import {
  BadRequestException,
  ForbiddenException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import type {
  CreateKnowledgeBaseRequest,
  CreateKnowledgeDocumentRequest,
  KnowledgeBaseDto,
  KnowledgeBaseOptionDto,
  KnowledgeDocumentDetailDto,
  KnowledgeDocumentDto,
  UpdateKnowledgeBaseRequest,
  UpdateKnowledgeDocumentRequest,
} from '@dukang/shared-types';
import { PrismaService } from '../../common/prisma/prisma.module';
import { serializeBigInt } from '../../common/decorators/current-user.decorator';

type ActorCtx = { actorId: bigint; isSuperAdmin: boolean };

const TEXT_EXT = /\.(txt|md|markdown|csv|json|log)$/i;

@Injectable()
export class AdminKnowledgeBasesService {
  constructor(private readonly prisma: PrismaService) {}

  async resolveActor(actorId: bigint): Promise<ActorCtx> {
    const account = await this.prisma.hqAccount.findUnique({
      where: { id: actorId },
      select: { adminRole: true, status: true },
    });
    if (!account || account.status !== 'ACTIVE') {
      throw new ForbiddenException('账号不可用');
    }
    return {
      actorId,
      isSuperAdmin: account.adminRole === 'SUPER_ADMIN',
    };
  }

  async list(
    actor: ActorCtx,
    query: { name?: string; enabled?: string; page?: number; pageSize?: number },
  ) {
    const page = query.page ?? 1;
    const pageSize = query.pageSize ?? 20;
    const where: {
      name?: { contains: string };
      enabled?: boolean;
      createdByHqAccountId?: bigint;
    } = {};
    if (!actor.isSuperAdmin) where.createdByHqAccountId = actor.actorId;
    if (query.name?.trim()) where.name = { contains: query.name.trim() };
    if (query.enabled === 'true' || query.enabled === 'false') {
      where.enabled = query.enabled === 'true';
    }

    const [items, total] = await Promise.all([
      this.prisma.knowledgeBase.findMany({
        where,
        orderBy: [{ id: 'desc' }],
        skip: (page - 1) * pageSize,
        take: pageSize,
        include: { _count: { select: { documents: true } } },
      }),
      this.prisma.knowledgeBase.count({ where }),
    ]);

    const ownerIds = [...new Set(items.map((i) => i.createdByHqAccountId))];
    const owners = ownerIds.length
      ? await this.prisma.hqAccount.findMany({
          where: { id: { in: ownerIds } },
          select: { id: true, name: true },
        })
      : [];
    const ownerMap = new Map(owners.map((o) => [o.id.toString(), o.name]));

    return serializeBigInt({
      items: items.map((row) =>
        this.toKbDto(row, actor, ownerMap.get(row.createdByHqAccountId.toString()) ?? null, row._count.documents),
      ),
      total,
      page,
      pageSize,
    });
  }

  async options(actor: ActorCtx): Promise<KnowledgeBaseOptionDto[]> {
    const where: { enabled: boolean; createdByHqAccountId?: bigint } = { enabled: true };
    if (!actor.isSuperAdmin) where.createdByHqAccountId = actor.actorId;
    const rows = await this.prisma.knowledgeBase.findMany({
      where,
      orderBy: [{ id: 'desc' }],
      include: { _count: { select: { documents: true } } },
    });
    return rows.map((r) => ({
      id: r.id.toString(),
      name: r.name,
      enabled: r.enabled,
      documentCount: r._count.documents,
    }));
  }

  async detail(actor: ActorCtx, id: bigint) {
    const row = await this.requireKb(actor, id);
    const count = await this.prisma.knowledgeDocument.count({ where: { knowledgeBaseId: id } });
    const owner = await this.prisma.hqAccount.findUnique({
      where: { id: row.createdByHqAccountId },
      select: { name: true },
    });
    return this.toKbDto(row, actor, owner?.name ?? null, count);
  }

  async create(actor: ActorCtx, dto: CreateKnowledgeBaseRequest) {
    const name = dto.name?.trim();
    if (!name) throw new BadRequestException('请填写名称');
    const row = await this.prisma.knowledgeBase.create({
      data: {
        name,
        description: dto.description?.trim() || null,
        enabled: dto.enabled !== false,
        createdByHqAccountId: actor.actorId,
      },
    });
    return this.toKbDto(row, actor, null, 0);
  }

  async update(actor: ActorCtx, id: bigint, dto: UpdateKnowledgeBaseRequest) {
    const row = await this.requireKb(actor, id);
    this.requireWrite(actor, row);

    if (!actor.isSuperAdmin) {
      // 创建人可改名称/描述/启用
      const data: {
        name?: string;
        description?: string | null;
        enabled?: boolean;
      } = {};
      if (dto.name !== undefined) {
        const name = dto.name.trim();
        if (!name) throw new BadRequestException('名称不能为空');
        data.name = name;
      }
      if (dto.description !== undefined) data.description = dto.description?.trim() || null;
      if (dto.enabled !== undefined) data.enabled = dto.enabled;
      const updated = await this.prisma.knowledgeBase.update({ where: { id }, data });
      const count = await this.prisma.knowledgeDocument.count({ where: { knowledgeBaseId: id } });
      return this.toKbDto(updated, actor, null, count);
    }

    const data: {
      name?: string;
      description?: string | null;
      enabled?: boolean;
    } = {};
    if (dto.name !== undefined) {
      const name = dto.name.trim();
      if (!name) throw new BadRequestException('名称不能为空');
      data.name = name;
    }
    if (dto.description !== undefined) data.description = dto.description?.trim() || null;
    if (dto.enabled !== undefined) data.enabled = dto.enabled;
    const updated = await this.prisma.knowledgeBase.update({ where: { id }, data });
    const count = await this.prisma.knowledgeDocument.count({ where: { knowledgeBaseId: id } });
    return this.toKbDto(updated, actor, null, count);
  }

  async remove(actor: ActorCtx, id: bigint) {
    const row = await this.requireKb(actor, id);
    this.requireWrite(actor, row);
    await this.prisma.knowledgeBase.delete({ where: { id } });
    return { ok: true };
  }

  async listDocuments(actor: ActorCtx, kbId: bigint) {
    await this.requireKb(actor, kbId);
    const rows = await this.prisma.knowledgeDocument.findMany({
      where: { knowledgeBaseId: kbId },
      orderBy: [{ id: 'desc' }],
    });
    return serializeBigInt({ items: rows.map((r) => this.toDocDto(r)) });
  }

  async addDocument(actor: ActorCtx, kbId: bigint, dto: CreateKnowledgeDocumentRequest) {
    const kb = await this.requireKb(actor, kbId);
    this.requireWrite(actor, kb);

    const title = dto.title?.trim();
    if (!title) throw new BadRequestException('请填写标题');

    let contentText = dto.contentText?.trim() || '';
    let status: 'READY' | 'EMPTY' | 'FAILED' = 'EMPTY';
    let errorMessage: string | null = null;

    if (contentText) {
      status = 'READY';
    } else if (dto.fileUrl?.trim()) {
      const fileName = dto.fileName?.trim() || '';
      if (TEXT_EXT.test(fileName) || isLikelyTextMime(dto.mimeType)) {
        try {
          contentText = await fetchText(dto.fileUrl.trim());
          status = contentText.trim() ? 'READY' : 'EMPTY';
          if (!contentText.trim()) errorMessage = '文件内容为空';
        } catch (e) {
          status = 'FAILED';
          errorMessage = e instanceof Error ? e.message : String(e);
        }
      } else {
        status = 'EMPTY';
        errorMessage = '非文本文件未抽取正文，请粘贴文本或上传 .txt/.md';
      }
    } else {
      throw new BadRequestException('请粘贴正文或上传文件');
    }

    const row = await this.prisma.knowledgeDocument.create({
      data: {
        knowledgeBaseId: kbId,
        title,
        fileName: dto.fileName?.trim() || null,
        fileUrl: dto.fileUrl?.trim() || null,
        mimeType: dto.mimeType?.trim() || null,
        sizeBytes: dto.sizeBytes ?? null,
        contentText: contentText || null,
        status,
        errorMessage,
      },
    });
    return this.toDocDto(row);
  }

  async getDocument(actor: ActorCtx, kbId: bigint, docId: bigint): Promise<KnowledgeDocumentDetailDto> {
    await this.requireKb(actor, kbId);
    const doc = await this.prisma.knowledgeDocument.findFirst({
      where: { id: docId, knowledgeBaseId: kbId },
    });
    if (!doc) throw new NotFoundException('文档不存在');
    return {
      ...this.toDocDto(doc),
      contentText: doc.contentText,
    };
  }

  async updateDocument(
    actor: ActorCtx,
    kbId: bigint,
    docId: bigint,
    dto: UpdateKnowledgeDocumentRequest,
  ) {
    const kb = await this.requireKb(actor, kbId);
    this.requireWrite(actor, kb);
    const doc = await this.prisma.knowledgeDocument.findFirst({
      where: { id: docId, knowledgeBaseId: kbId },
    });
    if (!doc) throw new NotFoundException('文档不存在');

    const data: {
      title?: string;
      fileName?: string | null;
      fileUrl?: string | null;
      mimeType?: string | null;
      sizeBytes?: number | null;
      contentText?: string | null;
      status?: 'READY' | 'EMPTY' | 'FAILED';
      errorMessage?: string | null;
    } = {};

    if (dto.title !== undefined) {
      const title = dto.title.trim();
      if (!title) throw new BadRequestException('请填写标题');
      data.title = title;
    }

    const hasContentInput =
      dto.contentText !== undefined ||
      dto.fileUrl !== undefined ||
      dto.fileName !== undefined ||
      dto.mimeType !== undefined;

    if (hasContentInput) {
      let contentText = dto.contentText !== undefined ? dto.contentText?.trim() || '' : doc.contentText?.trim() || '';
      let status: 'READY' | 'EMPTY' | 'FAILED' = doc.status as 'READY' | 'EMPTY' | 'FAILED';
      let errorMessage: string | null = doc.errorMessage;

      if (dto.contentText !== undefined) {
        if (contentText) {
          status = 'READY';
          errorMessage = null;
        } else if (!dto.fileUrl?.trim() && !doc.fileUrl) {
          status = 'EMPTY';
          errorMessage = null;
        }
        data.contentText = contentText || null;
      }

      if (dto.fileUrl !== undefined) data.fileUrl = dto.fileUrl?.trim() || null;
      if (dto.fileName !== undefined) data.fileName = dto.fileName?.trim() || null;
      if (dto.mimeType !== undefined) data.mimeType = dto.mimeType?.trim() || null;
      if (dto.sizeBytes !== undefined) data.sizeBytes = dto.sizeBytes ?? null;

      const fileUrl = dto.fileUrl?.trim() || doc.fileUrl;
      const fileName = dto.fileName?.trim() || doc.fileName || '';
      const mimeType = dto.mimeType?.trim() || doc.mimeType;

      if (dto.fileUrl?.trim() && dto.contentText === undefined) {
        if (TEXT_EXT.test(fileName) || isLikelyTextMime(mimeType)) {
          try {
            contentText = await fetchText(dto.fileUrl.trim());
            data.contentText = contentText || null;
            status = contentText.trim() ? 'READY' : 'EMPTY';
            errorMessage = contentText.trim() ? null : '文件内容为空';
          } catch (e) {
            status = 'FAILED';
            errorMessage = e instanceof Error ? e.message : String(e);
          }
        } else {
          status = 'EMPTY';
          errorMessage = '非文本文件未抽取正文，请粘贴文本或上传 .txt/.md';
        }
      } else if (dto.contentText !== undefined && contentText) {
        status = 'READY';
        errorMessage = null;
      } else if (dto.contentText !== undefined && !contentText && !fileUrl) {
        status = 'EMPTY';
        errorMessage = null;
      }

      data.status = status;
      data.errorMessage = errorMessage;
    }

    const updated = await this.prisma.knowledgeDocument.update({
      where: { id: docId },
      data,
    });
    return this.toDocDto(updated);
  }

  async removeDocument(actor: ActorCtx, kbId: bigint, docId: bigint) {
    const kb = await this.requireKb(actor, kbId);
    this.requireWrite(actor, kb);
    const doc = await this.prisma.knowledgeDocument.findFirst({
      where: { id: docId, knowledgeBaseId: kbId },
    });
    if (!doc) throw new NotFoundException('文档不存在');
    await this.prisma.knowledgeDocument.delete({ where: { id: docId } });
    return { ok: true };
  }

  private async requireKb(actor: ActorCtx, id: bigint) {
    const row = await this.prisma.knowledgeBase.findUnique({ where: { id } });
    if (!row) throw new NotFoundException('知识库不存在');
    if (!actor.isSuperAdmin && row.createdByHqAccountId !== actor.actorId) {
      throw new ForbiddenException('无权查看该知识库');
    }
    return row;
  }

  private requireWrite(
    actor: ActorCtx,
    row: { createdByHqAccountId: bigint },
  ) {
    if (actor.isSuperAdmin) return;
    if (row.createdByHqAccountId !== actor.actorId) {
      throw new ForbiddenException('只能操作自己创建的知识库');
    }
  }

  private toKbDto(
    row: {
      id: bigint;
      name: string;
      description: string | null;
      enabled: boolean;
      createdByHqAccountId: bigint;
      createdAt: Date;
      updatedAt: Date;
    },
    actor: ActorCtx,
    createdByName: string | null,
    documentCount: number,
  ): KnowledgeBaseDto {
    const isOwner = row.createdByHqAccountId === actor.actorId;
    return {
      id: row.id.toString(),
      name: row.name,
      description: row.description,
      enabled: row.enabled,
      documentCount,
      createdByHqAccountId: row.createdByHqAccountId.toString(),
      createdByName,
      isOwner,
      canEditFull: actor.isSuperAdmin || isOwner,
      createdAt: row.createdAt.toISOString(),
      updatedAt: row.updatedAt.toISOString(),
    };
  }

  private toDocDto(row: {
    id: bigint;
    knowledgeBaseId: bigint;
    title: string;
    fileName: string | null;
    fileUrl: string | null;
    mimeType: string | null;
    sizeBytes: number | null;
    contentText: string | null;
    status: string;
    errorMessage: string | null;
    createdAt: Date;
    updatedAt: Date;
  }): KnowledgeDocumentDto {
    const status =
      row.status === 'READY' || row.status === 'FAILED' || row.status === 'EMPTY'
        ? row.status
        : 'EMPTY';
    return {
      id: row.id.toString(),
      knowledgeBaseId: row.knowledgeBaseId.toString(),
      title: row.title,
      fileName: row.fileName,
      fileUrl: row.fileUrl,
      mimeType: row.mimeType,
      sizeBytes: row.sizeBytes,
      hasContent: !!(row.contentText && row.contentText.trim()),
      status,
      errorMessage: row.errorMessage,
      createdAt: row.createdAt.toISOString(),
      updatedAt: row.updatedAt.toISOString(),
    };
  }
}

function isLikelyTextMime(mime?: string | null) {
  if (!mime) return false;
  return (
    mime.startsWith('text/') ||
    mime === 'application/json' ||
    mime === 'application/markdown'
  );
}

async function fetchText(url: string): Promise<string> {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`下载文件失败 HTTP ${res.status}`);
  const buf = await res.arrayBuffer();
  if (buf.byteLength > 2 * 1024 * 1024) throw new Error('文本文件超过 2MB');
  return new TextDecoder('utf-8', { fatal: false }).decode(buf);
}