import { ok, err, type CommandContext } from "@tailor-platform/erp-kit/core";
import type { Transaction } from "../generated/kysely-tailordb";
import { ShiftNotFoundError, ShiftAlreadyCancelledError } from "../lib/errors.generated";

export interface CancelShiftInput {
  id: string;
}

/**
 * Function: cancelShift
 * Description: Withdraws a single slot by stamping `cancelledAt`, the one thing a shift-schedule-level
 * status cannot express ("the period is confirmed but this one night shift is no longer needed").
 * The row is kept rather than deleted, for the same reason a ShiftPlacement is superseded
 * rather than removed: a confirmed shiftSchedule is read back through its history.
 */
export async function run(db: Transaction, input: CancelShiftInput, _ctx: CommandContext) {
  const shift = await db
    .selectFrom("Shift")
    .selectAll()
    .where("id", "=", input.id)
    .forUpdate()
    .executeTakeFirst();
  if (!shift) {
    return err(new ShiftNotFoundError(input.id));
  }
  if (shift.cancelledAt !== null) {
    return err(new ShiftAlreadyCancelledError(input.id));
  }

  const updated = await db
    .updateTable("Shift")
    .set({ cancelledAt: new Date() })
    .where("id", "=", input.id)
    .returningAll()
    .executeTakeFirstOrThrow();

  return ok({ shift: updated });
}