UrlBuilder.java

package eu.europeana.cloud.service.commons.urls;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class UrlBuilder {

    private Map<UrlPart, String> parts;
    private Set<ValuedUrlPart> partsToInclude = new HashSet<>();

    UrlBuilder(Map<UrlPart, String> parts) {
        partsToInclude = new HashSet<>();
        partsToInclude.add(new ValuedUrlPart(UrlPart.CONTEXT, true));
        this.parts = parts;
    }

    public UrlBuilder clear() {
        partsToInclude = new HashSet<>();
        partsToInclude.add(new ValuedUrlPart(UrlPart.CONTEXT, true));
        return this;
    }

    public UrlBuilder withCloudID() {
        partsToInclude.add(new ValuedUrlPart(UrlPart.RECORDS, true));
        return this;
    }

    public UrlBuilder withRepresentation() {
        partsToInclude.add(new ValuedUrlPart(UrlPart.REPRESENTATIONS, true));
        return this;
    }

    public UrlBuilder withVersion() {
        partsToInclude.add(new ValuedUrlPart(UrlPart.VERSIONS, true));
        return this;
    }

    public UrlBuilder withVersionWithoutValue() {

        partsToInclude.add(new ValuedUrlPart(UrlPart.VERSIONS, false));
        return this;
    }

    public UrlBuilder withDataProvider() {
        partsToInclude.add(new ValuedUrlPart(UrlPart.DATA_PROVIDERS, true));
        return this;
    }

    public UrlBuilder withDataSet() {
        partsToInclude.add(new ValuedUrlPart(UrlPart.DATA_SETS, true));
        return this;
    }

    public UrlBuilder withDataSetWithoutValue() {
        partsToInclude.add(new ValuedUrlPart(UrlPart.DATA_SETS, false));
        return this;
    }


    public String build() throws UrlBuilderException {
        String result = "";

        for (Map.Entry<UrlPart, String> entry : parts.entrySet()) {
            ValuedUrlPart key = new ValuedUrlPart(entry.getKey(), true);
            String value = entry.getValue();
            if (shouldBeIncludedInResult(entry.getKey())) {
                ValuedUrlPart currentPart = removeFromPartsToInclude(entry.getKey());
                //
                if (currentPart.isAddValue()) {
                    if (value != null) {
                        if("".equals(key.getPart().getValue())){
                            result += "/" + value;    
                        }else{
                            result += "/" + key.getPart().getValue() + "/" + value;
                        }
                    } else {
                        throw new UrlBuilderException("Value for: " + key + " is empty");
                    }
                } else {
                    result += "/" + key.getPart().getValue();
                }
            }
        }
        if (partsToInclude.size() > 0) {
            String errorMessage = createErrorMessage(partsToInclude);
            throw new UrlBuilderException("Missing parts for given request: " + errorMessage);
        }
        return result;
    }

    private boolean shouldBeIncludedInResult(UrlPart urlPart) {
        Iterator<ValuedUrlPart> it = partsToInclude.iterator();
        while (it.hasNext()) {
            if (it.next().getPart().equals(urlPart)) {
                return true;
            }
        }
        return false;
    }

    private ValuedUrlPart removeFromPartsToInclude(UrlPart urlPart) {
        Iterator<ValuedUrlPart> it = partsToInclude.iterator();
        while (it.hasNext()) {
            ValuedUrlPart currentPart = it.next();
            if (currentPart.getPart().equals(urlPart)) {
                it.remove();
                return currentPart;
            }
        }
        return null;
    }
    private String createErrorMessage(Set<ValuedUrlPart> leftParts){
        String result = "";
        for (ValuedUrlPart leftPart : leftParts) {
            result += leftPart.getPart() + " ";
        }
        return result;
        
    }
}

/**
 * Stores url part with information if value of this part should be displayed
 */
class ValuedUrlPart {
    private UrlPart part;
    private boolean addValue;

    public ValuedUrlPart(UrlPart part, boolean addValue) {
        this.part = part;
        this.addValue = addValue;
    }

    public UrlPart getPart() {
        return part;
    }

    public boolean isAddValue() {
        return addValue;
    }
}