gson-compile/gson-compile-processor/src/main/java/io/gitlab/jfronny/gson/compile/processor/util/valueprocessor/Property.java

package io.gitlab.jfronny.gson.compile.processor.util.valueprocessor;

import org.jetbrains.annotations.ApiStatus;

import javax.lang.model.element.*;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import java.util.List;

public abstract sealed class Property<T extends Element> {
    protected final T element;
    private List<? extends AnnotationMirror> annotations;

    public Property(T element) {
        this.element = element;
        this.annotations = element.getAnnotationMirrors();
    }

    public T getElement() {
        return element;
    }

    /**
     * The name of the property. For fields and params this is the name in code. For getters, it may have the 'get' or
     * 'is' prefix stripped.
     * @see #getCallableName()
     */
    public String getName() {
        return element.getSimpleName().toString();
    }

    /**
     * The actual name of the property. This will not have any 'get' or 'is' prefix stripped.
     * @see #getName()
     */
    public String getCallableName() {
        return getName();
    }

    /**
     * The property's type.
     */
    public TypeMirror getType() {
        return element.asType();
    }

    /**
     * Annotations relevant to the property. These may be copied from another source. For example, if this is a getter
     * it may contain the annotations on the backing private field.
     */
    public List<? extends AnnotationMirror> getAnnotations() {
        return annotations;
    }

    public void setAnnotations(List<? extends AnnotationMirror> annotations) {
        this.annotations = annotations;
    }

    @Override
    public String toString() {
        return getName() + ": " + getType();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) return false;
        if (this == obj) return true;
        if (!(obj instanceof Property<?> other)) return false;
        return element.equals(other.element);
    }

    @Override
    public int hashCode() {
        return element.hashCode();
    }

    public static final class Field extends Property<VariableElement> {
        public Field(VariableElement element) {
            super(element);
        }
    }

    public static final class Getter extends Property<ExecutableElement> {
        private static final String BEAN_PREFIX = "get";
        private static final String BEAN_PREFIX_BOOL = "is";

        private boolean stripBean = false;

        public Getter(ExecutableElement element) {
            super(element);
        }

        public boolean isBean() {
            return getBeanPrefix() != null;
        }

        @Override
        public String getName() {
            String name = super.getName();
            if (stripBean) {
                String prefix = getBeanPrefix();
                if (prefix != null) {
                    return Character.toLowerCase(name.charAt(prefix.length())) + name.substring(prefix.length() + 1);
                }
            }
            return name;
        }

        @Override
        public String getCallableName() {
            return super.getName();
        }

        @Override
        public TypeMirror getType() {
            return element.getReturnType();
        }

        @ApiStatus.Internal
        public void stripBean() {
            stripBean = true;
        }

        private String getBeanPrefix() {
            String name = super.getName();
            if (element.getReturnType().getKind() == TypeKind.BOOLEAN) {
                if (name.length() > BEAN_PREFIX_BOOL.length() && name.startsWith(BEAN_PREFIX_BOOL)) {
                    return BEAN_PREFIX_BOOL;
                }
            }
            return name.length() > BEAN_PREFIX.length() && name.startsWith(BEAN_PREFIX) ? BEAN_PREFIX : null;
        }
    }

    public static sealed abstract class Param extends Property<VariableElement> {
        public Param(VariableElement element) {
            super(element);
        }
    }

    public static final class ConstructorParam extends Param {
        public ConstructorParam(VariableElement element) {
            super(element);
        }
    }

    public static final class BuilderParam extends Param {
        private final ExecutableElement method;

        public BuilderParam(ExecutableElement method) {
            super(method.getParameters().get(0));
            this.method = method;
        }

        @Override
        public String getCallableName() {
            return method.getSimpleName().toString();
        }
    }
}