import * as core from '@actions/core'
import {HttpClient, HttpCodes} from '@actions/http-client'
import {BearerCredentialHandler} from '@actions/http-client/auth'
import {
  IHttpClientResponse,
  IRequestOptions,
  ITypedResponse
} from '@actions/http-client/interfaces'
import * as crypto from 'crypto'
import * as fs from 'fs'
import * as stream from 'stream'
import * as util from 'util'

import * as utils from './cacheUtils'
import {CompressionMethod, SocketTimeout} from './constants'
import {
  ArtifactCacheEntry,
  CacheOptions,
  CommitCacheRequest,
  ReserveCacheRequest,
  ReserveCacheResponse
} from './contracts'
import {UploadOptions} from '../options'

const versionSalt = '1.0'

function isSuccessStatusCode(statusCode?: number): boolean {
  if (!statusCode) {
    return false
  }
  return statusCode >= 200 && statusCode < 300
}

function isServerErrorStatusCode(statusCode?: number): boolean {
  if (!statusCode) {
    return true
  }
  return statusCode >= 500
}

function isRetryableStatusCode(statusCode?: number): boolean {
  if (!statusCode) {
    return false
  }
  const retryableStatusCodes = [
    HttpCodes.BadGateway,
    HttpCodes.ServiceUnavailable,
    HttpCodes.GatewayTimeout
  ]
  return retryableStatusCodes.includes(statusCode)
}

function getCacheApiUrl(resource: string): string {
  // Ideally we just use ACTIONS_CACHE_URL
  const baseUrl: string = (
    process.env['ACTIONS_CACHE_URL'] ||
    process.env['ACTIONS_RUNTIME_URL'] ||
    ''
  ).replace('pipelines', 'artifactcache')
  if (!baseUrl) {
    throw new Error('Cache Service Url not found, unable to restore cache.')
  }

  const url = `${baseUrl}_apis/artifactcache/${resource}`
  core.debug(`Resource Url: ${url}`)
  return url
}

function createAcceptHeader(type: string, apiVersion: string): string {
  return `${type};api-version=${apiVersion}`
}

function getRequestOptions(): IRequestOptions {
  const requestOptions: IRequestOptions = {
    headers: {
      Accept: createAcceptHeader('application/json', '6.0-preview.1')
    }
  }

  return requestOptions
}

function createHttpClient(): HttpClient {
  const token = process.env['ACTIONS_RUNTIME_TOKEN'] || ''
  const bearerCredentialHandler = new BearerCredentialHandler(token)

  return new HttpClient(
    'actions/cache',
    [bearerCredentialHandler],
    getRequestOptions()
  )
}

export function getCacheVersion(
  paths: string[],
  compressionMethod?: CompressionMethod
): string {
  const components = paths.concat(
    compressionMethod === CompressionMethod.Zstd ? [compressionMethod] : []
  )

  // Add salt to cache version to support breaking changes in cache entry
  components.push(versionSalt)

  return crypto
    .createHash('sha256')
    .update(components.join('|'))
    .digest('hex')
}

export async function retry<T>(
  name: string,
  method: () => Promise<T>,
  getStatusCode: (arg0: T) => number | undefined,
  maxAttempts = 2
): Promise<T> {
  let response: T | undefined = undefined
  let statusCode: number | undefined = undefined
  let isRetryable = false
  let errorMessage = ''
  let attempt = 1

  while (attempt <= maxAttempts) {
    try {
      response = await method()
      statusCode = getStatusCode(response)

      if (!isServerErrorStatusCode(statusCode)) {
        return response
      }

      isRetryable = isRetryableStatusCode(statusCode)
      errorMessage = `Cache service responded with ${statusCode}`
    } catch (error) {
      isRetryable = true
      errorMessage = error.message
    }

    core.debug(
      `${name} - Attempt ${attempt} of ${maxAttempts} failed with error: ${errorMessage}`
    )

    if (!isRetryable) {
      core.debug(`${name} - Error is not retryable`)
      break
    }

    attempt++
  }

  throw Error(`${name} failed: ${errorMessage}`)
}

export async function retryTypedResponse<T>(
  name: string,
  method: () => Promise<ITypedResponse<T>>,
  maxAttempts = 2
): Promise<ITypedResponse<T>> {
  return await retry(
    name,
    method,
    (response: ITypedResponse<T>) => response.statusCode,
    maxAttempts
  )
}

export async function retryHttpClientResponse<T>(
  name: string,
  method: () => Promise<IHttpClientResponse>,
  maxAttempts = 2
): Promise<IHttpClientResponse> {
  return await retry(
    name,
    method,
    (response: IHttpClientResponse) => response.message.statusCode,
    maxAttempts
  )
}

export async function getCacheEntry(
  keys: string[],
  paths: string[],
  options?: CacheOptions
): Promise<ArtifactCacheEntry | null> {
  const httpClient = createHttpClient()
  const version = getCacheVersion(paths, options?.compressionMethod)
  const resource = `cache?keys=${encodeURIComponent(
    keys.join(',')
  )}&version=${version}`

  const response = await retryTypedResponse('getCacheEntry', async () =>
    httpClient.getJson<ArtifactCacheEntry>(getCacheApiUrl(resource))
  )
  if (response.statusCode === 204) {
    return null
  }
  if (!isSuccessStatusCode(response.statusCode)) {
    throw new Error(`Cache service responded with ${response.statusCode}`)
  }

  const cacheResult = response.result
  const cacheDownloadUrl = cacheResult?.archiveLocation
  if (!cacheDownloadUrl) {
    throw new Error('Cache not found.')
  }
  core.setSecret(cacheDownloadUrl)
  core.debug(`Cache Result:`)
  core.debug(JSON.stringify(cacheResult))

  return cacheResult
}

async function pipeResponseToStream(
  response: IHttpClientResponse,
  output: NodeJS.WritableStream
): Promise<void> {
  const pipeline = util.promisify(stream.pipeline)
  await pipeline(response.message, output)
}

export async function downloadCache(
  archiveLocation: string,
  archivePath: string
): Promise<void> {
  const writeStream = fs.createWriteStream(archivePath)
  const httpClient = new HttpClient('actions/cache')
  const downloadResponse = await retryHttpClientResponse(
    'downloadCache',
    async () => httpClient.get(archiveLocation)
  )

  // Abort download if no traffic received over the socket.
  downloadResponse.message.socket.setTimeout(SocketTimeout, () => {
    downloadResponse.message.destroy()
    core.debug(`Aborting download, socket timed out after ${SocketTimeout} ms`)
  })

  await pipeResponseToStream(downloadResponse, writeStream)

  // Validate download size.
  const contentLengthHeader = downloadResponse.message.headers['content-length']

  if (contentLengthHeader) {
    const expectedLength = parseInt(contentLengthHeader)
    const actualLength = utils.getArchiveFileSize(archivePath)

    if (actualLength !== expectedLength) {
      throw new Error(
        `Incomplete download. Expected file size: ${expectedLength}, actual file size: ${actualLength}`
      )
    }
  } else {
    core.debug('Unable to validate download, no Content-Length header')
  }
}

// Reserve Cache
export async function reserveCache(
  key: string,
  paths: string[],
  options?: CacheOptions
): Promise<number> {
  const httpClient = createHttpClient()
  const version = getCacheVersion(paths, options?.compressionMethod)

  const reserveCacheRequest: ReserveCacheRequest = {
    key,
    version
  }
  const response = await retryTypedResponse('reserveCache', async () =>
    httpClient.postJson<ReserveCacheResponse>(
      getCacheApiUrl('caches'),
      reserveCacheRequest
    )
  )
  return response?.result?.cacheId ?? -1
}

function getContentRange(start: number, end: number): string {
  // Format: `bytes start-end/filesize
  // start and end are inclusive
  // filesize can be *
  // For a 200 byte chunk starting at byte 0:
  // Content-Range: bytes 0-199/*
  return `bytes ${start}-${end}/*`
}

async function uploadChunk(
  httpClient: HttpClient,
  resourceUrl: string,
  openStream: () => NodeJS.ReadableStream,
  start: number,
  end: number
): Promise<void> {
  core.debug(
    `Uploading chunk of size ${end -
      start +
      1} bytes at offset ${start} with content range: ${getContentRange(
      start,
      end
    )}`
  )
  const additionalHeaders = {
    'Content-Type': 'application/octet-stream',
    'Content-Range': getContentRange(start, end)
  }

  await retryHttpClientResponse(
    `uploadChunk (start: ${start}, end: ${end})`,
    async () =>
      httpClient.sendStream(
        'PATCH',
        resourceUrl,
        openStream(),
        additionalHeaders
      )
  )
}

async function uploadFile(
  httpClient: HttpClient,
  cacheId: number,
  archivePath: string,
  options?: UploadOptions
): Promise<void> {
  // Upload Chunks
  const fileSize = fs.statSync(archivePath).size
  const resourceUrl = getCacheApiUrl(`caches/${cacheId.toString()}`)
  const fd = fs.openSync(archivePath, 'r')

  const concurrency = options?.uploadConcurrency ?? 4 // # of HTTP requests in parallel
  const MAX_CHUNK_SIZE = options?.uploadChunkSize ?? 32 * 1024 * 1024 // 32 MB Chunks
  core.debug(`Concurrency: ${concurrency} and Chunk Size: ${MAX_CHUNK_SIZE}`)

  const parallelUploads = [...new Array(concurrency).keys()]
  core.debug('Awaiting all uploads')
  let offset = 0

  try {
    await Promise.all(
      parallelUploads.map(async () => {
        while (offset < fileSize) {
          const chunkSize = Math.min(fileSize - offset, MAX_CHUNK_SIZE)
          const start = offset
          const end = offset + chunkSize - 1
          offset += MAX_CHUNK_SIZE

          await uploadChunk(
            httpClient,
            resourceUrl,
            () =>
              fs
                .createReadStream(archivePath, {
                  fd,
                  start,
                  end,
                  autoClose: false
                })
                .on('error', error => {
                  throw new Error(
                    `Cache upload failed because file read failed with ${error.Message}`
                  )
                }),
            start,
            end
          )
        }
      })
    )
  } finally {
    fs.closeSync(fd)
  }
  return
}

async function commitCache(
  httpClient: HttpClient,
  cacheId: number,
  filesize: number
): Promise<ITypedResponse<null>> {
  const commitCacheRequest: CommitCacheRequest = {size: filesize}
  return await retryTypedResponse('commitCache', async () =>
    httpClient.postJson<null>(
      getCacheApiUrl(`caches/${cacheId.toString()}`),
      commitCacheRequest
    )
  )
}

export async function saveCache(
  cacheId: number,
  archivePath: string,
  options?: UploadOptions
): Promise<void> {
  const httpClient = createHttpClient()

  core.debug('Upload cache')
  await uploadFile(httpClient, cacheId, archivePath, options)

  // Commit Cache
  core.debug('Commiting cache')
  const cacheSize = utils.getArchiveFileSize(archivePath)
  const commitCacheResponse = await commitCache(httpClient, cacheId, cacheSize)
  if (!isSuccessStatusCode(commitCacheResponse.statusCode)) {
    throw new Error(
      `Cache service responded with ${commitCacheResponse.statusCode} during commit cache.`
    )
  }

  core.info('Cache saved successfully')
}