import { ok, err } from "@tailor-platform/erp-kit/core";
import type { Transaction } from "../generated/kysely-tailordb";
import {
  AssignmentNotFoundError,
  RoleNotFoundError,
  UserNotFoundError,
} from "../lib/errors.generated";
import { recomputeUserPermissions } from "../lib/recomputeUserPermissions";

export interface RevokeRoleFromUserInput {
  userId: string;
  roleId: string;
}

/**
 * Function: revokeRoleFromUser
 *
 * Removes a role from a user.
 * Throws an error if the assignment does not exist.
 */
export async function run(db: Transaction, input: RevokeRoleFromUserInput) {
  const user = await db
    .selectFrom("User")
    .selectAll()
    .where("id", "=", input.userId)
    .executeTakeFirst();

  if (!user) {
    return err(new UserNotFoundError(input.userId));
  }

  const role = await db
    .selectFrom("Role")
    .selectAll()
    .where("id", "=", input.roleId)
    .executeTakeFirst();

  if (!role) {
    return err(new RoleNotFoundError(input.roleId));
  }

  const existingAssignment = await db
    .selectFrom("UserRole")
    .selectAll()
    .where("userId", "=", input.userId)
    .where("roleId", "=", input.roleId)
    .forUpdate()
    .executeTakeFirst();

  if (!existingAssignment) {
    return err(new AssignmentNotFoundError(`User ${input.userId} -> Role ${input.roleId}`));
  }

  await db
    .deleteFrom("UserRole")
    .where("id", "=", existingAssignment.id)
    .returningAll()
    .executeTakeFirst();

  const updatedUser = await recomputeUserPermissions(db, input.userId);

  return ok({ user: updatedUser });
}