createBaseQuery.ts

import {
  notifyManager,
  type QueryKey,
  type QueryObserver,
} from '@tanstack/query-core'
import type { CreateBaseQueryOptions, CreateBaseQueryResult } from './types'
import { useQueryClient } from './useQueryClient'
import { derived, readable } from 'svelte/store'

export function createBaseQuery<
  TQueryFnData,
  TError,
  TData,
  TQueryData,
  TQueryKey extends QueryKey,
>(
  options: CreateBaseQueryOptions<
    TQueryFnData,
    TError,
    TData,
    TQueryData,
    TQueryKey
  >,
  Observer: typeof QueryObserver,
): CreateBaseQueryResult<TData, TError> {
  const queryClient = useQueryClient()
  const defaultedOptions = queryClient.defaultQueryOptions(options)
  defaultedOptions._optimisticResults = 'optimistic'

  let observer = new Observer<
    TQueryFnData,
    TError,
    TData,
    TQueryData,
    TQueryKey
  >(queryClient, defaultedOptions)

  // Include callbacks in batch renders
  if (defaultedOptions.onError) {
    defaultedOptions.onError = notifyManager.batchCalls(
      defaultedOptions.onError,
    )
  }

  if (defaultedOptions.onSuccess) {
    defaultedOptions.onSuccess = notifyManager.batchCalls(
      defaultedOptions.onSuccess,
    )
  }

  if (defaultedOptions.onSettled) {
    defaultedOptions.onSettled = notifyManager.batchCalls(
      defaultedOptions.onSettled,
    )
  }

  readable(observer).subscribe(($observer) => {
    observer = $observer
    // Do not notify on updates because of changes in the options because
    // these changes should already be reflected in the optimistic result.
    observer.setOptions(defaultedOptions, { listeners: false })
  })

  const result = readable(observer.getCurrentResult(), (set) => {
    return observer.subscribe(notifyManager.batchCalls(set))
  })

  const { subscribe } = derived(result, ($result) => {
    $result = observer.getOptimisticResult(defaultedOptions)
    return !defaultedOptions.notifyOnChangeProps
      ? observer.trackResult($result)
      : $result
  })

  return { subscribe }
}