#pragma once

#include <string>

#include "envoy/http/header_map.h"

#include "source/common/singleton/const_singleton.h"

#include "source/common/singleton/threadsafe_singleton.h"

namespace Envoy {

namespace Http {

// This class allows early override of the x-envoy prefix from bootstrap config,

// so that servers can configure their own x-custom-string prefix.

//

// Once the HeaderValues const singleton has been created, changing the prefix

// is disallowed. Essentially this is write-once then read-only.

class PrefixValue {

public:

  // The char* prefix is used directly, so must be available for the interval where prefix() may be

  // called.

private:

  absl::Mutex m_;

  bool read_ = false;

  std::string prefix_ = "x-envoy";

};

/**

 * These are headers that are used in extension custom O(1) header registration. These headers

 * *must* not contain any prefix override headers, as static init order requires that HeaderValues

 * be instantiated for the first time after bootstrap is loaded and before the header maps are

 * finalized.

 */

class CustomHeaderValues {

public:

  const LowerCaseString Accept{"accept"};

  const LowerCaseString AcceptEncoding{"accept-encoding"};

  const LowerCaseString AccessControlRequestHeaders{"access-control-request-headers"};

  const LowerCaseString AccessControlRequestMethod{"access-control-request-method"};

  const LowerCaseString AccessControlAllowOrigin{"access-control-allow-origin"};

  const LowerCaseString AccessControlAllowHeaders{"access-control-allow-headers"};

  const LowerCaseString AccessControlAllowMethods{"access-control-allow-methods"};

  const LowerCaseString AccessControlExposeHeaders{"access-control-expose-headers"};

  const LowerCaseString AccessControlMaxAge{"access-control-max-age"};

  const LowerCaseString AccessControlAllowCredentials{"access-control-allow-credentials"};

  const LowerCaseString AccessControlRequestPrviateNetwork{

      "access-control-request-private-network"};

  const LowerCaseString AccessControlAllowPrviateNetwork{"access-control-allow-private-network"};

  const LowerCaseString Age{"age"};

  const LowerCaseString AltSvc{"alt-svc"};

  const LowerCaseString Authentication{"authentication"};

  const LowerCaseString Authorization{"authorization"};

  const LowerCaseString CacheControl{"cache-control"};

  const LowerCaseString CacheStatus{"cache-status"};

  const LowerCaseString CdnLoop{"cdn-loop"};

  const LowerCaseString ContentEncoding{"content-encoding"};

  const LowerCaseString ConnectAcceptEncoding{"connect-accept-encoding"};

  const LowerCaseString ConnectContentEncoding{"connect-content-encoding"};

  const LowerCaseString ConnectProtocolVersion{"connect-protocol-version"};

  const LowerCaseString ConnectTimeoutMs{"connect-timeout-ms"};

  const LowerCaseString Etag{"etag"};

  const LowerCaseString Expires{"expires"};

  const LowerCaseString GrpcAcceptEncoding{"grpc-accept-encoding"};

  const LowerCaseString GrpcEncoding{"grpc-encoding"};

  const LowerCaseString GrpcMessageType{"grpc-message-type"};

  const LowerCaseString GrpcTimeout{"grpc-timeout"};

  const LowerCaseString IfMatch{"if-match"};

  const LowerCaseString IfNoneMatch{"if-none-match"};

  const LowerCaseString IfModifiedSince{"if-modified-since"};

  const LowerCaseString IfUnmodifiedSince{"if-unmodified-since"};

  const LowerCaseString IfRange{"if-range"};

  const LowerCaseString LastModified{"last-modified"};

  const LowerCaseString Origin{"origin"};

  const LowerCaseString OtSpanContext{"x-ot-span-context"};

  const LowerCaseString Pragma{"pragma"};

  const LowerCaseString Referer{"referer"};

  const LowerCaseString Vary{"vary"};

  struct {

    const std::string Gzip{"gzip"};

    const std::string Identity{"identity"};

    const std::string Wildcard{"*"};

  } AcceptEncodingValues;

  struct {

    const std::string All{"*"};

  } AccessControlAllowOriginValue;

  struct {

    const std::string NoCache{"no-cache"};

    const std::string NoCacheMaxAge0{"no-cache, max-age=0"};

    const std::string NoTransform{"no-transform"};

    const std::string Private{"private"};

  } CacheControlValues;

  struct {

    const std::string Brotli{"br"};

    const std::string Gzip{"gzip"};

    const std::string Zstd{"zstd"};

  } ContentEncodingValues;

  struct {

    const std::string True{"true"};

  } CORSValues;

  struct {

    const std::string Default{"identity"};

  } GrpcAcceptEncodingValues;

  struct {

    const std::string AcceptEncoding{"Accept-Encoding"};

    const std::string Wildcard{"*"};

  } VaryValues;

};

using CustomHeaders = ConstSingleton<CustomHeaderValues>;

/**

 * Constant HTTP headers and values. All lower case. This group of headers can contain prefix

 * override headers.

 */

class HeaderValues {

public:

  const LowerCaseString ProxyAuthenticate{"proxy-authenticate"};

  const LowerCaseString ProxyAuthorization{"proxy-authorization"};

  const LowerCaseString CapsuleProtocol{"capsule-protocol"};

  const LowerCaseString ClientTraceId{"x-client-trace-id"};

  const LowerCaseString Connection{"connection"};

  const LowerCaseString ContentLength{"content-length"};

  const LowerCaseString ContentRange{"content-range"};

  const LowerCaseString ContentType{"content-type"};

  const LowerCaseString Cookie{"cookie"};

  const LowerCaseString Date{"date"};

  const LowerCaseString EnvoyAttemptCount{absl::StrCat(prefix(), "-attempt-count")};

  const LowerCaseString EnvoyCluster{absl::StrCat(prefix(), "-cluster")};

  const LowerCaseString EnvoyDegraded{absl::StrCat(prefix(), "-degraded")};

  const LowerCaseString EnvoyDownstreamServiceCluster{

      absl::StrCat(prefix(), "-downstream-service-cluster")};

  const LowerCaseString EnvoyDownstreamServiceNode{

      absl::StrCat(prefix(), "-downstream-service-node")};

  const LowerCaseString EnvoyExternalAddress{absl::StrCat(prefix(), "-external-address")};

  const LowerCaseString EnvoyForceTrace{absl::StrCat(prefix(), "-force-trace")};

  const LowerCaseString EnvoyHedgeOnPerTryTimeout{

      absl::StrCat(prefix(), "-hedge-on-per-try-timeout")};

  const LowerCaseString EnvoyImmediateHealthCheckFail{

      absl::StrCat(prefix(), "-immediate-health-check-fail")};

  const LowerCaseString EnvoyIsTimeoutRetry{absl::StrCat(prefix(), "-is-timeout-retry")};

  const LowerCaseString EnvoyOriginalUrl{absl::StrCat(prefix(), "-original-url")};

  const LowerCaseString EnvoyInternalRequest{absl::StrCat(prefix(), "-internal")};

  // TODO(mattklein123): EnvoyIpTags should be a custom header registered with the IP tagging

  // filter. We need to figure out if we can remove this header from the set of headers that

  // participate in prefix overrides.

  const LowerCaseString EnvoyIpTags{absl::StrCat(prefix(), "-ip-tags")};

  const LowerCaseString EnvoyLocalOverloaded{absl::StrCat(prefix(), "-local-overloaded")};

  const LowerCaseString EnvoyMaxRetries{absl::StrCat(prefix(), "-max-retries")};

  const LowerCaseString EnvoyNotForwarded{absl::StrCat(prefix(), "-not-forwarded")};

  const LowerCaseString EnvoyOriginalDstHost{absl::StrCat(prefix(), "-original-dst-host")};

  const LowerCaseString EnvoyOriginalMethod{absl::StrCat(prefix(), "-original-method")};

  const LowerCaseString EnvoyOriginalPath{absl::StrCat(prefix(), "-original-path")};

  const LowerCaseString EnvoyOriginalHost{absl::StrCat(prefix(), "-original-host")};

  const LowerCaseString EnvoyOverloaded{absl::StrCat(prefix(), "-overloaded")};

  const LowerCaseString EnvoyDropOverload{absl::StrCat(prefix(), "-drop-overload")};

  const LowerCaseString EnvoyUnconditionalDropOverload{

      absl::StrCat(prefix(), "-unconditional-drop-overload")};

  const LowerCaseString EnvoyRateLimited{absl::StrCat(prefix(), "-ratelimited")};

  const LowerCaseString EnvoyRetryOn{absl::StrCat(prefix(), "-retry-on")};

  const LowerCaseString EnvoyRetryGrpcOn{absl::StrCat(prefix(), "-retry-grpc-on")};

  const LowerCaseString EnvoyRetriableStatusCodes{

      absl::StrCat(prefix(), "-retriable-status-codes")};

  const LowerCaseString EnvoyRetriableHeaderNames{

      absl::StrCat(prefix(), "-retriable-header-names")};

  const LowerCaseString EnvoyUpstreamAltStatName{absl::StrCat(prefix(), "-upstream-alt-stat-name")};

  const LowerCaseString EnvoyUpstreamCanary{absl::StrCat(prefix(), "-upstream-canary")};

  const LowerCaseString EnvoyUpstreamHostAddress{absl::StrCat(prefix(), "-upstream-host-address")};

  const LowerCaseString EnvoyUpstreamHostname{absl::StrCat(prefix(), "-upstream-hostname")};

  const LowerCaseString EnvoyUpstreamRequestTimeoutAltResponse{

      absl::StrCat(prefix(), "-upstream-rq-timeout-alt-response")};

  const LowerCaseString EnvoyUpstreamRequestTimeoutMs{

      absl::StrCat(prefix(), "-upstream-rq-timeout-ms")};

  const LowerCaseString EnvoyUpstreamRequestPerTryTimeoutMs{

      absl::StrCat(prefix(), "-upstream-rq-per-try-timeout-ms")};

  const LowerCaseString EnvoyExpectedRequestTimeoutMs{

      absl::StrCat(prefix(), "-expected-rq-timeout-ms")};

  const LowerCaseString EnvoyUpstreamServiceTime{absl::StrCat(prefix(), "-upstream-service-time")};

  const LowerCaseString EnvoyUpstreamHealthCheckedCluster{

      absl::StrCat(prefix(), "-upstream-healthchecked-cluster")};

  const LowerCaseString EnvoyUpstreamStreamDurationMs{

      absl::StrCat(prefix(), "-upstream-stream-duration-ms")};

  const LowerCaseString EnvoyDecoratorOperation{absl::StrCat(prefix(), "-decorator-operation")};

  const LowerCaseString EnvoyCompressionStatus{absl::StrCat(prefix(), "-compression-status")};

  const LowerCaseString Expect{"expect"};

  const LowerCaseString ForwardedClientCert{"x-forwarded-client-cert"};

  const LowerCaseString ForwardedFor{"x-forwarded-for"};

  const LowerCaseString ForwardedHost{"x-forwarded-host"};

  const LowerCaseString ForwardedPort{"x-forwarded-port"};

  const LowerCaseString ForwardedProto{"x-forwarded-proto"};

  const LowerCaseString GrpcMessage{"grpc-message"};

  const LowerCaseString GrpcStatus{"grpc-status"};

  const LowerCaseString GrpcTimeout{"grpc-timeout"};

  const LowerCaseString GrpcStatusDetailsBin{"grpc-status-details-bin"};

  const LowerCaseString Host{":authority"};

  const LowerCaseString HostLegacy{"host"};

  const LowerCaseString Http2Settings{"http2-settings"};

  const LowerCaseString KeepAlive{"keep-alive"};

  const LowerCaseString Location{"location"};

  const LowerCaseString Method{":method"};

  const LowerCaseString Path{":path"};

  const LowerCaseString Protocol{":protocol"};

  const LowerCaseString ProxyConnection{"proxy-connection"};

  const LowerCaseString ProxyStatus{"proxy-status"};

  const LowerCaseString Range{"range"};

  const LowerCaseString RequestId{"x-request-id"};

  const LowerCaseString Scheme{":scheme"};

  const LowerCaseString Server{"server"};

  const LowerCaseString SetCookie{"set-cookie"};

  const LowerCaseString Status{":status"};

  const LowerCaseString TransferEncoding{"transfer-encoding"};

  const LowerCaseString TE{"te"};

  const LowerCaseString Upgrade{"upgrade"};

  const LowerCaseString UserAgent{"user-agent"};

  const LowerCaseString Via{"via"};

  const LowerCaseString WWWAuthenticate{"www-authenticate"};

  const LowerCaseString XContentTypeOptions{"x-content-type-options"};

  const LowerCaseString EarlyData{"early-data"};

  struct {

    const std::string Close{"close"};

    const std::string Http2Settings{"http2-settings"};

    const std::string KeepAlive{"keep-alive"};

    const std::string Upgrade{"upgrade"};

  } ConnectionValues;

  struct {

    const std::string H2c{"h2c"};

    const std::string WebSocket{"websocket"};

    const std::string ConnectUdp{"connect-udp"};

  } UpgradeValues;

  struct {

    const std::string Text{"text/plain"};

    const std::string TextEventStream{"text/event-stream"};

    const std::string TextUtf8{"text/plain; charset=UTF-8"}; // TODO(jmarantz): fold this into Text

    const std::string Html{"text/html; charset=UTF-8"};

    const std::string Connect{"application/connect"};

    const std::string ConnectProto{"application/connect+proto"};

    const std::string Grpc{"application/grpc"};

    const std::string GrpcWeb{"application/grpc-web"};

    const std::string GrpcWebProto{"application/grpc-web+proto"};

    const std::string GrpcWebText{"application/grpc-web-text"};

    const std::string GrpcWebTextProto{"application/grpc-web-text+proto"};

    const std::string Json{"application/json"};

    const std::string Protobuf{"application/x-protobuf"};

    const std::string FormUrlEncoded{"application/x-www-form-urlencoded"};

    const std::string Thrift{"application/x-thrift"};

  } ContentTypeValues;

  struct {

    const std::string True{"true"};

  } EnvoyImmediateHealthCheckFailValues;

  struct {

    const std::string True{"true"};

  } EnvoyInternalRequestValues;

  struct {

    const std::string True{"true"};

  } EnvoyOverloadedValues;

  struct {

    const std::string True{"true"};

  } EnvoyDropOverloadValues;

  struct {

    const std::string True{"true"};

  } EnvoyUnconditionalDropOverloadValues;

  struct {

    const std::string True{"true"};

  } EnvoyRateLimitedValues;

  struct {

    const std::string _5xx{"5xx"};

    const std::string GatewayError{"gateway-error"};

    const std::string ConnectFailure{"connect-failure"};

    const std::string EnvoyRateLimited{"envoy-ratelimited"};

    const std::string RefusedStream{"refused-stream"};

    const std::string Retriable4xx{"retriable-4xx"};

    const std::string RetriableStatusCodes{"retriable-status-codes"};

    const std::string RetriableHeaders{"retriable-headers"};

    const std::string Reset{"reset"};

    const std::string ResetBeforeRequest{"reset-before-request"};

    const std::string Http3PostConnectFailure{"http3-post-connect-failure"};

  } EnvoyRetryOnValues;

  struct {

    const std::string Cancelled{"cancelled"};

    const std::string DeadlineExceeded{"deadline-exceeded"};

    const std::string ResourceExhausted{"resource-exhausted"};

    const std::string Unavailable{"unavailable"};

    const std::string Internal{"internal"};

  } EnvoyRetryOnGrpcValues;

  struct {

    const std::string _100Continue{"100-continue"};

  } ExpectValues;

  struct {

    const std::string Connect{"CONNECT"};

    const std::string Delete{"DELETE"};

    const std::string Get{"GET"};

    const std::string Head{"HEAD"};

    const std::string Options{"OPTIONS"};

    const std::string Patch{"PATCH"};

    const std::string Post{"POST"};

    const std::string Put{"PUT"};

    const std::string Trace{"TRACE"};

  } MethodValues;

  struct {

    // per https://tools.ietf.org/html/draft-kinnear-httpbis-http2-transport-02

    const std::string Bytestream{"bytestream"};

  } ProtocolValues;

  struct {

    const std::string Http{"http"};

    const std::string Https{"https"};

  } SchemeValues;

  struct {

    const std::string Brotli{"br"};

    const std::string Compress{"compress"};

    const std::string Chunked{"chunked"};

    const std::string Deflate{"deflate"};

    const std::string Gzip{"gzip"};

    const std::string Identity{"identity"};

    const std::string Zstd{"zstd"};

  } TransferEncodingValues;

  struct {

    const std::string EnvoyHealthChecker{"Envoy/HC"};

    const std::string GoBrowser{"Go-browser"};

  } UserAgentValues;

  struct {

    const std::string Trailers{"trailers"};

  } TEValues;

  struct {

    const std::string Nosniff{"nosniff"};

  } XContentTypeOptionValues;

  struct {

    const std::string Http10String{"HTTP/1.0"};

    const std::string Http11String{"HTTP/1.1"};

    const std::string Http2String{"HTTP/2"};

    const std::string Http3String{"HTTP/3"};

  } ProtocolStrings;

  struct {

    const std::string ContentLengthTooSmall{"ContentLengthTooSmall"};

    const std::string ContentTypeNotAllowed{"ContentTypeNotAllowed"};

    const std::string EtagNotAllowed{"EtagNotAllowed"};

    const std::string StatusCodeNotAllowed{"StatusCodeNotAllowed"};

    const std::string Compressed{"Compressed"};

    const std::string OriginalLengthPrefix{"OriginalLength="};

    const std::string Separator{";"};

    const std::string ValueSeparator{","};

  } EnvoyCompressionStatusValues;

};

using Headers = ConstSingleton<HeaderValues>;

} // namespace Http

} // namespace Envoy