/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package org.apache.hc.client5.http.impl.async;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Set;
import java.util.function.UnaryOperator;

import org.apache.hc.client5.http.async.AsyncExecCallback;
import org.apache.hc.client5.http.async.AsyncExecChain;
import org.apache.hc.client5.http.async.AsyncExecChainHandler;
import org.apache.hc.client5.http.async.methods.InflatingAsyncDataConsumer;
import org.apache.hc.client5.http.async.methods.InflatingBrotliDataConsumer;
import org.apache.hc.client5.http.async.methods.InflatingGzipDataConsumer;
import org.apache.hc.client5.http.async.methods.InflatingZstdDataConsumer;
import org.apache.hc.client5.http.entity.compress.ContentCoding;
import org.apache.hc.client5.http.impl.Brotli4jRuntime;
import org.apache.hc.client5.http.impl.ContentCodingSupport;
import org.apache.hc.client5.http.impl.ZstdRuntime;
import org.apache.hc.client5.http.protocol.HttpClientContext;
import org.apache.hc.core5.annotation.Contract;
import org.apache.hc.core5.annotation.Internal;
import org.apache.hc.core5.annotation.ThreadingBehavior;
import org.apache.hc.core5.http.EntityDetails;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpHeaders;
import org.apache.hc.core5.http.HttpRequest;
import org.apache.hc.core5.http.HttpResponse;
import org.apache.hc.core5.http.config.Lookup;
import org.apache.hc.core5.http.config.RegistryBuilder;
import org.apache.hc.core5.http.message.MessageSupport;
import org.apache.hc.core5.http.nio.AsyncDataConsumer;
import org.apache.hc.core5.http.nio.AsyncEntityProducer;
import org.apache.hc.core5.util.Args;

@Contract(threading = ThreadingBehavior.STATELESS)
@Internal
public final class ContentCompressionAsyncExec implements AsyncExecChainHandler {

    private final Lookup<UnaryOperator<AsyncDataConsumer>> decoders;
    private final List<String> acceptTokens;
    private final int maxCodecListLen;

    public ContentCompressionAsyncExec(
            final LinkedHashMap<String, UnaryOperator<AsyncDataConsumer>> decoderMap,
            final int maxCodecListLen) {
        Args.notEmpty(decoderMap, "Decoder map");

        final RegistryBuilder<UnaryOperator<AsyncDataConsumer>> rb = RegistryBuilder.create();
        decoderMap.forEach(rb::register);
        this.decoders = rb.build();
        this.acceptTokens = new ArrayList<>(decoderMap.keySet());
        this.maxCodecListLen = maxCodecListLen;
    }

    public ContentCompressionAsyncExec(
            final LinkedHashMap<String, UnaryOperator<AsyncDataConsumer>> decoderMap) {
        this(decoderMap, ContentCodingSupport.MAX_CODEC_LIST_LEN);
    }

    /**
     * Default: DEFLATE + GZIP (plus <code>x-gzip</code> alias).
     */
    public ContentCompressionAsyncExec(final int maxCodecListLen) {
        final LinkedHashMap<String, UnaryOperator<AsyncDataConsumer>> map = new LinkedHashMap<>();
        map.put(ContentCoding.DEFLATE.token(), d -> new InflatingAsyncDataConsumer(d, null));
        map.put(ContentCoding.GZIP.token(), InflatingGzipDataConsumer::new);
        map.put(ContentCoding.X_GZIP.token(), InflatingGzipDataConsumer::new);

        final RegistryBuilder<UnaryOperator<AsyncDataConsumer>> rb =
                RegistryBuilder.<UnaryOperator<AsyncDataConsumer>>create()
                        .register(ContentCoding.GZIP.token(), InflatingGzipDataConsumer::new)
                        .register(ContentCoding.X_GZIP.token(), InflatingGzipDataConsumer::new)
                        .register(ContentCoding.DEFLATE.token(), d -> new InflatingAsyncDataConsumer(d, null));

        // Add zstd only when zstd-jni is present (no reflection needed)
        final List<String> tokens = new ArrayList<>(Arrays.asList("gzip", "x-gzip", "deflate"));
        if (ZstdRuntime.available()) {
            rb.register(ContentCoding.ZSTD.token(), InflatingZstdDataConsumer::new);
            tokens.add("zstd");
        }

        if (Brotli4jRuntime.available()) {
            rb.register(ContentCoding.BROTLI.token(), InflatingBrotliDataConsumer::new);
            tokens.add(ContentCoding.BROTLI.token());
        }

        this.decoders = rb.build();
        this.acceptTokens = tokens;
        this.maxCodecListLen = maxCodecListLen;
    }

    public ContentCompressionAsyncExec() {
        this(ContentCodingSupport.MAX_CODEC_LIST_LEN);
    }

    @Override
    public void execute(
            final HttpRequest request,
            final AsyncEntityProducer producer,
            final AsyncExecChain.Scope scope,
            final AsyncExecChain chain,
            final AsyncExecCallback cb) throws IOException, HttpException {

        final HttpClientContext ctx = scope != null ? scope.clientContext : HttpClientContext.create();
        final boolean enabled = ctx.getRequestConfigOrDefault().isContentCompressionEnabled();

        if (enabled && !request.containsHeader(HttpHeaders.ACCEPT_ENCODING)) {
            request.addHeader(MessageSupport.headerOfTokens(HttpHeaders.ACCEPT_ENCODING, acceptTokens));
        }

        chain.proceed(request, producer, scope, new AsyncExecCallback() {

            @Override
            public AsyncDataConsumer handleResponse(final HttpResponse rsp,
                                                    final EntityDetails details)
                    throws HttpException, IOException {

                if (!enabled) {
                    return cb.handleResponse(rsp, details);
                }

                final List<String> codecs = ContentCodingSupport.parseContentCodecs(details);
                ContentCodingSupport.validate(codecs, maxCodecListLen);
                if (!codecs.isEmpty()) {
                    AsyncDataConsumer downstream = cb.handleResponse(rsp, wrapEntityDetails(details));
                    if (downstream == null) {
                        return null;
                    }
                    for (int i = codecs.size() - 1; i >= 0; i--) {
                        final String codec = codecs.get(i);
                        final UnaryOperator<AsyncDataConsumer> op = decoders.lookup(codec);
                        if (op != null) {
                            downstream = op.apply(downstream);
                        } else {
                            throw new HttpException("Unsupported Content-Encoding: " + codec);
                        }
                    }
                    return downstream;
                }

                return cb.handleResponse(rsp, details);
            }

            @Override
            public void handleInformationResponse(final HttpResponse r)
                    throws HttpException, IOException {
                cb.handleInformationResponse(r);
            }

            @Override
            public void completed() {
                cb.completed();
            }

            @Override
            public void failed(final Exception ex) {
                cb.failed(ex);
            }
        });
    }

    private static EntityDetails wrapEntityDetails(final EntityDetails original) {
        return new EntityDetails() {
            @Override
            public long getContentLength() {
                return -1;
            }

            @Override
            public String getContentType() {
                return original.getContentType();
            }

            @Override
            public String getContentEncoding() {
                return null;
            }

            @Override
            public boolean isChunked() {
                return true;
            }

            @Override
            public Set<String> getTrailerNames() {
                return original.getTrailerNames();
            }
        };
    }
}
