/* BSD 2-Clause License - see OPAL/LICENSE for details. */
package org.opalj
package bi
package reader

import scala.reflect.ClassTag

import java.io.DataInputStream
import scala.collection.immutable.ArraySeq

import org.opalj.control.fillArraySeq

/**
 * Generic parser for the ''Record'' attribute (Java 16).
 *
 * '''From the Specification'''
 * The Record attribute is a variable-length attribute in the attributes table of a ClassFile
 * structure (§4.1). The Record attribute indicates that the current class is a record class, and
 * stores information about the record components of the record class
 *
 * @author Dominik Helm
 */
trait Record_attributeReader extends AttributeReader {

    //
    // TYPE DEFINITIONS AND FACTORY METHODS
    //

    type Record_attribute >: Null <: Attribute

    type RecordComponent <: AnyRef: ClassTag
    type RecordComponents = ArraySeq[RecordComponent]

    def Record_attribute(
        cp:                   Constant_Pool,
        ap_name_index:        Constant_Pool_Index,
        ap_descriptor_index:  Constant_Pool_Index,
        attribute_name_index: Constant_Pool_Index,
        components:           RecordComponents
    ): Record_attribute

    def RecordComponent(
        cp:               Constant_Pool,
        name_index:       Constant_Pool_Index,
        descriptor_index: Constant_Pool_Index,
        attributes:       Attributes
    ): RecordComponent

    protected def Attributes(
        cp:                  Constant_Pool,
        ap:                  AttributeParent,
        ap_name_index:       Constant_Pool_Index,
        ap_descriptor_index: Constant_Pool_Index,
        in:                  DataInputStream
    ): Attributes

    //
    // IMPLEMENTATION
    //

    /**
     * <pre>
     * Record_attribute {
     *      u2 attribute_name_index;
     *      u4 attribute_length;
     *      u2 components_count;
     *      record_component_info[components_count];
     * }
     *
     * record_component_info {
     *      u2 name_index;
     *      u2 descriptor_index;
     *      u2 attributes_count;
     *      attribute_info attributes[attributes_count];
     * }
     * </pre>
     */
    private def parserFactory() = (
        cp:                   Constant_Pool,
        ap:                   AttributeParent,
        ap_name_index:        Constant_Pool_Index,
        ap_descriptor_index:  Constant_Pool_Index,
        attribute_name_index: Constant_Pool_Index,
        in:                   DataInputStream
    ) =>
        {
            /*val attribute_length =*/
            in.readInt()
            val components_count = in.readUnsignedShort
            if (components_count > 0 || reifyEmptyAttributes) {
                Record_attribute(
                    cp,
                    ap_name_index,
                    ap_descriptor_index,
                    attribute_name_index,
                    fillArraySeq(components_count) {
                        {
                            val name_index = in.readUnsignedShort
                            val descriptor_index = in.readUnsignedShort
                            RecordComponent(
                                cp,
                                name_index,
                                descriptor_index,
                                Attributes(
                                    cp,
                                    AttributesParent.RecordComponent,
                                    name_index,
                                    descriptor_index,
                                    in
                                )
                            )
                        }
                    }
                )
            } else {
                null
            }
        }: Record_attribute

    registerAttributeReader(RecordAttribute.Name -> parserFactory())

}