//
//
// Copyright 2018 gRPC authors.
//
// 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.
//
//

#ifndef GRPC_SRC_CPP_EXT_FILTERS_CENSUS_CONTEXT_H
#define GRPC_SRC_CPP_EXT_FILTERS_CENSUS_CONTEXT_H

#include <grpc/grpc.h>
#include <grpc/slice.h>
#include <grpc/status.h>
#include <grpc/support/port_platform.h>
#include <grpcpp/opencensus.h>
#include <stddef.h>
#include <stdint.h>

#include "absl/strings/string_view.h"
#include "absl/strings/strip.h"
#include "opencensus/trace/span.h"
#include "opencensus/trace/span_context.h"
#include "src/core/lib/channel/channel_stack.h"
#include "src/core/lib/slice/slice.h"

namespace grpc {

using experimental::CensusContext;

// Serializes the outgoing trace context. tracing_buf must be
// opencensus::trace::propagation::kGrpcTraceBinHeaderLen bytes long.
size_t TraceContextSerialize(const ::opencensus::trace::SpanContext& context,
                             char* tracing_buf, size_t tracing_buf_size);

// Serializes the outgoing stats context.  Field IDs are 1 byte followed by
// field data. A 1 byte version ID is always encoded first. Tags are directly
// serialized into the given grpc_slice.
size_t StatsContextSerialize(size_t max_tags_len, grpc_slice* tags);

// Serialize outgoing server stats. Returns the number of bytes serialized.
size_t ServerStatsSerialize(uint64_t server_elapsed_time, char* buf,
                            size_t buf_size);

// Deserialize incoming server stats. Returns the number of bytes deserialized.
size_t ServerStatsDeserialize(const char* buf, size_t buf_size,
                              uint64_t* server_elapsed_time);

// Deserialize the incoming SpanContext and generate a new server context based
// on that. This new span will never be a root span. This should only be called
// with a blank CensusContext as it overwrites it.
void GenerateServerContext(absl::string_view tracing, absl::string_view method,
                           CensusContext* context);

// Creates a new client context that is by default a new root context.
// If the current context is the default context then the newly created
// span automatically becomes a root span. This should only be called with a
// blank CensusContext as it overwrites it.
void GenerateClientContext(absl::string_view method, CensusContext* ctxt,
                           CensusContext* parent_ctx);

// Returns the incoming data size from the grpc call final info.
uint64_t GetIncomingDataSize(const grpc_call_final_info* final_info);

// Returns the outgoing data size from the grpc call final info.
uint64_t GetOutgoingDataSize(const grpc_call_final_info* final_info);

// These helper functions return the SpanContext and Span, respectively
// associated with the census_context* stored by grpc. The user will need to
// call this for manual propagation of tracing data.
::opencensus::trace::SpanContext SpanContextFromCensusContext(
    const census_context* ctxt);
::opencensus::trace::Span SpanFromCensusContext(const census_context* ctxt);

// Returns a string representation of the StatusCode enum.
absl::string_view StatusCodeToString(grpc_status_code code);

inline absl::string_view GetMethod(const grpc_core::Slice& path) {
  if (path.empty()) {
    return "";
  }
  // Check for leading '/' and trim it if present.
  return absl::StripPrefix(path.as_string_view(), "/");
}

}  // namespace grpc

#endif  // GRPC_SRC_CPP_EXT_FILTERS_CENSUS_CONTEXT_H