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package org.jooby.internal;

import com.google.common.base.Strings;
import com.google.common.base.Throwables;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Sets;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.name.Names;
import com.typesafe.config.Config;
import static java.util.Objects.requireNonNull;
import org.jooby.Deferred;
import org.jooby.Err;
import org.jooby.Err.Handler;
import org.jooby.MediaType;
import org.jooby.Renderer;
import org.jooby.Request;
import org.jooby.Response;
import org.jooby.Route;
import org.jooby.Session;
import org.jooby.Sse;
import org.jooby.Status;
import org.jooby.WebSocket;
import org.jooby.WebSocket.Definition;
import org.jooby.internal.parser.ParserExecutor;
import org.jooby.spi.HttpHandler;
import org.jooby.spi.NativeRequest;
import org.jooby.spi.NativeResponse;
import org.jooby.spi.NativeWebSocket;
import org.jooby.funzy.Try;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Provider;
import javax.inject.Singleton;
import java.nio.charset.Charset;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.Executor;
import java.util.function.Function;
import java.util.stream.Collectors;

@Singleton
public class HttpHandlerImpl implements HttpHandler {

    private static class RouteKey {

        private final String method;

        private final String path;

        private final MediaType consumes;

        private final List<MediaType> produces;

        private final String key;

        public RouteKey(final String method, final String path, final MediaType consumes,
                final List<MediaType> produces) {
            String c = consumes.name();
            String p = produces.toString();
            key = new StringBuilder(method.length() + path.length() + c.length() + p.length()).append(method)
                    .append(path).append(c).append(p).toString();
            this.method = method;
            this.path = path;
            this.consumes = consumes;
            this.produces = produces;
        }

        @Override
        public int hashCode() {
            return key.hashCode();
        }

        @Override
        public boolean equals(final Object obj) {
            RouteKey that = (RouteKey) obj;
            return key.equals(that.key);
        }
    }

    private static final String NO_CACHE = "must-revalidate,no-cache,no-store";

    private static final String WEB_SOCKET = "WebSocket";

    private static final String UPGRADE = "Upgrade";

    private static final String REFERER = "Referer";

    private static final String PATH = "path";

    private static final String CONTEXT_PATH = "contextPath";

    private static final Key<Request> REQ = Key.get(Request.class);

    private static final Key<Route.Chain> CHAIN = Key.get(Route.Chain.class);

    private static final Key<Response> RSP = Key.get(Response.class);

    private static final Key<Sse> SSE = Key.get(Sse.class);

    private static final Key<Session> SESS = Key.get(Session.class);

    private static final Key<String> DEF_EXEC = Key.get(String.class, Names.named("deferred"));

    private static final String BYTE_RANGE = "Range";

    /**
     * The logging system.
     */
    private Injector injector;

    private Set<Err.Handler> err;

    private String applicationPath;

    private RequestScope requestScope;

    private Set<Definition> socketDefs;

    private Config config;

    private int port;

    private String _method;

    private Charset charset;

    private List<Renderer> renderers;

    private ParserExecutor parserExecutor;

    private List<Locale> locales;

    private final LoadingCache<RouteKey, Route[]> routeCache;

    private final String redirectHttps;

    private Function<String, String> rpath = null;

    private String contextPath;

    private boolean hasSockets;

    private final Map<String, Renderer> rendererMap;

    private StatusCodeProvider sc;

    /**
     * Global deferred executor.
     */
    private Key<Executor> gexec;

    @Inject
    public HttpHandlerImpl(final Injector injector, final RequestScope requestScope,
            final Set<Route.Definition> routes, final Set<WebSocket.Definition> sockets,
            final @Named("application.path") String path, final ParserExecutor parserExecutor,
            final Set<Renderer> renderers, final Set<Err.Handler> err, final StatusCodeProvider sc,
            final Charset charset, final List<Locale> locale) {
        this.injector = requireNonNull(injector, "An injector is required.");
        this.requestScope = requireNonNull(requestScope, "A request scope is required.");
        this.socketDefs = requireNonNull(sockets, "Sockets are required.");
        this.hasSockets = socketDefs.size() > 0;
        this.applicationPath = normalizeURI(requireNonNull(path, "An application.path is required."));
        this.err = requireNonNull(err, "An err handler is required.");
        this.sc = sc;
        this.config = injector.getInstance(Config.class);
        _method = Strings.emptyToNull(this.config.getString("server.http.Method").trim());
        this.port = config.getInt("application.port");
        this.charset = charset;
        this.locales = locale;
        this.parserExecutor = parserExecutor;
        this.renderers = new ArrayList<>(renderers);
        rendererMap = new HashMap<>();
        this.renderers.forEach(r -> rendererMap.put(r.name(), r));

        // route cache
        routeCache = routeCache(routes, config);
        // force https
        String redirectHttps = config.getString("application.redirect_https").trim();
        this.redirectHttps = redirectHttps.length() > 0 ? redirectHttps : null;

        // custom path?
        if (applicationPath.equals("/")) {
            this.contextPath = "";
        } else {
            this.contextPath = applicationPath;
            this.rpath = rootpath(applicationPath);
        }
        // global deferred executor
        this.gexec = Key.get(Executor.class, Names.named(injector.getInstance(DEF_EXEC)));
    }

    @Override
    public void handle(final NativeRequest request, final NativeResponse response) throws Exception {
        long start = System.currentTimeMillis();

        Map<String, Object> locals = new HashMap<>(16);

        Map<Object, Object> scope = new HashMap<>(16);

        String method = _method == null ? request.method() : method(_method, request);
        String path = normalizeURI(request.path());
        if (rpath != null) {
            path = rpath.apply(path);
        }

        // put request attributes first to make sure we don't override defaults
        Map<String, Object> nativeAttrs = request.attributes();
        if (nativeAttrs.size() > 0) {
            locals.putAll(nativeAttrs);
        }
        // default locals
        locals.put(CONTEXT_PATH, contextPath);
        locals.put(PATH, path);

        Route notFound = RouteImpl.notFound(method, path);

        RequestImpl req = new RequestImpl(injector, request, contextPath, port, notFound, charset, locales, scope,
                locals, start);

        ResponseImpl rsp = new ResponseImpl(req, parserExecutor, response, notFound, renderers, rendererMap, locals,
                req.charset(), request.header(REFERER), request.header(BYTE_RANGE));

        MediaType type = req.type();

        // seed req & rsp
        scope.put(REQ, req);
        scope.put(RSP, rsp);

        // seed sse
        Provider<Sse> sse = () -> Try.apply(() -> request.upgrade(Sse.class)).get();
        scope.put(SSE, sse);

        // seed session
        Provider<Session> session = () -> req.session();
        scope.put(SESS, session);

        boolean deferred = false;
        Throwable x = null;
        try {

            requestScope.enter(scope);

            // force https?
            if (redirectHttps != null) {
                if (!req.secure()) {
                    rsp.redirect(MessageFormat.format(redirectHttps, path.substring(1)));
                    return;
                }
            }

            // websocket?
            if (hasSockets) {
                if (upgrade(request)) {
                    Optional<WebSocket> sockets = findSockets(socketDefs, path);
                    if (sockets.isPresent()) {
                        NativeWebSocket ws = request.upgrade(NativeWebSocket.class);
                        ws.onConnect(() -> ((WebSocketImpl) sockets.get()).connect(injector, req, ws));
                        return;
                    }
                }
            }

            // usual req/rsp
            Route[] routes = routeCache.getUnchecked(new RouteKey(method, path, type, req.accept()));

            RouteChain chain = new RouteChain(req, rsp, routes);
            scope.put(CHAIN, chain);
            chain.next(req, rsp);

        } catch (DeferredExecution ex) {
            deferred = true;
            onDeferred(scope, request, req, rsp, ex.deferred);
        } catch (Throwable ex) {
            x = ex;
        } finally {
            cleanup(req, rsp, true, x, !deferred);
        }
    }

    private boolean upgrade(final NativeRequest request) {
        Optional<String> upgrade = request.header(UPGRADE);
        return upgrade.isPresent() && upgrade.get().equalsIgnoreCase(WEB_SOCKET);
    }

    private void done(final RequestImpl req, final ResponseImpl rsp, final Throwable x, final boolean close) {
        // mark request/response as done.
        req.done();
        if (close) {
            rsp.done(Optional.ofNullable(x));
        }
    }

    private void onDeferred(final Map<Object, Object> scope, final NativeRequest request, final RequestImpl req,
            final ResponseImpl rsp, final Deferred deferred) {
        /** Deferred executor. */
        Key<Executor> execKey = deferred.executor().map(it -> Key.get(Executor.class, Names.named(it)))
                .orElse(gexec);

        /** Get executor. */
        Executor executor = injector.getInstance(execKey);

        request.startAsync(executor, () -> {
            try {
                deferred.handler(req, (success, x) -> {
                    boolean close = false;
                    Optional<Throwable> failure = Optional.ofNullable(x);
                    try {
                        requestScope.enter(scope);
                        if (success != null) {
                            close = true;
                            rsp.send(success);
                        }
                    } catch (Throwable exerr) {
                        failure = Optional.of(failure.orElse(exerr));
                    } finally {
                        Throwable cause = failure.orElse(null);
                        if (cause != null) {
                            close = true;
                        }
                        cleanup(req, rsp, close, cause, true);
                    }
                });
            } catch (Exception ex) {
                handleErr(req, rsp, ex);
            }
        });
    }

    private void cleanup(final RequestImpl req, final ResponseImpl rsp, final boolean close, final Throwable x,
            final boolean done) {
        if (x != null) {
            handleErr(req, rsp, x);
        }
        if (done) {
            done(req, rsp, x, close);
        }
        requestScope.exit();
    }

    private void handleErr(final RequestImpl req, final ResponseImpl rsp, final Throwable ex) {
        Logger log = LoggerFactory.getLogger(HttpHandler.class);
        try {
            log.debug("execution of: {}{} resulted in exception", req.method(), req.path(), ex);
            // execution failed, find status code
            Status status = sc.apply(ex);

            if (status == Status.REQUESTED_RANGE_NOT_SATISFIABLE) {
                String range = rsp.header("Content-Length").toOptional().map(it -> "bytes */" + it).orElse("*");
                rsp.reset();
                rsp.header("Content-Range", range);
            } else {
                rsp.reset();
            }

            rsp.header("Cache-Control", NO_CACHE);
            rsp.status(status);

            Err err = ex instanceof Err ? (Err) ex : new Err(status, ex);

            Iterator<Handler> it = this.err.iterator();
            while (!rsp.committed() && it.hasNext()) {
                Err.Handler next = it.next();
                log.debug("handling err with: {}", next);
                next.handle(req, rsp, err);
            }
        } catch (Throwable errex) {
            log.error("error handler resulted in exception: {}{}\nRoute:\n{}\n\nStacktrace:\n{}\nSource:",
                    req.method(), req.path(), req.route().print(6), Throwables.getStackTraceAsString(errex), ex);
        }
    }

    private static String normalizeURI(final String uri) {
        int len = uri.length();
        return len > 1 && uri.charAt(len - 1) == '/' ? uri.substring(0, len - 1) : uri;
    }

    private static Route[] routes(final Set<Route.Definition> routeDefs, final String method, final String path,
            final MediaType type, final List<MediaType> accept) {
        List<Route> routes = findRoutes(routeDefs, method, path, type, accept);

        routes.add(RouteImpl.fallback((req, rsp, chain) -> {
            if (!rsp.status().isPresent()) {
                // 406 or 415
                Err ex = handle406or415(routeDefs, method, path, type, accept);
                if (ex != null) {
                    throw ex;
                }
                // 405
                ex = handle405(routeDefs, method, path, type, accept);
                if (ex != null) {
                    throw ex;
                }
                // favicon.ico
                if (path.equals("/favicon.ico")) {
                    // default /favicon.ico handler:
                    rsp.status(Status.NOT_FOUND).end();
                } else {
                    throw new Err(Status.NOT_FOUND, req.path(true));
                }
            }
        }, method, path, "err", accept));

        return routes.toArray(new Route[routes.size()]);
    }

    private static List<Route> findRoutes(final Set<Route.Definition> routeDefs, final String method,
            final String path, final MediaType type, final List<MediaType> accept) {

        List<Route> routes = new ArrayList<>();
        for (Route.Definition routeDef : routeDefs) {
            Optional<Route> route = routeDef.matches(method, path, type, accept);
            if (route.isPresent()) {
                routes.add(route.get());
            }
        }
        return routes;
    }

    private static Optional<WebSocket> findSockets(final Set<WebSocket.Definition> sockets, final String path) {
        for (WebSocket.Definition socketDef : sockets) {
            Optional<WebSocket> match = socketDef.matches(path);
            if (match.isPresent()) {
                return match;
            }
        }
        return Optional.empty();
    }

    private static Err handle405(final Set<Route.Definition> routeDefs, final String method, final String path,
            final MediaType type, final List<MediaType> accept) {

        if (alternative(routeDefs, method, path).size() > 0) {
            return new Err(Status.METHOD_NOT_ALLOWED, method);
        }

        return null;
    }

    private static List<Route> alternative(final Set<Route.Definition> routeDefs, final String verb,
            final String uri) {
        List<Route> routes = new LinkedList<>();
        Set<String> verbs = Sets.newHashSet(Route.METHODS);
        verbs.remove(verb);
        for (String alt : verbs) {
            findRoutes(routeDefs, alt, uri, MediaType.all, MediaType.ALL).stream()
                    // skip glob pattern
                    .filter(r -> !r.pattern().contains("*")).forEach(routes::add);

        }
        return routes;
    }

    private static Err handle406or415(final Set<Route.Definition> routeDefs, final String method, final String path,
            final MediaType contentType, final List<MediaType> accept) {
        for (Route.Definition routeDef : routeDefs) {
            Optional<Route> route = routeDef.matches(method, path, MediaType.all, MediaType.ALL);
            if (route.isPresent() && !route.get().pattern().contains("*")) {
                if (!routeDef.canProduce(accept)) {
                    return new Err(Status.NOT_ACCEPTABLE,
                            accept.stream().map(MediaType::name).collect(Collectors.joining(", ")));
                }
                if (!contentType.isAny()) {
                    return new Err(Status.UNSUPPORTED_MEDIA_TYPE, contentType.name());
                }
            }
        }
        return null;
    }

    private static String method(final String methodParam, final NativeRequest request) throws Exception {
        Optional<String> header = request.header(methodParam);
        if (header.isPresent()) {
            return header.get();
        }
        List<String> param = request.params(methodParam);
        return param.size() == 0 ? request.method() : param.get(0);
    }

    private static LoadingCache<RouteKey, Route[]> routeCache(final Set<Route.Definition> routes,
            final Config conf) {
        return CacheBuilder.from(conf.getString("server.routes.Cache")).build(new CacheLoader<RouteKey, Route[]>() {
            @Override
            public Route[] load(final RouteKey key) throws Exception {
                return routes(routes, key.method, key.path, key.consumes, key.produces);
            }
        });
    }

    private static Function<String, String> rootpath(final String applicationPath) {
        return p -> {
            if (applicationPath.equals(p)) {
                return "/";
            } else if (p.startsWith(applicationPath)) {
                return p.substring(applicationPath.length());
            } else {
                // mark as failure
                return Route.errpath(p);
            }
        };
    }

}