import { NextRequest, NextResponse } from 'next/server'
import connectDB from '@/lib/mongodb'
import TopicModel, { transformToTopics } from '@/models/topic'

export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ slug: string }> }
) {
  try {
    await connectDB()

    const { slug } = await params
    const searchParams = request.nextUrl.searchParams
    const limit = parseInt(searchParams.get('limit') || '2')

    if (!slug) {
      return NextResponse.json(
        {
          success: false,
          error: {
            message: 'Topic slug is required',
            code: 'SLUG_REQUIRED',
          },
        },
        { status: 400 }
      )
    }

    // First, get the current post to find its ID and tags
    const currentPost = await TopicModel.findOne({ 
      slug, 
      isDraft: false 
    }).lean()

    if (!currentPost) {
      return NextResponse.json({
        success: true,
        data: [],
      })
    }

    // Find related posts by excluding the current post and sorting by publishedAt
    const relatedPosts = await TopicModel.find({
      id: { $ne: currentPost.id },
      isDraft: false,
    })
      .sort({ publishedAt: -1 })
      .limit(limit)
      .lean()

    // Transform to proper format
    const transformedPosts = transformToTopics(relatedPosts)

    return NextResponse.json({
      success: true,
      data: transformedPosts,
    })
  } catch (error) {
    console.error('Error fetching related posts:', error)
    return NextResponse.json(
      {
        success: false,
        error: {
          message: 'Failed to fetch related posts',
          code: 'SERVER_ERROR',
        },
      },
      { status: 500 }
    )
  }
}