package io.dropwizard.jersey.params;

import io.dropwizard.util.Strings;
import org.glassfish.jersey.internal.inject.ExtractorException;
import org.glassfish.jersey.server.internal.LocalizationMessages;

import javax.annotation.Nullable;
import javax.ws.rs.ProcessingException;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.ext.ParamConverter;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

Converter to Jersey for Dropwizard's *Param classes.
When a param class is used as a resource parameter this converter will instantiate the parameter class with the
value provided and the name of the parameter, so if value parsing fails the parameter name can be used in the error
message. If the param class does not have a two-string constructor this provider will return null, causing jersey
to use the single-string constructor for the parameter type as it normally would.
Since:
2.0/**
 * Converter to Jersey for Dropwizard's *Param classes.
 *
 * <p>When a param class is used as a resource parameter this converter will instantiate the parameter class with the
 * value provided and the name of the parameter, so if value parsing fails the parameter name can be used in the error
 * message. If the param class does not have a two-string constructor this provider will return null, causing jersey
 * to use the single-string constructor for the parameter type as it normally would.</p>
 *
 * @since 2.0
 */
public class AbstractParamConverter<T> implements ParamConverter<T> {
    private final Constructor<T> constructor;
    private final String parameterName;
    @Nullable
    private final String defaultValue;

    public AbstractParamConverter(Constructor<T> constructor, String parameterName, @Nullable String defaultValue) {
        this.constructor = constructor;
        this.parameterName = parameterName;
        this.defaultValue = defaultValue;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    @Nullable
    public T fromString(String value) {
        try {
            if (Strings.isNullOrEmpty(value) && defaultValue != null && !defaultValue.equals(value)) {
                return _fromString(defaultValue);
            } else {
                return _fromString(value);
            }
        } catch (InvocationTargetException ex) {
            final Throwable cause = ex.getCause();
            if (cause instanceof WebApplicationException) {
                throw (WebApplicationException) cause;
            } else {
                throw new ExtractorException(cause);
            }
        } catch (final Exception ex) {
            throw new ProcessingException(ex);
        }
    }

    private T _fromString(String value) throws Exception {
        return constructor.newInstance(value, parameterName);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public String toString(T value) throws IllegalArgumentException {
        if (value == null) {
            throw new IllegalArgumentException(LocalizationMessages.METHOD_PARAMETER_CANNOT_BE_NULL("value"));
        }
        return value.toString();
    }

}