import type { CollectionAfterChangeHook, CollectionBeforeChangeHook, CollectionConfig } from "payload";
import { APIError } from "payload";
import { allowVerificationEmail } from "@/lib/auth/verificationRateLimit";
import { isAdmin, isAdminFieldLevel } from "@/access";
import { EMAIL_VERIFICATION_TTL_MS, generateVerificationToken, hashVerificationToken, verificationExpiryISO } from "@/lib/auth/verification";
import { verificationEmail } from "@/lib/email/authTemplates";
import { sendEmail } from "@/lib/email/sendBookingEmails";

// Routes through the shared isAdmin check (role === "admin", not just
// collection === "users") so this stays correct if a non-admin role is ever
// added to Users - see the comment on isAdmin in access/index.ts.
const isSelfOrAdmin: typeof isAdmin = (args) => {
  const user = args.req.user;
  if (!user) return false;
  if (user.collection === "users") return isAdmin(args);
  if (user.collection === "customers") return { id: { equals: user.id } };
  return false;
};

// Runs on every new customer account, and again whenever an existing
// customer changes their email address: issues a random, single-use,
// time-limited email-verification token and resets emailVerified to false.
// Only the token's hash is ever persisted (see emailVerificationTokenHash
// below) - the plaintext exists only in req.context for the afterChange
// hook below to email out, and is never written to the database or logged.
//
// The email-change case matters because `update` access on this collection
// is isSelfOrAdmin and the auto-added `email` field carries no field-level
// access of its own - without this, a customer could verify a throwaway
// address once and then repoint `email` at an address they don't own while
// keeping emailVerified: true (which gates booking-confirmation emails).
const issueVerificationToken: CollectionBeforeChangeHook = ({ data, originalDoc, operation, req }) => {
  const emailChanged =
    operation === "update" &&
    typeof data.email === "string" &&
    typeof originalDoc?.email === "string" &&
    data.email !== originalDoc.email;
  if (operation !== "create" && !emailChanged) return data;

  if (!allowVerificationEmail(req, String(data.email ?? originalDoc?.email ?? ""), originalDoc?.id)) {
    throw new APIError("Zu viele Bestätigungs-E-Mails. Bitte versuche es später erneut.", 429, undefined, true);
  }

  const token = generateVerificationToken();
  data.emailVerified = false;
  data.emailVerificationTokenHash = hashVerificationToken(token);
  data.emailVerificationExpires = verificationExpiryISO();
  req.context.pendingVerificationToken = token;
  return data;
};

const sendVerificationEmail: CollectionAfterChangeHook = async ({ doc, req }) => {
  const token = req.context.pendingVerificationToken;
  if (typeof token !== "string") return doc;
  delete req.context.pendingVerificationToken;
  try {
    const serverUrl = process.env.NEXT_PUBLIC_SERVER_URL || "http://localhost:3000";
    await sendEmail(
      doc.email,
      verificationEmail({
        name: doc.name,
        verifyUrl: `${serverUrl}/auth/verify-email/${token}`,
        expiresHours: Math.round(EMAIL_VERIFICATION_TTL_MS / (60 * 60 * 1000)),
      }),
    );
  } catch (err) {
    req.payload.logger.error({ err, msg: "customers sendVerificationEmail failed" });
  }
  return doc;
};

export const Customers: CollectionConfig = {
  slug: "customers",
  labels: {
    singular: "Kundin/Kunde",
    plural: "Kunden",
  },
  admin: {
    useAsTitle: "name",
    defaultColumns: ["name", "email", "phone"],
    group: "Buchungen",
    description: "Konten der Website-Besucher (nicht die Admin-Zugänge unter „Benutzer“).",
  },
  auth: {
    maxLoginAttempts: 8,
    lockTime: 10 * 60 * 1000,
  },
  access: {
    // Anyone can create their own account (registration); reading/updating
    // is restricted to the account owner or an admin.
    create: () => true,
    read: isSelfOrAdmin,
    update: isSelfOrAdmin,
    delete: isAdmin,
  },
  hooks: {
    beforeChange: [issueVerificationToken],
    afterChange: [sendVerificationEmail],
  },
  fields: [
    {
      name: "name",
      type: "text",
      label: "Name",
      required: true,
    },
    {
      name: "phone",
      type: "text",
      label: "Telefonnummer",
      required: false,
      admin: {
        description: "Optional - für eine spätere Nutzung vorbereitet, aktuell nicht verpflichtend.",
      },
    },
    {
      name: "emailVerified",
      type: "checkbox",
      label: "E-Mail bestätigt",
      defaultValue: false,
      // "create" AND "update" must both be locked down - otherwise a
      // customer could simply include emailVerified: true in their own
      // registration or profile request and skip verification entirely.
      access: { create: isAdminFieldLevel, update: isAdminFieldLevel },
      admin: {
        position: "sidebar",
        description: "Wird automatisch gesetzt, sobald der Bestätigungslink aus der E-Mail angeklickt wird. Kann hier bei Bedarf manuell gesetzt werden.",
      },
    },
    {
      name: "emailVerificationTokenHash",
      type: "text",
      // Never exposed or settable via any API - only the two hooks above
      // (running through the trusted Local API) ever touch this field.
      access: { create: () => false, read: () => false, update: () => false },
      admin: { hidden: true },
      index: true,
    },
    {
      name: "emailVerificationExpires",
      type: "date",
      access: { create: () => false, read: () => false, update: () => false },
      admin: { hidden: true },
    },
    // "email" and "password" are added automatically by the auth config.
  ],
};