// Copyright (C) 2018 The Android Open Source Project
//
// Licensed 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.

package com.googlesource.gerrit.plugins.replication;

import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.config.SitePaths;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.ProvisionException;
import java.nio.file.Files;
import java.nio.file.Path;
import javax.net.ssl.SSLContext;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.HttpClientConnectionManager;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.ssl.SSLContexts;
import org.eclipse.jgit.lib.Config;

/** Provides an HTTP client with SSL capabilities. */
class HttpClientProvider implements Provider<CloseableHttpClient> {
  private static final int CONNECTIONS_PER_ROUTE = 100;

  // Up to 2 target instances with the max number of connections per host:
  private static final int MAX_CONNECTIONS = 2 * CONNECTIONS_PER_ROUTE;

  private static final int MAX_CONNECTION_INACTIVITY = 10000;
  private static final int DEFAULT_TIMEOUT_MS = 5000;

  private final Config cfg;
  private final SitePaths site;

  @Inject
  HttpClientProvider(@GerritServerConfig Config cfg, SitePaths site) {
    this.cfg = cfg;
    this.site = site;
  }

  @Override
  public CloseableHttpClient get() {
    try {
      return HttpClients.custom()
          .setConnectionManager(customConnectionManager())
          .setDefaultRequestConfig(customRequestConfig())
          .build();
    } catch (Exception e) {
      throw new ProvisionException("Couldn't create CloseableHttpClient", e);
    }
  }

  private RequestConfig customRequestConfig() {
    return RequestConfig.custom()
        .setConnectTimeout(DEFAULT_TIMEOUT_MS)
        .setSocketTimeout(DEFAULT_TIMEOUT_MS)
        .setConnectionRequestTimeout(DEFAULT_TIMEOUT_MS)
        .build();
  }

  private HttpClientConnectionManager customConnectionManager() throws Exception {
    Registry<ConnectionSocketFactory> socketFactoryRegistry =
        RegistryBuilder.<ConnectionSocketFactory>create()
            .register("https", buildSslSocketFactory())
            .register("http", PlainConnectionSocketFactory.INSTANCE)
            .build();
    PoolingHttpClientConnectionManager connManager =
        new PoolingHttpClientConnectionManager(socketFactoryRegistry);
    connManager.setDefaultMaxPerRoute(CONNECTIONS_PER_ROUTE);
    connManager.setMaxTotal(MAX_CONNECTIONS);
    connManager.setValidateAfterInactivity(MAX_CONNECTION_INACTIVITY);
    return connManager;
  }

  private SSLConnectionSocketFactory buildSslSocketFactory() throws Exception {
    String keyStore = cfg.getString("httpd", null, "sslKeyStore");
    if (keyStore == null) {
      keyStore = "etc/keystore";
    }
    return new SSLConnectionSocketFactory(createSSLContext(site.resolve(keyStore)));
  }

  private SSLContext createSSLContext(Path keyStorePath) throws Exception {
    SSLContext ctx;
    if (Files.exists(keyStorePath)) {
      ctx = SSLContexts.custom().loadTrustMaterial(keyStorePath.toFile()).build();
    } else {
      ctx = SSLContext.getDefault();
    }
    return ctx;
  }
}