syntax = "proto3";

/*
  Layer defines some default layers for compositing animations onto for 
  various purposes, and also defines some generic layers. Each service 
  should be allocated a unique enum eventually. 
  
  In the future, this system should be replaced by a configuration file
  that assigns priorities to each service.
*/
enum Layer {
  NONE = 0;
  // Well-known layers
  LIGHT = 10;
  COLOR = 20;
  NOTIFICATIONS = 90;
  // Public layers
  GENERAL_0 = 40;
  GENERAL_1 = 41;
  GENERAL_2 = 42; 
  GENERAL_3 = 43; 
  GENERAL_4 = 44; 
  GENERAL_5 = 45; 
  GENERAL_6 = 46; 
  GENERAL_7 = 47; 
  GENERAL_8 = 48; 
  GENERAL_9 = 49; 
}

/*
  FrameData represents either an array of dots or a fixed fill color to apply
  to all dots. Having two use cases makes it easier for applications to
  draw solid fill colors.
*/
message FrameData {
  // ARGB
  repeated fixed32 dots = 1;
  fixed32 fill = 2;  
}

/*
  FrameBuffer represents an entire frame together with a layer tag. It also
  defines a timestamp that can be used within a FrameSequence to define the 
  duration a frame will be shown. 
*/
message FrameBuffer {
  FrameData frame = 1;
  fixed32 timestamp = 3;
  Layer layer = 4;
}

/*
  FrameSequence buffers a series of frames to be drawn one by one at intervals
  defined by the timestamp included in the FrameBuffers. Useful for running 
  smooth animations. 

  In the future, this should have more metadata like looping counts and async
  animations. 
*/
message FrameSequence {
  repeated FrameBuffer frames = 1;
}

message DrawResponse {
}

service Drawer {
  // DrawFrame draws one frame
  rpc DrawFrame (FrameBuffer) returns (DrawResponse) {}
  // DrawFrames draws a series of frames
  rpc DrawFrames (FrameSequence) returns (DrawResponse) {}
}