/**
 * 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.
 */
package org.apache.hadoop.hdfs.server.federation.router;

import static org.apache.hadoop.util.StringUtils.getTrimmedStringCollection;

import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
import org.apache.hadoop.hdfs.server.common.JspHelper;
import org.apache.hadoop.hdfs.server.federation.router.security.RouterSecurityManager;
import org.apache.hadoop.hdfs.server.namenode.web.resources.NamenodeWebHdfsMethods;

import javax.servlet.http.HttpServletRequest;
import javax.ws.rs.Path;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.sun.jersey.spi.container.ResourceFilters;
import org.apache.hadoop.hdfs.web.JsonUtil;
import org.apache.hadoop.hdfs.web.ParamFilter;
import org.apache.hadoop.hdfs.web.WebHdfsFileSystem;
import org.apache.hadoop.hdfs.web.resources.AccessTimeParam;
import org.apache.hadoop.hdfs.web.resources.AclPermissionParam;
import org.apache.hadoop.hdfs.web.resources.BlockSizeParam;
import org.apache.hadoop.hdfs.web.resources.BufferSizeParam;
import org.apache.hadoop.hdfs.web.resources.ConcatSourcesParam;
import org.apache.hadoop.hdfs.web.resources.CreateFlagParam;
import org.apache.hadoop.hdfs.web.resources.CreateParentParam;
import org.apache.hadoop.hdfs.web.resources.DelegationParam;
import org.apache.hadoop.hdfs.web.resources.DestinationParam;
import org.apache.hadoop.hdfs.web.resources.DoAsParam;
import org.apache.hadoop.hdfs.web.resources.ECPolicyParam;
import org.apache.hadoop.hdfs.web.resources.ExcludeDatanodesParam;
import org.apache.hadoop.hdfs.web.resources.FsActionParam;
import org.apache.hadoop.hdfs.web.resources.GetOpParam;
import org.apache.hadoop.hdfs.web.resources.GroupParam;
import org.apache.hadoop.hdfs.web.resources.HttpOpParam;
import org.apache.hadoop.hdfs.web.resources.LengthParam;
import org.apache.hadoop.hdfs.web.resources.ModificationTimeParam;
import org.apache.hadoop.hdfs.web.resources.NameSpaceQuotaParam;
import org.apache.hadoop.hdfs.web.resources.NewLengthParam;
import org.apache.hadoop.hdfs.web.resources.NoRedirectParam;
import org.apache.hadoop.hdfs.web.resources.OffsetParam;
import org.apache.hadoop.hdfs.web.resources.OldSnapshotNameParam;
import org.apache.hadoop.hdfs.web.resources.OverwriteParam;
import org.apache.hadoop.hdfs.web.resources.OwnerParam;
import org.apache.hadoop.hdfs.web.resources.Param;
import org.apache.hadoop.hdfs.web.resources.PermissionParam;
import org.apache.hadoop.hdfs.web.resources.PostOpParam;
import org.apache.hadoop.hdfs.web.resources.PutOpParam;
import org.apache.hadoop.hdfs.web.resources.RenameOptionSetParam;
import org.apache.hadoop.hdfs.web.resources.RenewerParam;
import org.apache.hadoop.hdfs.web.resources.ReplicationParam;
import org.apache.hadoop.hdfs.web.resources.SnapshotNameParam;
import org.apache.hadoop.hdfs.web.resources.StartAfterParam;
import org.apache.hadoop.hdfs.web.resources.StoragePolicyParam;
import org.apache.hadoop.hdfs.web.resources.StorageSpaceQuotaParam;
import org.apache.hadoop.hdfs.web.resources.StorageTypeParam;
import org.apache.hadoop.hdfs.web.resources.TokenArgumentParam;
import org.apache.hadoop.hdfs.web.resources.TokenKindParam;
import org.apache.hadoop.hdfs.web.resources.TokenServiceParam;
import org.apache.hadoop.hdfs.web.resources.UnmaskedPermissionParam;
import org.apache.hadoop.hdfs.web.resources.UriFsPathParam;
import org.apache.hadoop.hdfs.web.resources.UserParam;
import org.apache.hadoop.hdfs.web.resources.XAttrEncodingParam;
import org.apache.hadoop.hdfs.web.resources.XAttrNameParam;
import org.apache.hadoop.hdfs.web.resources.XAttrSetFlagParam;
import org.apache.hadoop.hdfs.web.resources.XAttrValueParam;
import org.apache.hadoop.ipc.ExternalCall;
import org.apache.hadoop.ipc.RetriableException;
import org.apache.hadoop.net.Node;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.security.token.TokenIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Random;

/**
 * WebHDFS Router implementation. This is an extension of
 * {@link NamenodeWebHdfsMethods}, and tries to reuse as much as possible.
 */
@Path("")
@ResourceFilters(ParamFilter.class)
public class RouterWebHdfsMethods extends NamenodeWebHdfsMethods {
  private static final Logger LOG =
      LoggerFactory.getLogger(RouterWebHdfsMethods.class);

  private @Context HttpServletRequest request;
  private String method;
  private String query;
  private String reqPath;
  private String remoteAddr;

  public RouterWebHdfsMethods(@Context HttpServletRequest request) {
    super(request);
    this.method = request.getMethod();
    this.query = request.getQueryString();
    this.reqPath = request.getServletPath();
    this.remoteAddr = JspHelper.getRemoteAddr(request);
  }

  @Override
  protected void init(final UserGroupInformation ugi,
                      final DelegationParam delegation,
                      final UserParam username, final DoAsParam doAsUser,
                      final UriFsPathParam path, final HttpOpParam<?> op,
                      final Param<?, ?>... parameters) {
    super.init(ugi, delegation, username, doAsUser, path, op, parameters);

    remoteAddr = JspHelper.getRemoteAddr(request);
  }

  @Override
  protected ClientProtocol getRpcClientProtocol() throws IOException {
    final Router router = getRouter();
    final RouterRpcServer routerRpcServer = router.getRpcServer();
    if (routerRpcServer == null) {
      throw new RetriableException("Router is in startup mode");
    }
    return routerRpcServer;
  }

  private void reset() {
    remoteAddr = null;
  }

  @Override
  protected String getRemoteAddr() {
    return remoteAddr;
  }

  @Override
  protected void queueExternalCall(ExternalCall call)
      throws IOException, InterruptedException {
    getRouter().getRpcServer().getServer().queueCall(call);
  }

  private Router getRouter() {
    return (Router)getContext().getAttribute("name.node");
  }

  private static RouterRpcServer getRPCServer(final Router router)
      throws IOException {
    final RouterRpcServer routerRpcServer = router.getRpcServer();
    if (routerRpcServer == null) {
      throw new RetriableException("Router is in startup mode");
    }
    return routerRpcServer;
  }

  @Override
  protected Response put(
      final UserGroupInformation ugi,
      final DelegationParam delegation,
      final UserParam username,
      final DoAsParam doAsUser,
      final String fullpath,
      final PutOpParam op,
      final DestinationParam destination,
      final OwnerParam owner,
      final GroupParam group,
      final PermissionParam permission,
      final UnmaskedPermissionParam unmaskedPermission,
      final OverwriteParam overwrite,
      final BufferSizeParam bufferSize,
      final ReplicationParam replication,
      final BlockSizeParam blockSize,
      final ModificationTimeParam modificationTime,
      final AccessTimeParam accessTime,
      final RenameOptionSetParam renameOptions,
      final CreateParentParam createParent,
      final TokenArgumentParam delegationTokenArgument,
      final AclPermissionParam aclPermission,
      final XAttrNameParam xattrName,
      final XAttrValueParam xattrValue,
      final XAttrSetFlagParam xattrSetFlag,
      final SnapshotNameParam snapshotName,
      final OldSnapshotNameParam oldSnapshotName,
      final ExcludeDatanodesParam exclDatanodes,
      final CreateFlagParam createFlagParam,
      final NoRedirectParam noredirectParam,
      final StoragePolicyParam policyName,
      final ECPolicyParam ecpolicy,
      final NameSpaceQuotaParam namespaceQuota,
      final StorageSpaceQuotaParam storagespaceQuota,
      final StorageTypeParam storageType
  ) throws IOException, URISyntaxException {

    switch(op.getValue()) {
    case CREATE:
    {
      final Router router = getRouter();
      final URI uri = redirectURI(router, ugi, delegation, username,
          doAsUser, fullpath, op.getValue(), -1L,
          exclDatanodes.getValue(), permission, unmaskedPermission,
          overwrite, bufferSize, replication, blockSize, createParent,
          createFlagParam);
      if (!noredirectParam.getValue()) {
        return Response.temporaryRedirect(uri)
            .type(MediaType.APPLICATION_OCTET_STREAM).build();
      } else {
        final String js = JsonUtil.toJsonString("Location", uri);
        return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
      }
    }
    case MKDIRS:
    case CREATESYMLINK:
    case RENAME:
    case SETREPLICATION:
    case SETOWNER:
    case SETPERMISSION:
    case SETTIMES:
    case RENEWDELEGATIONTOKEN:
    case CANCELDELEGATIONTOKEN:
    case MODIFYACLENTRIES:
    case REMOVEACLENTRIES:
    case REMOVEDEFAULTACL:
    case REMOVEACL:
    case SETACL:
    case SETXATTR:
    case REMOVEXATTR:
    case ALLOWSNAPSHOT:
    case CREATESNAPSHOT:
    case RENAMESNAPSHOT:
    case DISALLOWSNAPSHOT:
    case SETSTORAGEPOLICY:
    case ENABLEECPOLICY:
    case DISABLEECPOLICY:
    case SATISFYSTORAGEPOLICY:
    {
      // Whitelist operations that can handled by NamenodeWebHdfsMethods
      return super.put(ugi, delegation, username, doAsUser, fullpath, op,
          destination, owner, group, permission, unmaskedPermission,
          overwrite, bufferSize, replication, blockSize, modificationTime,
          accessTime, renameOptions, createParent, delegationTokenArgument,
          aclPermission, xattrName, xattrValue, xattrSetFlag, snapshotName,
          oldSnapshotName, exclDatanodes, createFlagParam, noredirectParam,
          policyName, ecpolicy, namespaceQuota, storagespaceQuota, storageType);
    }
    default:
      throw new UnsupportedOperationException(op + " is not supported");
    }
  }

  @Override
  protected Response post(
      final UserGroupInformation ugi,
      final DelegationParam delegation,
      final UserParam username,
      final DoAsParam doAsUser,
      final String fullpath,
      final PostOpParam op,
      final ConcatSourcesParam concatSrcs,
      final BufferSizeParam bufferSize,
      final ExcludeDatanodesParam excludeDatanodes,
      final NewLengthParam newLength,
      final NoRedirectParam noRedirectParam
  ) throws IOException, URISyntaxException {
    switch(op.getValue()) {
    case APPEND:
    {
      final Router router = getRouter();
      final URI uri = redirectURI(router, ugi, delegation, username,
          doAsUser, fullpath, op.getValue(), -1L,
          excludeDatanodes.getValue(), bufferSize);
      if (!noRedirectParam.getValue()) {
        return Response.temporaryRedirect(uri)
            .type(MediaType.APPLICATION_OCTET_STREAM).build();
      } else {
        final String js = JsonUtil.toJsonString("Location", uri);
        return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
      }
    }
    case CONCAT:
    case TRUNCATE:
    case UNSETSTORAGEPOLICY:
    {
      return super.post(ugi, delegation, username, doAsUser, fullpath, op,
          concatSrcs, bufferSize, excludeDatanodes, newLength,
          noRedirectParam);
    }
    default:
      throw new UnsupportedOperationException(op + " is not supported");
    }
  }

  @Override
  protected Response get(
      final UserGroupInformation ugi,
      final DelegationParam delegation,
      final UserParam username,
      final DoAsParam doAsUser,
      final String fullpath,
      final GetOpParam op,
      final OffsetParam offset,
      final LengthParam length,
      final RenewerParam renewer,
      final BufferSizeParam bufferSize,
      final List<XAttrNameParam> xattrNames,
      final XAttrEncodingParam xattrEncoding,
      final ExcludeDatanodesParam excludeDatanodes,
      final FsActionParam fsAction,
      final SnapshotNameParam snapshotName,
      final OldSnapshotNameParam oldSnapshotName,
      final TokenKindParam tokenKind,
      final TokenServiceParam tokenService,
      final NoRedirectParam noredirectParam,
      final StartAfterParam startAfter
  ) throws IOException, URISyntaxException {
    try {
      final Router router = getRouter();

      switch (op.getValue()) {
      case OPEN:
      {
        final URI uri = redirectURI(router, ugi, delegation, username,
            doAsUser, fullpath, op.getValue(), offset.getValue(),
            excludeDatanodes.getValue(), offset, length, bufferSize);
        if (!noredirectParam.getValue()) {
          return Response.temporaryRedirect(uri)
              .type(MediaType.APPLICATION_OCTET_STREAM).build();
        } else {
          final String js = JsonUtil.toJsonString("Location", uri);
          return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
        }
      }
      case GETFILECHECKSUM:
      {
        final URI uri = redirectURI(router, ugi, delegation, username,
            doAsUser, fullpath, op.getValue(), -1L, null);
        if (!noredirectParam.getValue()) {
          return Response.temporaryRedirect(uri)
              .type(MediaType.APPLICATION_OCTET_STREAM).build();
        } else {
          final String js = JsonUtil.toJsonString("Location", uri);
          return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
        }
      }
      case GETDELEGATIONTOKEN:
      case GET_BLOCK_LOCATIONS:
      case GETFILESTATUS:
      case LISTSTATUS:
      case GETCONTENTSUMMARY:
      case GETHOMEDIRECTORY:
      case GETACLSTATUS:
      case GETXATTRS:
      case LISTXATTRS:
      case CHECKACCESS:
      {
        return super.get(ugi, delegation, username, doAsUser, fullpath, op,
            offset, length, renewer, bufferSize, xattrNames, xattrEncoding,
            excludeDatanodes, fsAction, snapshotName, oldSnapshotName,
            tokenKind, tokenService, noredirectParam, startAfter);
      }
      default:
        throw new UnsupportedOperationException(op + " is not supported");
      }
    } finally {
      reset();
    }
  }

  /**
   * Get a URI to redirect an operation to.
   * @param router Router to check.
   * @param ugi User group information.
   * @param delegation Delegation token.
   * @param username User name.
   * @param doAsUser Do as user.
   * @param path Path to check.
   * @param op Operation to perform.
   * @param openOffset Offset for opening a file.
   * @param excludeDatanodes Blocks to excluded.
   * @param parameters Other parameters.
   * @return Redirection URI.
   * @throws URISyntaxException If it cannot parse the URI.
   * @throws IOException If it cannot create the URI.
   */
  private URI redirectURI(final Router router, final UserGroupInformation ugi,
      final DelegationParam delegation, final UserParam username,
      final DoAsParam doAsUser, final String path, final HttpOpParam.Op op,
      final long openOffset, final String excludeDatanodes,
      final Param<?, ?>... parameters) throws URISyntaxException, IOException {
    final DatanodeInfo dn =
        chooseDatanode(router, path, op, openOffset, excludeDatanodes);

    if (dn == null) {
      throw new IOException("Failed to find datanode, suggest to check cluster"
          + " health. excludeDatanodes=" + excludeDatanodes);
    }

    final String delegationQuery;
    if (!UserGroupInformation.isSecurityEnabled()) {
      // security disabled
      delegationQuery = Param.toSortedString("&", doAsUser, username);
    } else if (delegation.getValue() != null) {
      // client has provided a token
      delegationQuery = "&" + delegation;
    } else {
      // generate a token
      final Token<? extends TokenIdentifier> t = generateDelegationToken(
          ugi, ugi.getUserName());
      delegationQuery = "&delegation=" + t.encodeToUrlString();
    }

    final String redirectQuery = op.toQueryString() + delegationQuery
        + "&namenoderpcaddress=" + router.getRouterId()
        + Param.toSortedString("&", parameters);
    final String uripath = WebHdfsFileSystem.PATH_PREFIX + path;

    int port = "http".equals(getScheme()) ? dn.getInfoPort() :
        dn.getInfoSecurePort();
    final URI uri = new URI(getScheme(), null, dn.getHostName(), port, uripath,
        redirectQuery, null);

    if (LOG.isTraceEnabled()) {
      LOG.trace("redirectURI={}", uri);
    }
    return uri;
  }

  private DatanodeInfo chooseDatanode(final Router router,
      final String path, final HttpOpParam.Op op, final long openOffset,
      final String excludeDatanodes) throws IOException {
    final RouterRpcServer rpcServer = getRPCServer(router);
    DatanodeInfo[] dns = null;
    try {
      dns = rpcServer.getCachedDatanodeReport(DatanodeReportType.LIVE);
    } catch (IOException e) {
      LOG.error("Cannot get the datanodes from the RPC server", e);
    }

    HashSet<Node> excludes = new HashSet<Node>();
    if (excludeDatanodes != null) {
      Collection<String> collection =
          getTrimmedStringCollection(excludeDatanodes);
      for (DatanodeInfo dn : dns) {
        if (collection.contains(dn.getName())) {
          excludes.add(dn);
        }
      }
    }

    if (op == GetOpParam.Op.OPEN ||
        op == PostOpParam.Op.APPEND ||
        op == GetOpParam.Op.GETFILECHECKSUM) {
      // Choose a datanode containing a replica
      final ClientProtocol cp = getRpcClientProtocol();
      final HdfsFileStatus status = cp.getFileInfo(path);
      if (status == null) {
        throw new FileNotFoundException("File " + path + " not found.");
      }
      final long len = status.getLen();
      if (op == GetOpParam.Op.OPEN) {
        if (openOffset < 0L || (openOffset >= len && len > 0)) {
          throw new IOException("Offset=" + openOffset
              + " out of the range [0, " + len + "); " + op + ", path=" + path);
        }
      }

      if (len > 0) {
        final long offset = op == GetOpParam.Op.OPEN ? openOffset : len - 1;
        final LocatedBlocks locations = cp.getBlockLocations(path, offset, 1);
        final int count = locations.locatedBlockCount();
        if (count > 0) {
          LocatedBlock location0 = locations.get(0);
          return bestNode(location0.getLocations(), excludes);
        }
      }
    }

    return getRandomDatanode(dns, excludes);
  }

  /**
   * Get a random Datanode from a subcluster.
   * @param dns Nodes to be chosen from.
   * @param excludes Nodes to be excluded from.
   * @return Random datanode from a particular subluster.
   */
  private static DatanodeInfo getRandomDatanode(
      final DatanodeInfo[] dns, final HashSet<Node> excludes) {
    DatanodeInfo dn = null;

    if (dns == null) {
      return dn;
    }

    int numDNs = dns.length;
    int availableNodes = 0;
    if (excludes.isEmpty()) {
      availableNodes = numDNs;
    } else {
      for (DatanodeInfo di : dns) {
        if (!excludes.contains(di)) {
          availableNodes++;
        }
      }
    }

    // Return a random one from the list
    if (availableNodes > 0) {
      while (dn == null || excludes.contains(dn)) {
        Random rnd = new Random();
        int idx = rnd.nextInt(numDNs);
        dn = dns[idx];
      }
    }
    return dn;
  }

  /**
   * Generate the credentials for this request.
   * @param ugi User group information.
   * @param renewer Who is asking for the renewal.
   * @return Credentials holding delegation token.
   * @throws IOException If it cannot create the credentials.
   */
  @Override
  public Credentials createCredentials(
      final UserGroupInformation ugi,
      final String renewer) throws IOException {
    final Router router = (Router)getContext().getAttribute("name.node");
    final Credentials c = RouterSecurityManager.createCredentials(router, ugi,
        renewer != null? renewer: ugi.getShortUserName());
    return c;
  }
}