/**
 * Room.scene 控制器的纯函数核心。
 *
 * 设计意图:RoomSceneStart.ts 依赖 Cocos(cc 模块),在 node + tsx 下不可加载。
 * 本文件抽出与 cc 无关的:
 *   - 输入校验(count / layout / seat)
 *   - 槽位操作(active flag / position / player data)
 *   - PlayerInfoView 交互(applyPlayer 一致调用)
 * 让单元测试可直接 import,而 RoomSceneStart 只做 cc 包装 + 转发。
 *
 * CLAUDE.md 第二准则:不兜底。非法输入一律 throw,不静默 fallback / ?? 兜底。
 */
import {
  computeActiveFlags,
  computePositions,
  MAX_SEATS,
  type SeatLayout,
} from './room-scene-layout.ts';

export type { SeatLayout };
export { computeActiveFlags, computePositions, MAX_SEATS };

/** PlayerState 子集,PlayerInfoView.applyPlayer 实际消费(其它字段由视图内部兜底)。 */
export interface PlayerViewData {
  nickname: string;
  bean: number;
  avatar: string;
}

/** Mock 槽位契约(由 RoomSceneStart 持有真 Node,测试用普通对象)。 */
export interface PlayerSlotLike {
  active: boolean;
  setPosition(x: number, y: number, z: number): void;
  getComponent(name: string): unknown;
}

/** PlayerInfoView 公共契约(测试可提供 fake,真实现见 assets/scripts/views/PlayerInfoView.ts)。 */
export interface PlayerInfoViewLike {
  applyPlayer?(p: PlayerViewData): void;
  bindTo?(session: unknown): void;
}

/** 占位 PlayerViewData(clearSeats 使用)。 */
export const PLACEHOLDER_VIEW_DATA: PlayerViewData = Object.freeze({
  nickname: '占位',
  bean: 0,
  avatar: '',
});

/** 取槽位上的 PlayerInfoView 组件,缺则 null(供测试 spy / 真实组件共用)。 */
export function extractPlayerView(slot: PlayerSlotLike | null): PlayerInfoViewLike | null {
  if (!slot) return null;
  const view = slot.getComponent('PlayerInfoView') as PlayerInfoViewLike | null;
  return view ?? null;
}

/** 校验 count ∈ [1, MAX_SEATS] 且为整数;非法 throw。 */
export function validateCount(n: number): void {
  if (typeof n !== 'number' || Number.isNaN(n) || !Number.isInteger(n)) {
    throw new Error(`[RoomSceneStart] count must be an integer, got ${String(n)}`);
  }
  if (n < 1 || n > MAX_SEATS) {
    throw new Error(`[RoomSceneStart] count must be 1-${MAX_SEATS}, got ${n}`);
  }
}

/** 校验 layout ∈ VALID_LAYOUTS;非法 throw。 */
const VALID_LAYOUTS: readonly SeatLayout[] = ['horizontal', '2x2', 'triangle', 'square'];
export function validateLayout(layout: SeatLayout): void {
  if (!VALID_LAYOUTS.includes(layout)) {
    throw new Error(
      `[RoomSceneStart] layout must be one of ${VALID_LAYOUTS.join('|')}, got ${String(layout)}`,
    );
  }
}

/** 校验 seat ∈ [1, currentCount] 且为整数;非法 throw。 */
export function validateSeat(seat: number, currentCount: number): void {
  if (typeof seat !== 'number' || Number.isNaN(seat) || !Number.isInteger(seat)) {
    throw new Error(`[RoomSceneStart] seat must be an integer, got ${String(seat)}`);
  }
  if (seat < 1 || seat > currentCount) {
    throw new Error(
      `[RoomSceneStart] seat ${seat} out of range 1-${currentCount}`,
    );
  }
}

/**
 * 设置每个槽位的 active 标志(前 count 个 true,其余 false)。
 * 委托 computeActiveFlags + 校验(已在 computeActiveFlags 内)。
 */
export function applyPlayerCount(slots: PlayerSlotLike[], n: number): void {
  validateCount(n);
  const flags = computeActiveFlags(n, slots.length);
  for (let i = 0; i < slots.length; i++) {
    const slot = slots[i];
    if (slot) slot.active = flags[i];
  }
}

/**
 * 按 layout + count 计算位置,设置到前 count 个槽位。
 * 校验(layout / count 在 computePositions 内)。
 */
export function applySeatLayoutPositions(
  slots: PlayerSlotLike[],
  layout: SeatLayout,
  count: number,
): void {
  validateCount(count);
  validateLayout(layout);
  const positions = computePositions(layout, count);
  for (let i = 0; i < count && i < positions.length; i++) {
    const slot = slots[i];
    if (slot) slot.setPosition(positions[i].x, positions[i].y, 0);
  }
}

/**
 * 从完整 PlayerState 中抽取 PlayerInfoView.applyPlayer 实际需要的 3 个字段。
 * 缺字段一律显式 throw(不 ?? 兜底,CLAUDE.md 第二准则)。
 */
export function extractPlayerViewData(data: { nickname?: unknown; bean?: unknown; avatar?: unknown }): PlayerViewData {
  if (!data || typeof data !== 'object') {
    throw new Error(`[RoomSceneStart] setPlayerData: data must be an object, got ${String(data)}`);
  }
  if (typeof data.nickname !== 'string') {
    throw new Error(`[RoomSceneStart] setPlayerData: data.nickname must be string, got ${String(data.nickname)}`);
  }
  if (typeof data.bean !== 'number' || Number.isNaN(data.bean)) {
    throw new Error(`[RoomSceneStart] setPlayerData: data.bean must be number, got ${String(data.bean)}`);
  }
  if (typeof data.avatar !== 'string') {
    throw new Error(`[RoomSceneStart] setPlayerData: data.avatar must be string, got ${String(data.avatar)}`);
  }
  return { nickname: data.nickname, bean: data.bean, avatar: data.avatar };
}

/**
 * 把玩家数据推入指定槽位的 PlayerInfoView。
 * 优先用 applyPlayer(一次设置);缺 applyPlayer 才用 bindTo + proper reactive store。
 * 若两者皆缺,throw(明确暴露组件挂载错误,不静默跳过)。
 *
 * 校验:seat 必须为整数 ∈ [1, currentCount];data 必须含 3 个合法字段。
 */
export function applyPlayerData(
  slots: PlayerSlotLike[],
  seat: number,
  currentCount: number,
  data: { nickname?: unknown; bean?: unknown; avatar?: unknown },
): void {
  validateSeat(seat, currentCount);
  const viewData = extractPlayerViewData(data);
  const slot = slots[seat - 1];
  if (!slot) {
    throw new Error(`[RoomSceneStart] setPlayerData: slot ${seat} is null/undefined`);
  }
  const view = extractPlayerView(slot);
  if (!view) {
    throw new Error(
      `[RoomSceneStart] setPlayerData: slot ${seat} has no PlayerInfoView component`,
    );
  }
  if (typeof view.applyPlayer === 'function') {
    view.applyPlayer(viewData);
    return;
  }
  if (typeof view.bindTo === 'function') {
    // 退化路径:为 view.bindTo 构造一个 minimal reactive store
    // (满足 ViewStore 契约:有 subscribe + value),保证不抛 TypeError。
    view.bindTo(buildOneShotSession(viewData));
    return;
  }
  throw new Error(
    `[RoomSceneStart] setPlayerData: slot ${seat} view has neither applyPlayer nor bindTo`,
  );
}

/** 占位用的 minimal reactive store(只触发一次订阅,值不再变化)。 */
function buildOneShotSession(viewData: PlayerViewData): { player: { state: { value: PlayerViewData; subscribe(cb: () => void): () => void } } } {
  const state = {
    value: viewData,
    subscribe(_cb: () => void): () => void {
      return () => { /* no-op unsubscribe */ };
    },
  };
  return { player: { state } };
}

/**
 * 把当前可见槽位刷成占位数据(clearSeats)。
 * 数据非法时抛错,不部分清空。
 */
export function clearSlots(slots: PlayerSlotLike[], currentCount: number): void {
  for (let i = 0; i < currentCount; i++) {
    applyPlayerData(slots, i + 1, currentCount, PLACEHOLDER_VIEW_DATA);
  }
}