syntax = "proto3";

package accord;
option go_package = ".;pb";

import "google/protobuf/timestamp.proto";

message AddChannelRequest {
  string name = 1;
  bool isPublic = 2;
}

message AddChannelResponse {}

message RemoveChannelRequest { fixed64 channel_id = 1; }

message RemoveChannelResponse {}

message GetChannelRequest { fixed64 channel_id = 1; }

message GetChannelResponse {
  fixed64 channel_id = 1;
  string name = 2;
  bool isPublic = 3;
  repeated User users = 4;
  // and more to be added.

  message User {
    string username = 1;
    string role = 2;
    // and more to be added.
  }
}

message ServerStreamRequest { string username = 1; }

message ServerStreamResponse {
  oneof event {
    ChannelAction channel_action = 1;
    AnyOtherServerConfigChange any_other_server_config_change = 2;
  }

  // After users call unary rpc to add/remove channel, it gets
  // broadcasted to all users (including the caller) through
  // this message.
  message ChannelAction {
    fixed64 channel_id = 1;
    oneof action {
      // AddChannel is for broadcasting to users that a new channel
      // has been added.
      AddChannel add_channel = 2;
      // Broadcasting to users that a channel has been removed.
      RemoveChannel remove_channel = 3;
    }

    message AddChannel {
      string name = 1;
      bool isPublic = 2;
    }

    message RemoveChannel {}
  }

  // This is a placeholder to be renamed for emerging needs for
  // server configuration changes.
  message AnyOtherServerConfigChange {}
}

// Used in ChannelStreamRequest- and Response to initiate and broadcast
// channel-related changes.
message ChannelConfigMessage {
  oneof msg {
    NameChannelConfigMessage name_msg = 1;
    PermissionChannelConfigMessage permission_msg = 2;
    PinChannelConfigMessage pin_msg = 3;
  }

  message NameChannelConfigMessage { string new_channel_name = 1; }

  enum AddRemoveAction {
    UNKNOWN_ACTION = 0;
    ADD_ACTION = 1;
    REMOVE_ACTION = 2;
  }

  enum Permission {
    // default role in case api user leaves this field empty
    UNKNOWN_PERMISSION = 0;
    // permission to read for subscribed users or any member of the channel
    READ = 1;
    // includes writing, modifying, and deletion of own messages
    WRITE = 2;
    // allows deleting othes users' messages
    DELETE = 3;
    // allows to modify channel configurations
    MODIFY = 4;
    // for kicking users out of the channel
    KICK = 5;
    // for banning users
    BAN = 6;
    // permanently removing the channel and all its data
    REMOVE_CHANNEL = 7;
  }

  message PermissionChannelConfigMessage {
    AddRemoveAction action = 1;
    Permission permission = 2;
    string role = 3;
  }

  message PinChannelConfigMessage { fixed64 message_id = 1; }
}

// Stream response for bidirectional streaming of user and  config
// messages with a single channel.
message ChannelStreamRequest {
  string username = 1;
  fixed64 channel_id = 2;

  oneof msg {
    UserMessage user_msg = 3;
    ChannelConfigMessage config_msg = 4;
  }

  message UserMessage {
    oneof user_msg {
      NewUserMessage new_user_msg = 1;
      EditUserMessage edit_user_msg = 2;
      DeleteUserMessage delete_user_msg = 3;
    }

    message NewUserMessage { string content = 1; }

    message EditUserMessage {
      fixed64 message_id = 1;
      string content = 2;
    }

    message DeleteUserMessage { fixed64 message_id = 1; }
  }
}

// Stream response for bidirectional streaming of user and  config
// messages with a single channel.
message ChannelStreamResponse {
  oneof msg {
    UserMessage user_msg = 1;
    ChannelConfigMessage config_msg = 2;
  }

  message UserMessage {
    fixed64 message_id = 1;
    oneof user_msg {
      NewAndUpdateUserMessage new_and_update_user_msg = 2;
      DeleteUserMessage delete_user_msg = 3;
    }

    message NewAndUpdateUserMessage {
      google.protobuf.Timestamp timestamp = 1;
      string content = 2;
    }

    message DeleteUserMessage {}
  }
}

service Chat {
  rpc AddChannel(AddChannelRequest) returns (AddChannelResponse) {}
  rpc RemoveChannel(RemoveChannelRequest) returns (RemoveChannelResponse) {}

  // Returns all the information about a particular channel.
  rpc GetChannel(GetChannelRequest) returns (GetChannelResponse) {}

  // Stream's server-scope information to user, such as addition or
  // removal of channels, and change in other server configurations.
  rpc ServerStream(ServerStreamRequest) returns (stream ServerStreamResponse) {}

  // Bidirectional stream of user and channel configuration messages
  // with a single channel.
  // NOTE: the fields and nested messages were designed with a single
  // channel in mind. So while it may be possible to use this RPC to
  // stream with multiple channels simultaneously, no adequate result
  // should be expected. Thus, it is developer's responsibility to make
  // sure that separate Stream RPCs are invoked for each channel.
  rpc ChannelStream(stream ChannelStreamRequest)
      returns (stream ChannelStreamResponse) {}
}