import {
  projectDeviceSyncFields,
  type ProjectDeviceSyncField,
} from "../../shared/constants/project-device-sync-fields.js";

export function parseOverriddenFields(
  value: string | null | undefined
): ProjectDeviceSyncField[] {
  if (!value) {
    return [];
  }
  try {
    const parsed: unknown = JSON.parse(value);
    if (!Array.isArray(parsed)) {
      return [];
    }
    return parsed.filter((field): field is ProjectDeviceSyncField =>
      projectDeviceSyncFields.includes(field as ProjectDeviceSyncField)
    );
  } catch {
    return [];
  }
}

export function serializeOverriddenFields(
  fields: Iterable<ProjectDeviceSyncField>
): string | undefined {
  const fieldSet = new Set(fields);
  const unique = projectDeviceSyncFields.filter((field) => fieldSet.has(field));
  return unique.length > 0 ? JSON.stringify(unique) : undefined;
}

export function deriveOverriddenFieldsForLocalEdit(
  current: {
    linkedProjectDeviceId: string | null | undefined;
    overriddenFields: string | null | undefined;
  } & Partial<Record<ProjectDeviceSyncField, unknown>>,
  patch: Partial<Record<ProjectDeviceSyncField | "overriddenFields", unknown>>
): string | null | undefined {
  if (
    !current.linkedProjectDeviceId ||
    Object.prototype.hasOwnProperty.call(patch, "overriddenFields")
  ) {
    return patch.overriddenFields as string | null | undefined;
  }

  const overrides = new Set(parseOverriddenFields(current.overriddenFields));
  for (const field of projectDeviceSyncFields) {
    if (
      Object.prototype.hasOwnProperty.call(patch, field) &&
      (patch[field] ?? null) !== (current[field] ?? null)
    ) {
      overrides.add(field);
    }
  }
  return serializeOverriddenFields(overrides);
}