import * as os from 'os'
import * as path from 'path'
import * as core from '@actions/core'
import * as artifact from '@actions/artifact'
import {Inputs, Outputs} from './constants'

const PARALLEL_DOWNLOADS = 5

export const chunk = <T>(arr: T[], n: number): T[][] =>
  arr.reduce((acc, cur, i) => {
    const index = Math.floor(i / n)
    acc[index] = [...(acc[index] || []), cur]
    return acc
  }, [] as T[][])

async function run(): Promise<void> {
  const inputs = {
    name: core.getInput(Inputs.Name, {required: false}),
    path: core.getInput(Inputs.Path, {required: false}),
    token: core.getInput(Inputs.GitHubToken, {required: true}),
    repository: core.getInput(Inputs.Repository, {required: true}),
    runID: parseInt(core.getInput(Inputs.RunID, {required: true}))
  }

  if (!inputs.path) {
    inputs.path = process.env['GITHUB_WORKSPACE'] || process.cwd()
  }

  if (inputs.path.startsWith(`~`)) {
    inputs.path = inputs.path.replace('~', os.homedir())
  }

  const isSingleArtifactDownload: boolean = !!inputs.name
  const resolvedPath = path.resolve(inputs.path)
  core.debug(`Resolved path is ${resolvedPath}`)

  const [owner, repo] = inputs.repository.split('/')
  if (!owner || !repo) {
    throw new Error(
      `Invalid repository: '${inputs.repository}'. Must be in format owner/repo`
    )
  }

  const artifactClient = artifact.create()
  let artifacts: artifact.Artifact[] = []

  if (isSingleArtifactDownload) {
    core.info(`Downloading single artifact`)

    const {artifact: targetArtifact} = await artifactClient.getArtifact(
      inputs.name,
      inputs.runID,
      owner,
      repo,
      inputs.token
    )

    if (!targetArtifact) {
      throw new Error(`Artifact '${inputs.name}' not found`)
    }

    core.debug(
      `Found named artifact '${inputs.name}' (ID: ${targetArtifact.id}, Size: ${targetArtifact.size})`
    )

    artifacts = [targetArtifact]
  } else {
    core.info(`No input name specified, downloading all artifacts. Extra directory with the artifact name will be created for each download`)

    const listArtifactResponse = await artifactClient.listArtifacts(
      inputs.runID,
      owner,
      repo,
      inputs.token
    )

    if (listArtifactResponse.artifacts.length === 0) {
      throw new Error(
        `No artifacts found for run '${inputs.runID}' in '${inputs.repository}'`
      )
    }

    core.debug(`Found ${listArtifactResponse.artifacts.length} artifacts`)
    artifacts = listArtifactResponse.artifacts
  }

  const downloadPromises = artifacts.map(artifact =>
    artifactClient.downloadArtifact(artifact.id, owner, repo, inputs.token, {
      path: isSingleArtifactDownload ? resolvedPath : path.join(resolvedPath, artifact.name)
    })
  )

  const chunkedPromises = chunk(downloadPromises, PARALLEL_DOWNLOADS)
  for (const chunk of chunkedPromises) {
    await Promise.all(chunk)
  }

  core.info(`Total of ${artifacts.length} artifact(s) downloaded`)
  core.setOutput(Outputs.DownloadPath, resolvedPath)
  core.info('Download artifact has finished successfully')
}

run().catch(err =>
  core.setFailed(`Unable to download artifact(s): ${err.message}`)
)
