import middy from '@middy/core'
import { Options as MiddyOptions } from '@middy/util'
import { Context as LambdaContext } from 'aws-lambda'
import { GetObjectCommandInput, S3Client, S3ClientConfig } from '@aws-sdk/client-s3'

export type GetObjectCommandInputNoChecksumMode = Omit<GetObjectCommandInput, 'ChecksumMode'> & {
  ChecksumMode?: never
}
export type ParamType<T> = GetObjectCommandInputNoChecksumMode & { __returnType?: T }
export declare function s3Req<T> (req: GetObjectCommandInputNoChecksumMode): ParamType<T>

export type S3Options<AwsS3Client = S3Client> = Omit<MiddyOptions<AwsS3Client, S3ClientConfig>, 'fetchData'>
& {
  fetchData?: {
    [key: string]: GetObjectCommandInputNoChecksumMode | ParamType<unknown>
  }
}

export type Context<TOptions extends S3Options | undefined> =
TOptions extends { setToContext: true }
  ? TOptions extends { fetchData: infer TFetchData }
    ? LambdaContext & {
      [Key in keyof TFetchData]: TFetchData[Key] extends ParamType<infer T>
        ? T
        : unknown
    }
    : never
  : LambdaContext

export type Internal<TOptions extends S3Options | undefined> =
TOptions extends S3Options
  ? TOptions extends { fetchData: infer TFetchData }
    ? {
        [Key in keyof TFetchData]: TFetchData[Key] extends ParamType<infer T>
          ? T
          : unknown
      }
    : {}
  : {}

declare function s3Middleware<TOptions extends S3Options | undefined> (
  options?: TOptions
): middy.MiddlewareObj<unknown, any, Error, Context<TOptions>, Internal<TOptions>>

export default s3Middleware