import type {
  ResourceBookCardPresentation,
  ResourceBookCategory,
  ResourceBookState,
} from './resourceBookModel';
import {
  resourceBookCategoryCardPresentation,
  resourceBookShowsExitingCards,
} from './resourceBookModel';
import {
  RESOURCE_CANVAS_CARD_HEIGHT,
  RESOURCE_CANVAS_CARD_WIDTH,
  type ResourceCanvasCardSize,
} from './resourceCanvasLayoutModel';
import type { ProjectResource } from './resourceProjectionModel';
import { projectResourceTypeLabel } from './resourceProjectionModel';

export type ResourceBookOverviewRect = {
  left: number;
  top: number;
  width: number;
  height: number;
};

export type ResourceBookStack = [type: string, items: ProjectResource[]];

export type ResourceBookCardLayout = {
  x: number;
  y: number;
  width: number;
  height: number;
  dragX: number;
  dragY: number;
  rotation: number;
};

// 总览每个资源类型最多铺这么多张卡片；其余数量由标题栏的“N 项”表达。
// 叠放角度同样只取这几个值，避免素材变多后旋转角随下标无限增大。
const overviewStackRotations = [0.5, -1.5, 2.5] as const;

export const RESOURCE_BOOK_OVERVIEW_STACK_LIMIT = overviewStackRotations.length;

export function groupResourceBookStacks(
  resources: readonly ProjectResource[],
): ResourceBookStack[] {
  const groups = new Map<string, ProjectResource[]>();
  for (const resource of resources) {
    const items = groups.get(projectResourceTypeLabel(resource)) ?? [];
    items.push(resource);
    groups.set(projectResourceTypeLabel(resource), items);
  }
  return Array.from(
    groups,
    ([type, items]) => [type, items] as ResourceBookStack,
  );
}

export function groupResourceBookResourcesByCategory(
  resources: readonly ProjectResource[],
) {
  const result = new Map<ResourceBookCategory, ProjectResource[]>();
  for (const resource of resources) {
    const items = result.get(resource.category) ?? [];
    items.push(resource);
    result.set(resource.category, items);
  }
  return result;
}

/**
 * 总览摞只铺有限张卡。挑哪几张决定了进入子画布时的观感：若按数组顺序取，
 * 用户看到的卡和入场视口里最近的卡不是同一批，FLIP 找不到对应终点，动画会
 * 退化成淡入淡出、返回时还会跳成另一张图。这里改为取离当前视图中心最近的卡。
 */
export function selectResourceBookOverviewCards({
  resources,
  visibleResourceIds,
  positions,
  cardSizes,
  viewCenter,
  limit = RESOURCE_BOOK_OVERVIEW_STACK_LIMIT,
}: {
  resources: readonly ProjectResource[];
  visibleResourceIds: ReadonlySet<string>;
  positions: ReadonlyMap<string, { x: number; y: number }>;
  cardSizes: ReadonlyMap<string, ResourceCanvasCardSize>;
  viewCenter: { x: number; y: number } | undefined;
  limit?: number;
}): ProjectResource[] {
  const visible = resources.filter((resource) =>
    visibleResourceIds.has(resource.id),
  );
  if (!viewCenter || visible.length <= limit) {
    return visible.slice(0, limit);
  }
  const distance = (resource: ProjectResource) => {
    const position = positions.get(resource.id);
    if (!position) return Number.POSITIVE_INFINITY;
    const size = cardSizes.get(resource.id) ?? {
      width: RESOURCE_CANVAS_CARD_WIDTH,
      height: RESOURCE_CANVAS_CARD_HEIGHT,
    };
    const centerX = position.x + size.width / 2;
    const centerY = position.y + size.height / 2;
    return (centerX - viewCenter.x) ** 2 + (centerY - viewCenter.y) ** 2;
  };
  return visible
    .map((resource, index) => ({
      resource,
      index,
      distance: distance(resource),
    }))
    .sort(
      (left, right) =>
        left.distance - right.distance || left.index - right.index,
    )
    .slice(0, limit)
    .map((entry) => entry.resource);
}

export function resourceBookOverviewCardLayout({
  rect,
  stackIndex,
  stackColumn,
}: {
  rect: ResourceBookOverviewRect | undefined;
  stackIndex: number;
  stackColumn: number;
}): ResourceBookCardLayout {
  const rotationIndex = Math.min(
    Math.max(stackIndex, 0),
    overviewStackRotations.length - 1,
  );
  return {
    x: (rect?.left ?? 0) + 18 + (stackColumn % 3) * 102,
    y: (rect?.top ?? 0) + 58 + Math.min(stackIndex, 2) * 5,
    width: 92,
    height: 64,
    dragX: 0,
    dragY: 0,
    rotation: overviewStackRotations[rotationIndex] ?? 0,
  };
}

export function resourceBookChildCardLayout({
  position,
  size,
}: {
  position: { x: number; y: number } | undefined;
  size: ResourceCanvasCardSize;
}): ResourceBookCardLayout {
  const x = position?.x ?? 0;
  const y = position?.y ?? 0;
  // The child scene applies the viewport transform on its card-world wrapper.
  // Keep card geometry logical here so persistence, drag callbacks, and the
  // public ResourceCard style contract are not polluted by screen space.
  return {
    x,
    y,
    width: size.width,
    height: size.height,
    dragX: x,
    dragY: y,
    rotation: 0,
  };
}

const RESOURCE_BOOK_CARD_FALLBACK_SIZE: ResourceCanvasCardSize = {
  width: 180,
  height: 128,
};

export function resourceBookSceneCardKey(resourceId: string) {
  return `card:${resourceId}`;
}

export function resourceBookSceneTitleKey(category: ResourceBookCategory) {
  return `title:${category}`;
}

export type ResourceBookSceneCardPlan = {
  key: string;
  category: ResourceBookCategory;
  resource: ProjectResource;
  presentation: ResourceBookCardPresentation;
  stackIndex: number;
  stackColumn: number;
  /** 同一类型摞里的卡片总数，用于总览态 z-index。 */
  stackCount: number;
  layout: ResourceBookCardLayout;
};

export type ResourceBookSceneCategoryPlan = {
  category: ResourceBookCategory;
  resourceCount: number;
  titlebarActive: boolean;
  titlebarOpacity: number;
  cards: ResourceBookSceneCardPlan[];
};

/**
 * 画本场景渲染计划。渲染、转场签名和淡出集合共用这一份计划，避免"渲染用一套、
 * 测量用另一套"的错位：
 * - 总览/返回态全部用总览摞布局；
 * - 进入栏目时当前栏目换成子画布布局，其他栏目留在 DOM 里按总览布局淡出；
 * - 返回总览时源栏目未回到摞上的卡片按子画布布局淡出；
 * - 搜索/排序导致的卸载由 `exitingCards` 保留一帧，用同一套淡出撤下。
 */
export function buildResourceBookScenePlan({
  state,
  visibleCategoryOrder,
  resourcesByCategory,
  overviewRects,
  positions,
  cardSizes,
  visibleResourceIds,
  categoryViewCenters,
  cardsReady,
  exitingCategory = null,
  exitingCards = [],
}: {
  state: ResourceBookState;
  visibleCategoryOrder: readonly ResourceBookCategory[];
  resourcesByCategory: ReadonlyMap<ResourceBookCategory, ProjectResource[]>;
  overviewRects: ReadonlyMap<ResourceBookCategory, ResourceBookOverviewRect>;
  positions: ReadonlyMap<string, { x: number; y: number }>;
  cardSizes: ReadonlyMap<string, ResourceCanvasCardSize>;
  visibleResourceIds: ReadonlySet<string>;
  categoryViewCenters: ReadonlyMap<
    ResourceBookCategory,
    { x: number; y: number }
  >;
  cardsReady: boolean;
  exitingCategory?: ResourceBookCategory | null;
  exitingCards?: readonly ResourceBookSceneCardPlan[];
}): ResourceBookSceneCategoryPlan[] {
  return visibleCategoryOrder.map((category) => {
    const presentation = resourceBookCategoryCardPresentation(state, category);
    const rect = overviewRects.get(category);
    const cards: ResourceBookSceneCardPlan[] = [];
    const categoryResources = resourcesByCategory.get(category) ?? [];
    const stacks = groupResourceBookStacks(categoryResources);
    const childLayout = presentation === 'child';
    if (cardsReady && presentation) {
      stacks.forEach(([, items], stackColumn) => {
        // 总览只铺有限张，数量由栏目标题栏的“N 项”表达；子画布渲染全部资源。
        const stackItems = childLayout
          ? items
          : selectResourceBookOverviewCards({
              resources: items,
              visibleResourceIds,
              positions,
              cardSizes,
              viewCenter: categoryViewCenters.get(category),
            });
        stackItems.forEach((resource, stackIndex) => {
          cards.push({
            key: resourceBookSceneCardKey(resource.id),
            category,
            resource,
            presentation: childLayout ? 'child' : 'overview',
            stackIndex,
            stackColumn,
            stackCount: stackItems.length,
            layout: childLayout
              ? resourceBookChildCardLayout({
                  position: positions.get(resource.id),
                  size:
                    cardSizes.get(resource.id) ??
                    RESOURCE_BOOK_CARD_FALLBACK_SIZE,
                })
              : resourceBookOverviewCardLayout({
                  rect,
                  stackIndex,
                  stackColumn,
                }),
          });
        });
      });
    }
    if (
      resourceBookShowsExitingCards(state) &&
      exitingCategory === category &&
      cardsReady
    ) {
      const onStack = new Set(
        cards
          .filter((card) => card.presentation === 'overview')
          .map((card) => card.key),
      );
      categoryResources.forEach((resource) => {
        const key = resourceBookSceneCardKey(resource.id);
        if (onStack.has(key)) return;
        if (!visibleResourceIds.has(resource.id)) return;
        cards.push({
          key,
          category,
          resource,
          presentation: 'exiting',
          stackIndex: 0,
          stackColumn: 0,
          stackCount: 1,
          layout: resourceBookChildCardLayout({
            position: positions.get(resource.id),
            size:
              cardSizes.get(resource.id) ?? RESOURCE_BOOK_CARD_FALLBACK_SIZE,
          }),
        });
      });
    }
    exitingCards.forEach((card) => {
      if (card.category !== category) return;
      if (cards.some((entry) => entry.key === card.key)) return;
      cards.push({ ...card, presentation: 'exiting' });
    });
    return {
      category,
      resourceCount: categoryResources.length,
      titlebarActive: presentation === 'child',
      titlebarOpacity: childLayout || state.view === 'main' ? 1 : 0,
      cards,
    };
  });
}

export function resourceBookSceneCardLayoutSignature(
  card: ResourceBookSceneCardPlan,
) {
  return `${card.presentation}:${card.layout.x},${card.layout.y}:${card.layout.width},${card.layout.height}:${card.layout.rotation}`;
}