import { createClient } from '@/lib/supabase/server'
import { NextResponse } from 'next/server'
import { reverseEntry } from '@/lib/bookkeeping/engine'
import { bookkeepingErrorResponse } from '@/lib/bookkeeping/errors'
import { ensureInitialized } from '@/lib/init'
import { requireCompanyId } from '@/lib/company/context'
import { requireWritePermission } from '@/lib/auth/require-write'

ensureInitialized()

export async function POST(
  _request: Request,
  { params }: { params: Promise<{ id: string }> }
) {
  const supabase = await createClient()
  const { data: { user } } = await supabase.auth.getUser()
  if (!user) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  const writeCheck = await requireWritePermission(supabase, user.id)
  if (!writeCheck.ok) return writeCheck.response

  const companyId = await requireCompanyId(supabase, user.id)

  const { id } = await params

  // Fetch transaction
  const { data: transaction, error: txError } = await supabase
    .from('transactions')
    .select('id, journal_entry_id')
    .eq('id', id)
    .eq('company_id', companyId)
    .single()

  if (txError || !transaction) {
    return NextResponse.json({ error: 'Transaction not found' }, { status: 404 })
  }

  if (!transaction.journal_entry_id) {
    return NextResponse.json({ error: 'Transaction has no journal entry' }, { status: 400 })
  }

  // Verify journal entry is posted
  const { data: entry, error: entryError } = await supabase
    .from('journal_entries')
    .select('id, status')
    .eq('id', transaction.journal_entry_id)
    .eq('company_id', companyId)
    .single()

  if (entryError || !entry) {
    return NextResponse.json({ error: 'Journal entry not found' }, { status: 400 })
  }

  if (entry.status !== 'posted') {
    return NextResponse.json({ error: 'Journal entry is not posted' }, { status: 400 })
  }

  // Storno reversal (legally compliant — never deletes)
  try {
    await reverseEntry(supabase, companyId, user.id, transaction.journal_entry_id)
  } catch (err) {
    const typed = bookkeepingErrorResponse(err)
    if (typed) return typed
    const message = err instanceof Error ? err.message : 'Reversal failed'
    return NextResponse.json({ error: message }, { status: 500 })
  }

  // Reset transaction categorization
  const { error: updateError } = await supabase
    .from('transactions')
    .update({
      is_business: null,
      category: null,
      journal_entry_id: null,
    })
    .eq('id', id)
    .eq('company_id', companyId)

  if (updateError) {
    return NextResponse.json({ error: 'Failed to reset transaction' }, { status: 500 })
  }

  return NextResponse.json({ success: true })
}