import { AffineTransform, Point, Rect } from "@noya-app/noya-geometry";
import { clamp01 } from "@noya-app/noya-utils";
import {
  GradientEditorGradient,
  GradientStopHandle,
} from "./gradientEditorPlugin";

export type GradientEditorLinearGradient = {
  from: Point;
  to: Point;
  stops: {
    color: string;
    offset: number;
  }[];
};

export type GradientEditorDetails = {
  gradient: GradientEditorGradient;
  stopMap: Map<string, number>;
};

export function createGradientEditorDetails({
  linearGradient,
  artRect,
  transform,
}: {
  linearGradient: GradientEditorLinearGradient;
  artRect: Rect;
  transform: AffineTransform;
}): GradientEditorDetails {
  const rect = transform.applyTo(artRect);

  const from = {
    x: clamp01(linearGradient.from.x),
    y: clamp01(linearGradient.from.y),
  };

  const to = {
    x: clamp01(linearGradient.to.x),
    y: clamp01(linearGradient.to.y),
  };

  const stops: GradientStopHandle[] = linearGradient.stops.map(
    (stop, index, allStops) => {
      const position =
        allStops.length > 1
          ? clamp01(stop.offset ?? index / (allStops.length - 1))
          : 0;

      const normalizedPoint = {
        x: from.x + (to.x - from.x) * position,
        y: from.y + (to.y - from.y) * position,
      };

      const point = transform.applyTo({
        x: artRect.x + normalizedPoint.x * artRect.width,
        y: artRect.y + normalizedPoint.y * artRect.height,
      });

      const type: GradientStopHandle["type"] =
        index === 0 ? "start" : index === allStops.length - 1 ? "end" : "stop";

      return {
        id: `stop-${index}`,
        index,
        type,
        position,
        point,
        color: stop.color,
      };
    }
  );

  const stopMap = new Map(stops.map((stop) => [stop.id, stop.index]));

  return {
    gradient: {
      rect,
      stops,
    },
    stopMap,
  };
}