// Output geometry for a take, in output pixels. Used both by the ffmpeg export and by the
// browser preview, so that what you see while editing is what gets rendered.

import type { BackgroundMode, CameraShape, Layout, OutputSettings } from './types.ts';
import { backgroundOf } from './types.ts';

export interface Box {
  x: number;
  y: number;
  w: number;
  h: number;
}

export interface Geometry {
  W: number;
  H: number;
  screen: Box | null; // screen is always fit (letterboxed) inside its box
  camera: Camera | null;
}

export interface Camera {
  box: Box;
  fit: 'cover' | 'contain';
  shape: CameraShape;
  radius: number;
  // Effective background: 'cutout' (no box, just the person) only applies to picture-in-picture;
  // elsewhere it falls back to 'color'.
  background: BackgroundMode;
  color: string;
  blurSigma: number; // in output pixels
}

export const FPS = 30;

const even = (n: number) => Math.max(2, Math.round(n / 2) * 2);

export function outputSize(output: OutputSettings) {
  const H = output.height;
  return { W: even((H * 16) / 9), H };
}

export function computeGeometry(layout: Layout, output: OutputSettings, hasScreen: boolean, hasCamera: boolean): Geometry {
  const { W, H } = outputSize(output);
  const full: Box = { x: 0, y: 0, w: W, h: H };
  let mode = layout.mode;
  if (!hasCamera) mode = 'screen-only';
  else if (!hasScreen) mode = 'camera-only';

  const bg = backgroundOf(layout);
  const background: BackgroundMode = bg.mode === 'cutout' && mode !== 'pip' ? 'color' : bg.mode;
  const camera = (box: Box, fit: 'cover' | 'contain', shape: CameraShape, radius: number): Camera => ({
    box,
    fit,
    shape,
    radius,
    background,
    color: bg.color,
    blurSigma: Math.round((bg.blur * H) / 1080 * 10) / 10,
  });

  if (mode === 'screen-only') return { W, H, screen: full, camera: null };
  if (mode === 'camera-only') return { W, H, screen: null, camera: camera(full, 'contain', 'rect', 0) };

  const left = layout.corner === 'tl' || layout.corner === 'bl';
  if (mode === 'side-by-side') {
    const cw = even(W * 0.3);
    const camBox: Box = { x: left ? 0 : W - cw, y: 0, w: cw, h: H };
    const scrBox: Box = { x: left ? cw : 0, y: 0, w: W - cw, h: H };
    return { W, H, screen: scrBox, camera: camera(camBox, 'cover', 'rect', 0) };
  }

  // picture-in-picture
  const margin = even(W * 0.025);
  const cw = even(W * Math.min(0.5, Math.max(0.08, layout.size)));
  const top = layout.corner === 'tl' || layout.corner === 'tr';
  if (background === 'cutout') {
    // The person is cut off at the bottom of the camera frame, so sit that edge on the bottom of the video.
    const ch = even((cw * 9) / 16);
    const box: Box = { x: left ? margin : W - margin - cw, y: top ? margin : H - ch, w: cw, h: ch };
    return { W, H, screen: full, camera: camera(box, 'cover', 'rect', 0) };
  }
  const ch = layout.shape === 'circle' ? cw : even((cw * 9) / 16);
  const box: Box = { x: left ? margin : W - margin - cw, y: top ? margin : H - margin - ch, w: cw, h: ch };
  const radius = layout.shape === 'circle' ? cw / 2 : layout.shape === 'rounded' ? Math.round(Math.min(cw, ch) * 0.12) : 0;
  return { W, H, screen: full, camera: camera(box, 'cover', layout.shape, radius) };
}