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/**
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package org.jooby;

import static java.util.Objects.requireNonNull;

import java.io.InputStream;
import java.net.URL;

import com.google.common.io.BaseEncoding;
import com.google.common.primitives.Longs;

import javax.annotation.Nonnull;

/**
 * Usually a public file/resource like javascript, css, images files, etc...
 * An asset consist of content type, stream and last modified since attributes, between others.
 *
 * @author edgar
 * @since 0.1.0
 * @see Jooby#assets(String)
 */
public interface Asset {

    /**
     * Forwarding asset.
     *
     * @author edgar
     */
    public class Forwarding implements Asset {

        private Asset asset;

        public Forwarding(final Asset asset) {
            this.asset = requireNonNull(asset, "Asset is required.");
        }

        @Override
        public String etag() {
            return asset.etag();
        }

        @Override
        public String name() {
            return asset.name();
        }

        @Override
        public String path() {
            return asset.path();
        }

        @Override
        public URL resource() {
            return asset.resource();
        }

        @Override
        public long length() {
            return asset.length();
        }

        @Override
        public long lastModified() {
            return asset.lastModified();
        }

        @Override
        public InputStream stream() throws Exception {
            return asset.stream();
        }

        @Override
        public MediaType type() {
            return asset.type();
        }

    }

    /**
     * Examples:
     *
     * <pre>
     *  GET /assets/index.js {@literal ->} index.js
     *  GET /assets/js/index.js {@literal ->} index.js
     * </pre>
     *
     * @return The asset name (without path).
     */
    @Nonnull
    default String name() {
        String path = path();
        int slash = path.lastIndexOf('/');
        return path.substring(slash + 1);
    }

    /**
     * Examples:
     *
     * <pre>
     *  GET /assets/index.js {@literal ->} /assets/index.js
     *  GET /assets/js/index.js {@literal ->} /assets/js/index.js
     * </pre>
     *
     * @return The asset requested path, includes the name.
     */
    @Nonnull
    String path();

    /**
     * @return URL representing the resource.
     */
    @Nonnull
    URL resource();

    /**
     * @return Generate a weak Etag using the {@link #path()}, {@link #lastModified()} and
     *         {@link #length()}.
     */
    @Nonnull
    default String etag() {
        StringBuilder b = new StringBuilder(32);
        b.append("W/\"");

        BaseEncoding b64 = BaseEncoding.base64();
        int lhash = resource().hashCode();

        b.append(b64.encode(Longs.toByteArray(lastModified() ^ lhash)));
        b.append(b64.encode(Longs.toByteArray(length() ^ lhash)));
        b.append('"');
        return b.toString();
    }

    /**
     * @return Asset size (in bytes) or <code>-1</code> if undefined.
     */
    long length();

    /**
     * @return The last modified date if possible or -1 when isn't.
     */
    long lastModified();

    /**
     * @return The content of this asset.
     * @throws Exception If content can't be read it.
     */
    @Nonnull
    InputStream stream() throws Exception;

    /**
     * @return Asset media type.
     */
    @Nonnull
    MediaType type();
}