// SPDX-License-Identifier: MIT

syntax = "proto3";

package ermite;

import "ermite/merge_request.proto";
import "ermite/repo.proto";
import "ermite/run.proto";
import "google/protobuf/timestamp.proto";

// EventService streams what happens on the forge.
service EventService {
  // Watch streams events until the client cancels the call or the server shuts
  // down. Events are filtered by the caller's access: events of a private
  // repository are only sent to callers that may read it.
  //
  // The events are repo_created, repo_updated, repo_deleted, pushed, gap and,
  // for merge requests, merge_request_opened, merge_request_merged,
  // merge_request_closed and comment_added. Each one is delivered on the
  // "repo:<name>" topic of its repository and on "home", subject to the
  // visibility of the repository.
  //
  // Servers with the feature "ci.runs" also publish run_updated and
  // job_updated, only on the "repo:<name>" topic of their repository (never on
  // "home"), subject to the same visibility. They carry the state after the
  // change and are published when a run or a job is created, changes status
  // or conclusion, or when one of its steps starts or ends (never per log
  // line: follow a log with RunService.GetJobLog). The order of these events
  // is not guaranteed, between jobs and runs or between two updates of the same
  // one: a client keeps the copy with the higher Run.version or
  // RunJob.version and drops the other. There is no event for a change of title or
  // description, nor for a resolved comment: after a gap, or to see such
  // changes, clients read the merge request again. A merge publishes
  // merge_request_merged, then pushed for the target branch.
  //
  // The server keeps a bounded buffer of recent events. With resume_after set,
  // buffered events after that id are replayed first, then live events follow.
  // When resume_after is no longer buffered (or unknown), the stream begins
  // with a Gap event, then continues with the oldest buffered event: the client
  // must reload its state. Without resume_after, only new events are sent.
  //
  // The access of the caller is checked again for every event: the stream ends
  // with unauthenticated when the token was revoked or has expired (the server
  // may take a few seconds to notice). A repository that becomes private
  // sends one last repo_updated to the callers who could read it before, with
  // the new visibility and nothing else about it; no later event of it
  // reaches them. The server limits the watchers: more than 64 topics is
  // invalid_argument, and too many concurrent streams, in total or from one
  // client, is resource_exhausted.
  rpc Watch(WatchRequest) returns (stream WatchResponse);
}

// WatchRequest selects the events to receive.
message WatchRequest {
  // Topics are the subjects to follow: "home" for every repository visible to
  // the caller, or "repo:<name>" for one repository. Empty means "home".
  // Unknown topics are invalid_argument. A "repo:<name>" topic for a repository
  // that does not exist or is not visible is not_found.
  repeated string topics = 1;
  // ResumeAfter is the Event.id of the last event the client has seen. Empty
  // to receive only new events.
  string resume_after = 2;
}

// WatchResponse carries one event of the stream.
message WatchResponse {
  // Event is the event.
  Event event = 1;
}

// Event is something that happened on the forge.
message Event {
  // Id identifies the event and is passed as resume_after to resume a stream.
  // It is opaque and only comparable for equality; clients must not parse it.
  // Empty on a Gap event.
  string id = 1;
  // Time is when the event happened.
  google.protobuf.Timestamp time = 2;
  // Kind is the type and payload of the event. New kinds may be added; clients
  // must ignore kinds they do not know.
  oneof kind {
    // RepoCreated: a repository was created.
    RepoCreated repo_created = 3;
    // RepoUpdated: repository metadata changed.
    RepoUpdated repo_updated = 4;
    // RepoDeleted: a repository was deleted.
    RepoDeleted repo_deleted = 5;
    // Pushed: refs of a repository were updated by a push.
    Pushed pushed = 6;
    // Gap: events were lost, reload state.
    Gap gap = 7;
    // MergeRequestOpened: a merge request was opened.
    MergeRequestOpened merge_request_opened = 8;
    // MergeRequestMerged: a merge request was merged.
    MergeRequestMerged merge_request_merged = 9;
    // MergeRequestClosed: a merge request was closed without merging.
    MergeRequestClosed merge_request_closed = 10;
    // CommentAdded: a comment was added to a merge request.
    CommentAdded comment_added = 11;
    // RunUpdated: a CI run was created or changed.
    RunUpdated run_updated = 12;
    // JobUpdated: a CI job was created or changed.
    JobUpdated job_updated = 13;
  }
}

// RepoCreated reports a new repository.
message RepoCreated {
  // Repo is the new repository.
  Repo repo = 1;
}

// RepoUpdated reports a metadata change.
message RepoUpdated {
  // Repo is the repository after the change.
  Repo repo = 1;
}

// RepoDeleted reports a deleted repository.
message RepoDeleted {
  // Repo is the name of the deleted repository.
  string repo = 1;
}

// Pushed reports the ref updates of one push.
message Pushed {
  // Repo is the name of the repository.
  string repo = 1;
  // RefUpdates are the refs changed by the push.
  repeated RefUpdate ref_updates = 2;
}

// RefUpdate is the change of one ref.
message RefUpdate {
  // Ref is the full ref name, for example "refs/heads/main".
  string ref = 1;
  // OldId is the object id before the update. Empty when the ref was created.
  string old_id = 2;
  // NewId is the object id after the update. Empty when the ref was deleted.
  string new_id = 3;
}

// MergeRequestOpened reports a new merge request.
message MergeRequestOpened {
  // MergeRequest is the new merge request.
  MergeRequest merge_request = 1;
}

// MergeRequestMerged reports a merged merge request. It is published before
// the Pushed event of the target branch.
message MergeRequestMerged {
  // MergeRequest is the merge request after the merge.
  MergeRequest merge_request = 1;
}

// MergeRequestClosed reports a merge request closed without merging.
message MergeRequestClosed {
  // MergeRequest is the merge request after closing.
  MergeRequest merge_request = 1;
}

// CommentAdded reports a new comment on a merge request.
message CommentAdded {
  // Repo is the name of the repository.
  string repo = 1;
  // Number is the number of the merge request.
  int64 number = 2;
  // Comment is the new comment.
  Comment comment = 3;
}

// Gap tells the client that events were lost: the requested resume point is
// older than the server's buffer. It has no fields. The client should reload
// the state it displays (repositories, refs, merge requests and their
// comments, CI runs and their jobs) and carry on with the next events.
message Gap {}

// RunUpdated reports a CI run that was created or whose status, conclusion or
// timestamps changed. It is delivered on the "repo:<name>" topic only.
message RunUpdated {
  // Run is the run after the change, as of its latest attempt, without jobs.
  Run run = 1;
}

// JobUpdated reports a CI job that was created or whose status, conclusion,
// runner or steps changed. It is delivered on the "repo:<name>" topic only.
message JobUpdated {
  // Job is the job after the change, with its steps.
  RunJob job = 1;
}