import {
  Modules,
  Excavation,
  ImageSettings,
} from '@digigov/ui/app/QrCodeViewer/types';

const DEFAULT_IMG_SCALE = 0.1;
export const MARGIN_SIZE = 4;
export function generatePath(modules: Modules, margin = 0): string {
  const ops: string[] = [];
  modules.forEach(function (row, y) {
    let start: number | null = null;
    row.forEach(function (cell, x) {
      if (!cell && start !== null) {
        // M0 0h7v1H0z injects the space with the move and drops the comma,
        // saving a char per operation
        ops.push(
          `M${start + margin} ${y + margin}h${x - start}v1H${start + margin}z`
        );
        start = null;
        return;
      }

      // end of row, clean up or skip
      if (x === row.length - 1) {
        if (!cell) {
          // We would have closed the op above already so this can only mean
          // 2+ light modules in a row.
          return;
        }
        if (start === null) {
          // Just a single dark module.
          ops.push(`M${x + margin},${y + margin} h1v1H${x + margin}z`);
        } else {
          // Otherwise finish the current line.
          ops.push(
            `M${start + margin},${y + margin} h${x + 1 - start}v1H${
              start + margin
            }z`
          );
        }
        return;
      }

      if (cell && start === null) {
        start = x;
      }
    });
  });
  return ops.join('');
}

// We could just do this in generatePath, except that we want to support
// non-Path2D canvas, so we need to keep it an explicit step.
export function excavateModules(
  modules: Modules,
  excavation: Excavation
): Modules {
  return modules.slice().map((row, y) => {
    if (y < excavation.y || y >= excavation.y + excavation.h) {
      return row;
    }
    return row.map((cell, x) => {
      if (x < excavation.x || x >= excavation.x + excavation.w) {
        return cell;
      }
      return false;
    });
  });
}

export function getImageSettings(
  cells: Modules,
  size: number,
  includeMargin: boolean,
  imageSettings?: ImageSettings
): null | {
  x: number;
  y: number;
  h: number;
  w: number;
  excavation: Excavation | null;
} {
  if (imageSettings == null) {
    return null;
  }
  const margin = includeMargin ? MARGIN_SIZE : 0;
  const numCells = cells.length + margin * 2;
  const defaultSize = Math.floor(size * DEFAULT_IMG_SCALE);
  const scale = numCells / size;
  const w = (imageSettings.width || defaultSize) * scale;
  const h = (imageSettings.height || defaultSize) * scale;
  const x =
    imageSettings.x == null
      ? cells.length / 2 - w / 2
      : imageSettings.x * scale;
  const y =
    imageSettings.y == null
      ? cells.length / 2 - h / 2
      : imageSettings.y * scale;

  let excavation;
  if (imageSettings.excavate) {
    const floorX = Math.floor(x);
    const floorY = Math.floor(y);
    const ceilW = Math.ceil(w + x - floorX);
    const ceilH = Math.ceil(h + y - floorY);
    excavation = { x: floorX, y: floorY, w: ceilW, h: ceilH };
  }

  return { x, y, h, w, excavation };
}