import { Injectable, NotFoundException } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { NotificationService } from '../notification/notification.service';

@Injectable()
export class CommentService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly notificationService: NotificationService,
  ) {}

  async findAll(tenantId: string, ticketId: string) {
    const db = this.prisma.forTenant(tenantId);
    const ticket = await db.ticket.findFirst({ where: { id: ticketId } });
    if (!ticket) throw new NotFoundException('Ticket not found');

    return this.prisma.ticketComment.findMany({
      where: { tenantId, ticketId },
      include: {
        author: { select: { id: true, firstName: true, lastName: true } },
        attachments: true,
      },
      orderBy: { createdAt: 'asc' },
    });
  }

  async create(
    tenantId: string,
    ticketId: string,
    userId: string,
    content: string,
    files?: Express.Multer.File[],
  ) {
    const db = this.prisma.forTenant(tenantId);
    const ticket = await db.ticket.findFirst({ where: { id: ticketId } });
    if (!ticket) throw new NotFoundException('Ticket not found');

    const comment = await this.prisma.ticketComment.create({
      data: {
        tenantId,
        ticketId,
        userId,
        content,
        attachments: files?.length
          ? {
              create: files.map((f) => ({
                fileName: f.originalname,
                filePath: f.filename,
                fileType: f.mimetype,
                fileSize: f.size,
              })),
            }
          : undefined,
      },
      include: {
        author: { select: { id: true, firstName: true, lastName: true } },
        attachments: true,
      },
    });

    // Parse @mentions and notify mentioned users
    const mentions = this.parseMentions(content);
    if (mentions.length > 0) {
      const db2 = this.prisma.forTenant(tenantId);
      const users = await db2.user.findMany({
        where: { tenantId, isActive: true },
        select: { id: true, firstName: true, lastName: true },
      });

      const commenterName = `${comment.author.firstName} ${comment.author.lastName}`;

      for (const mention of mentions) {
        const mentionedUser = users.find(
          (u) =>
            `${u.firstName} ${u.lastName}`.toLowerCase() === mention.toLowerCase() ||
            u.firstName.toLowerCase() === mention.toLowerCase(),
        );
        if (mentionedUser && mentionedUser.id !== userId) {
          await this.notificationService.create(tenantId, {
            userId: mentionedUser.id,
            type: 'in_app',
            channel: 'mention',
            title: 'You were mentioned',
            message: `${commenterName} mentioned you in "${ticket.title}"`,
            ticketId,
          });
        }
      }
    }

    // Notify ticket creator (if not the commenter)
    if (ticket.createdById && ticket.createdById !== userId) {
      const commenterName = `${comment.author.firstName} ${comment.author.lastName}`;
      await this.notificationService.create(tenantId, {
        userId: ticket.createdById,
        type: 'in_app',
        channel: 'comment_added',
        title: 'New comment on your ticket',
        message: `${commenterName} commented on "${ticket.title}"`,
        ticketId,
      });
    }

    return comment;
  }

  /** Extract @FirstName or @FirstNameLastName from content */
  private parseMentions(content: string): string[] {
    const regex = /@(\w+(?:\s+\w+)?)/g;
    const matches: string[] = [];
    let match: RegExpExecArray | null;
    while ((match = regex.exec(content)) !== null) {
      matches.push(match[1]);
    }
    return [...new Set(matches)];
  }
}