import { db } from '@sim/db'
import { user } from '@sim/db/schema'
import { createLogger } from '@sim/logger'
import { eq } from 'drizzle-orm'
import { type NextRequest, NextResponse } from 'next/server'
import type Stripe from 'stripe'
import { getInvoicesContract } from '@/lib/api/contracts/subscription'
import { parseRequest } from '@/lib/api/server'
import { getSession } from '@/lib/auth'
import { getOrganizationSubscription } from '@/lib/billing/core/billing'
import { isOrganizationOwnerOrAdmin } from '@/lib/billing/core/organization'
import { getStripeClient } from '@/lib/billing/stripe-client'
import { withRouteHandler } from '@/lib/core/utils/with-route-handler'

const logger = createLogger('BillingInvoices')

/** Cap the number of invoices returned to the most recent statements. */
const MAX_INVOICES = 10

/** Stripe page size when scanning for finalized invoices; also bounds the has-more probe. */
const STRIPE_PAGE_SIZE = MAX_INVOICES + 1

/** Safety cap on pagination when a customer has many draft invoices interspersed. */
const MAX_STRIPE_PAGES = 5

interface FinalizedInvoicesPage {
  invoices: Stripe.Invoice[]
  /**
   * Whether Stripe's raw cursor still had more records after the scan
   * stopped — either because `invoices.length` became conclusive, or the
   * `MAX_STRIPE_PAGES` safety cap was hit first. Callers must OR this into
   * `hasMore` so hitting the cap never silently hides a "View all" that a
   * customer with many consecutive drafts genuinely has.
   */
  stripeHasMore: boolean
}

/**
 * Pages through a customer's Stripe invoices, keeping only finalized ones,
 * until either more than `MAX_INVOICES` have been collected or Stripe's list
 * is exhausted (bounded by `MAX_STRIPE_PAGES`).
 *
 * Stripe's raw pagination cursor (`has_more`) counts draft invoices, which
 * the caller filters out — so a single page can under-report finalized
 * invoices while `has_more` is still true. Paging until the finalized count
 * is conclusive is what lets the caller derive an accurate `hasMore` for the
 * "View all" affordance.
 */
async function collectFinalizedInvoices(
  stripe: Stripe,
  stripeCustomerId: string
): Promise<FinalizedInvoicesPage> {
  const invoices: Stripe.Invoice[] = []
  let startingAfter: string | undefined
  let stripeHasMore = true

  for (
    let page = 0;
    page < MAX_STRIPE_PAGES && stripeHasMore && invoices.length <= MAX_INVOICES;
    page++
  ) {
    const result = await stripe.invoices.list({
      customer: stripeCustomerId,
      limit: STRIPE_PAGE_SIZE,
      starting_after: startingAfter,
    })

    invoices.push(
      ...result.data.filter((invoice) => invoice.id && invoice.status && invoice.status !== 'draft')
    )
    stripeHasMore = result.has_more
    startingAfter = result.data.at(-1)?.id
  }

  return { invoices, stripeHasMore }
}

/**
 * Lists finalized Stripe invoices for the caller's billing customer (personal
 * or organization-scoped). Returns an empty list when there is no Stripe
 * customer yet or when Stripe is not configured, so the UI can simply hide the
 * Invoices section instead of surfacing an error.
 */
export const GET = withRouteHandler(async (request: NextRequest) => {
  const session = await getSession()
  if (!session?.user?.id) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  const parsed = await parseRequest(getInvoicesContract, request, {})
  if (!parsed.success) return parsed.response

  const { context, organizationId } = parsed.data.query

  if (context === 'organization' && !organizationId) {
    return NextResponse.json(
      { error: 'organizationId is required when context=organization' },
      { status: 400 }
    )
  }

  let stripeCustomerId: string | null = null

  if (context === 'organization') {
    const hasPermission = await isOrganizationOwnerOrAdmin(session.user.id, organizationId!)
    if (!hasPermission) {
      return NextResponse.json({ error: 'Permission denied' }, { status: 403 })
    }

    // Resolve the org's customer via the canonical resolver so we deterministically
    // pick the same subscription (most recent entitled, ordered) the rest of the
    // billing UI uses — a bare limit(1) here could select a stale row.
    const orgSubscription = await getOrganizationSubscription(organizationId!)
    stripeCustomerId = orgSubscription?.stripeCustomerId ?? null
  } else {
    const rows = await db
      .select({ customer: user.stripeCustomerId })
      .from(user)
      .where(eq(user.id, session.user.id))
      .limit(1)

    stripeCustomerId = rows.length > 0 ? rows[0].customer || null : null
  }

  const stripe = getStripeClient()
  if (!stripeCustomerId || !stripe) {
    return NextResponse.json({ success: true, invoices: [], hasMore: false })
  }

  try {
    const finalized = await collectFinalizedInvoices(stripe, stripeCustomerId)
    const hasMore = finalized.invoices.length > MAX_INVOICES || finalized.stripeHasMore
    const invoices = finalized.invoices.slice(0, MAX_INVOICES).map((invoice) => ({
      id: invoice.id as string,
      number: invoice.number ?? null,
      created: invoice.created,
      total: invoice.total,
      amountPaid: invoice.amount_paid,
      currency: invoice.currency,
      status: invoice.status ?? null,
      hostedInvoiceUrl: invoice.hosted_invoice_url ?? null,
      invoicePdf: invoice.invoice_pdf ?? null,
    }))

    return NextResponse.json({ success: true, invoices, hasMore })
  } catch (error) {
    logger.error('Failed to list invoices', { error, userId: session.user.id, context })
    return NextResponse.json({ error: 'Failed to list invoices' }, { status: 500 })
  }
})