import { dbGlobal } from "drizzle-pkg/lib/db";
import { categories, cards, type CardType } from "drizzle-pkg/lib/schema/content";
import { eq, asc } from "drizzle-orm";

// ============ Types ============
export interface CategoryTreeNode {
  id: string;
  name: string;
  image: string | null;
  parentId: string | null;
  sortOrder: number;
  count: number;
  defaultCardType: CardType | null;
  createdAt: Date;
  updatedAt: Date;
  children: CategoryTreeNode[];
}

export interface CreateCategoryInput {
  name: string;
  image?: string;
  parentId?: string | null;
  sortOrder?: number;
  defaultCardType?: CardType | null;
}

export interface UpdateCategoryInput {
  name?: string;
  image?: string | null;
  parentId?: string | null;
  sortOrder?: number;
  count?: number;
  defaultCardType?: CardType | null;
}

// ============ Helpers ============
function uuid() {
  return crypto.randomUUID();
}

function now() {
  return new Date();
}

// ============ CRUD ============

export async function listCategories(): Promise<CategoryTreeNode[]> {
  const rows = await dbGlobal
    .select()
    .from(categories)
    .orderBy(asc(categories.sortOrder), asc(categories.createdAt));

  return buildTree(rows);
}

export async function getCategoryById(id: string) {
  const rows = await dbGlobal
    .select()
    .from(categories)
    .where(eq(categories.id, id))
    .limit(1);
  return rows[0] ?? null;
}

export async function createCategory(input: CreateCategoryInput) {
  const id = uuid();
  await dbGlobal.insert(categories).values({
    id,
    name: input.name,
    image: input.image ?? null,
    parentId: input.parentId ?? null,
    sortOrder: input.sortOrder ?? 0,
    count: 0,
    defaultCardType: input.defaultCardType ?? null,
  });
  return getCategoryById(id);
}

export async function updateCategory(id: string, input: UpdateCategoryInput) {
  const existing = await getCategoryById(id);
  if (!existing) return null;

  await dbGlobal
    .update(categories)
    .set({
      ...(input.name !== undefined && { name: input.name }),
      ...(input.image !== undefined && { image: input.image }),
      ...(input.parentId !== undefined && { parentId: input.parentId }),
      ...(input.sortOrder !== undefined && { sortOrder: input.sortOrder }),
      ...(input.count !== undefined && { count: input.count }),
      ...(input.defaultCardType !== undefined && { defaultCardType: input.defaultCardType }),
      updatedAt: now(),
    })
    .where(eq(categories.id, id));

  return getCategoryById(id);
}

export async function deleteCategory(id: string) {
  // Move cards in this category to uncategorized (null)
  await dbGlobal
    .update(cards)
    .set({ categoryId: null })
    .where(eq(cards.categoryId, id));
  await dbGlobal.delete(categories).where(eq(categories.id, id));
}

// ============ Tree Builder ============

function buildTree(
  rows: (typeof categories.$inferSelect)[],
): CategoryTreeNode[] {
  const map = new Map<string, CategoryTreeNode>();
  const roots: CategoryTreeNode[] = [];

  // First pass: create nodes
  for (const row of rows) {
    map.set(row.id, {
      id: row.id,
      name: row.name,
      image: row.image,
      parentId: row.parentId,
      sortOrder: row.sortOrder,
      count: row.count,
      defaultCardType: row.defaultCardType,
      createdAt: row.createdAt,
      updatedAt: row.updatedAt,
      children: [],
    });
  }

  // Second pass: build hierarchy
  for (const node of map.values()) {
    if (node.parentId && map.has(node.parentId)) {
      map.get(node.parentId)!.children.push(node);
    } else {
      roots.push(node);
    }
  }

  return roots;
}