/**

* Jooby https://jooby.io

* Apache License Version 2.0 https://jooby.io/LICENSE.txt

* Copyright 2014 Edgar Espina

*/

package io.jooby;

import javax.annotation.Nonnull;

import java.time.Duration;

import java.time.Instant;

import java.util.List;

import java.util.function.Function;

import static java.util.Objects.requireNonNull;

/**

* Handler for static resources represented by the {@link Asset} contract.

*

* It has built-in support for static-static as well as SPAs (single page applications).

*

* @author edgar

* @since 2.0.0

*/

public class AssetHandler implements Route.Handler {

private static final int ONE_SEC = 1000;

private final AssetSource[] sources;

private final CacheControl defaults = CacheControl.defaults();

private String filekey;

private String fallback;

private Function<String, CacheControl> cacheControl = path -> defaults;

/**

* Creates a new asset handler that fallback to the given fallback asset when the asset

* is not found. Instead of produces a <code>404</code> its fallback to the given asset.

*

* <pre>{@code

* {

* assets("/?*", new AssetHandler("index.html", AssetSource.create(Paths.get("...")));

* }

* }</pre>

*

* The fallback option makes the asset handler to work like a SPA (Single-Application-Page).

*

* @param fallback Fallback asset.

* @param sources Asset sources. At least one source is required.

*/

public AssetHandler(@Nonnull String fallback, AssetSource... sources) {

this.fallback = fallback;

this.sources = checkSource(sources);

}

/**

* Creates a new asset handler.

*

* @param sources Asset sources. At least one source is required.

*/

public AssetHandler(AssetSource... sources) {

this.sources = checkSource(sources);

}

@Nonnull @Override public Object apply(@Nonnull Context ctx) throws Exception {

final String resolvedPath;

String filepath = ctx.pathMap().getOrDefault(filekey, "index.html");

Asset asset = resolve(filepath);

if (asset == null) {

if (fallback != null) {

asset = resolve(fallback);

}

// Still null?

if (asset == null) {

ctx.send(StatusCode.NOT_FOUND);

return ctx;

} else {

resolvedPath = fallback;

}

} else {

resolvedPath = filepath;

}

CacheControl cacheParams = cacheControl.apply(resolvedPath);

// handle If-None-Match

if (cacheParams.isEtag()) {

String ifnm = ctx.header("If-None-Match").value((String) null);

if (ifnm != null && ifnm.equals(asset.getEtag())) {

ctx.send(StatusCode.NOT_MODIFIED);

asset.close();

return ctx;

} else {

ctx.setResponseHeader("ETag", asset.getEtag());

}

}

// Handle If-Modified-Since

if (cacheParams.isLastModified()) {

long lastModified = asset.getLastModified();

if (lastModified > 0) {

long ifms = ctx.header("If-Modified-Since").longValue(-1);

if (lastModified / ONE_SEC <= ifms / ONE_SEC) {

ctx.send(StatusCode.NOT_MODIFIED);

asset.close();

return ctx;

}

ctx.setResponseHeader("Last-Modified", Instant.ofEpochMilli(lastModified));

}

}

// cache control

if (cacheParams.getMaxAge() >= 0) {

ctx.setResponseHeader("Cache-Control", "max-age=" + cacheParams.getMaxAge());

} else if (cacheParams.getMaxAge() == CacheControl.NO_CACHE) {

ctx.setResponseHeader("Cache-Control", "no-store, must-revalidate");

}

long length = asset.getSize();

if (length != -1) {

ctx.setResponseLength(length);

}

ctx.setResponseType(asset.getContentType());

return ctx.send(asset.stream());

}

/**

* Turn on/off e-tag support.

*

* @param etag True for turning on.

* @return This handler.

*/

public AssetHandler setETag(boolean etag) {

defaults.setETag(etag);

return this;

}

/**

* Turn on/off handling of {@code If-Modified-Since} header.

*

* @param lastModified True for turning on. Default is: true.

* @return This handler.

*/

public AssetHandler setLastModified(boolean lastModified) {

defaults.setLastModified(lastModified);

return this;

}

/**

* Set cache-control header with the given max-age value. If max-age is greater than 0.

*

* @param maxAge Max-age value in seconds.

* @return This handler.

*/

public AssetHandler setMaxAge(long maxAge) {

defaults.setMaxAge(maxAge);

return this;

}

/**

* Set cache-control header with the given max-age value. If max-age is greater than 0.

*

* @param maxAge Max-age value in seconds.

* @return This handler.

*/

public AssetHandler setMaxAge(Duration maxAge) {

defaults.setMaxAge(maxAge);

return this;

}

/**

* Set cache-control header to {@code no-store, must-revalidate}, disables e-tag

* and {@code If-Modified-Since} header support.

*

* @return This handler.

*/

public AssetHandler setNoCache() {

defaults.setNoCache();

return this;

}

/**

* Sets a custom function that provides caching configuration for each individual

* asset response overriding the defaults set in {@link AssetHandler}.

*

* @param cacheControl a cache configuration provider function.

* @return this instance.

* @see CacheControl

*/

public AssetHandler cacheControl(@Nonnull Function<String, CacheControl> cacheControl) {

this.cacheControl = requireNonNull(cacheControl);

return this;

}

private Asset resolve(String filepath) {

for (AssetSource source : sources) {

Asset asset = source.resolve(filepath);

if (asset != null) {

return asset;

}

}

return null;

}

@Override public void setRoute(Route route) {

List<String> keys = route.getPathKeys();

this.filekey = keys.size() == 0 ? route.getPattern().substring(1) : keys.get(0);

// NOTE: It send an inputstream we don't need a renderer

route.setReturnType(Context.class);

}

private static AssetSource[] checkSource(AssetSource[] sources) {

if (sources.length == 0) {

throw new IllegalArgumentException("At least one source is required.");

}

return sources;

}

}