import { S3 } from '@aws-sdk/client-s3'

//以下のリソースがあることを確認する
//arn:aws:s3:::sample-log/a/b/c/d.log
it('list s3 object', async () => {
  const s3 = new S3({
    region: 'ap-northeast-1',
  })

  const prefix =
    'a/b/c/'
  const response = await s3.listObjectsV2({
    Bucket: 'sample-log',
    Prefix: prefix,
  })
  if (!response.Contents) {
    throw new Error('failed')
  }
  expect(response.Contents.length).toBe(1)
  expect(response.Contents[0].Key).toBe(
    prefix + 'd.log'
  )
})

import { S3 } from '@aws-sdk/client-s3'

import { Readable } from 'stream'

// Apparently the stream parameter should be of type Readable|ReadableStream|Blob
// The latter 2 don't seem to exist anywhere.
//https://github.com/aws/aws-sdk-js-v3/issues/1877#issuecomment-755430937
async function streamToString(stream: Readable): Promise<string> {
  return await new Promise((resolve, reject) => {
    const chunks: Uint8Array[] = []
    stream.on('data', (chunk) => chunks.push(chunk))
    stream.on('error', reject)
    stream.on('end', () => resolve(Buffer.concat(chunks).toString('utf-8')))
  })
}

export const getObjectContent: (bucket: string, key: string) => Promise<{ contents: string }> =
  async (bucket: string, key: string) => {
    let contents = ''
    const s3 = new S3({})
    const response = await s3.getObject({
      Bucket: bucket,
      Key: key,
    })
    contents = await streamToString(response.Body as Readable)

    return {
      contents: contents,
    }
  }