// Copyright 2015 The LUCI Authors. All rights reserved.
// Use of this source code is governed under the Apache License, Version 2.0
// that can be found in the LICENSE file.

syntax = "proto3";

package logpb;

option go_package = "go.chromium.org/luci/logdog/api/logpb";

import "google/protobuf/timestamp.proto";
import "google/protobuf/duration.proto";

/* A log stream type. */
enum StreamType {
  TEXT = 0;
  BINARY = 1;
  DATAGRAM = 2;
}

/**
 * Log stream descriptor data. This is the full set of information that
 * describes a logging stream.
 */
message LogStreamDescriptor {
  /*
   * The stream's prefix (required).
   *
   * Logs originating from the same Butler instance will share a Prefix.
   *
   * A valid prefix value is a StreamName described in:
   * https://go.chromium.org/luci/logdog/common/types#StreamName
   */
  string prefix = 1;
  /*
   * The log stream's name (required).
   *
   * This is used to uniquely identify a log stream within the scope of its
   * prefix.
   *
   * A valid name value is a StreamName described in:
   * https://go.chromium.org/luci/logdog/common/types#StreamName
   */
  string name = 2;

  /* The log stream's content type (required). */
  StreamType stream_type = 3;

  /*
   * The stream's content type (required).
   *
   * This must be an HTTP Content-Type value. Begins with MIME media type; may
   * include a charset directive. It is made available to LogDog clients when
   * querying stream metadata. It will also be applied to archived binary log
   * data.
   */
  string content_type = 4;

  /*
   * The log stream's base timestamp (required).
   *
   * This notes the start time of the log stream. All LogEntries express their
   * timestamp as microsecond offsets from this field.
   */
  google.protobuf.Timestamp timestamp = 5;

  /*
   * Tag is an arbitrary key/value tag associated with this log stream.
   *
   * LogDog clients can query for log streams based on tag values.
   */
  map<string, string> tags = 6;

  /*
   * If set, the stream will be joined together during archival to recreate the
   * original stream and made available at <prefix>/+/<name>.ext.
   */
  string binary_file_ext = 7;
}

/* Text stream content. */
message Text {
  /*
   * Contiguous text lines and their delimiters.
   *
   * The array of lines follows the following pattern:
   *   - 0 or 1 completion lines completing the last LogEntry's Text (i.e. with
   *     a delimiter but not itself the full line)
   *   - any number of complete lines (i.e. with delimiter, each its own line)
   *   - 0 or 1 partial lines
   */
  message Line {
    /* The line's text content, not including its delimiter. */
    bytes value = 1;

    /*
     * The line's delimiter string.
     *
     * If this is an empty string, this line is continued in the next sequential
     * line, and the line's sequence number does not advance.
     */
    string delimiter = 2;
  }
  repeated Line lines = 1;
}

/* Binary stream content. */
message Binary {
  // Formerly the LogEntry.Sequence value was duplicated here.
  reserved 1;

  /* The binary stream's data. */
  bytes data = 2;
}

/* Datagram stream content type. */
message Datagram {
  /* This datagram data. */
  bytes data = 1;

  /*
   * If this is not a partial datagram, this field will include reassembly and
   * state details for the full datagram.
   */
  message Partial {
    /*
     * The index, starting with zero, of this datagram fragment in the full
     * datagram.
     */
    uint32 index = 1;

    /* The size of the full datagram */
    uint64 size = 2;

    /* If true, this is the last partial datagram in the overall datagram. */
    bool last = 3;
  }
  Partial partial = 2;
}

/**
 * An individual log entry.
 *
 * This contains the superset of transmissible log data. Its content fields
 * should be interpreted in the context of the log stream's content type.
 */
message LogEntry {
  /*
   * The stream time offset for this content.
   *
   * This offset is added to the log stream's base "timestamp" to resolve the
   * timestamp for this specific Content.
   */
  google.protobuf.Duration time_offset = 1;

  /*
   * The message index within the Prefix (required).
   *
   * This is value is unique to this LogEntry across the entire set of entries
   * sharing the stream's Prefix. It is used to designate unambiguous log
   * ordering.
   */
  uint64 prefix_index = 2;

  /*
   * The message index within its Stream (required).
   *
   * This value is unique across all entries sharing the same Prefix and Stream
   * Name. It is used to designate unambiguous log ordering within the stream.
   */
  uint64 stream_index = 3;

  /*
   * The sequence number of the first content entry in this LogEntry.
   *
   * Text: This is the line index of the first included line. Line indices begin
   *     at zero.
   * Binary: This is the byte offset of the first byte in the included data.
   * Datagram: This is the index of the datagram. The first datagram has index
   *     zero.
   */
  uint64 sequence = 4;

  /*
   * The content of the message. The field that is populated here must
   * match the log's `stream_type`.
   */
  oneof content {
    /* Text Stream: Lines of log text. */
    Text text = 10;

    /* Binary stream: data segment. */
    Binary binary = 11;

    /* Datagram stream: Datagrams. */
    Datagram datagram = 12;
  }
}

/**
 * LogIndex is an index into an at-rest log storage.
 *
 * The log stream and log index are generated by the Archivist during archival.
 *
 * An archived log stream is a series of contiguous LogEntry frames. The index
 * maps a log's logical logation in its stream, prefix, and timeline to its
 * frame's binary offset in the archived log stream blob.
 */
message LogIndex {
  /*
   * The LogStreamDescriptor for this log stream (required).
   *
   * The index stores the stream's LogStreamDescriptor so that a client can
   * know the full set of log metadata by downloading its index.
   */
  LogStreamDescriptor desc = 1;

  /*
   * Entry is a single index entry.
   *
   * The index is composed of a series of entries, each corresponding to a
   * sequential snapshot of of the log stream.
   */
  message Entry {
    /*
     * The byte offset in the emitted log stream of the RecordIO entry for the
     * LogEntry corresponding to this Entry.
     */
    uint64 offset = 1;
    /*
     * The sequence number of the first content entry.
     *
     * Text: This is the line index of the first included line. Line indices
     *     begin at zero.
     * Binary: This is the byte offset of the first byte in the included data.
     * Datagram: This is the index of the datagram. The first datagram has index
     *     zero.
     */
    uint64 sequence = 2;

    /*
     * The log index that this entry describes (required).
     *
     * This is used by clients to identify a specific LogEntry within a set of
     * streams sharing a Prefix.
     */
    uint64 prefix_index = 3;

    /*
     * The time offset of this log entry (required).
     *
     * This is used by clients to identify a specific LogEntry within a log
     * stream.
     */
    uint64 stream_index = 4;

    /*
     * The time offset of this log entry, in microseconds.
     *
     * This is added to the descriptor's "timestamp" field to identify the
     * specific timestamp of this log. It is used by clients to identify a
     * specific LogEntry by time.
     */
    google.protobuf.Duration time_offset = 5;
  }

  /*
   * A series of ascending-ordered Entry messages representing snapshots of an
   * archived log stream.
   *
   * Within this set of Entry messages, the "offset", "prefix_index",
   * "stream_index", and "time_offset" fields will be ascending.
   *
   * The frequency of Entry messages is not defined; it is up to the Archivist
   * process to choose a frequency.
   */
  repeated Entry entries = 2;

  /**
   * The last prefix index in the log stream.
   *
   * This is optional. If zero, there is either no information about the last
   * prefix index, or there are zero entries in the prefix.
   */
  uint64 last_prefix_index = 3;
  /**
   * The last stream index in the log stream.
   *
   * This is optional. If zero, there is either no information about the last
   * stream index, or there are zero entries in the stream.
   */
  uint64 last_stream_index = 4;
  /**
   * The number of log entries in the stream.
   *
   * This is optional. If zero, there is either no information about the number
   * of log entries, or there are zero entries in the stream.
   */
  uint64 log_entry_count = 5;
}