import { and, desc, eq } from "drizzle-orm"
import { db } from "@/lib/db"
import { leases, signature_requests } from "@/lib/db/schema"
import { readFile, saveBuffer } from "@/lib/storage"
import { getAdapter } from "./registry"
import { resolveEsignCreds, markEsignError } from "./credentials"
import type { ESignProvider } from "./types"

export type { ESignProvider } from "./types"
export { getAdapter, listEsignAdapters } from "./registry"
export {
  resolveEsignCreds,
  listEsignConnections,
  getEsignConnection,
  saveEsignConnection,
  disconnectEsign,
} from "./credentials"

const FILES_PREFIX = "/api/files/"

/** The webhook URL a provider should call back — used for DocuSign envelope-level Connect. */
function webhookUrl(provider: ESignProvider): string {
  const base = (process.env.NEXT_PUBLIC_APP_URL ?? "http://localhost:3000").replace(/\/+$/, "")
  return `${base}/api/esign/${provider}/webhook`
}

/** Read the lease's stored document. Only /api/files keys are allowed (no SSRF). */
async function getDocumentBytes(documentUrl: string): Promise<{ bytes: Buffer; name: string }> {
  if (!documentUrl.startsWith(FILES_PREFIX)) {
    throw new Error("Lease document must be an uploaded file")
  }
  const key = documentUrl.slice(FILES_PREFIX.length)
  return { bytes: await readFile(key), name: key.split("/").pop() ?? "lease.pdf" }
}

/**
 * Send a lease for signature through the owner's OWN connected account.
 * Requires the provider to be connected (per-user OAuth / API key).
 */
export async function sendLeaseForSignature(ownerId: string, leaseId: string, provider: ESignProvider) {
  const adapter = getAdapter(provider)
  if (!adapter) throw new Error("Unknown provider")

  const creds = await resolveEsignCreds(ownerId, provider)
  if (!creds) throw new Error(`Connect your ${adapter.label} account in Settings → Integrations first`)

  const lease = await db.query.leases.findFirst({
    where: and(eq(leases.id, leaseId), eq(leases.user_id, ownerId)),
    with: { tenant: { columns: { first_name: true, last_name: true, email: true } } },
  })
  if (!lease) throw new Error("Lease not found")
  if (!lease.document_url) throw new Error("Upload a lease document before sending it for signature")
  const email = lease.tenant?.email
  if (!email) throw new Error("The tenant has no email address on file")
  const signerName = `${lease.tenant?.first_name ?? ""} ${lease.tenant?.last_name ?? ""}`.trim() || "Tenant"

  const { bytes, name } = await getDocumentBytes(lease.document_url)

  try {
    const { externalId } = await adapter.send(creds, {
      document: bytes,
      documentName: name,
      signerEmail: email,
      signerName,
      subject: "Please sign your lease agreement",
      message: "Your landlord has sent your lease agreement for electronic signature.",
      webhookUrl: webhookUrl(provider),
    })
    const [row] = await db
      .insert(signature_requests)
      .values({ user_id: ownerId, lease_id: leaseId, provider, external_id: externalId, status: "sent", signer_email: email, signer_name: signerName, document_name: name })
      .returning()
    return row
  } catch (e) {
    const msg = (e as Error).message.slice(0, 500)
    await markEsignError(ownerId, provider, msg)
    await db
      .insert(signature_requests)
      .values({ user_id: ownerId, lease_id: leaseId, provider, status: "error", signer_email: email, signer_name: signerName, document_name: name, last_error: msg })
    throw new Error(msg)
  }
}

export async function listRequestsForLease(ownerId: string, leaseId: string) {
  return db.query.signature_requests.findMany({
    where: and(eq(signature_requests.user_id, ownerId), eq(signature_requests.lease_id, leaseId)),
    orderBy: desc(signature_requests.sent_at),
  })
}

/**
 * Process an inbound provider webhook. The body is UNTRUSTED: we use it only to
 * find which signature request (and therefore which owner + credentials) it
 * concerns, then authenticate the event via the adapter (DocuSign pull-verify /
 * Dropbox HMAC) before updating status and archiving the signed document.
 */
export async function handleEsignWebhook(provider: string, body: string, headers: Headers) {
  const adapter = getAdapter(provider)
  if (!adapter) return

  const externalId = adapter.peekExternalId(body)
  if (!externalId) return

  const reqRow = await db.query.signature_requests.findFirst({
    where: eq(signature_requests.external_id, externalId),
    columns: { id: true, user_id: true, status: true },
  })
  if (!reqRow) return

  const creds = await resolveEsignCreds(reqRow.user_id, provider as ESignProvider)
  if (!creds) return

  const status = await adapter.verifyAndGetStatus(creds, externalId, body, headers)
  if (!status) return

  await db
    .update(signature_requests)
    .set({
      status,
      completed_at: status === "signed" ? new Date().toISOString() : null,
      updated_at: new Date().toISOString(),
    })
    .where(eq(signature_requests.id, reqRow.id))

  // Archive the executed document so the landlord can download the signed copy.
  if (status === "signed") {
    try {
      const bytes = await adapter.getSignedDocument(creds, externalId)
      if (bytes && bytes.length) {
        const { key } = await saveBuffer(bytes, { userId: reqRow.user_id, scope: "esign", ext: "pdf" })
        await db
          .update(signature_requests)
          .set({ signed_document_url: `${FILES_PREFIX}${key}` })
          .where(eq(signature_requests.id, reqRow.id))
      }
    } catch {
      // Best-effort — status is already recorded.
    }
  }
}