import { ok, err, type CommandContext } from "@tailor-platform/erp-kit/core";
import { shiftPlacementLifecycle } from "../db/shiftPlacement.lifecycle.generated";
import type { Transaction } from "../generated/kysely-tailordb";
import { ShiftPlacementNotFoundError, ShiftPlacementNotActiveError } from "../lib/errors.generated";

export interface ReleaseShiftPlacementInput {
  id: string;
}

/**
 * Function: releaseShiftPlacement
 * Description: Unstaffs a slot by moving the placement to CANCELLED. Replaces the former
 * deleteShiftPlacement: a placement is never physically removed, because "X was planned on
 * this slot until it was released" is exactly the fact a confirmed shiftSchedule has to be able to
 * answer afterwards. Releasing leaves the slot open again (it has no ACTIVE placement), which
 * is what listOpenShifts keys on.
 */
export async function run(
  db: Transaction,
  input: ReleaseShiftPlacementInput,
  _ctx: CommandContext,
) {
  const shiftPlacement = await db
    .selectFrom("ShiftPlacement")
    .selectAll()
    .where("id", "=", input.id)
    .forUpdate()
    .executeTakeFirst();
  if (!shiftPlacement) {
    return err(new ShiftPlacementNotFoundError(input.id));
  }
  // Release is the ACTIVE -> CANCELLED edge of the generated lifecycle (docs/model/
  // ShiftPlacement.md's State Transitions table). The module's own error is kept: a caller told
  // "not active" learns why the release was refused, which a generic invalid-transition code hides.
  const nextStatus = shiftPlacementLifecycle.tryTransition(shiftPlacement.status, "release");
  if (!nextStatus) {
    return err(new ShiftPlacementNotActiveError(input.id));
  }

  const updated = await db
    .updateTable("ShiftPlacement")
    .set({ status: nextStatus, releasedAt: new Date() })
    .where("id", "=", input.id)
    .returningAll()
    .executeTakeFirstOrThrow();

  return ok({ shiftPlacement: updated });
}