import { eq } from "drizzle-orm";
import { db } from "@/lib/db/client";
import { customers, tickets } from "@/lib/db/schema";
import { recordAgentReply, recordInternalNote, getEmailThreadContext } from "@/lib/tickets/service";
import { sendTelegramMessage, sendTelegramFile } from "@/lib/telegram/bot";
import { sendTicketReplyEmail } from "@/lib/mail/smtp";

interface AttachmentPayload {
  filename: string;
  mimeType: string;
  sizeBytes: number;
  storageKey: string;
  buffer: Buffer;
}

/**
 * Shared by the text-reply and attachment-upload admin routes: creates the
 * message (public reply or internal note) and, for public replies, delivers
 * it over the ticket's channel (email/Telegram). Not used for portal/widget
 * replies — those never need outbound channel delivery.
 */
export async function deliverAgentMessage(params: {
  ticketId: string;
  agentId: string;
  agentName: string;
  body: string;
  visibility: "public" | "internal";
  attachment?: AttachmentPayload;
}) {
  const ticket = await db.query.tickets.findFirst({ where: eq(tickets.id, params.ticketId) });
  if (!ticket) throw new Error("Ticket not found");

  const attachmentInput = params.attachment
    ? {
        filename: params.attachment.filename,
        mimeType: params.attachment.mimeType,
        sizeBytes: params.attachment.sizeBytes,
        storageKey: params.attachment.storageKey,
      }
    : undefined;

  if (params.visibility === "internal") {
    return recordInternalNote({
      ticketId: params.ticketId,
      agentId: params.agentId,
      agentName: params.agentName,
      body: params.body,
      attachments: attachmentInput ? [attachmentInput] : undefined,
    });
  }

  // Channel delivery (email/Telegram) is best-effort: the agent's reply is
  // the thing that must never be lost. Previously an SMTP/Telegram failure
  // here threw straight out of this function, so recordAgentReply below was
  // never reached — the reply vanished entirely (not recorded, nothing
  // shown in the thread) and the API route's catch-all turned it into a
  // misleading "Ticket not found". A broken mail/bot account should degrade
  // to "reply saved internally, not delivered" — never silent data loss.
  // A ticket only ever has one channel, so at most one of the two branches
  // below runs — this single flag is the outcome of whichever one does, and
  // is what lets the agent tell "saved" from "the customer actually got
  // this" in the UI (see messages.deliveryFailed).
  let emailMessageId: string | undefined;
  let deliveryFailed = false;

  if (ticket.channel === "email") {
    const context = await getEmailThreadContext(params.ticketId);
    if (context) {
      try {
        emailMessageId = await sendTicketReplyEmail({
          to: context.customerEmail,
          subject: context.subject,
          body: params.body,
          inReplyTo: context.inReplyTo,
          attachment: params.attachment
            ? { filename: params.attachment.filename, content: params.attachment.buffer }
            : undefined,
        });
      } catch (err) {
        console.error(`Failed to send reply email for ticket ${params.ticketId}:`, err);
        deliveryFailed = true;
      }
    }
  } else if (ticket.channel === "telegram") {
    const customer = await db.query.customers.findFirst({
      where: eq(customers.id, ticket.customerId),
    });
    if (customer?.telegramChatId) {
      try {
        if (params.attachment) {
          await sendTelegramFile(
            customer.telegramChatId,
            { buffer: params.attachment.buffer, filename: params.attachment.filename, mimeType: params.attachment.mimeType },
            params.body,
          );
        } else {
          await sendTelegramMessage(customer.telegramChatId, params.body);
        }
      } catch (err) {
        console.error(`Failed to deliver reply via Telegram for ticket ${params.ticketId}:`, err);
        deliveryFailed = true;
      }
    }
  }

  const result = await recordAgentReply({
    ticketId: params.ticketId,
    agentId: params.agentId,
    agentName: params.agentName,
    body: params.body,
    emailMessageId,
    deliveryFailed,
    attachments: attachmentInput ? [attachmentInput] : undefined,
  });

  return result;
}