const visit = require('unist-util-visit')
const latestEnterpriseRelease = require('../../enterprise-server-releases').latest
const nonEnterpriseDefaultVersion = require('../../non-enterprise-default-version')
const { getS3BucketPathFromVersion } = require('../../s3-bucket-path-utils')
const allVersions = require('../../all-versions')
const s3BasePath = 'https://github-images.s3.amazonaws.com'

const matcher = node => (
  node.type === 'element' &&
  node.tagName === 'img' &&
  node.properties.src &&
  node.properties.src.startsWith('/assets/images')
)

// This module rewrites asset paths on Enterprise versions to S3 paths.
// Source example: /assets/images/foo.png
// Rewritten: https://github-images.s3.amazonaws.com/enterprise/2.20/assets/images/foo.png
// The one exception is Admin pages on the latest GHES release.
module.exports = function rewriteAssetPathsToS3 ({ currentVersion, relativePath }) {
  // Bail if we don't have a relativePath in this context
  if (!relativePath) return

  // skip if this is the homepage
  if (relativePath === 'index.md') return

  // if the current version is non-enterprise, do not rewrite
  if (currentVersion === nonEnterpriseDefaultVersion) return

  // the relativePath starts with the product, like /admin/foo or /github/foo
  const product = relativePath.split('/')[0]

  // if this is an Admin page on the latest GHES release, do not rewrite
  if (product === 'admin' && allVersions[currentVersion].currentRelease === latestEnterpriseRelease) return

  // if the version is enterprise-server@2.22, use `enterprise/2.22` as the bucket path
  // otherwise, use the plan name, e.g., `github-ae`
  const bucketPath = getS3BucketPathFromVersion(currentVersion)

  return tree => {
    visit(tree, matcher, node => {
      // Rewrite the node's src
      node.properties.src = `${s3BasePath}/${bucketPath}${node.properties.src}`
    })
  }
}