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

export async function openCursor(accessors: CoreAccessors, direction?: IDBCursorDirection, range?: IDBKeyRange): Promise<IDBCursorWithValue | null> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const request = range ? store.openCursor(range, direction) : store.openCursor(direction)
    return await wrapCursorRequest(request, 'openCursor', storeName)
  } catch (error) {
    throw ensureIndexedDBError(error, 'openCursor', storeName)
  }
}

export async function openCursorOnIndex(
  accessors: CoreAccessors,
  indexName: string,
  direction?: IDBCursorDirection,
  range?: IDBKeyRange
): Promise<IDBCursorWithValue | null> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const index = store.index(indexName)
    const request = range ? index.openCursor(range, direction) : index.openCursor(direction)
    return await wrapCursorRequest(request, 'openCursorOnIndex', storeName)
  } catch (error) {
    throw ensureIndexedDBError(error, 'openCursorOnIndex', storeName)
  }
}

export async function count(accessors: CoreAccessors, range?: IDBKeyRange): Promise<number> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const request = range ? store.count(range) : store.count()
    return await wrapNumberRequest(request, 'count', storeName)
  } catch (error) {
    throw ensureIndexedDBError(error, 'count', storeName)
  }
}

export async function countByIndex(accessors: CoreAccessors, indexName: string, range?: IDBKeyRange): Promise<number> {
  const {storeName} = accessors.getConfig()
  try {
    const store = await getObjectStore(accessors, 'readonly')
    const index = store.index(indexName)
    const request = range ? index.count(range) : index.count()
    return await wrapNumberRequest(request, 'countByIndex', storeName)
  } catch (error) {
    throw ensureIndexedDBError(error, 'countByIndex', storeName)
  }
}

function wrapCursorRequest(requestParam: IDBRequest, operation: string, storeName: string): Promise<IDBCursorWithValue | null> {
  return new Promise((resolve, reject) => {
    const request = requestParam
    request.onsuccess = (): void => resolve(request.result as IDBCursorWithValue | null)
    request.onerror = (): void => reject(new IndexedDBError(`Failed to ${operation}: ${request.error}`, operation, storeName, request.error))
  })
}

function wrapNumberRequest(requestParam: IDBRequest, operation: string, storeName: string): Promise<number> {
  return new Promise((resolve, reject) => {
    const request = requestParam
    request.onsuccess = (): void => resolve(request.result as number)
    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)
}