import { NextRequest, NextResponse } from 'next/server'
import { prisma } from '@/lib/prisma'
import { noteSchema } from '@/lib/validators'

export async function GET() {
  const notes = await prisma.note.findMany({
    include: { tags: { include: { tag: true } } },
  })

  const exportData = notes.map(note => ({
    ...note,
    tags: note.tags.map(nt => nt.tag.name),
    createdAt: note.createdAt.toISOString(),
    updatedAt: note.updatedAt.toISOString(),
  }))

  return NextResponse.json(exportData, { status: 200 })
}

export async function POST(req: NextRequest) {
  const body = await req.json()

  if (!Array.isArray(body)) {
    return NextResponse.json({ error: 'Invalid format: expected array' }, { status: 400 })
  }

  const importedNotes: Array<{ id?: string; title: string }> = []
  const errors: string[] = []

  for (let i = 0; i < body.length; i++) {
    const result = noteSchema.safeParse(body[i])
    if (!result.success) {
      errors.push(`Item ${i}: ${result.error.issues.map(e => e.message).join(', ')}`)
      continue
    }
    importedNotes.push(result.data)
  }

  if (errors.length > 0) {
    return NextResponse.json({ error: 'Validation failed', details: errors }, { status: 400 })
  }

  const parseDate = (dateStr: string | undefined): Date => {
    if (!dateStr) return new Date()
    const parsed = new Date(dateStr)
    return isNaN(parsed.getTime()) ? new Date() : parsed
  }

  let processed = 0

  await prisma.$transaction(async (tx) => {
    for (const item of importedNotes) {
      const tags = item.tags || []
      const { tags: _, ...noteData } = item

      const createdAt = parseDate((item as { createdAt?: string }).createdAt)
      const updatedAt = parseDate((item as { updatedAt?: string }).updatedAt)

      if (item.id) {
        const existing = await tx.note.findUnique({ where: { id: item.id } })
        if (existing) {
          await tx.note.update({
            where: { id: item.id },
            data: { ...noteData, createdAt, updatedAt },
          })
          await tx.noteTag.deleteMany({ where: { noteId: item.id } })
          processed++
        } else {
          await tx.note.create({
            data: {
              ...noteData,
              id: item.id,
              createdAt,
              updatedAt,
            },
          })
          processed++
        }
      } else {
        const existingByTitle = await tx.note.findFirst({
          where: { title: item.title },
        })
        if (existingByTitle) {
          await tx.note.update({
            where: { id: existingByTitle.id },
            data: { ...noteData, updatedAt },
          })
          await tx.noteTag.deleteMany({ where: { noteId: existingByTitle.id } })
        } else {
          await tx.note.create({
            data: {
              ...noteData,
              createdAt,
              updatedAt,
            },
          })
        }
        processed++
      }

      const noteId = item.id
        ? (await tx.note.findUnique({ where: { id: item.id } }))?.id
        : (await tx.note.findFirst({ where: { title: item.title } }))?.id

      if (noteId && tags.length > 0) {
        for (const tagName of tags) {
          const tag = await tx.tag.upsert({
            where: { name: tagName },
            create: { name: tagName },
            update: {},
          })
          await tx.noteTag.create({
            data: { noteId, tagId: tag.id },
          })
        }
      }
    }
  })

  return NextResponse.json({ success: true, count: processed }, { status: 201 })
}