import * as fabric from "fabric";
import { pathLengthPx, type ElDef, type ThreadColor } from "@/lib/tatting-ru";

export type TattingObject = fabric.Group & {
  elId?: string;
  elName?: string;
  knots?: number;
  pathPx?: number;
  threadName?: string;
  isGrid?: boolean;
  isRuler?: boolean;
};

export const CUSTOM_PROPS = ["elId", "elName", "knots", "pathPx", "threadName", "isGrid", "isRuler"];

const strokeOf = (t: ThreadColor, size: number): string | fabric.Gradient<"linear"> =>
  t.to
    ? new fabric.Gradient({
        type: "linear",
        gradientUnits: "pixels",
        coords: { x1: -size, y1: -size, x2: size, y2: size },
        colorStops: [
          { offset: 0, color: t.value },
          { offset: 1, color: t.to },
        ],
      })
    : t.value;

export function buildElement(def: ElDef, thread: ThreadColor, width: number): TattingObject {
  const r = def.radius;
  if (def.kind === "text") {
    const text = new fabric.IText(def.id === "rownum" ? "Ряд 1" : "Подпись", {
      fontSize: def.radius * 1.6,
      fontFamily: "DM Sans, system-ui, sans-serif",
      fill: thread.value,
      originX: "center",
      originY: "center",
    }) as unknown as TattingObject;
    text.elId = def.id;
    text.elName = def.name;
    text.knots = 0;
    text.pathPx = 0;
    text.threadName = thread.name;
    return text;
  }
  const stroke = strokeOf(thread, r * 1.4);
  const picotR = Math.max(3, r * 0.13);
  const base = { fill: "", stroke, strokeWidth: width, originX: "center", originY: "center" } as const;
  const parts: fabric.FabricObject[] = [];

  const picotRing = (count: number, rad: number) => {
    for (let i = 0; i < count; i++) {
      const a = (i / count) * Math.PI * 2 - Math.PI / 2;
      parts.push(
        new fabric.Circle({
          ...base,
          radius: picotR,
          left: Math.cos(a) * (rad + picotR * 0.8),
          top: Math.sin(a) * (rad + picotR * 0.8),
        }),
      );
    }
  };

  if (def.kind === "ring") {
    parts.push(new fabric.Circle({ ...base, radius: r, left: 0, top: 0 }));
    parts.push(
      new fabric.Circle({ ...base, radius: r - 5, left: 0, top: 0, strokeWidth: width * 0.4, opacity: 0.5 }),
    );
    picotRing(def.picots, r);
  } else if (def.kind === "arc" || def.kind === "arc-curved") {
    const sweep = def.kind === "arc-curved" ? 1.35 : 1;
    const half = (Math.PI * sweep) / 2;
    const x0 = -Math.sin(half) * r;
    const y0 = Math.cos(half) * r;
    parts.push(
      new fabric.Path(`M ${x0} ${y0} A ${r} ${r} 0 ${sweep > 1 ? 1 : 0} 1 ${-x0} ${y0}`, {
        ...base,
        left: 0,
        top: 0,
      }),
    );
    parts.push(
      new fabric.Path(`M ${x0 * 0.88} ${y0 * 0.88} A ${r - 5} ${r - 5} 0 ${sweep > 1 ? 1 : 0} 1 ${-x0 * 0.88} ${y0 * 0.88}`, {
        ...base,
        left: 0,
        top: 0,
        strokeWidth: width * 0.4,
        opacity: 0.5,
      }),
    );
    for (let i = 0; i < def.picots; i++) {
      const t = (i + 1) / (def.picots + 1);
      const a = -half + t * half * 2;
      parts.push(
        new fabric.Circle({
          ...base,
          radius: picotR,
          left: Math.sin(a) * (r + picotR * 0.8),
          top: -Math.cos(a) * (r + picotR * 0.8) + r,
        }),
      );
    }
  } else if (def.kind === "picot") {
    parts.push(new fabric.Path(`M ${-r} 0 Q 0 ${-r * 1.8} ${r} 0`, { ...base, left: 0, top: 0 }));
    parts.push(new fabric.Circle({ ...base, radius: r * 0.35, left: 0, top: -r * 0.6 }));
  } else if (def.kind === "bead") {
    parts.push(
      new fabric.Circle({
        radius: r,
        left: 0,
        top: 0,
        originX: "center",
        originY: "center",
        fill: stroke,
        stroke,
        strokeWidth: 1,
      }),
    );
  } else {
    const pts = [
      { x: 0, y: -r * 1.3 },
      { x: r, y: 0 },
      { x: 0, y: r * 1.3 },
      { x: -r, y: 0 },
    ];
    parts.push(
      new fabric.Polygon(pts, {
        left: 0,
        top: 0,
        originX: "center",
        originY: "center",
        fill: stroke,
        stroke,
        strokeWidth: 1,
      }),
    );
    parts.push(new fabric.Polygon(pts.map((p) => ({ x: p.x * 0.5, y: p.y * 0.5 })), {
      left: 0,
      top: 0,
      originX: "center",
      originY: "center",
      fill: "",
      stroke: "#ffffff",
      opacity: 0.6,
      strokeWidth: 1,
    }));
  }

  const group = new fabric.Group(parts, {
    originX: "center",
    originY: "center",
    objectCaching: false,
  }) as TattingObject;
  group.elId = def.id;
  group.elName = def.name;
  group.knots = def.knots;
  group.pathPx = pathLengthPx(def);
  group.threadName = thread.name;
  return group;
}

export function applyThread(obj: TattingObject, thread: ThreadColor) {
  if (typeof obj.getObjects !== "function") {
    obj.set("fill", thread.value);
    obj.threadName = thread.name;
    obj.dirty = true;
    return;
  }
  const size = Math.max(obj.width ?? 40, obj.height ?? 40) * 0.7;
  const filled = obj.elId === "bead" || obj.elId === "crystal";
  obj.getObjects().forEach((child, i) => {
    child.set("stroke", strokeOf(thread, size));
    if (filled && i === 0) child.set("fill", strokeOf(thread, size));
  });
  obj.threadName = thread.name;
  obj.dirty = true;
}

export function applyWidth(obj: TattingObject, width: number) {
  if (typeof obj.getObjects !== "function") return;
  obj.getObjects().forEach((child) => {
    const thin = (child.strokeWidth ?? 1) < 1.5;
    child.set("strokeWidth", thin ? width * 0.4 : width);
  });
  obj.dirty = true;
}