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/*
 * Original Author -> Harry Yang ([email protected]) https://taketoday.cn
 * Copyright © TODAY & 2017 - 2022 All Rights Reserved.
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see [http://www.gnu.org/licenses/]
 */

package cn.taketoday.expression.common;

import cn.taketoday.core.TypeDescriptor;
import cn.taketoday.expression.EvaluationContext;
import cn.taketoday.expression.EvaluationException;
import cn.taketoday.expression.Expression;
import cn.taketoday.expression.TypedValue;
import cn.taketoday.lang.Nullable;

/**
 * Represents a template expression broken into pieces. Each piece will be an Expression
 * but pure text parts to the template will be represented as LiteralExpression objects.
 * An example of a template expression might be:
 *
 *  * "Hello ${getName()}"
 * 
 *
 * which will be represented as a CompositeStringExpression of two parts. The first part
 * being a LiteralExpression representing 'Hello ' and the second part being a real
 * expression that will call {@code getName()} when invoked.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @since 4.0
 */
public class CompositeStringExpression implements Expression {

  private final String expressionString;

  /** The array of expressions that make up the composite expression. */
  private final Expression[] expressions;

  public CompositeStringExpression(String expressionString, Expression[] expressions) {
    this.expressionString = expressionString;
    this.expressions = expressions;
  }

  @Override
  public final String getExpressionString() {
    return this.expressionString;
  }

  public final Expression[] getExpressions() {
    return this.expressions;
  }

  @Override
  public String getValue() throws EvaluationException {
    StringBuilder sb = new StringBuilder();
    for (Expression expression : this.expressions) {
      String value = expression.getValue(String.class);
      if (value != null) {
        sb.append(value);
      }
    }
    return sb.toString();
  }

  @Override
  @Nullable
  public  T getValue(@Nullable Class expectedResultType) throws EvaluationException {
    Object value = getValue();
    return ExpressionUtils.convertTypedValue(null, new TypedValue(value), expectedResultType);
  }

  @Override
  public String getValue(@Nullable Object rootObject) throws EvaluationException {
    StringBuilder sb = new StringBuilder();
    for (Expression expression : this.expressions) {
      String value = expression.getValue(rootObject, String.class);
      if (value != null) {
        sb.append(value);
      }
    }
    return sb.toString();
  }

  @Override
  @Nullable
  public  T getValue(@Nullable Object rootObject, @Nullable Class desiredResultType) throws EvaluationException {
    Object value = getValue(rootObject);
    return ExpressionUtils.convertTypedValue(null, new TypedValue(value), desiredResultType);
  }

  @Override
  public String getValue(EvaluationContext context) throws EvaluationException {
    StringBuilder sb = new StringBuilder();
    for (Expression expression : this.expressions) {
      String value = expression.getValue(context, String.class);
      if (value != null) {
        sb.append(value);
      }
    }
    return sb.toString();
  }

  @Override
  @Nullable
  public  T getValue(EvaluationContext context, @Nullable Class expectedResultType)
          throws EvaluationException {

    Object value = getValue(context);
    return ExpressionUtils.convertTypedValue(context, new TypedValue(value), expectedResultType);
  }

  @Override
  public String getValue(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException {
    StringBuilder sb = new StringBuilder();
    for (Expression expression : this.expressions) {
      String value = expression.getValue(context, rootObject, String.class);
      if (value != null) {
        sb.append(value);
      }
    }
    return sb.toString();
  }

  @Override
  @Nullable
  public  T getValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Class desiredResultType)
          throws EvaluationException {

    Object value = getValue(context, rootObject);
    return ExpressionUtils.convertTypedValue(context, new TypedValue(value), desiredResultType);
  }

  @Override
  public Class getValueType() {
    return String.class;
  }

  @Override
  public Class getValueType(EvaluationContext context) {
    return String.class;
  }

  @Override
  public Class getValueType(@Nullable Object rootObject) throws EvaluationException {
    return String.class;
  }

  @Override
  public Class getValueType(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException {
    return String.class;
  }

  @Override
  public TypeDescriptor getValueTypeDescriptor() {
    return TypeDescriptor.valueOf(String.class);
  }

  @Override
  public TypeDescriptor getValueTypeDescriptor(@Nullable Object rootObject) throws EvaluationException {
    return TypeDescriptor.valueOf(String.class);
  }

  @Override
  public TypeDescriptor getValueTypeDescriptor(EvaluationContext context) {
    return TypeDescriptor.valueOf(String.class);
  }

  @Override
  public TypeDescriptor getValueTypeDescriptor(EvaluationContext context, @Nullable Object rootObject)
          throws EvaluationException {

    return TypeDescriptor.valueOf(String.class);
  }

  @Override
  public boolean isWritable(@Nullable Object rootObject) throws EvaluationException {
    return false;
  }

  @Override
  public boolean isWritable(EvaluationContext context) {
    return false;
  }

  @Override
  public boolean isWritable(EvaluationContext context, @Nullable Object rootObject) throws EvaluationException {
    return false;
  }

  @Override
  public void setValue(@Nullable Object rootObject, @Nullable Object value) throws EvaluationException {
    throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
  }

  @Override
  public void setValue(EvaluationContext context, @Nullable Object value) throws EvaluationException {
    throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
  }

  @Override
  public void setValue(EvaluationContext context, @Nullable Object rootObject, @Nullable Object value) throws EvaluationException {
    throw new EvaluationException(this.expressionString, "Cannot call setValue on a composite expression");
  }

}