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A web micro-framework for Java

There is a newer version: 0.15.0

package com.vtence.molecule.http;

import com.vtence.molecule.Request;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Locale;

import static com.vtence.molecule.http.HeaderNames.ACCEPT_LANGUAGE;
import static java.util.stream.Collectors.toList;

public class AcceptLanguage {
    private final List locales = new ArrayList<>();

    public static AcceptLanguage of(Request request) {
        String header = request.header(ACCEPT_LANGUAGE);
        return header != null ? new AcceptLanguage(header) : new AcceptLanguage("");
    }

    public AcceptLanguage(String header) {
        this(new Header(header));
    }

    public AcceptLanguage(Header header) {
        parseLocales(header);
    }

    private void parseLocales(Header header) {
        locales.addAll(header.values().stream().filter(locale -> !locale.equals(""))
                             .map(Locale::forLanguageTag).collect(toList()));
    }

    public List list() {
        return Collections.unmodifiableList(locales);
    }

    public Locale selectBest(Locale... candidates) {
        return selectBest(Arrays.asList(candidates));
    }

    public Locale selectBest(Collection candidates) {
        for (Locale accepted : list()) {
            if (candidates.contains(accepted)) return accepted;
            if (candidates.contains(languageOf(accepted))) return languageOf(accepted);
            for (Locale candidate : candidates) {
                if (sameLanguage(accepted, candidate)) return candidate;
            }
        }
        return null;
    }

    private boolean sameLanguage(Locale accepted, Locale candidate) {
        return candidate.getLanguage().equals(accepted.getLanguage());
    }

    private Locale languageOf(Locale accepted) {
        return new Locale(accepted.getLanguage());
    }
}