// The interface shared by the CPU and the GPU time loops.
export interface ChunkResult {
  firstSample: number;            // audio index of pressureFront[0]
  pressureFront: Float32Array;    // baffled Rayleigh pressure [Pa]
  pressureBack: Float32Array;     // diffracted back term [Pa]; unbaffled = front - back
  frames: Float32Array[];         // displacement w at every node, captured every `movieEvery` audio samples
  frameSamples: number[];         // audio sample index of each frame
}

export interface HitState { peakForce: number; contactTime: number; velocity: number; height: number }

export interface Diagnostics {
  time: number; kinetic: number; membrane: number; bending: number; exciters: number; maxWoverH: number; hits: HitState[];
}

export interface SimulatorBackend {
  readonly kind: "cpu" | "gpu";
  readonly samplesDone: number;
  /** Largest chunk (audio samples) runChunk accepts. */
  readonly maxChunk: number;
  /** Advance by nSamples audio samples and return the pressure samples completed meanwhile. */
  runChunk(nSamples: number): Promise<ChunkResult>;
  diagnostics(): Promise<Diagnostics>;
  /** Transverse displacement w at every node, for the plate view. */
  displacement(): Promise<Float32Array>;
  dispose(): void;
}