import type { SourceState } from '@wix/bex-core';
import type { EditableTableMutationHandlers } from '../state/EditableTable';

const newLocalId = () =>
  `new-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;

/**
 * Row write handlers read from the source's state — the schema-entry default,
 * so an editable table needs no `mutations` config. The schema loads before
 * any row can be added or edited.
 */
export function sourceMutations<T>(
  sourceState: SourceState<T>,
): EditableTableMutationHandlers<T> {
  const backend = () => {
    const loaded = sourceState.loadedSchema;
    if (!loaded) {
      throw new Error('The schema is not loaded yet');
    }
    return loaded.backend;
  };
  const required = <F>(fn: F | undefined, action: string): F => {
    if (!fn) {
      throw new Error(`The source doesn't support ${action} items`);
    }
    return fn;
  };

  return {
    createItem: () =>
      ({ [sourceState.schema?.idField ?? '_id']: newLocalId() } as T),
    submitCreate: (items) =>
      Promise.all(
        items.map((item) => required(backend().create, 'creating')(item)),
      ),
    submitUpdate: (items) =>
      Promise.all(
        items.map((item) => required(backend().update, 'updating')(item)),
      ),
    submitDelete: async (items) => {
      await required(
        backend().bulkDelete,
        'deleting',
      )(items.map((item) => sourceState.source.itemKey(item)));
    },
  };
}