HonoX Islands Detection

inject-importing-islands.ts

import { existsSync } from 'fs'
import { lstat, readFile } from 'fs/promises'
import path from 'path'
import MagicString from 'magic-string'
import precinct from 'precinct'
import { normalizePath, type Plugin } from 'vite'
import { IMPORTING_ISLANDS_ID } from '../constants'

export function injectImportingIslands(): Plugin {
  const isIslandRegex = new RegExp(/\/islands\//)
  const routesRegex = new RegExp(/routes\/.*\.[t|j]sx$/)

  return {
    name: 'inject-importing-islands',
    async transform(sourceCode, id) {
      if (!routesRegex.test(id)) {
        return
      }

      const hasIslandsImport = (await walkDependencyTree(id))
        .flat()
        .some((x) => isIslandRegex.test(normalizePath(x)))

      if (!hasIslandsImport) {
        return
      }

      const islandEnabledSource = new MagicString(sourceCode)
      islandEnabledSource.append(`export const ${IMPORTING_ISLANDS_ID} = true;`)

      return { code: islandEnabledSource.toString(), map: islandEnabledSource.generateMap() }
    },
  }
}

const cache: Record<string, string> = {}

const walkDependencyTree: (baseFile: string, dependencyFile?: string) => Promise<string[]> = async (
  baseFile: string,
  dependencyFile?: string
) => {
  const depPath = dependencyFile
    ? path.join(path.dirname(baseFile), dependencyFile) + '.tsx' //TODO: This only includes tsx files
    : baseFile
  const deps = [depPath]

  if (!existsSync(depPath) || (await lstat(depPath)).isDirectory()) {
    return deps
  }

  if (!cache[depPath]) {
    cache[depPath] = (await readFile(depPath)).toString()
  }

  const currentFileDeps = precinct(cache[depPath]) as string[]

  const childDeps = await Promise.all(
    currentFileDeps.map(async (x) => await walkDependencyTree(depPath, x))
  )
  deps.push(...childDeps.flat())
  return deps
}