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package io.katharsis.meta.model;

import java.util.List;

import com.fasterxml.jackson.annotation.JsonIgnore;

import io.katharsis.core.internal.utils.ClassUtils;
import io.katharsis.core.internal.utils.PreconditionUtil;
import io.katharsis.resource.annotations.JsonApiResource;
import io.katharsis.resource.annotations.JsonApiToMany;

@JsonApiResource(type = "meta/key")
public class MetaKey extends MetaElement {

	private static final String ID_ELEMENT_SEPARATOR = "-";

	@JsonApiToMany
	private List elements;

	private boolean unique;

	public List getElements() {
		return elements;
	}

	public boolean isUnique() {
		return unique;
	}

	public void setElements(List elements) {
		this.elements = elements;
	}

	public void setUnique(boolean unique) {
		this.unique = unique;
	}

	@JsonIgnore
	public MetaAttribute getUniqueElement() {
		if (elements.size() != 1)
			throw new IllegalStateException(getName() + " must contain a single primary key attribute");
		return elements.get(0);
	}

	public Object fromKeyString(String idString) {

		// => support compound keys with unique ids
		if (elements.size() == 1) {
			MetaAttribute keyAttr = elements.get(0);
			MetaType keyType = keyAttr.getType();

			if (keyType instanceof MetaDataObject) {
				return parseEmbeddableString((MetaDataObject) keyType, idString);
			}
			else {
				return keyType.fromString(idString);
			}
		}
		else {
			throw new UnsupportedOperationException();
		}
	}

	private Object parseEmbeddableString(MetaDataObject embType, String idString) {
		String[] keyElements = idString.split(ID_ELEMENT_SEPARATOR);

		Object id = ClassUtils.newInstance(embType.getImplementationClass());

		List embAttrs = embType.getAttributes();
		if (keyElements.length != embAttrs.size()) {
			throw new UnsupportedOperationException(
					"failed to parse " + idString + ", expected " + elements.size() + " elements");
		}
		for (int i = 0; i < keyElements.length; i++) {
			MetaAttribute embAttr = embAttrs.get(i);
			Object idElement = embAttr.getType().fromString(keyElements[i]);
			embAttr.setValue(id, idElement);
		}
		return id;
	}

	public String toKeyString(Object id) {
		// => support compound keys with unique ids
		PreconditionUtil.assertEquals("compound primary key not supported", 1, elements.size());
		MetaAttribute keyAttr = elements.get(0);
		MetaType keyType = keyAttr.getType();
		if (keyType instanceof MetaDataObject) {
			MetaDataObject embType = (MetaDataObject) keyType;
			return toEmbeddableKeyString(embType, id);
		}
		else {
			return id.toString();
		}
	}

	private static String toEmbeddableKeyString(MetaDataObject embType, Object id) {
		StringBuilder builder = new StringBuilder();
		List embAttrs = embType.getAttributes();
		for (int i = 0; i < embAttrs.size(); i++) {
			MetaAttribute embAttr = embAttrs.get(i);
			Object idElement = embAttr.getValue(id);
			if (i > 0) {
				builder.append(ID_ELEMENT_SEPARATOR);
			}
			builder.append(idElement);
		}
		return builder.toString();
	}

}