import {
  BadRequestException,
  ForbiddenException,
  Injectable,
  NotFoundException,
} from '@nestjs/common';
import {
  ContentStatus,
  MediaEntityType,
  Prisma,
} from '@prisma/client';
import { AuthUser } from '../auth/auth.types';
import { PermissionsService } from '../auth/permissions.service';
import { BusinessSettingsService } from '../business-settings/business-settings.service';
import { PrismaService } from '../prisma/prisma.service';
import { TenantService } from '../tenant/tenant.service';
import {
  CreateBlogCommentDto,
  CreateBlogDto,
  ListBlogsDto,
  ListPublicBlogsDto,
  UpdateBlogDto,
} from './dto/blog.dto';

function slugify(value: string): string {
  return (
    value
      .toLowerCase()
      .trim()
      .replace(/[^a-z0-9]+/g, '-')
      .replace(/^-+|-+$/g, '') || 'blog'
  );
}

type BlogWithRelations = Prisma.blogsGetPayload<{
  include: {
    media: true;
    users: { select: { id: true; firstName: true; lastName: true; email: true } };
  };
}>;

const blogInclude = {
  media: true,
  users: {
    select: {
      id: true,
      firstName: true,
      lastName: true,
      email: true,
    },
  },
} satisfies Prisma.blogsInclude;

@Injectable()
export class BlogsService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly permissions: PermissionsService,
    private readonly tenant: TenantService,
    private readonly businessSettings: BusinessSettingsService,
  ) {}

  async list(businessIdRaw: string, query: ListBlogsDto, actor: AuthUser) {
    const businessId = BigInt(businessIdRaw);
    await this.assertPermission(businessId, actor.id, 'blogs.read');

    const page = query.page ?? 1;
    const pageSize = query.pageSize ?? 12;
    const skip = (page - 1) * pageSize;

    const where = await this.buildWhere(businessId, query);

    const [items, total] = await Promise.all([
      this.prisma.blogs.findMany({
        where,
        orderBy: [{ published_at: 'desc' }, { created_at: 'desc' }],
        skip,
        take: pageSize,
        include: blogInclude,
      }),
      this.prisma.blogs.count({ where }),
    ]);

    const serialized = await Promise.all(
      items.map((item) => this.serializeBlog(item, { includeComments: true })),
    );

    return { items: serialized, total, page, pageSize };
  }

  async getOne(businessIdRaw: string, blogIdRaw: string, actor: AuthUser) {
    const businessId = BigInt(businessIdRaw);
    const blogId = BigInt(blogIdRaw);
    await this.assertPermission(businessId, actor.id, 'blogs.read');

    const blog = await this.findBlogOrThrow(businessId, blogId);

    return { blog: await this.serializeBlog(blog, { includeComments: true }) };
  }

  async create(businessIdRaw: string, dto: CreateBlogDto, actor: AuthUser) {
    const businessId = BigInt(businessIdRaw);
    await this.assertPermission(businessId, actor.id, 'blogs.create');

    const slug = await this.ensureUniqueSlug(
      businessId,
      dto.slug ?? slugify(dto.title),
    );

    const status = dto.status ?? ContentStatus.draft;
    const featuredMediaId = dto.featuredMediaId
      ? BigInt(dto.featuredMediaId)
      : null;

    if (featuredMediaId) {
      await this.assertMediaBelongsToBusiness(businessId, featuredMediaId);
    }

    const authorId = dto.authorId ? BigInt(dto.authorId) : actor.id;
    await this.assertAuthorBelongsToBusiness(businessId, authorId);

    if (dto.categoryId) {
      await this.assertCategoryBelongsToBusiness(businessId, BigInt(dto.categoryId));
    }

    const created = await this.prisma.$transaction(async (tx) => {
      const blog = await tx.blogs.create({
        data: {
          business_id: businessId,
          author_id: authorId,
          title: dto.title.trim(),
          slug,
          excerpt: dto.abstract?.trim() || null,
          content: this.buildContent(dto.mainTextHtml) as Prisma.InputJsonValue,
          post_type: dto.type,
          status,
          featured_media_id: featuredMediaId,
          published_at: status === ContentStatus.published ? new Date() : null,
          metadata: this.buildMetadata(dto.tags) as Prisma.InputJsonValue,
        },
        include: blogInclude,
      });

      if (dto.categoryId) {
        await tx.categoryAssignment.create({
          data: {
            businessId,
            categoryId: BigInt(dto.categoryId),
            entityType: MediaEntityType.blog,
            entityId: blog.id,
          },
        });
      }

      return blog;
    });

    return {
      message: 'Blog post created successfully',
      blog: await this.serializeBlog(created),
    };
  }

  async update(
    businessIdRaw: string,
    blogIdRaw: string,
    dto: UpdateBlogDto,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    const blogId = BigInt(blogIdRaw);
    await this.assertPermission(businessId, actor.id, 'blogs.update');

    const existing = await this.prisma.blogs.findFirst({
      where: { id: blogId, business_id: businessId },
    });

    if (!existing) {
      throw new NotFoundException('Blog post not found');
    }

    let slug = existing.slug;
    if (dto.slug) {
      slug = await this.ensureUniqueSlug(businessId, dto.slug, blogId);
    } else if (dto.title && dto.title !== existing.title) {
      slug = await this.ensureUniqueSlug(businessId, slugify(dto.title), blogId);
    }

    let featuredMediaId: bigint | null | undefined = undefined;
    if (dto.featuredMediaId !== undefined) {
      if (dto.featuredMediaId === null || dto.featuredMediaId === '') {
        featuredMediaId = null;
      } else {
        featuredMediaId = BigInt(dto.featuredMediaId);
        await this.assertMediaBelongsToBusiness(businessId, featuredMediaId);
      }
    }

    let authorId: bigint | null | undefined = undefined;
    if (dto.authorId !== undefined) {
      if (dto.authorId === null || dto.authorId === '') {
        authorId = null;
      } else {
        authorId = BigInt(dto.authorId);
        await this.assertAuthorBelongsToBusiness(businessId, authorId);
      }
    }

    const existingContent = this.asRecord(existing.content);
    const existingMetadata = this.asRecord(existing.metadata);

    const nextContent = { ...existingContent };
    if (dto.mainTextHtml !== undefined) {
      nextContent.html = dto.mainTextHtml ?? '';
    }

    const nextMetadata = { ...existingMetadata };
    if (dto.tags !== undefined) {
      nextMetadata.tags = dto.tags;
    }

    let publishedAt: Date | null | undefined = undefined;
    if (dto.status !== undefined) {
      if (dto.status === ContentStatus.published && existing.status !== ContentStatus.published) {
        publishedAt = new Date();
      }
      if (dto.status !== ContentStatus.published) {
        publishedAt = null;
      }
    }

    const updated = await this.prisma.$transaction(async (tx) => {
      const blog = await tx.blogs.update({
        where: { id: blogId },
        data: {
          ...(dto.title !== undefined ? { title: dto.title.trim() } : {}),
          ...(dto.abstract !== undefined
            ? { excerpt: dto.abstract?.trim() || null }
            : {}),
          ...(dto.type !== undefined ? { post_type: dto.type } : {}),
          ...(dto.status !== undefined ? { status: dto.status } : {}),
          ...(featuredMediaId !== undefined ? { featured_media_id: featuredMediaId } : {}),
          ...(authorId !== undefined ? { author_id: authorId } : {}),
          ...(publishedAt !== undefined ? { published_at: publishedAt } : {}),
          slug,
          content: nextContent as Prisma.InputJsonValue,
          metadata: nextMetadata as Prisma.InputJsonValue,
        },
        include: blogInclude,
      });

      if (dto.categoryId !== undefined) {
        await tx.categoryAssignment.deleteMany({
          where: {
            businessId,
            entityType: MediaEntityType.blog,
            entityId: blogId,
          },
        });

        if (dto.categoryId) {
          const categoryId = BigInt(dto.categoryId);
          await this.assertCategoryBelongsToBusiness(businessId, categoryId);
          await tx.categoryAssignment.create({
            data: {
              businessId,
              categoryId,
              entityType: MediaEntityType.blog,
              entityId: blogId,
            },
          });
        }
      }

      return blog;
    });

    return {
      message: 'Blog post updated successfully',
      blog: await this.serializeBlog(updated),
    };
  }

  async remove(businessIdRaw: string, blogIdRaw: string, actor: AuthUser) {
    const businessId = BigInt(businessIdRaw);
    const blogId = BigInt(blogIdRaw);
    await this.assertPermission(businessId, actor.id, 'blogs.delete');

    const existing = await this.prisma.blogs.findFirst({
      where: { id: blogId, business_id: businessId },
    });

    if (!existing) {
      throw new NotFoundException('Blog post not found');
    }

    await this.prisma.$transaction([
      this.prisma.comment.deleteMany({
        where: {
          businessId,
          entityType: MediaEntityType.blog,
          entityId: blogId,
        },
      }),
      this.prisma.categoryAssignment.deleteMany({
        where: {
          businessId,
          entityType: MediaEntityType.blog,
          entityId: blogId,
        },
      }),
      this.prisma.blogs.delete({ where: { id: blogId } }),
    ]);

    return { message: 'Blog post deleted successfully' };
  }

  async listPublic(host: string, query: ListPublicBlogsDto) {
    const business = await this.tenant.resolveBusinessByDomain(host);
    const businessId = business.id;

    const page = query.page ?? 1;
    const pageSize = query.pageSize ?? 12;
    const skip = (page - 1) * pageSize;

    const where = await this.buildWhere(businessId, {
      ...query,
      status: ContentStatus.published,
    });

    const [items, total] = await Promise.all([
      this.prisma.blogs.findMany({
        where,
        orderBy: [{ published_at: 'desc' }, { created_at: 'desc' }],
        skip,
        take: pageSize,
        include: blogInclude,
      }),
      this.prisma.blogs.count({ where }),
    ]);

    const serialized = await Promise.all(
      items.map((item) =>
        this.serializeBlog(item, { includeComments: true, approvedCommentsOnly: true }),
      ),
    );

    return { items: serialized, total, page, pageSize };
  }

  async getPublicBySlug(host: string, slug: string) {
    const business = await this.tenant.resolveBusinessByDomain(host);
    const businessId = business.id;

    const blog = await this.prisma.blogs.findFirst({
      where: {
        business_id: businessId,
        slug,
        status: ContentStatus.published,
      },
      include: blogInclude,
    });

    if (!blog) {
      throw new NotFoundException('Blog post not found');
    }

    return {
      blog: await this.serializeBlog(blog, {
        includeComments: true,
        approvedCommentsOnly: true,
      }),
    };
  }

  async listCommentsPublic(host: string, blogIdRaw: string) {
    const business = await this.tenant.resolveBusinessByDomain(host);
    const businessId = business.id;
    const blogId = BigInt(blogIdRaw);

    await this.assertPublishedBlogExists(businessId, blogId);

    const items = await this.prisma.comment.findMany({
      where: {
        businessId,
        entityType: MediaEntityType.blog,
        entityId: blogId,
        isApproved: true,
      },
      orderBy: { createdAt: 'desc' },
      include: { approver: true },
    });

    return { items: items.map((item) => this.serializeComment(item)) };
  }

  async createCommentPublic(
    host: string,
    blogIdRaw: string,
    dto: CreateBlogCommentDto,
  ) {
    const business = await this.tenant.resolveBusinessByDomain(host);
    const businessId = business.id;
    const blogId = BigInt(blogIdRaw);

    await this.assertPublishedBlogExists(businessId, blogId);

    const autoApprove = await this.businessSettings.isCommentsAutoApprove(businessId);
    const approvedAt = autoApprove ? new Date() : null;

    const created = await this.prisma.comment.create({
      data: {
        businessId,
        entityType: MediaEntityType.blog,
        entityId: blogId,
        authorName: dto.authorName.trim(),
        authorEmail: dto.authorEmail?.trim() || null,
        text: dto.text.trim(),
        isApproved: autoApprove,
        approvedAt,
      },
      include: { approver: true },
    });

    return {
      comment: this.serializeComment(created),
      message: autoApprove
        ? 'Comment submitted and is approved'
        : 'Comment submitted and is pending approval',
    };
  }

  async listCommentsAdmin(
    businessIdRaw: string,
    blogIdRaw: string,
    actor: AuthUser,
  ) {
    const businessId = BigInt(businessIdRaw);
    const blogId = BigInt(blogIdRaw);
    await this.assertPermission(businessId, actor.id, 'comments.read');

    const blog = await this.prisma.blogs.findFirst({
      where: { id: blogId, business_id: businessId },
      select: { id: true },
    });

    if (!blog) {
      throw new NotFoundException('Blog post not found');
    }

    const items = await this.prisma.comment.findMany({
      where: {
        businessId,
        entityType: MediaEntityType.blog,
        entityId: blogId,
      },
      orderBy: { createdAt: 'desc' },
      include: { approver: true },
    });

    return { items: items.map((item) => this.serializeComment(item)) };
  }

  private async buildWhere(
    businessId: bigint,
    query: (ListBlogsDto | ListPublicBlogsDto) & { status?: ContentStatus },
  ): Promise<Prisma.blogsWhereInput> {
    let entityIds: bigint[] | undefined;

    if (query.categoryId) {
      const assignments = await this.prisma.categoryAssignment.findMany({
        where: {
          businessId,
          categoryId: BigInt(query.categoryId),
          entityType: MediaEntityType.blog,
        },
        select: { entityId: true },
      });

      entityIds = assignments.map((item) => item.entityId);

      if (entityIds.length === 0) {
        return { id: { in: [] } };
      }
    }

    return {
      business_id: businessId,
      ...(query.status ? { status: query.status } : {}),
      ...(query.type ? { post_type: query.type } : {}),
      ...(entityIds ? { id: { in: entityIds } } : {}),
      ...(query.title?.trim()
        ? {
            title: { contains: query.title.trim(), mode: 'insensitive' },
          }
        : {}),
    };
  }

  private async findBlogOrThrow(businessId: bigint, blogId: bigint) {
    const blog = await this.prisma.blogs.findFirst({
      where: { id: blogId, business_id: businessId },
      include: blogInclude,
    });

    if (!blog) {
      throw new NotFoundException('Blog post not found');
    }

    return blog;
  }

  private async assertPublishedBlogExists(businessId: bigint, blogId: bigint) {
    const blog = await this.prisma.blogs.findFirst({
      where: {
        id: blogId,
        business_id: businessId,
        status: ContentStatus.published,
      },
      select: { id: true },
    });

    if (!blog) {
      throw new NotFoundException('Blog post not found');
    }
  }

  private async serializeBlog(
    blog: BlogWithRelations,
    options: {
      includeComments?: boolean;
      approvedCommentsOnly?: boolean;
    } = {},
  ) {
    const content = this.asRecord(blog.content);
    const metadata = this.asRecord(blog.metadata);

    const [categoryAssignment, commentData] = await Promise.all([
      this.prisma.categoryAssignment.findFirst({
        where: {
          businessId: blog.business_id,
          entityType: MediaEntityType.blog,
          entityId: blog.id,
        },
        include: { category: true },
      }),
      options.includeComments
        ? this.loadComments(blog.business_id, blog.id, options.approvedCommentsOnly)
        : Promise.resolve({ commentCount: 0, comments: [] }),
    ]);

    return {
      id: blog.id.toString(),
      businessId: blog.business_id.toString(),
      title: blog.title,
      slug: blog.slug,
      type: blog.post_type,
      abstract: blog.excerpt ?? '',
      mainTextHtml: (content.html as string | undefined) ?? '',
      status: blog.status,
      categoryId: categoryAssignment?.categoryId.toString() ?? null,
      categoryName: categoryAssignment?.category.name ?? '',
      tags: Array.isArray(metadata.tags) ? (metadata.tags as string[]) : [],
      authorId: blog.author_id?.toString() ?? null,
      author: blog.users
        ? {
            id: blog.users.id.toString(),
            firstName: blog.users.firstName,
            lastName: blog.users.lastName,
            email: blog.users.email,
          }
        : null,
      titleImageUrl: blog.media?.publicUrl ?? null,
      featuredMediaId: blog.featured_media_id?.toString() ?? null,
      commentCount: commentData.commentCount,
      comments: commentData.comments,
      publishedAt: blog.published_at,
      createdAt: blog.created_at,
      updatedAt: blog.updated_at,
    };
  }

  private async loadComments(
    businessId: bigint,
    blogId: bigint,
    approvedOnly?: boolean,
  ) {
    const where: Prisma.CommentWhereInput = {
      businessId,
      entityType: MediaEntityType.blog,
      entityId: blogId,
      ...(approvedOnly ? { isApproved: true } : {}),
    };

    const [commentCount, comments] = await Promise.all([
      this.prisma.comment.count({ where }),
      this.prisma.comment.findMany({
        where,
        orderBy: { createdAt: 'desc' },
        take: approvedOnly ? 50 : undefined,
        include: { approver: true },
      }),
    ]);

    return {
      commentCount,
      comments: comments.map((item) => this.serializeComment(item)),
    };
  }

  private serializeComment(
    comment: Prisma.CommentGetPayload<{ include: { approver: true } }>,
  ) {
    return {
      id: comment.id.toString(),
      businessId: comment.businessId.toString(),
      entityType: comment.entityType,
      entityId: comment.entityId.toString(),
      authorName: comment.authorName,
      authorEmail: comment.authorEmail,
      text: comment.text,
      isApproved: comment.isApproved,
      approvedAt: comment.approvedAt,
      approvedBy: comment.approvedBy?.toString() ?? null,
      approver: comment.approver
        ? {
            id: comment.approver.id.toString(),
            firstName: comment.approver.firstName,
            lastName: comment.approver.lastName,
          }
        : null,
      createdAt: comment.createdAt,
      updatedAt: comment.updatedAt,
    };
  }

  private buildContent(mainTextHtml?: string) {
    return {
      html: mainTextHtml ?? '',
    };
  }

  private buildMetadata(tags?: string[]) {
    return {
      tags: tags?.map((tag) => tag.trim()).filter(Boolean) ?? [],
    };
  }

  private asRecord(value: Prisma.JsonValue): Record<string, unknown> {
    if (value && typeof value === 'object' && !Array.isArray(value)) {
      return value as Record<string, unknown>;
    }
    return {};
  }

  private async assertMediaBelongsToBusiness(businessId: bigint, mediaId: bigint) {
    const media = await this.prisma.media.findFirst({
      where: { id: mediaId, businessId },
    });
    if (!media) {
      throw new BadRequestException('Media not found for this business');
    }
  }

  private async assertCategoryBelongsToBusiness(
    businessId: bigint,
    categoryId: bigint,
  ) {
    const category = await this.prisma.category.findFirst({
      where: {
        id: categoryId,
        businessId,
        entityType: MediaEntityType.blog,
        isActive: true,
      },
    });
    if (!category) {
      throw new BadRequestException('Blog category not found for this business');
    }
  }

  private async assertAuthorBelongsToBusiness(businessId: bigint, authorId: bigint) {
    const member = await this.prisma.businessUser.findFirst({
      where: { businessId, userId: authorId },
    });

    if (!member) {
      throw new BadRequestException('Author must be a team member of this business');
    }
  }

  private async ensureUniqueSlug(
    businessId: bigint,
    baseSlug: string,
    excludeId?: bigint,
  ) {
    let slug = baseSlug;
    let suffix = 1;

    while (true) {
      const existing = await this.prisma.blogs.findFirst({
        where: {
          business_id: businessId,
          slug,
          ...(excludeId ? { NOT: { id: excludeId } } : {}),
        },
      });

      if (!existing) {
        return slug;
      }

      suffix += 1;
      slug = `${baseSlug}-${suffix}`;
    }
  }

  private async assertPermission(
    businessId: bigint,
    userId: bigint,
    permission: string,
  ) {
    const allowed = await this.permissions.hasBusinessPermission(
      userId,
      businessId,
      permission,
    );

    if (!allowed) {
      throw new ForbiddenException(`Missing permission: ${permission} for this business`);
    }
  }
}