syntax = "proto3";

package frost.fs.object;

import "refs/types.proto";
import "session/types.proto";

// Type of the object payload content. Only `REGULAR` type objects can be split,
// hence `TOMBSTONE` and `LOCK` payload is limited by the
// maximum object size.
//
// String presentation of object type is the same as definition:
// * REGULAR
// * TOMBSTONE
// * LOCK
enum ObjectType {
  // Just a normal object
  REGULAR = 0;

  // Used internally to identify deleted objects
  TOMBSTONE = 1;

  // Unused (previously storageGroup information)
  // _ = 2;

  // Object lock
  LOCK = 3;
}

// Type of match expression
enum MatchType {
  // Unknown. Not used
  MATCH_TYPE_UNSPECIFIED = 0;

  // Full string match
  STRING_EQUAL = 1;

  // Full string mismatch
  STRING_NOT_EQUAL = 2;

  // Lack of key
  NOT_PRESENT = 3;

  // String prefix match
  COMMON_PREFIX = 4;
}

// Short header fields
message ShortHeader {
  // Object format version. Effectively, the version of API library used to
  // create particular object.
  frost.fs.refs.Version version = 1 [ json_name = "version" ];

  // Epoch when the object was created
  uint64 creation_epoch = 2 [ json_name = "creationEpoch" ];

  // Object's owner
  frost.fs.refs.OwnerID owner_id = 3 [ json_name = "ownerID" ];

  // Type of the object payload content
  ObjectType object_type = 4 [ json_name = "objectType" ];

  // Size of payload in bytes.
  // `0xFFFFFFFFFFFFFFFF` means `payload_length` is unknown
  uint64 payload_length = 5 [ json_name = "payloadLength" ];

  // Hash of payload bytes
  frost.fs.refs.Checksum payload_hash = 6 [ json_name = "payloadHash" ];

  // Homomorphic hash of the object payload
  frost.fs.refs.Checksum homomorphic_hash = 7 [ json_name = "homomorphicHash" ];
}

// Object Header
message Header {
  // Object format version. Effectively, the version of API library used to
  // create particular object
  frost.fs.refs.Version version = 1 [ json_name = "version" ];

  // Object's container
  frost.fs.refs.ContainerID container_id = 2 [ json_name = "containerID" ];

  // Object's owner
  frost.fs.refs.OwnerID owner_id = 3 [ json_name = "ownerID" ];

  // Object creation Epoch
  uint64 creation_epoch = 4 [ json_name = "creationEpoch" ];

  // Size of payload in bytes.
  // `0xFFFFFFFFFFFFFFFF` means `payload_length` is unknown.
  uint64 payload_length = 5 [ json_name = "payloadLength" ];

  // Hash of payload bytes
  frost.fs.refs.Checksum payload_hash = 6 [ json_name = "payloadHash" ];

  // Type of the object payload content
  ObjectType object_type = 7 [ json_name = "objectType" ];

  // Homomorphic hash of the object payload
  frost.fs.refs.Checksum homomorphic_hash = 8 [ json_name = "homomorphicHash" ];

  // Session token, if it was used during Object creation. Need it to verify
  // integrity and authenticity out of Request scope.
  frost.fs.session.SessionToken session_token = 9
      [ json_name = "sessionToken" ];

  // `Attribute` is a user-defined Key-Value metadata pair attached to an
  // object.
  //
  // Key name must be an object-unique valid UTF-8 string. Value can't be empty.
  // Objects with duplicated attribute names or attributes with empty values
  // will be considered invalid.
  //
  // There are some "well-known" attributes starting with `__SYSTEM__`
  // prefix that affect system behaviour:
  //
  // * [ __SYSTEM__UPLOAD_ID ] \
  //   Marks smaller parts of a split bigger object
  // * [ __SYSTEM__EXPIRATION_EPOCH ] \
  //   The epoch after which object with no LOCKs on it becomes unavailable.
  //   Locked object continues to be available until each of the LOCKs expire.
  // * [ __SYSTEM__TICK_EPOCH ] \
  //   Decimal number that defines what epoch must produce
  //   object notification with UTF-8 object address in a
  //   body (`0` value produces notification right after
  //   object put)
  // * [ __SYSTEM__TICK_TOPIC ] \
  //   UTF-8 string topic ID that is used for object notification
  //
  // And some well-known attributes used by applications only:
  //
  // * Name \
  //   Human-friendly name
  // * FileName \
  //   File name to be associated with the object on saving
  // * FilePath \
  //   Full path to be associated with the object on saving. Should start with a
  //   '/' and use '/' as a delimiting symbol. Trailing '/' should be
  //   interpreted as a virtual directory marker. If an object has conflicting
  //   FilePath and FileName, FilePath should have higher priority, because it
  //   is used to construct the directory tree. FilePath with trailing '/' and
  //   non-empty FileName attribute should not be used together.
  // * Timestamp \
  //   User-defined local time of object creation in Unix Timestamp format
  // * Content-Type \
  //   MIME Content Type of object's payload
  //
  // For detailed description of each well-known attribute please see the
  // corresponding section in FrostFS Technical Specification.
  message Attribute {
    // string key to the object attribute
    string key = 1 [ json_name = "key" ];
    // string value of the object attribute
    string value = 2 [ json_name = "value" ];
  }
  // User-defined object attributes
  repeated Attribute attributes = 10 [ json_name = "attributes" ];

  // Bigger objects can be split into a chain of smaller objects. Information
  // about inter-dependencies between spawned objects and how to re-construct
  // the original one is in the `Split` headers. Parent and children objects
  // must be within the same container.
  message Split {
    // Identifier of the origin object. Known only to the minor child.
    frost.fs.refs.ObjectID parent = 1 [ json_name = "parent" ];

    // Identifier of the left split neighbor
    frost.fs.refs.ObjectID previous = 2 [ json_name = "previous" ];

    // `signature` field of the parent object. Used to reconstruct parent.
    frost.fs.refs.Signature parent_signature = 3
        [ json_name = "parentSignature" ];

    // `header` field of the parent object. Used to reconstruct parent.
    Header parent_header = 4 [ json_name = "parentHeader" ];

    // List of identifiers of the objects generated by splitting current one.
    repeated frost.fs.refs.ObjectID children = 5 [ json_name = "children" ];

    // 16 byte UUIDv4 used to identify the split object hierarchy parts. Must be
    // unique inside container. All objects participating in the split must have
    // the same `split_id` value.
    bytes split_id = 6 [ json_name = "splitID" ];
  }
  // Position of the object in the split hierarchy
  Split split = 11 [ json_name = "split" ];

  // Erasure code can be applied to any object.
  // Information about encoded object structure is stored in `EC` header.
  // All objects belonging to a single EC group have the same `parent` field.
  message EC {
    // Identifier of the origin object. Known to all chunks.
    frost.fs.refs.ObjectID parent = 1 [ json_name = "parent" ];
    // Index of this chunk.
    uint32 index = 2 [ json_name = "index" ];
    // Total number of chunks in this split.
    uint32 total = 3 [ json_name = "total" ];
    // Total length of a parent header. Used to trim padding zeroes.
    uint32 header_length = 4 [ json_name = "headerLength" ];
    // Chunk of a parent header.
    bytes header = 5 [ json_name = "header" ];
    // As the origin object is EC-splitted its identifier is known to all
    // chunks as parent. But parent itself can be a part of Split (does not
    // relate to EC-split). In this case parent_split_id should be set.
    bytes parent_split_id = 6 [ json_name = "parentSplitID" ];
    // EC-parent's parent ID. parent_split_parent_id is set if EC-parent,
    // itself, is a part of Split and if an object ID of its parent is
    // presented. The field allows to determine how EC-chunk is placed in Split
    // hierarchy.
    frost.fs.refs.ObjectID parent_split_parent_id = 7
        [ json_name = "parentSplitParentID" ];
    // EC parent's attributes.
    repeated Attribute parent_attributes = 8 [ json_name = "parentAttributes" ];
  }
  // Erasure code chunk information.
  EC ec = 12 [ json_name = "ec" ];
}

// Object structure. Object is immutable and content-addressed. It means
// `ObjectID` will change if the header or the payload changes. It's calculated
// as a hash of header field which contains hash of the object's payload.
//
// For non-regular object types payload format depends on object type specified
// in the header.
message Object {
  // Object's unique identifier.
  frost.fs.refs.ObjectID object_id = 1 [ json_name = "objectID" ];

  // Signed object_id
  frost.fs.refs.Signature signature = 2 [ json_name = "signature" ];

  // Object metadata headers
  Header header = 3 [ json_name = "header" ];

  // Payload bytes
  bytes payload = 4 [ json_name = "payload" ];
}

// Meta information of split hierarchy for object assembly. With the last part
// one can traverse linked list of split hierarchy back to the first part and
// assemble the original object. With a linking object one can assemble an
// object right from the object parts.
message SplitInfo {
  // 16 byte UUID used to identify the split object hierarchy parts.
  bytes split_id = 1;

  // The identifier of the last object in split hierarchy parts. It contains
  // split header with the original object header.
  frost.fs.refs.ObjectID last_part = 2;

  // The identifier of a linking object for split hierarchy parts. It contains
  // split header with the original object header and a sorted list of
  // object parts.
  frost.fs.refs.ObjectID link = 3;
}

// Meta information for the erasure-encoded object.
message ECInfo {
  message Chunk {
    // Object ID of the chunk.
    frost.fs.refs.ObjectID id = 1;
    // Index of the chunk.
    uint32 index = 2;
    // Total number of chunks in this split.
    uint32 total = 3;
  }
  // Chunk stored on the node.
  repeated Chunk chunks = 1;
}