import type { Vector3Tuple } from "./dungeonTypes";

export interface SpectatorCameraAxes {
  readonly forward: number;
  readonly right: number;
  readonly vertical: number;
}

const MAX_CAMERA_FRAME_SECONDS = 0.1;
const KEYBOARD_YAW_RADIANS_PER_SECOND = 2.25;
const KEYBOARD_PITCH_RADIANS_PER_SECOND = 1.55;

function held(codes: ReadonlySet<string>, ...candidates: readonly string[]): number {
  return Number(candidates.some((code) => codes.has(code)));
}

export function spectatorKeyboardAxes(codes: ReadonlySet<string>): SpectatorCameraAxes {
  return {
    forward: held(codes, "KeyW") - held(codes, "KeyS"),
    right: held(codes, "KeyD") - held(codes, "KeyA"),
    vertical: held(codes, "KeyE", "Space") - held(codes, "KeyQ", "ControlLeft", "ControlRight"),
  };
}

export function spectatorCameraBoosted(codes: ReadonlySet<string>): boolean {
  return codes.has("ShiftLeft") || codes.has("ShiftRight");
}

/** Returns frame-bounded arrow-key look deltas in the same orientation as mouse look. */
export function spectatorKeyboardLookDelta(
  codes: ReadonlySet<string>,
  deltaSeconds: number,
): readonly [horizontal: number, vertical: number] {
  const seconds = Number.isFinite(deltaSeconds)
    ? Math.max(0, Math.min(MAX_CAMERA_FRAME_SECONDS, deltaSeconds))
    : 0;
  return [
    (held(codes, "ArrowRight") - held(codes, "ArrowLeft")) * seconds * KEYBOARD_YAW_RADIANS_PER_SECOND,
    (held(codes, "ArrowDown") - held(codes, "ArrowUp")) * seconds * KEYBOARD_PITCH_RADIANS_PER_SECOND,
  ];
}

/** Returns a bounded, normalized free-flight translation for one render frame. */
export function spectatorCameraTranslation(
  yaw: number,
  pitch: number,
  axes: SpectatorCameraAxes,
  deltaSeconds: number,
  boosted: boolean,
): Vector3Tuple {
  if (![yaw, pitch, deltaSeconds, axes.forward, axes.right, axes.vertical].every(Number.isFinite)) return [0, 0, 0];
  const forwardX = Math.sin(yaw) * Math.cos(pitch);
  const forwardY = Math.sin(pitch);
  const forwardZ = Math.cos(yaw) * Math.cos(pitch);
  // With Three's +Z-forward camera convention, screen-right is -X at zero
  // yaw. Keep this basis aligned with cameraRelativeMovement.
  const rightX = -Math.cos(yaw);
  const rightZ = Math.sin(yaw);
  let x = forwardX * axes.forward + rightX * axes.right;
  let y = forwardY * axes.forward + axes.vertical;
  let z = forwardZ * axes.forward + rightZ * axes.right;
  const length = Math.hypot(x, y, z);
  if (length <= 1e-6) return [0, 0, 0];
  const scale = (boosted ? 28 : 10) * Math.max(0, Math.min(MAX_CAMERA_FRAME_SECONDS, deltaSeconds)) / Math.max(1, length);
  x *= scale;
  y *= scale;
  z *= scale;
  return [x, y, z];
}