import { NextResponse } from "next/server";
import {
  EMPTY_WORKSHOP_FORM_VALUES,
  type WorkshopFieldErrors,
  type WorkshopFormValues,
} from "../workshopSignup";

export const WORKSHOP_SIGNUP_DRAFT_COOKIE = "workshop_signup_draft";

export interface WorkshopSignupDraft {
  values: WorkshopFormValues;
  fieldErrors: WorkshopFieldErrors;
}

export function encodeWorkshopSignupDraft(draft: WorkshopSignupDraft): string {
  return Buffer.from(JSON.stringify(draft), "utf8").toString("base64url");
}

export function decodeWorkshopSignupDraft(raw: string | undefined): WorkshopSignupDraft | null {
  if (!raw) return null;
  try {
    const parsed = JSON.parse(Buffer.from(raw, "base64url").toString("utf8")) as Partial<WorkshopSignupDraft>;
    if (!parsed.values || typeof parsed.values !== "object") return null;
    return {
      values: { ...EMPTY_WORKSHOP_FORM_VALUES, ...parsed.values },
      fieldErrors: parsed.fieldErrors ?? {},
    };
  } catch {
    return null;
  }
}

export function attachWorkshopSignupDraft(
  response: NextResponse,
  draft: WorkshopSignupDraft,
): NextResponse {
  response.cookies.set(WORKSHOP_SIGNUP_DRAFT_COOKIE, encodeWorkshopSignupDraft(draft), {
    httpOnly: true,
    sameSite: "lax",
    secure: process.env.NODE_ENV === "production",
    path: "/workshops",
    maxAge: 60 * 15,
  });
  return response;
}