import { AlignX, AlignY, Point, Rect, Size } from "./engine/datatypes.ts";
import { D } from "./engine/public.ts";
import { getHud } from "./hud.ts";
import { getHotbar } from "./hotbar.ts";

// general
let margin = 8;
export function getLayoutRect(
  size: Size,
  options?: { alignX?: AlignX; alignY?: AlignY },
): Rect {
  let { w: screenW, h: screenH } = D.size;

  // first of all: place the _internal_ screen inside the real screen
  let marginalScreenW = screenW - margin * 2;
  let marginalScreenH = screenH - margin * 2;
  let marginalScreenX = margin;
  let marginalScreenY = margin;

  // NOTE: If the screen is too small, remainingSpace will be negative
  // This is fine -- it actually results in reasonable outcomes except
  // that the size of the box is exceeded in the opposite of the align direction.
  let { w: innerW, h: innerH } = size;
  let remainingSpaceX = marginalScreenW - innerW;
  let remainingSpaceY = marginalScreenH - innerH;

  let alignXCoef =
    options?.alignX == AlignX.Left
      ? 0.0
      : options?.alignX == AlignX.Center
        ? 0.5
        : options?.alignX == AlignX.Right
          ? 1.0
          : 0.5;
  let alignYCoef =
    options?.alignY == AlignY.Top
      ? 0.0
      : options?.alignY == AlignY.Middle
        ? 0.5
        : options?.alignY == AlignY.Bottom
          ? 1.0
          : 0.5;

  let x = marginalScreenX + alignXCoef * remainingSpaceX;
  let y = marginalScreenY + alignYCoef * remainingSpaceY;

  return new Rect(new Point(Math.floor(x), Math.floor(y)), size);
}

export function withCamera(part: UIPart, cb: () => void) {
  let region = getPartLocation(part);

  D.withCamera(D.camera.offset(region.top.negate()), cb);
}

// specific
export type UIPart =
  | "BottomModal"
  | "FullscreenPopover"
  | "Hotbar"
  | "HUD"
  | "Gameplay"
  | "Thralls";


export function getPartLocation(part: UIPart) {
  switch (part) {
    case "BottomModal":
      return getLayoutRect(new Size(384, 128), {
        alignX: AlignX.Center,
        alignY: AlignY.Bottom,
      });
    case "FullscreenPopover":
      return getLayoutRect(new Size(384, 384));
    case "Gameplay":
    case "Thralls":
      return getLayoutRect(new Size(384, 384));
    case "Hotbar":
      return getLayoutRect(getHotbar().size, {
        alignX: AlignX.Center,
        alignY: AlignY.Bottom,
      });
    case "HUD":
      return getLayoutRect(getHud().size, {
        alignX: AlignX.Left,
        alignY: AlignY.Top,
      });
  }
  throw `not sure what layout rect to use ${part}`;
}