/*
 * Copyright © 2021 DataSQRL (contact@datasqrl.com)
 *
 * 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.datasqrl.function.translation.duckdb.builtin;

import com.datasqrl.function.CalciteFunctionUtil;
import com.datasqrl.function.translation.DuckDbSqlTranslation;
import com.datasqrl.function.translation.SqlTranslation;
import com.google.auto.service.AutoService;
import org.apache.calcite.sql.SqlCall;
import org.apache.calcite.sql.SqlLiteral;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.type.SqlTypeName;

@AutoService(SqlTranslation.class)
public class ArrayRemoveSqlTranslation extends DuckDbSqlTranslation {

  public ArrayRemoveSqlTranslation() {
    super(CalciteFunctionUtil.lightweightOp("ARRAY_REMOVE"));
  }

  @Override
  public void unparse(SqlCall call, SqlWriter writer, int leftPrec, int rightPrec) {
    var arr = call.operand(0);
    var elemToRemove = call.operand(1);

    // Non-null elem to remove: list_filter(arr, x -> x <> elem_to_remove);
    // Null as elem to remove:  list_filter(arr, x -> x IS NOT NULL);
    var listFilter = writer.startFunCall("list_filter");
    arr.unparse(writer, 0, 0);
    writer.sep(",", true);

    if (isNullLiteral(elemToRemove)) {
      writer.print("x -> x IS NOT NULL");

    } else {
      writer.print("x -> x <> ");
      elemToRemove.unparse(writer, 0, 0);
    }

    writer.endFunCall(listFilter);
  }

  private static boolean isNullLiteral(SqlNode node) {
    return node instanceof SqlLiteral lit && lit.getTypeName() == SqlTypeName.NULL;
  }
}
