import { CellRef } from "../../types";
import excursion from "./excursion";
import { getRenderedCell, RenderedCell, RenderedGrid } from "./renderGrid";
import { GridSelection } from "./selection";

export interface SelectionStyles {
  activeCellStroke: string;
  selectionRangeFill: string;
  selectionRangeStroke: string;
}

function strokeActiveCell(
  ctx: CanvasRenderingContext2D,
  styles: SelectionStyles,
  grid: RenderedGrid,
  cell: RenderedCell,
) {
  excursion(ctx, () => {
    const isLastCell = cell.rect.bottomRight.x === grid.rect.bottomRight.x;
    const isLastRow = cell.rect.bottomRight.y === grid.rect.bottomRight.y;

    ctx.strokeStyle = styles.activeCellStroke;
    ctx.lineWidth = 2;

    ctx.strokeRect(
      cell.rect.topLeft.x + 1,
      cell.rect.topLeft.y + 1,
      isLastCell ? cell.rect.width - 2 : cell.rect.width - 1,
      isLastRow ? cell.rect.height - 2 : cell.rect.height - 1,
    );
  });
}

function drawCellRange(
  ctx: CanvasRenderingContext2D,
  styles: SelectionStyles,
  grid: RenderedGrid,
  start: CellRef,
  end: CellRef,
  { stroke }: { stroke: boolean },
) {
  excursion(ctx, () => {
    const startCell = getRenderedCell(grid, start);
    const endCell = getRenderedCell(grid, end);

    if (!startCell || !endCell) return;

    const rect = startCell.rect.extend(endCell.rect);

    const isRightEdge = rect.bottomRight.x === grid.rect.bottomRight.x;
    const isBottomEdge = rect.bottomRight.y === grid.rect.bottomRight.y;

    ctx.fillStyle = styles.selectionRangeFill;

    ctx.fillRect(
      rect.topLeft.x + 1,
      rect.topLeft.y + 1,
      isRightEdge ? rect.width - 2 : rect.width - 1,
      isBottomEdge ? rect.height - 2 : rect.height - 1,
    );

    if (!stroke) return;

    ctx.strokeStyle = styles.selectionRangeStroke;

    ctx.strokeRect(
      rect.topLeft.x + 0.5,
      rect.topLeft.y + 0.5,
      isRightEdge ? rect.width - 1 : rect.width,
      isBottomEdge ? rect.height - 1 : rect.height,
    );
  });
}

export default function drawSelection(
  ctx: CanvasRenderingContext2D,
  styles: SelectionStyles,
  grid: RenderedGrid,
  selection: GridSelection | undefined,
  { pending }: { pending: boolean },
) {
  ctx.clearRect(0, 0, grid.rect.width, grid.rect.height);

  if (!selection) return;

  const activeCell = getRenderedCell(grid, selection.activeCellRef);

  if (!activeCell) return;

  if (selection.range) {
    drawCellRange(ctx, styles, grid, selection.range[0], selection.range[1], {
      stroke: !pending,
    });
  }

  strokeActiveCell(ctx, styles, grid, activeCell);
}