import {
  getNodeDimensions,
  pickSideFromPoint,
  START_NODE_ID,
  type HandleSide,
} from './strategyFlowLayout';

export type EdgeDragZone = 'source' | 'middle' | 'target';

/** 연결선 상 클릭/드래그 위치 → 좌(소스) / 중(경로) / 우(타겟) 구간 */
export function getEdgeDragZone(
  sourceX: number,
  sourceY: number,
  targetX: number,
  targetY: number,
  pointerX: number,
  pointerY: number,
): EdgeDragZone {
  const dx = targetX - sourceX;
  const dy = targetY - sourceY;
  const len2 = dx * dx + dy * dy;
  if (len2 < 4) return 'middle';
  const t = ((pointerX - sourceX) * dx + (pointerY - sourceY) * dy) / len2;
  const clamped = Math.max(0, Math.min(1, t));
  if (clamped < 1 / 3) return 'source';
  if (clamped > 2 / 3) return 'target';
  return 'middle';
}

function sideToSourceHandle(side: HandleSide): string {
  return `s-${side}`;
}

function sideToTargetHandle(side: HandleSide): string {
  return `t-${side}`;
}

/** 드래그 위치에 맞는 소스(출발) 핸들 */
export function pickSourceHandleAtPoint(
  nodeId: string,
  flowPos: { x: number; y: number },
  positions: Map<string, { x: number; y: number }>,
): string {
  const pos = positions.get(nodeId) ?? { x: 0, y: 0 };
  const dim = getNodeDimensions(nodeId);
  return sideToSourceHandle(pickSideFromPoint(flowPos, pos, dim));
}

/** 드래그 위치에 맞는 타겟(도착) 핸들 */
export function pickTargetHandleAtPoint(
  nodeId: string,
  flowPos: { x: number; y: number },
  positions: Map<string, { x: number; y: number }>,
): string {
  const pos = positions.get(nodeId) ?? { x: 0, y: 0 };
  const dim = getNodeDimensions(nodeId);
  return sideToTargetHandle(pickSideFromPoint(flowPos, pos, dim));
}

export function buildPositionsFromNodes(
  nodes: { id: string; position: { x: number; y: number } }[],
): Map<string, { x: number; y: number }> {
  const map = new Map<string, { x: number; y: number }>();
  for (const n of nodes) {
    map.set(n.id, { x: n.position.x, y: n.position.y });
  }
  if (!map.has(START_NODE_ID)) {
    map.set(START_NODE_ID, { x: 0, y: 220 });
  }
  return map;
}