import { IndexedDBError } from './IndexedDBError'
import type { CoreAccessors } from './core'
import { getObjectStore } from './store'

export async function getValue<T>(accessors: CoreAccessors, key: string | number): Promise<T | null> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    return await wrapRequest<T | null>(store.get(key), 'get', storeName, (r) => (r.result as T) ?? null)
  } catch (error) {
    throw ensureIndexedDBError(error, 'get', storeName)
  }
}

export async function getByIndex<T>(accessors: CoreAccessors, indexName: string, key: string | number): Promise<T | null> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const index = store.index(indexName)
    return await wrapRequest<T | null>(index.get(key), 'getByIndex', storeName, (r) => (r.result as T) ?? null)
  } catch (error) {
    throw ensureIndexedDBError(error, 'getByIndex', storeName)
  }
}

export async function getAllByIndex<T>(accessors: CoreAccessors, indexName: string, key?: IDBValidKey | IDBKeyRange): Promise<T[]> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const index = store.index(indexName)
    const request = key !== undefined ? index.getAll(key) : index.getAll()
    return await wrapRequest<T[]>(request, 'getAllByIndex', storeName, (r) => (r.result as T[]) ?? [])
  } catch (error) {
    throw ensureIndexedDBError(error, 'getAllByIndex', storeName)
  }
}

export async function getAll<T>(accessors: CoreAccessors, range?: IDBKeyRange, count?: number): Promise<T[]> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const request = range ? store.getAll(range, count) : store.getAll(undefined, count)
    return await wrapRequest<T[]>(request, 'getAll', storeName, (r) => (r.result as T[]) ?? [])
  } catch (error) {
    throw ensureIndexedDBError(error, 'getAll', storeName)
  }
}

function wrapRequest<TResult>(
  requestParam: IDBRequest,
  operation: string,
  storeName: string,
  mapResult: (request: IDBRequest) => TResult
): Promise<TResult> {
  return new Promise<TResult>((resolve, reject) => {
    const request = requestParam
    request.onsuccess = (): void => resolve(mapResult(request))
    request.onerror = (): void => reject(new IndexedDBError(`Failed to ${operation}: ${request.error}`, operation, storeName, request.error))
  })
}

function ensureIndexedDBError(error: unknown, operation: string, storeName: string): IndexedDBError {
  if (error instanceof IndexedDBError) {
    return error
  }
  return new IndexedDBError(error instanceof Error ? error.message : 'Unknown error', operation, storeName, error)
}