import { NextResponse } from 'next/server'
import { ensureInitialized } from '@/lib/init'
import { withRouteContext } from '@/lib/api/with-route-context'
import { validateBody } from '@/lib/api/validate'
import { CreateTransactionFromDocumentSchema } from '@/lib/api/schemas'

ensureInitialized()

/**
 * POST /api/transactions/create-from-document
 *
 * Creates an uncategorized manual bank transaction prefilled from an
 * invoice_inbox_items row, then attaches the inbox item's document to it
 * and links the inbox item to the new transaction. The user categorizes
 * the new transaction through the normal /transactions flow (which routes
 * through the bookkeeping engine and respects period locks, etc.).
 *
 * Use case: receipt in the inbox has no matching bank transaction
 * (cash purchase, personal-card expense, missed sync).
 */
export const POST = withRouteContext(
  'transaction.create_from_document',
  async (request, { supabase, user, companyId }) => {
    const validation = await validateBody(request, CreateTransactionFromDocumentSchema)
    if (!validation.success) return validation.response
    const { inbox_item_id, amount, transaction_date, description } = validation.data

    const { data: item, error: itemError } = await supabase
      .from('invoice_inbox_items')
      .select('id, document_id, matched_transaction_id, created_supplier_invoice_id, extracted_data')
      .eq('id', inbox_item_id)
      .eq('company_id', companyId)
      .maybeSingle()

    if (itemError || !item) {
      return NextResponse.json({ error: 'Inbox item not found' }, { status: 404 })
    }
    if (item.matched_transaction_id) {
      return NextResponse.json(
        { error: 'Inkorgsposten är redan kopplad till en transaktion.' },
        { status: 409 },
      )
    }
    if (item.created_supplier_invoice_id) {
      return NextResponse.json(
        { error: 'Inkorgsposten är redan bokförd som leverantörsfaktura.' },
        { status: 409 },
      )
    }

    // Allowlist the currency: extracted_data.invoice.currency comes from the
    // (deterministic, but still untrusted) PDF extractor, so an arbitrary
    // string like "XYZ" or '"SEK\'"' could otherwise be persisted directly to
    // the transactions table and break later formatCurrency / journal-entry
    // bookings (BFL 5 kap 6 §). Coerce anything outside the supported set
    // to SEK; the user can change it manually on the transaction.
    const ALLOWED_CURRENCIES = new Set(['SEK', 'EUR', 'USD', 'GBP', 'NOK', 'DKK'])
    const extractedCurrency = (
      item.extracted_data as { invoice?: { currency?: string } } | null
    )?.invoice?.currency
    const currency =
      extractedCurrency && ALLOWED_CURRENCIES.has(extractedCurrency)
        ? extractedCurrency
        : 'SEK'

    const { data: newTx, error: insertError } = await supabase
      .from('transactions')
      .insert({
        company_id: companyId,
        user_id: user.id,
        date: transaction_date,
        description,
        amount,
        currency,
        category: 'uncategorized',
        is_business: null,
        import_source: 'manual',
        document_id: item.document_id,
      })
      .select('id')
      .single()

    if (insertError || !newTx) {
      console.error('[create-from-document] Failed to insert transaction:', insertError)
      return NextResponse.json({ error: 'Kunde inte skapa transaktion.' }, { status: 500 })
    }

    // Concurrency guard: the .is('matched_transaction_id', null) predicate +
    // the rows-affected check turn this into an optimistic-lock release. If
    // two requests with the same inbox_item_id race past the earlier
    // matched_transaction_id check, only the first UPDATE will match a row
    // here. The loser's transaction insert is then an orphan we proactively
    // delete so the user doesn't get a duplicate uncategorized row.
    const { data: linked, error: linkError } = await supabase
      .from('invoice_inbox_items')
      .update({ matched_transaction_id: newTx.id })
      .eq('id', inbox_item_id)
      .eq('company_id', companyId)
      .is('matched_transaction_id', null)
      .select('id')

    if (linkError) {
      console.error('[create-from-document] Failed to link inbox item:', linkError)
      // Transaction was created; surface a 200 with a warning so the user can
      // still find it under Transaktioner: the inbox-link orphan is recoverable.
      return NextResponse.json({
        data: { transaction_id: newTx.id, inbox_link_failed: true },
      })
    }

    if (!linked || linked.length === 0) {
      // Lost a race: another concurrent request linked the inbox item first.
      // Roll back our newly-created transaction (only safe because we own it
      // and it has no journal_entry_id yet) and return 409 so the client can
      // refetch and reuse the winning transaction instead of creating a dupe.
      // Re-assert company_id on the delete (defence in depth: newTx.id is a
      // fresh UUID from a company-scoped insert above, but scoping the rollback
      // makes the invariant explicit).
      await supabase.from('transactions').delete().eq('id', newTx.id).eq('company_id', companyId)
      return NextResponse.json(
        { error: 'Inkorgsposten kopplades av en parallell begäran. Försök igen.' },
        { status: 409 },
      )
    }

    return NextResponse.json({
      data: { transaction_id: newTx.id, inbox_item_id, document_id: item.document_id },
    })
  },
  { requireWrite: true },
)