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package org.jooby.handlers;

import com.google.common.base.Strings;

import com.typesafe.config.ConfigFactory;

import com.typesafe.config.ConfigValueFactory;

import static java.util.Objects.requireNonNull;

import org.jooby.Asset;

import org.jooby.Err;

import org.jooby.Jooby;

import org.jooby.MediaType;

import org.jooby.Request;

import org.jooby.Response;

import org.jooby.Route;

import org.jooby.Status;

import org.jooby.funzy.Throwing;

import org.jooby.funzy.Try;

import org.jooby.internal.URLAsset;

import java.net.MalformedURLException;

import java.net.URL;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.text.MessageFormat;

import java.time.Duration;

import java.util.Date;

import java.util.Map;

/**

* Serve static resources, via {@link Jooby#assets(String)} or variants.

*

* <h1>e-tag support</h1>

* <p>

* It generates <code>ETag</code> headers using {@link Asset#etag()}. It handles

* <code>If-None-Match</code> header automatically.

* </p>

* <p>

* <code>ETag</code> handling is enabled by default. If you want to disabled etag support

* {@link #etag(boolean)}.

* </p>

*

* <h1>modified since support</h1>

* <p>

* It generates <code>Last-Modified</code> header using {@link Asset#lastModified()}. It handles

* <code>If-Modified-Since</code> header automatically.

* </p>

*

* <h1>CDN support</h1>

* <p>

* Asset can be serve from a content delivery network (a.k.a cdn). All you have to do is to set the

* <code>assets.cdn</code> property.

* </p>

*

* <pre>

* assets.cdn = "http://d7471vfo50fqt.cloudfront.net"

* </pre>

*

* <p>

* Resolved assets are redirected to the cdn.

* </p>

*

* @author edgar

* @since 0.1.0

*/

public class AssetHandler implements Route.Handler {

private interface Loader {

URL getResource(String name);

}

private static final Throwing.Function<String, String> prefix = prefix().memoized();

private Throwing.Function2<Request, String, String> fn;

private Loader loader;

private String cdn;

private boolean etag = true;

private long maxAge = -1;

private boolean lastModified = true;

private int statusCode = 404;

/**

* <p>

* Creates a new {@link AssetHandler}. The handler accepts a location pattern, that serve for

* locating the static resource.

* </p>

*

* Given <code>assets("/assets/**", "/")</code> with:

*

* <pre>

* GET /assets/js/index.js it translates the path to: /assets/js/index.js

* </pre>

*

* Given <code>assets("/js/**", "/assets")</code> with:

*

* <pre>

* GET /js/index.js it translate the path to: /assets/js/index.js

* </pre>

*

* Given <code>assets("/webjars/**", "/META-INF/resources/webjars/{0}")</code> with:

*

* <pre>

* GET /webjars/jquery/2.1.3/jquery.js it translate the path to: /META-INF/resources/webjars/jquery/2.1.3/jquery.js

* </pre>

*

* @param pattern Pattern to locate static resources.

* @param loader The one who load the static resources.

*/

public AssetHandler(final String pattern, final ClassLoader loader) {

init(Route.normalize(pattern), Paths.get("public"), loader);

}

/**

* <p>

* Creates a new {@link AssetHandler}. The handler accepts a location pattern, that serve for

* locating the static resource.

* </p>

*

* Given <code>assets("/assets/**", "/")</code> with:

*

* <pre>

* GET /assets/js/index.js it translates the path to: /assets/js/index.js

* </pre>

*

* Given <code>assets("/js/**", "/assets")</code> with:

*

* <pre>

* GET /js/index.js it translate the path to: /assets/js/index.js

* </pre>

*

* Given <code>assets("/webjars/**", "/META-INF/resources/webjars/{0}")</code> with:

*

* <pre>

* GET /webjars/jquery/2.1.3/jquery.js it translate the path to: /META-INF/resources/webjars/jquery/2.1.3/jquery.js

* </pre>

*

* @param basedir Base directory.

*/

public AssetHandler(final Path basedir) {

init("/{0}", basedir, getClass().getClassLoader());

}

/**

* <p>

* Creates a new {@link AssetHandler}. The location pattern can be one of.

* </p>

*

* Given <code>/</code> like in <code>assets("/assets/**", "/")</code> with:

*

* <pre>

* GET /assets/js/index.js it translates the path to: /assets/js/index.js

* </pre>

*

* Given <code>/assets</code> like in <code>assets("/js/**", "/assets")</code> with:

*

* <pre>

* GET /js/index.js it translate the path to: /assets/js/index.js

* </pre>

*

* Given <code>/META-INF/resources/webjars/{0}</code> like in

* <code>assets("/webjars/**", "/META-INF/resources/webjars/{0}")</code> with:

*

* <pre>

* GET /webjars/jquery/2.1.3/jquery.js it translate the path to: /META-INF/resources/webjars/jquery/2.1.3/jquery.js

* </pre>

*

* @param pattern Pattern to locate static resources.

*/

public AssetHandler(final String pattern) {

init(Route.normalize(pattern), Paths.get("public"), getClass().getClassLoader());

}

/**

* @param etag Turn on/off etag support.

* @return This handler.

*/

public AssetHandler etag(final boolean etag) {

this.etag = etag;

return this;

}

/**

* @param enabled Turn on/off last modified support.

* @return This handler.

*/

public AssetHandler lastModified(final boolean enabled) {

this.lastModified = enabled;

return this;

}

/**

* @param cdn If set, every resolved asset will be serve from it.

* @return This handler.

*/

public AssetHandler cdn(final String cdn) {

this.cdn = Strings.emptyToNull(cdn);

return this;

}

/**

* @param maxAge Set the cache header max-age value.

* @return This handler.

*/

public AssetHandler maxAge(final Duration maxAge) {

return maxAge(maxAge.getSeconds());

}

/**

* @param maxAge Set the cache header max-age value in seconds.

* @return This handler.

*/

public AssetHandler maxAge(final long maxAge) {

this.maxAge = maxAge;

return this;

}

/**

* Parse value as {@link Duration}. If the value is already a number then it uses as seconds.

* Otherwise, it parse expressions like: 8m, 1h, 365d, etc...

*

* @param maxAge Set the cache header max-age value in seconds.

* @return This handler.

*/

public AssetHandler maxAge(final String maxAge) {

Try.apply(() -> Long.parseLong(maxAge))

.recover(x -> ConfigFactory.empty()

.withValue("v", ConfigValueFactory.fromAnyRef(maxAge))

.getDuration("v")

.getSeconds())

.onSuccess(this::maxAge);

return this;

}

/**

* Indicates what to do when an asset is missing (not resolved). Default action is to resolve them

* as <code>404 (NOT FOUND)</code> request.

*

* If you specify a status code &lt;= 0, missing assets are ignored and the next handler on pipeline

* will be executed.

*

* @param statusCode HTTP code or 0.

* @return This handler.

*/

public AssetHandler onMissing(final int statusCode) {

this.statusCode = statusCode;

return this;

}

@Override

public void handle(final Request req, final Response rsp) throws Throwable {

String path = req.path();

URL resource = resolve(req, path);

if (resource != null) {

String localpath = resource.getPath();

int jarEntry = localpath.indexOf("!/");

if (jarEntry > 0) {

localpath = localpath.substring(jarEntry + 2);

}

URLAsset asset = new URLAsset(resource, path,

MediaType.byPath(localpath).orElse(MediaType.octetstream));

if (asset.exists()) {

// cdn?

if (cdn != null) {

String absUrl = cdn + path;

rsp.redirect(absUrl);

rsp.end();

} else {

doHandle(req, rsp, asset);

}

}

} else if (statusCode > 0) {

throw new Err(statusCode);

}

}

private void doHandle(final Request req, final Response rsp, final Asset asset) throws Throwable {

// handle etag

if (this.etag) {

String etag = asset.etag();

boolean ifnm = req.header("If-None-Match").toOptional()

.map(etag::equals)

.orElse(false);

if (ifnm) {

rsp.header("ETag", etag).status(Status.NOT_MODIFIED).end();

return;

}

rsp.header("ETag", etag);

}

// Handle if modified since

if (this.lastModified) {

long lastModified = asset.lastModified();

if (lastModified > 0) {

boolean ifm = req.header("If-Modified-Since").toOptional(Long.class)

.map(ifModified -> lastModified / 1000 <= ifModified / 1000)

.orElse(false);

if (ifm) {

rsp.status(Status.NOT_MODIFIED).end();

return;

}

rsp.header("Last-Modified", new Date(lastModified));

}

}

// cache max-age

if (maxAge > 0) {

rsp.header("Cache-Control", "max-age=" + maxAge);

}

send(req, rsp, asset);

}

/**

* Send an asset to the client.

*

* @param req Request.

* @param rsp Response.

* @param asset Resolve asset.

* @throws Exception If send fails.

*/

protected void send(final Request req, final Response rsp, final Asset asset) throws Throwable {

rsp.send(asset);

}

private URL resolve(final Request req, final String path) throws Throwable {

String target = fn.apply(req, path);

return resolve(target);

}

/**

* Resolve a path as a {@link URL}.

*

* @param path Path of resource to resolve.

* @return A URL or <code>null</code> for unresolved resource.

* @throws Exception If something goes wrong.

*/

protected URL resolve(final String path) throws Exception {

return loader.getResource(path);

}

private void init(final String pattern, final Path basedir, final ClassLoader loader) {

requireNonNull(loader, "Resource loader is required.");

this.fn = pattern.equals("/")

? (req, p) -> prefix.apply(p)

: (req, p) -> MessageFormat.format(prefix.apply(pattern), vars(req));

this.loader = loader(basedir, loader);

}

private static Object[] vars(final Request req) {

Map<Object, String> vars = req.route().vars();

return vars.values().toArray(new Object[vars.size()]);

}

private static Loader loader(final Path basedir, final ClassLoader classloader) {

if (Files.exists(basedir)) {

return name -> {

Path path = basedir.resolve(name).normalize();

if (Files.exists(path) && path.startsWith(basedir)) {

try {

return path.toUri().toURL();

} catch (MalformedURLException x) {

// shh

}

}

return classloader.getResource(name);

};

}

return classloader::getResource;

}

private static Throwing.Function<String, String> prefix() {

return p -> p.substring(1);

}

}