import type { Role } from './types.js'

import { ROLE_HIERARCHY } from './types.js'

/**
 * The plugin can't know the client's generated User type, and Payload types
 * `req.user` loosely (UntypedUser | null). Predicates therefore accept an
 * unknown-ish user and read `roles` defensively — no assumptions about shape
 * beyond an optional roles array.
 */
type MaybeUser = { roles?: null | Role[] } | null | Record<string, unknown> | undefined

/** Safely extracts the roles array from a loosely-typed user. */
function getRoles(user: MaybeUser): Role[] {
  if (!user || typeof user !== 'object') {return []}
  const roles = (user as { roles?: unknown }).roles
  if (!Array.isArray(roles)) {return []}
  return roles.filter((role): role is Role => ROLE_HIERARCHY.includes(role as Role))
}

/** Highest-privilege role index the user holds, or -1 if none. */
function highestRoleIndex(user: MaybeUser): number {
  const roles = getRoles(user)
  if (!roles.length) {return -1}
  return Math.max(...roles.map((role) => ROLE_HIERARCHY.indexOf(role)))
}

/**
 * True if the user holds at least the given role in the hierarchy.
 * admin satisfies 'editor' and 'user'; editor satisfies 'user'.
 */
export function hasMinimumRole(user: MaybeUser, minimum: Role): boolean {
  return highestRoleIndex(user) >= ROLE_HIERARCHY.indexOf(minimum)
}

/** True if the user is an admin. */
export function isAdmin(user: MaybeUser): boolean {
  return hasMinimumRole(user, 'admin')
}

/** True if the user is an editor or higher (editor, admin). */
export function isEditor(user: MaybeUser): boolean {
  return hasMinimumRole(user, 'editor')
}