package org.jboss.resteasy.test.resource.param.resource;

import jakarta.ws.rs.ext.ParamConverter;

public class MultiValuedParamConverter implements ParamConverter<MultiValuedParam<?>> {

    private final ParamConverter<?> paramConverter;

    public MultiValuedParamConverter(final ParamConverter<?> paramConverter) {
        this.paramConverter = paramConverter;
    }

    @Override
    public MultiValuedParam<?> fromString(String param) {
        if (param == null || param.trim().isEmpty()) {
            return null;
        }
        return parse(param.split(","), this.paramConverter);
    }

    @Override
    public String toString(MultiValuedParam<?> multiValuedParam) {
        if (multiValuedParam == null || multiValuedParam.isEmpty()) {
            return null;
        }
        return format(multiValuedParam, this.paramConverter);
    }

    private static <T> MultiValuedParam<T> parse(String[] params, ParamConverter<T> paramConverter) {
        MultiValuedParam<T> multiValuedParam = new MultiValuedParam<>();
        for (String param : params) {
            multiValuedParam.add(paramConverter.fromString(param));
        }
        return multiValuedParam;
    }

    @SuppressWarnings("unchecked")
    private static <T> String format(MultiValuedParam<?> multiValuedParam, ParamConverter<T> paramConverter) {
        StringBuilder stringBuilder = new StringBuilder();
        int size = multiValuedParam.size();
        for (int i = 0; i < size; i++) {
            stringBuilder.append(paramConverter.toString((T) multiValuedParam.get(i)));
            if (i != size - 1) {
                stringBuilder.append(',');
            }
        }
        return stringBuilder.toString();
    }

}
