/*
    * Copyright 2021 TiKV Project 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
    *
    * 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 org.tikv.common.expression;
  
  import static java.util.Objects.requireNonNull;
  import static org.tikv.common.expression.StringRegExpression.Type.*;
  
  import com.google.common.collect.ImmutableList;
  import java.util.List;
  import java.util.Objects;
  import org.tikv.common.key.TypedKey;
  import org.tikv.common.types.DataType;
  import org.tikv.common.types.IntegerType;
  
  public class StringRegExpression extends Expression {
    private final Expression left;
    private final Expression right;
    private final Expression reg;
    private final Type regType;
    private transient TypedKey key;
  
    public StringRegExpression(Type type, Expression left, Expression right, Expression reg) {
      super(IntegerType.BOOLEAN);
      resolved = true;
      this.left = requireNonNull(left, "left expression is null");
      this.right = requireNonNull(right, "right expression is null");
      this.regType = requireNonNull(type, "type is null");
      this.reg = requireNonNull(reg, "reg string is null");
    }
  
    public static StringRegExpression startsWith(Expression left, Expression right) {
      Expression reg = Constant.create(((Constant) right).getValue() + "%", right.getDataType());
      return new StringRegExpression(STARTS_WITH, left, right, reg);
    }
  
    public static StringRegExpression contains(Expression left, Expression right) {
      Expression reg =
          Constant.create("%" + ((Constant) right).getValue() + "%", right.getDataType());
      return new StringRegExpression(CONTAINS, left, right, reg);
    }
  
    public static StringRegExpression endsWith(Expression left, Expression right) {
      Expression reg = Constant.create("%" + ((Constant) right).getValue(), right.getDataType());
      return new StringRegExpression(ENDS_WITH, left, right, reg);
    }
  
    public static StringRegExpression like(Expression left, Expression right) {
      return new StringRegExpression(LIKE, left, right, right);
    }
  
    public ColumnRef getColumnRef() {
      return (ColumnRef) getLeft();
    }
  
    public Constant getValue() {
      return (Constant) getRight();
    }
  
    public TypedKey getTypedLiteral() {
      return getTypedLiteral(DataType.UNSPECIFIED_LEN);
    }
  
    public TypedKey getTypedLiteral(int prefixLength) {
      if (key == null) {
        key = TypedKey.toTypedKey(getValue().getValue(), getColumnRef().getDataType(), prefixLength);
      }
      return key;
    }
  
    @Override
    public List<Expression> getChildren() {
      // For LIKE statement, an extra ESCAPE parameter is required as the third parameter for
      // ScalarFunc.
      // However in Spark ESCAPE is not supported so we simply set this value to zero.
      return ImmutableList.of(left, reg, Constant.create(0, IntegerType.BIGINT));
    }
  
    @Override
    public <R, C> R accept(Visitor<R, C> visitor, C context) {
      return visitor.visit(this, context);
    }
  
    public Expression getLeft() {
      return left;
   }
 
   public Expression getRight() {
     return right;
   }
 
   public Type getRegType() {
     return regType;
   }
 
   public Expression getReg() {
     return reg;
   }
 
   @Override
   public String toString() {
     return String.format("[%s %s %s reg: %s]", getLeft(), getRegType(), getRight(), getReg());
   }
 
   @Override
   public boolean equals(Object other) {
     if (this == other) {
       return true;
     }
     if (!(other instanceof StringRegExpression)) {
       return false;
     }
 
     StringRegExpression that = (StringRegExpression) other;
     return (regType == that.regType)
         && Objects.equals(left, that.left)
         && Objects.equals(right, that.right)
         && Objects.equals(reg, that.reg);
   }
 
   @Override
   public int hashCode() {
     return Objects.hash(regType, left, right, reg);
   }
 
   public enum Type {
     STARTS_WITH,
     CONTAINS,
     ENDS_WITH,
     LIKE
   }
 }