import type { Access, AccessArgs, AccessResult, Payload, PayloadRequest } from "payload";
import { loadUserPermissions } from "@/utils/access-control/loadUserPermissions";
import type { Permission } from "@/permissions";

/**
 * Minimal user shape for permission checks.
 * Accepts the full Payload User or a stripped-down { id } from server actions.
 */
interface UserLike {
  id: number | string;
  roleDocs?: unknown;
}

/**
 * Check whether a user has a specific permission.
 *
 * Resolution order:
 * 1. No user → false.
 * 2. User has a role with `isSuperuser: true` → true (bypasses all checks).
 * 3. User has a role whose `permissions` array includes the given permission → true.
 * 4. Otherwise → false.
 *
 * Results are cached per-user for 30s (see `loadUserPermissions`).
 *
 * @example
 * const canCreate = await hasPermission(payload, user, "users:create");
 */
export async function hasPermission(
  payload: Payload,
  user: UserLike | null | undefined,
  permission: Permission,
): Promise<boolean> {
  if (!user) return false;

  const { permissions, isSuperuser } = await loadUserPermissions(payload, user);
  if (isSuperuser) return true;
  return permissions.has(permission);
}

/**
 * Check whether a user has a superuser role (bypasses all permission checks).
 *
 * Use this for the legacy `isDeveloper` replacement where the check was
 * "can do anything" rather than a specific permission.
 */
export async function isSuperuser(
  payload: Payload,
  user: UserLike | null | undefined,
): Promise<boolean> {
  if (!user) return false;
  const { isSuperuser: su } = await loadUserPermissions(payload, user);
  return su;
}

/**
 * Check whether a user has ANY of the given permissions.
 */
export async function hasAnyPermission(
  payload: Payload,
  user: UserLike | null | undefined,
  ...permissions: Permission[]
): Promise<boolean> {
  if (!user) return false;
  const { permissions: userPerms, isSuperuser: su } = await loadUserPermissions(payload, user);
  if (su) return true;
  return permissions.some((p) => userPerms.has(p));
}

/**
 * Check whether a user has ALL of the given permissions.
 */
export async function hasAllPermissions(
  payload: Payload,
  user: UserLike | null | undefined,
  ...permissions: Permission[]
): Promise<boolean> {
  if (!user) return false;
  const { permissions: userPerms, isSuperuser: su } = await loadUserPermissions(payload, user);
  if (su) return true;
  return permissions.every((p) => userPerms.has(p));
}

/**
 * Detect whether a request targets the Payload admin panel.
 *
 * The admin panel is served under `config.routes.admin` (default `/admin`).
 * `req.pathname` is the request URL pathname (set by Payload's request
 * creation), so this reliably distinguishes admin-panel requests from REST
 * API requests — unlike `x-invoke-path`, which is unreliable in layouts.
 * Local API calls (server actions, seeds, MCP, bots) get a non-admin
 * pathname and therefore keep the original access behavior.
 */
function isAdminPanelRequest(req: PayloadRequest): boolean {
  const adminRoute = req.payload.config.routes?.admin ?? "/admin";
  const pathname = req.pathname;
  if (!pathname) return false;
  return pathname === adminRoute || pathname.startsWith(`${adminRoute}/`);
}

/**
 * Factory that wraps a collection's `read` access so that the Payload admin
 * panel only shows/interacts with the collection when the user holds BOTH
 * `<slug>:read` AND `admin:<slug>:manage`. Non-admin (REST/API) reads keep
 * the original access behavior unchanged.
 *
 * Apply centrally to every collection in `payload.config.ts`:
 *
 * @example
 * collections: collections.map((collection) => ({
 *   ...collection,
 *   access: {
 *     ...collection.access,
 *     read: requireAdminPageAccess(collection.slug, collection.access?.read),
 *   },
 * }))
 */
export function requireAdminPageAccess(collectionSlug: string, readAccess?: Access | boolean) {
  return async (args: AccessArgs): Promise<AccessResult> => {
    const { req } = args;

    if (isAdminPanelRequest(req)) {
      // Admin panel: require both the collection read permission and the
      // admin page-manage permission. Must return a plain boolean — a `Where`
      // here would be treated as "no permission" by the admin UI.
      return hasAllPermissions(
        req.payload,
        req.user,
        `${collectionSlug}:read` as Permission,
        `admin:${collectionSlug}:manage` as Permission,
      );
    }

    // Non-admin (REST/API): preserve the original read access behavior.
    if (typeof readAccess === "function") return readAccess(args);
    if (readAccess === true) return true;
    if (readAccess === false) return false;
    // Omitted read access → Payload default: any logged-in user can read.
    return Boolean(req.user);
  };
}

/**
 * Factory that creates a Payload collection access function requiring a specific
 * permission. Drop-in replacement for `isDeveloper` / `isAdmin` in collection
 * `access` blocks.
 *
 * @example
 * access: {
 *   create: requirePermission("users:create"),
 *   update: requirePermission("users:update"),
 * }
 */
export function requirePermission(permission: Permission) {
  return async ({ req }: { req: PayloadRequest }): Promise<boolean> => {
    return hasPermission(req.payload, req.user, permission);
  };
}

/**
 * Factory that creates a Payload collection access function requiring ANY of
 * the given permissions.
 *
 * @example
 * access: {
  *   update: requireAnyPermission("tickets:update", "tickets:staff"),
  * }
  */
export function requireAnyPermission(...permissions: Permission[]) {
  return async ({ req }: { req: PayloadRequest }): Promise<boolean> => {
    return hasAnyPermission(req.payload, req.user, ...permissions);
  };
}

/**
 * Factory that creates a Payload collection access function requiring campaign ownership.
 *
 * A user can access a campaign if:
 * 1. They own the campaign (owner field matches their user ID), OR
 * 2. They have the "campaigns:manage" permission
 *
 * @example
 * access: {
 *   update: requireCampaignOwnership("campaigns:update"),
 *   delete: requireCampaignOwnership("campaigns:delete"),
 * }
 */
export function requireCampaignOwnership(permission: Permission) {
  return async ({ req, id }: { req: PayloadRequest; id?: any }) => {
    if (!req.user) return false;

    // Check permission first (grants access to all campaigns for managers)
    const { permissions: userPerms, isSuperuser: su } = await loadUserPermissions(req.payload, req.user);
    if (su || userPerms.has(permission)) return true;

    // If no user permissions for manage, check ownership
    let campaign;
    try {
      campaign = await req.payload.findByID({
        collection: "campaigns",
        id: id,
        depth: 1,
        overrideAccess: true,
      });
    } catch (error) {
      // If campaign lookup fails (e.g. invalid ID), deny access
      return false;
    }

    if (!campaign) return false;

    // User owns the campaign if owner field matches their ID
    // campaign.owner can be number (ID) or User object
    const campaignOwnerId = campaign.owner ? (typeof campaign.owner === "object" ? campaign.owner.id : campaign.owner) : null;
    const userId = Number(req.user.id);

    if (campaignOwnerId && campaignOwnerId === userId) return true;

    // User does not own this campaign and lacks manage permission
    return false;
  };
}