0, id1, id3);
    return self();
  }

  @Override
  public final SqlBuilder keyword(String keyword) {
    write(keyword);
    return self();
  }

  @Override
  public final SqlBuilderOn on(char separator) {
    return on(String.valueOf(separator));
  }

  @Override
  public final SqlBuilderOn on(String separator) {
    Objects.requireNonNull(separator);
    return new SqlBuilderOn() {
      @Override
      public SqlBuilder join(SqlElement... elements) {
        return join0(self(), elements);
      }

      @Override
      public SqlBuilder join(char prefix, char suffix, SqlElement... elements) {
        write(prefix);
        SqlBuilder s = join0(autoSpaceOff(), elements);
        sql.append(suffix);
        return s;
      }

      private SqlBuilder join0(SqlBuilder s, SqlElement... elements) {
        if (elements.length == 0) {
          return s;
        }

        elements[0].accept(s);

        if (elements.length == 1) {
          return s;
        }

        s = autoSpaceOff();

        for (int i = 1; i < elements.length; i++) {
          s.add(separator);
          elements[i].accept(s);
        }

        return s.autoSpaceOn();
      }
    };
  }

  @Override
  public final SqlBuilder qualifiedNamesOff() {
    return factory(Name.SIMPLE, space, sql);
  }

  @Override
  public final SqlBuilder qualifiedNamesOn() {
    return factory(Name.QUALIFIED, space, sql);
  }

  @Override
  public final String toString() {
    return sql.toString();
  }

  protected abstract SqlBuilder factory(Name name, Space space, StringBuilder sql);

  protected abstract SqlBuilder factoryDelayed(Name name, StringBuilder sql);

  protected SqlBuilder self() {
    return this;
  }

  protected String quote(String text) {
    return text;
  }

  private void identifier0(String identifier) {
    write(quote(identifier));
  }

  private void qualifiedName(String... identifiers) {
    write(name.write(this::quote, identifiers));
  }

  private void write(char c) {
    space.write(sql);
    sql.append(c);
  }

  private void write(String text) {
    space.write(sql);
    sql.append(text);
  }

}