/*
    *    Copyright 2016-2025 the original author or authors.
    *
    *    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
    *
    *       https://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 org.mybatis.dynamic.sql.render;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Optional;
  
  import org.mybatis.dynamic.sql.SqlTable;
  
  public class ExplicitTableAliasCalculator implements TableAliasCalculator {
      private final Map<SqlTable, String> aliases;
  
      protected ExplicitTableAliasCalculator(Map<SqlTable, String> aliases) {
          this.aliases = Objects.requireNonNull(aliases);
      }
  
      @Override
      public Optional<String> aliasForColumn(SqlTable table) {
          return explicitAliasOrTableAlias(table);
      }
  
      @Override
      public Optional<String> aliasForTable(SqlTable table) {
          return explicitAliasOrTableAlias(table);
      }
  
      private Optional<String> explicitAliasOrTableAlias(SqlTable table) {
          String alias = aliases.get(table);
          if (alias == null) {
              return table.tableAlias();
          } else {
              return Optional.of(alias);
          }
      }
  
      public static TableAliasCalculator of(SqlTable table, String alias) {
          Map<SqlTable, String> tableAliases = new HashMap<>();
          tableAliases.put(table, alias);
          return of(tableAliases);
      }
  
      public static TableAliasCalculator of(Map<SqlTable, String> aliases) {
          return new ExplicitTableAliasCalculator(aliases);
      }
  }