export interface NormalizedHudPosition {
  readonly x: number;
  readonly y: number;
}

export interface HudSize {
  readonly width: number;
  readonly height: number;
}

export const DEFAULT_THREAT_METER_POSITION: NormalizedHudPosition = Object.freeze({
  x: 0.78,
  y: 0.18,
});

function finite(value: number, fallback: number): number {
  return Number.isFinite(value) ? value : fallback;
}

function clamp(value: number, minimum: number, maximum: number): number {
  return Math.max(minimum, Math.min(maximum, value));
}

export function normalizeHudPosition(
  value: unknown,
  fallback: NormalizedHudPosition = DEFAULT_THREAT_METER_POSITION,
): NormalizedHudPosition {
  if (!value || typeof value !== "object") return fallback;
  const candidate = value as Partial<NormalizedHudPosition>;
  return {
    x: clamp(finite(candidate.x ?? Number.NaN, fallback.x), 0, 1),
    y: clamp(finite(candidate.y ?? Number.NaN, fallback.y), 0, 1),
  };
}

/**
 * Keeps a center-anchored HUD panel inside the visible viewport. Positions are
 * normalized so a saved desktop location remains meaningful on smaller screens.
 */
export function clampHudPositionToViewport(
  position: NormalizedHudPosition,
  viewport: HudSize,
  panel: HudSize,
  padding = 6,
): NormalizedHudPosition {
  const viewportWidth = Math.max(1, finite(viewport.width, 1));
  const viewportHeight = Math.max(1, finite(viewport.height, 1));
  const horizontalInset = Math.min(
    0.5,
    (Math.max(0, finite(panel.width, 0)) / 2 + Math.max(0, padding)) / viewportWidth,
  );
  const verticalInset = Math.min(
    0.5,
    (Math.max(0, finite(panel.height, 0)) / 2 + Math.max(0, padding)) / viewportHeight,
  );
  const normalized = normalizeHudPosition(position);
  return {
    x: clamp(normalized.x, horizontalInset, 1 - horizontalInset),
    y: clamp(normalized.y, verticalInset, 1 - verticalInset),
  };
}