import { mkdir, readFile, writeFile } from 'node:fs/promises';
import { dirname } from 'node:path';
import type { DomesticDataset } from '../../types/domestic-dataset.js';
import type {
  ProductKnowledgePage,
  ProductKnowledgeRecord,
  ProductKnowledgeRole,
  ProductKnowledgeStatus,
  ProductKnowledgeStore,
} from './product-knowledge.store.js';

interface LocalKnowledgeFile {
  schemaVersion: 1;
  items: ProductKnowledgeRecord[];
}

export class LocalProductKnowledgeStore implements ProductKnowledgeStore {
  private readonly records = new Map<string, ProductKnowledgeRecord>();

  constructor(
    dataset: DomesticDataset,
    private readonly workspaceId: string,
    initialItems: ProductKnowledgeRecord[] = [],
    private readonly persistencePath = '',
    private readonly now: () => Date = () => new Date(),
  ) {
    for (const item of initialItems) {
      if (item.workspaceId === workspaceId) this.records.set(item.productKey, { ...item, tags: [...item.tags] });
    }
    if (!this.records.size) this.seedTopProducts(dataset);
  }

  static async open(input: {
    dataset: DomesticDataset;
    workspaceId: string;
    persistencePath: string;
  }): Promise<LocalProductKnowledgeStore> {
    let items: ProductKnowledgeRecord[] = [];
    try {
      const parsed = JSON.parse(await readFile(input.persistencePath, 'utf8')) as Partial<LocalKnowledgeFile>;
      if (parsed.schemaVersion === 1 && Array.isArray(parsed.items)) items = parsed.items;
    } catch (error) {
      if ((error as NodeJS.ErrnoException).code !== 'ENOENT') throw error;
    }
    const store = new LocalProductKnowledgeStore(
      input.dataset,
      input.workspaceId,
      items,
      input.persistencePath,
    );
    await store.persist();
    return store;
  }

  async list(input: {
    workspaceId: string;
    limit: number;
    cursor: string | null;
    status?: ProductKnowledgeStatus;
    productRole?: ProductKnowledgeRole;
    featured?: boolean;
  }): Promise<ProductKnowledgePage> {
    if (input.workspaceId !== this.workspaceId) return { items: [], nextCursor: null };
    const items = [...this.records.values()]
      .filter((item) => !input.status || item.status === input.status)
      .filter((item) => !input.productRole || item.productRole === input.productRole)
      .filter((item) => input.featured === undefined || item.featured === input.featured)
      .sort((left, right) => left.productKey.localeCompare(right.productKey));
    const cursorIndex = input.cursor ? items.findIndex((item) => item.productKey === input.cursor) : -1;
    const start = cursorIndex + 1;
    const page = items.slice(start, start + input.limit + 1);
    const hasMore = page.length > input.limit;
    const visible = page.slice(0, input.limit).map((item) => ({ ...item, tags: [...item.tags] }));
    return {
      items: visible,
      nextCursor: hasMore ? visible.at(-1)?.productKey ?? null : null,
    };
  }

  async upsert(input: {
    workspaceId: string;
    productKey: string;
    productId: string;
    productRole: ProductKnowledgeRole;
    featured: boolean;
    status: ProductKnowledgeStatus;
    tags: string[];
    note: string;
    ownerUserId: string;
    actorUserId: string;
  }): Promise<ProductKnowledgeRecord> {
    const existing = this.records.get(input.productKey);
    const timestamp = this.now().toISOString();
    const item: ProductKnowledgeRecord = {
      id: existing?.id ?? `local-${input.productKey.replace(/[^a-zA-Z0-9_-]/g, '-')}`,
      workspaceId: input.workspaceId,
      productKey: input.productKey,
      productId: input.productId,
      productRole: input.productRole,
      featured: input.featured,
      status: input.status,
      tags: [...new Set(input.tags.map((tag) => tag.trim()).filter(Boolean))],
      note: input.note.trim(),
      ownerUserId: input.ownerUserId.trim(),
      createdBy: existing?.createdBy ?? input.actorUserId,
      updatedBy: input.actorUserId,
      createdAt: existing?.createdAt ?? timestamp,
      updatedAt: timestamp,
    };
    this.records.set(input.productKey, item);
    await this.persist();
    return { ...item, tags: [...item.tags] };
  }

  async archive(workspaceId: string, productKey: string, actorUserId: string): Promise<ProductKnowledgeRecord | null> {
    if (workspaceId !== this.workspaceId) return null;
    const existing = this.records.get(productKey);
    if (!existing) return null;
    const item: ProductKnowledgeRecord = {
      ...existing,
      featured: false,
      status: 'archived',
      updatedBy: actorUserId,
      updatedAt: this.now().toISOString(),
    };
    this.records.set(productKey, item);
    await this.persist();
    return { ...item, tags: [...item.tags] };
  }

  private seedTopProducts(dataset: DomesticDataset): void {
    const timestamp = this.now().toISOString();
    const candidates = [...dataset.products]
      .filter((product) => product.role === 'own')
      .sort((left, right) => right.summary.gmv - left.summary.gmv || right.summary.soldUnits - left.summary.soldUnits)
      .slice(0, 8);
    for (const product of candidates) {
      const category = product.category3 || product.category2 || product.category1;
      const item: ProductKnowledgeRecord = {
        id: `local-${product.productKey.replace(/[^a-zA-Z0-9_-]/g, '-')}`,
        workspaceId: this.workspaceId,
        productKey: product.productKey,
        productId: product.productId,
        productRole: product.role,
        featured: true,
        status: 'active',
        tags: ['经营TOP', ...(category ? [category] : [])],
        note: '按成交金额初始化的重点商品，可在知识库内补充关注事项。',
        ownerUserId: '',
        createdBy: 'local-bootstrap',
        updatedBy: 'local-bootstrap',
        createdAt: timestamp,
        updatedAt: timestamp,
      };
      this.records.set(product.productKey, item);
    }
  }

  private async persist(): Promise<void> {
    if (!this.persistencePath) return;
    await mkdir(dirname(this.persistencePath), { recursive: true });
    const payload: LocalKnowledgeFile = {
      schemaVersion: 1,
      items: [...this.records.values()].sort((left, right) => left.productKey.localeCompare(right.productKey)),
    };
    await writeFile(this.persistencePath, `${JSON.stringify(payload, null, 2)}\n`, 'utf8');
  }
}