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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2016-2024 Objectionary.com
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.eolang.jeo.representation.xmir;

import java.util.Optional;
import java.util.stream.Collectors;
import lombok.ToString;
import org.eolang.jeo.representation.PrefixedName;
import org.eolang.jeo.representation.bytecode.BytecodeAnnotations;
import org.eolang.jeo.representation.bytecode.BytecodeField;

/**
 * XML field.
 * @since 0.1
 */
@ToString
public class XmlField {

    /**
     * Field node.
     */
    private final XmlNode node;

    /**
     * Constructor.
     * @param xmlnode Field node.
     */
    XmlField(final XmlNode xmlnode) {
        this.node = xmlnode;
    }

    /**
     * Convert to bytecode.
     * @return Bytecode field.
     */
    public BytecodeField bytecode() {
        return new BytecodeField(
            this.name(),
            this.descriptor(),
            this.signature(),
            this.value(),
            this.access(),
            this.annotations().map(XmlAnnotations::bytecode).orElse(new BytecodeAnnotations())
        );
    }

    /**
     * Field name.
     * @return Name.
     */
    private String name() {
        return new PrefixedName(
            this.node.attribute("name").orElseThrow(
                () -> new IllegalStateException(
                    String.format("Can't find field name in '%s'", this.node)
                )
            )
        ).decode();
    }

    /**
     * Field access modifiers.
     * @return Access modifiers.
     */
    private int access() {
        return this.find(Attribute.ACCESS).map(XmlValue::integer).orElse(0);
    }

    /**
     * Field descriptor.
     * @return Descriptor.
     */
    private String descriptor() {
        return this.find(Attribute.DESCRIPTOR).map(XmlValue::string)
            .filter(descriptor -> !descriptor.isEmpty())
            .orElse(null);
    }

    /**
     * Field signature.
     * @return Signature.
     */
    private String signature() {
        return this.find(Attribute.SIGNATURE).map(XmlValue::string)
            .filter(signature -> !signature.isEmpty())
            .orElse(null);
    }

    /**
     * Field value.
     * @return Value.
     */
    private Object value() {
        return new XmlOperand(
            this.node.children()
                .collect(Collectors.toList())
                .get(Attribute.VALUE.ordinal())
        ).asObject();
    }

    /**
     * Field annotations.
     * @return Annotations.
     */
    private Optional annotations() {
        return this.node.optchild("name", String.format("annotations-%s", this.name()))
            .map(XmlAnnotations::new);
    }

    /**
     * Find node text by attribute.
     * @param attribute Attribute.
     * @return Text.
     */
    private Optional find(final Attribute attribute) {
        return Optional.of(
            new XmlValue(
                this.node.children().collect(Collectors.toList()).get(attribute.ordinal())
            )
        );
    }

    /**
     * Field attribute.
     * Pay attention that the order of the attributes is important.
     * They should be in the same order as in the XML representation.
     * @since 0.1
     */
    private enum Attribute {

        /**
         * Access modifier.
         * It's a number that represents sum of access modifiers.
         * For example, if the field is public and static, then the value will be 9.
         * See {@link org.objectweb.asm.Opcodes} for more details.
         */
        ACCESS,

        /**
         * Field descriptor.
         * For example, for field of type int the descriptor will be "I".
         */
        DESCRIPTOR,

        /**
         * Field signature.
         * The field signature is used for defining generic types.
         * Signature grammar:
         * 
         * {@code
         * TypeSignature: Z|C|B|S|I|F|J|D|FieldTypeSignature
         * FieldTypeSignature: ClassTypeSignature | [ TypeSignature | TypeVar
         * ClassTypeSignature: L Id ( / Id )* TypeArgs? ( . Id TypeArgs? )* ;
         * TypeArgs: < TypeArg+ >
         * TypeArg: * | ( + | - )? FieldTypeSignature
         * TypeVar: T Id ;
         * }
         * 
         * Examples:
         * 
         * {@code
         * List -> Ljava/util/List;
         * List -> Ljava/util/List<*>;
         * List -> Ljava/util/List<+Ljava/lang/Number;>;
         * List -> Ljava/util/List<-Ljava/lang/Integer;>;
         * List[]> -> Ljava/util/List<[Ljava/util/List;>;
         * HashMap.HashIterator -> Ljava/util/HashMap.HashIterator;
         * }
         * 
         * You can read more in 4.1.1 section of the ASM
         * manual 
         */
        SIGNATURE,

        /**
         * Initial field value.
         * For example, for field of type int with value 19, the value will be "13".
         * Any data type will be represented as a hex string.
         * May not be set.
         */
        VALUE;
    }
}