// Copyright (C) 2022 The OKit Authors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.

syntax = "proto3";

package obkit;

option go_package = "code.pitz.tech/mya/okit/pb";

// Duration provides a protocol local implementation of a duration.
message Duration {
  int64 nanos = 1;
}

// Timestamp provides a protocol local implementation of a timestamp.
message Timestamp {
  int64 seconds = 1;
  int32 nanos = 2;
}

// Tag defines a key-value element eligible for indexing.
message Tag {
  string key = 1;

  oneof value {
    string string = 5;
    int64 int64 = 6;
    double double = 7;
    bytes bytes = 8;
    bool bool = 9;
    Duration duration = 10;
    Timestamp timestamp = 11;
  }
}

// Kind represents the various types of elements that we're collecting.
enum Kind {
  Unknown = 0;
  Event = 1;
  Metric = 2;
  Trace = 3;
  Log = 4;
}

// Wire represents a common structure for communicating common observability elements. To help illustrate this, let us
// consider the following.
//
// - An Event is an Entry who's name is set and contains optional tags.
// - A Log is an Entry who's value is set to the verbosity of the message.
// - A Metric is an Event that has a value associated with the entry.
// - A Trace is a Metric whose tags have a specific structure that allow multiple to be correlated.
//
message Entry {
  // Timestamp defines when the entry was emit. This system assumes the client clock is accurate enough.
  Timestamp timestamp = 1;

  // Scope is used to identify the metric name, log message, or traced function.
  string scope = 2;

  // Kind is used to indicate what type of entry this is.
  Kind kind = 3;

  // Tags is an optional field that contains a list of metadata associated with the entry.
  repeated Tag tags = 4;

  // Value is an optional field that defines a value associated with the entry (e.g. in the case of a log, metric, or trace).
  oneof value {
    string string = 5;      // used for logs
    double double = 6;      // used for metrics
    Duration duration = 7;  // used for traces
  }
}

// ClientInfo is used to capture specific information about the client application that is emitting information.
message ClientInfo {
  // Name is the canonical, simple name of the application (redis, mysql, etc...).
  string name = 1;

  // Instance is a unique identifier assigned to the process. This can be a hostname in the case of containers. It could
  // also be a mac address in the case of physical machines.
  string instance = 2;
}

// Packet defines the set of data that is contained within each message sent to the server.
message Packet {
  // Client contains information that identifies the emitting client.
  ClientInfo client = 1;

  // Entries are processed in batches, allowing local clients to buffer if necessary.
  repeated Entry entries = 2;
}