import React, { useRef, useState } from 'react';

import type {
  ProjectNpc,
  SceneGrid,
  SceneNpcToken,
  SceneNpcTokensSessionState,
} from '../../../shared/types';
import { DEFAULT_NPC_TOKEN_SESSION_SCALE } from '../../../shared/types/appPlayers';
import { sceneGridTokenFitFactor } from '../../../shared/types/sceneGrid';
import { useAssetUrl } from '../useAssetImageUrl';

import { PlayerTokenView } from './PlayerTokenView';
import styles from './SceneNpcTokensOverlay.module.css';

type Viewport = { x: number; y: number; w: number; h: number };

function NpcSprite({
  placement,
  npc,
  nx,
  ny,
  viewport,
  editable,
  displayScale,
  gridFit,
  onMove,
}: {
  placement: SceneNpcToken;
  npc: ProjectNpc;
  nx: number;
  ny: number;
  viewport: Viewport;
  editable: boolean;
  displayScale: number;
  gridFit: number;
  onMove?: (placementId: string, nx: number, ny: number) => void;
}) {
  const imageUrl = useAssetUrl(npc.avatarAssetId);
  const [localPos, setLocalPos] = useState<{ nx: number; ny: number } | null>(null);
  const dragRef = useRef<{
    pointerId: number;
    startNx: number;
    startNy: number;
    pointerNx: number;
    pointerNy: number;
    lastNx: number;
    lastNy: number;
  } | null>(null);
  const pos = localPos ?? { nx, ny };
  const minDim = Math.min(viewport.w, viewport.h);
  const sizePx = Math.max(16, placement.sizeN * gridFit * displayScale * minDim);

  const point = (e: React.PointerEvent) => {
    const host = e.currentTarget.parentElement;
    const rect = host?.getBoundingClientRect();
    return {
      x: Math.max(0, Math.min(1, (e.clientX - ((rect?.left ?? 0) + viewport.x)) / Math.max(1, viewport.w))),
      y: Math.max(0, Math.min(1, (e.clientY - ((rect?.top ?? 0) + viewport.y)) / Math.max(1, viewport.h))),
    };
  };

  const end = (e: React.PointerEvent<HTMLDivElement>) => {
    const drag = dragRef.current;
    if (drag?.pointerId !== e.pointerId) return;
    dragRef.current = null;
    onMove?.(String(placement.id), drag.lastNx, drag.lastNy);
    setLocalPos(null);
  };

  return (
    <div
      className={[styles.token, editable ? styles.editable : ''].filter(Boolean).join(' ')}
      data-testid={`session-npc-token-${placement.id}`}
      style={{
        left: viewport.x + pos.nx * viewport.w,
        top: viewport.y + pos.ny * viewport.h,
        width: sizePx,
        height: sizePx,
      }}
      onPointerDown={
        editable && onMove !== undefined
          ? (e) => {
              if (e.button !== 0) return;
              e.preventDefault();
              e.stopPropagation();
              const p = point(e);
              dragRef.current = {
                pointerId: e.pointerId,
                startNx: pos.nx,
                startNy: pos.ny,
                pointerNx: p.x,
                pointerNy: p.y,
                lastNx: pos.nx,
                lastNy: pos.ny,
              };
              e.currentTarget.setPointerCapture(e.pointerId);
            }
          : undefined
      }
      onPointerMove={
        editable && onMove
          ? (e) => {
              const drag = dragRef.current;
              if (drag?.pointerId !== e.pointerId) return;
              const p = point(e);
              drag.lastNx = Math.max(0, Math.min(1, drag.startNx + p.x - drag.pointerNx));
              drag.lastNy = Math.max(0, Math.min(1, drag.startNy + p.y - drag.pointerNy));
              setLocalPos({ nx: drag.lastNx, ny: drag.lastNy });
            }
          : undefined
      }
      onPointerUp={end}
      onPointerCancel={end}
    >
      <PlayerTokenView
        name={npc.name}
        imageUrl={imageUrl}
        ringColor={npc.ringColor}
        imageOffset={npc.imageOffset}
        imageScale={npc.imageScale}
        sizePx={sizePx}
      />
    </div>
  );
}

export function SceneNpcTokensOverlay({
  placements,
  library,
  session,
  viewport,
  grid = null,
  editable = false,
  onMove,
}: {
  placements: readonly SceneNpcToken[];
  library: readonly ProjectNpc[];
  session: SceneNpcTokensSessionState | null;
  viewport: Viewport | null;
  /** Для гекса — вписанный диаметр ячейки, не описанный. */
  grid?: SceneGrid | null;
  editable?: boolean;
  onMove?: (placementId: string, nx: number, ny: number) => void;
}) {
  if (!viewport) return null;
  const byId = new Map(library.map((npc) => [npc.id, npc]));
  const displayScale = session?.scale ?? DEFAULT_NPC_TOKEN_SESSION_SCALE;
  const gridFit = sceneGridTokenFitFactor(grid);
  return (
    <div className={styles.layer}>
      {placements.map((placement) => {
        const npc = byId.get(placement.npcId);
        if (!npc) return null;
        const override = session?.byPlacementId[String(placement.id)];
        return (
          <NpcSprite
            key={placement.id}
            placement={placement}
            npc={npc}
            nx={override?.nx ?? placement.nx}
            ny={override?.ny ?? placement.ny}
            viewport={viewport}
            editable={editable}
            displayScale={displayScale}
            gridFit={gridFit}
            {...(onMove ? { onMove } : {})}
          />
        );
      })}
    </div>
  );
}