syntax = "proto3";

package chats;

option go_package = "./proto;chats";

service Chats {
	// Create a chat between two or more users, if a chat already exists for these users, the existing
	// chat will be returned
	rpc CreateChat(CreateChatRequest) returns (CreateChatResponse);
	// Create a message within a chat
	rpc SendMessage(SendMessageRequest) returns (SendMessageResponse);
	// List the messages within a chat in reverse chronological order, using sent_before to
	// offset as older messages need to be loaded
	rpc ListMessages(ListMessagesRequest) returns (ListMessagesResponse);
}

message Chat {
	// unique id of the chat
	string id = 1;
	// list of users in the chat
	repeated string user_ids = 2;
	// RFC3339 Nano timestamp e.g 2006-01-02T15:04:05.999999999Z07:00
	string created_at = 3;
}

message Message {
	// unique id of the message
	string id = 1;
	// user id of the message
	string author_id = 2;
	// chat id the message belongs to
	string chat_id = 3;
	// text within the message
	string text = 4;
	// RFC3339 Nano timestamp e.g 2006-01-02T15:04:05.999999999Z07:00
	string sent_at = 5;
}

// Create a new chat between mulitple users
message CreateChatRequest {
	// The chat ID
	string id = 1;
	// List of users in the chat
	repeated string user_ids = 2;
}

message CreateChatResponse {
	Chat chat = 1;
}

// Send a message to a chat room
message SendMessageRequest {
	string id = 1;
	string chat_id = 2;
	string author_id = 3;
	string text = 4;
}

message SendMessageResponse {
	Message message = 1;
}

// List messages within a chat
message ListMessagesRequest {
	// unique id of the chat
	string chat_id = 1;
	// limit the number of messages
	int64 limit = 2;
	// offset for the messages
	int64 offset = 3;
	// order "asc" or "desc" (defaults to reverse chronological)
	string order = 4;
}

message ListMessagesResponse {
	repeated Message messages = 1;
}