tailwindcss/integrations/utils.ts

import dedent from 'dedent'
import fastGlob from 'fast-glob'
import { exec, execFile, spawn, type ChildProcess } from 'node:child_process'
import fs from 'node:fs/promises'
import { createServer } from 'node:net'
import { platform, tmpdir } from 'node:os'
import path from 'node:path'
import { promisify, stripVTControlCharacters } from 'node:util'
import { RawSourceMap, SourceMapConsumer } from 'source-map-js'
import { test as defaultTest, type ExpectStatic } from 'vitest'
import * as Yaml from 'yaml'
import { createLineTable } from '../packages/tailwindcss/src/source-maps/line-table'
import { escape } from '../packages/tailwindcss/src/utils/escape'

const REPO_ROOT = path.join(__dirname, '..')
const ROOT_PNPM_WORKSPACE = Yaml.parse(
  await fs.readFile(path.join(REPO_ROOT, 'pnpm-workspace.yaml'), 'utf8'),
)
const PUBLIC_PACKAGES = (await fs.readdir(path.join(REPO_ROOT, 'dist'))).map((name) =>
  name.replace('tailwindcss-', '@tailwindcss/').replace('.tgz', ''),
)

interface SpawnedProcess {
  dispose: () => Promise<void>
  flush: () => void
  onStdout: (predicate: (message: string) => boolean) => Promise<void>
  onStderr: (predicate: (message: string) => boolean) => Promise<void>
}

interface ChildProcessOptions {
  cwd?: string
  env?: Record<string, string>
}

interface ExecOptions {
  ignoreStdErr?: boolean
  stdin?: string
}

interface TestConfig {
  fs: {
    [filePath: string]: string | Uint8Array
  }

  timeout?: number
  installDependencies?: boolean
  retry?: number
}
interface TestContext {
  root: string
  expect: ExpectStatic
  exec(command: string, options?: ChildProcessOptions, execOptions?: ExecOptions): Promise<string>
  spawn(command: string, options?: ChildProcessOptions): Promise<SpawnedProcess>
  parseSourceMap(opts: string | SourceMapOptions): SourceMap
  fs: {
    write(filePath: string, content: string, encoding?: BufferEncoding): Promise<void>
    symlink(dst: string, src: string): Promise<void>
    create(filePaths: string[]): Promise<void>
    read(filePath: string): Promise<string>
    delete(filePath: string): Promise<void>
    glob(pattern: string): Promise<[string, string][]>
    dumpFiles(pattern: string): Promise<string>
    expectFileToContain(
      filePath: string,
      contents: string | RegExp | (string | RegExp)[],
    ): Promise<void>
    expectFileNotToContain(filePath: string, contents: string[]): Promise<void>
  }
}
type TestCallback = (context: TestContext) => Promise<void> | void
interface TestFlags {
  only?: boolean
  skip?: boolean
  debug?: boolean
  concurrent?: boolean
}

type SpawnActor = { predicate: (message: string) => boolean; resolve: () => void }

export const IS_WINDOWS = platform() === 'win32'

const execFileAsync = promisify(execFile)

const TEST_TIMEOUT = IS_WINDOWS ? 120000 : 60000
const ASSERTION_TIMEOUT = IS_WINDOWS ? 10000 : 5000

// On Windows CI, tmpdir returns a path containing a weird RUNNER~1 folder that
// apparently causes the vite builds to not work.
const TMP_ROOT =
  process.env.CI && IS_WINDOWS ? path.dirname(process.env.GITHUB_WORKSPACE!) : tmpdir()

export function test(
  name: string,
  config: TestConfig,
  testCallback: TestCallback,
  { only = false, skip = false, debug = false, concurrent = false }: TestFlags = {},
) {
  return defaultTest(
    name,
    {
      timeout: config.timeout ?? TEST_TIMEOUT,
      retry: config.retry ?? (process.env.CI ? 2 : 0),
      only: only || (!process.env.CI && debug),
      skip,
      concurrent,
    },
    async (options) => {
      let rootDir = debug ? path.join(REPO_ROOT, '.debug') : TMP_ROOT
      await fs.mkdir(rootDir, { recursive: true })

      let root = await fs.mkdtemp(path.join(rootDir, 'tailwind-integrations'))

      if (debug) {
        console.log('Running test in debug mode. File system will be written to:')
        console.log(root)
        console.log()
      }

      let context = {
        root,
        expect: options.expect,
        parseSourceMap,
        async exec(
          command: string,
          childProcessOptions: ChildProcessOptions = {},
          execOptions: ExecOptions = {},
        ) {
          let cwd = childProcessOptions.cwd ?? root
          let originalCommand = command

          // Avoid `pnpm exec upgrade` on Windows because the upgrader runs
          // `pnpm add`, which rewrites Windows `.cmd` shims while the current
          // shim is still executing.
          //
          // Pretty sure this is a pnpm v11 bug on Windows.
          if (IS_WINDOWS && command.includes('pnpm exec upgrade')) {
            for (let base = cwd; ; base = path.dirname(base)) {
              let upgradeBin = path.join(
                base,
                'node_modules',
                '@tailwindcss',
                'upgrade',
                'dist',
                'index.mjs',
              )

              try {
                await fs.access(upgradeBin)
                command = command.replace('pnpm exec upgrade', `node "${upgradeBin}"`)
                break
              } catch (error: any) {
                if (error?.code !== 'ENOENT') throw error
              }

              let parent = path.dirname(base)
              if (parent === base) {
                throw new Error(`Unable to resolve @tailwindcss/upgrade from ${cwd}`)
              }
            }
          }

          if (debug && cwd !== root) {
            let relative = path.relative(root, cwd)
            if (relative[0] !== '.') relative = `./${relative}`
            console.log(`> cd ${relative}`)
          }
          if (debug) console.log(`> ${command}`)
          return new Promise((resolve, reject) => {
            let child = exec(
              command,
              {
                cwd,
                ...childProcessOptions,
                env: {
                  ...process.env,
                  ...childProcessOptions.env,
                },
              },
              (error, stdout, stderr) => {
                if (error) {
                  if (command !== originalCommand) {
                    error.message = error.message.replace(command, originalCommand)
                    let mappedError = error as any
                    mappedError.cmd = originalCommand
                  }
                  if (execOptions.ignoreStdErr !== true) console.error(stderr)
                  if (only || debug) {
                    console.error(stdout)
                  }
                  reject(error)
                } else {
                  if (only || debug) {
                    console.log(stdout.toString() + '\n\n' + stderr.toString())
                  }
                  resolve(stdout.toString() + '\n\n' + stderr.toString())
                }
              },
            )
            if (execOptions.stdin) {
              child.stdin?.write(execOptions.stdin)
              child.stdin?.end()
            }
          })
        },
        async spawn(command: string, childProcessOptions: ChildProcessOptions = {}) {
          let resolveDisposal: (() => void) | undefined
          let rejectDisposal: ((error: Error) => void) | undefined
          let disposePromise = new Promise<void>((resolve, reject) => {
            resolveDisposal = resolve
            rejectDisposal = reject
          })

          let cwd = childProcessOptions.cwd ?? root
          if (debug && cwd !== root) {
            let relative = path.relative(root, cwd)
            if (relative[0] !== '.') relative = `./${relative}`
            console.log(`> cd ${relative}`)
          }
          if (debug) console.log(`>& ${command}`)
          let child = spawn(command, {
            cwd,
            detached: !IS_WINDOWS,
            shell: true,
            ...childProcessOptions,
            env: {
              ...process.env,
              ...childProcessOptions.env,
            },
          })

          let disposed = false

          async function dispose() {
            if (disposed) return disposePromise
            disposed = true

            await killProcessTree(child)

            let timer = setTimeout(() => {
              forceKillProcessTree(child)
              rejectDisposal?.(new Error(`spawned process (${command}) did not exit in time`))
            }, ASSERTION_TIMEOUT)
            disposePromise.then(
              () => clearTimeout(timer),
              () => clearTimeout(timer),
            )
            return disposePromise
          }
          disposables.push(dispose)

          function onExit() {
            resolveDisposal?.()
          }

          let stdoutMessages: string[] = []
          let stderrMessages: string[] = []

          let stdoutActors: SpawnActor[] = []
          let stderrActors: SpawnActor[] = []

          function notifyNext(actors: SpawnActor[], messages: string[]) {
            if (actors.length <= 0) return
            let [next] = actors

            for (let [idx, message] of messages.entries()) {
              if (next.predicate(message)) {
                messages.splice(0, idx + 1)
                let actorIdx = actors.indexOf(next)
                actors.splice(actorIdx, 1)
                next.resolve()
                break
              }
            }
          }

          let combined: ['stdout' | 'stderr', string][] = []

          child.stdout.on('data', (result) => {
            let content = result.toString()
            if (debug || only) console.log(content)
            combined.push(['stdout', content])
            for (let line of content.split('\n')) {
              stdoutMessages.push(stripVTControlCharacters(line))
            }
            notifyNext(stdoutActors, stdoutMessages)
          })
          child.stderr.on('data', (result) => {
            let content = result.toString()
            if (debug || only) console.error(content)
            combined.push(['stderr', content])
            for (let line of content.split('\n')) {
              stderrMessages.push(stripVTControlCharacters(line))
            }
            notifyNext(stderrActors, stderrMessages)
          })
          child.on('exit', onExit)
          child.on('error', (error) => {
            if (error.name !== 'AbortError') {
              throw error
            }
          })

          options.onTestFailed(() => {
            // In only or debug mode, messages are logged to the console
            // immediately.
            if (only || debug) return

            for (let [type, message] of combined) {
              if (type === 'stdout') {
                console.log(message)
              } else {
                console.error(message)
              }
            }
          })

          return {
            dispose,
            flush() {
              stdoutActors.splice(0)
              stderrActors.splice(0)

              stdoutMessages.splice(0)
              stderrMessages.splice(0)
            },
            onStdout(predicate: (message: string) => boolean) {
              return new Promise<void>((resolve) => {
                stdoutActors.push({ predicate, resolve })
                notifyNext(stdoutActors, stdoutMessages)
              })
            },
            onStderr(predicate: (message: string) => boolean) {
              return new Promise<void>((resolve) => {
                stderrActors.push({ predicate, resolve })
                notifyNext(stderrActors, stderrMessages)
              })
            },
          }
        },
        fs: {
          async write(filename, content, encoding = 'utf8') {
            let full = path.join(root, filename)
            let dir = path.dirname(full)
            await fs.mkdir(dir, { recursive: true })

            if (typeof content !== 'string') {
              return await fs.writeFile(full, content)
            }

            if (filename.endsWith('package.json')) {
              content = await overwriteVersionsInPackageJson(content)
            } else if (filename.endsWith('pnpm-workspace.yaml')) {
              content = overwriteVersionsInPnpmWorkspace(content)
            }

            // Ensure that files written on Windows use \r\n line ending
            if (IS_WINDOWS) {
              content = content.replace(/\n/g, '\r\n')
            }

            await fs.writeFile(full, content, encoding)
          },

          async symlink(target, src) {
            let targetAbsolute = path.join(root, target)
            let targetParent = path.dirname(targetAbsolute)
            await fs.mkdir(targetParent, { recursive: true })

            let srcAbsolute = path.join(root, src)
            let srcParent = path.dirname(srcAbsolute)
            await fs.mkdir(srcParent, { recursive: true })

            await fs.symlink(targetAbsolute, srcAbsolute)
          },

          async create(filenames) {
            for (let filename of filenames) {
              let full = path.join(root, filename)

              let dir = path.dirname(full)
              await fs.mkdir(dir, { recursive: true })
              await fs.writeFile(full, '')
            }
          },

          async delete(filename) {
            await fs.unlink(path.join(root, filename))
          },

          async read(filePath) {
            let content = await fs.readFile(path.resolve(root, filePath), 'utf8')

            // Ensure that files read on Windows have \r\n line endings removed
            if (IS_WINDOWS) {
              content = content.replace(/\r\n/g, '\n')
            }

            return content
          },
          async glob(pattern) {
            let files = await fastGlob(pattern, { cwd: root })
            return Promise.all(
              files.map(async (file) => {
                let content = await fs.readFile(path.join(root, file), 'utf8')
                return [
                  file,
                  // Drop license comment
                  content.replace(/[\s\n]*\/\*![\s\S]*?\*\/[\s\n]*/g, ''),
                ]
              }),
            )
          },
          async dumpFiles(pattern) {
            let files = await context.fs.glob(pattern)
            return `\n${files
              .slice()
              .sort((a: [string], z: [string]) => {
                let aParts = a[0].split('/')
                let zParts = z[0].split('/')

                let aFile = aParts.at(-1)
                let zFile = zParts.at(-1)

                // Sort by depth, shallow first
                if (aParts.length < zParts.length) return -1
                if (aParts.length > zParts.length) return 1

                // Sort by folder names, alphabetically
                for (let i = 0; i < aParts.length - 1; i++) {
                  let diff = aParts[i].localeCompare(zParts[i])
                  if (diff !== 0) return diff
                }

                // Sort by filename, sort files named `index` before others
                if (aFile?.startsWith('index') && !zFile?.startsWith('index')) return -1
                if (zFile?.startsWith('index') && !aFile?.startsWith('index')) return 1

                // Sort by filename, alphabetically
                return a[0].localeCompare(z[0])
              })
              .map(([file, content]) => `--- ${file} ---\n${content || '<EMPTY>'}`)
              .join('\n\n')
              .trim()}\n`
          },
          async expectFileToContain(filePath, contents) {
            return retryAssertion(async () => {
              let fileContent = await this.read(filePath)
              for (let content of Array.isArray(contents) ? contents : [contents]) {
                if (content instanceof RegExp) {
                  options.expect(fileContent).toMatch(content)
                } else {
                  options.expect(fileContent).toContain(content)
                }
              }
            })
          },
          async expectFileNotToContain(filePath, contents) {
            return retryAssertion(async () => {
              let fileContent = await this.read(filePath)
              for (let content of contents) {
                options.expect(fileContent).not.toContain(content)
              }
            })
          },
        },
      } satisfies TestContext

      config.fs['.gitignore'] ??= txt`
        node_modules/
      `

      // Disable Git's automatic line ending conversion in these throwaway test
      // repositories. Tools like pnpm write files (e.g. `pnpm-lock.yaml`) with
      // LF endings, which on Windows (where `core.autocrlf=true` is common)
      // makes Git emit noisy "LF will be replaced by CRLF" warnings when it
      // touches those files.
      config.fs['.gitattributes'] ??= txt`
        * -text
      `

      // Ensure there is always a root `pnpm-workspace.yaml` so that transitive
      // dependency overrides (and the build allow list) are injected into it.
      // As of pnpm v10, these can no longer live in the `pnpm.overrides` field
      // of `package.json`.
      config.fs['pnpm-workspace.yaml'] ??= ''

      for (let [filename, content] of Object.entries(config.fs)) {
        if (content.toString().startsWith('symlink:')) {
          // The symlink path is relative to the target destination's path
          let target = path.join(
            filename,
            content.toString().slice('symlink:'.length), // Relative path
          )

          await context.fs.symlink(target, filename)
        } else {
          await context.fs.write(filename, content)
        }
      }

      let shouldInstallDependencies = config.installDependencies ?? true

      try {
        // Every test project gets its own root `pnpm-workspace.yaml` (see
        // above). This makes the test directory its own workspace root, so even
        // in debug mode — where the directory lives inside this repository's
        // pnpm workspace — `pnpm install` won't attach to the parent workspace.
        if (shouldInstallDependencies) {
          await context.exec(`pnpm install`)
        }
      } catch (error: any) {
        console.error(error)
        console.error(error.stdout?.toString())
        console.error(error.stderr?.toString())
        throw error
      }

      let disposables: (() => Promise<void>)[] = []

      async function dispose() {
        let results = await Promise.allSettled(disposables.map((dispose) => dispose()))

        if (!debug) {
          await gracefullyRemove(root)
        }

        let errors = results.flatMap((result) =>
          result.status === 'rejected' ? [result.reason] : [],
        )
        if (errors.length > 0) {
          throw new AggregateError(errors, 'Failed to clean up spawned processes')
        }
      }

      options.onTestFinished(dispose)

      // Make it a git repository, and commit all files
      if (only || debug) {
        try {
          await context.exec('git init', { cwd: root })
          await context.exec('git add --all', { cwd: root })
          await context.exec('git commit -m "before migration" --allow-empty', { cwd: root })
        } catch (error: any) {
          console.error(error)
          console.error(error.stdout?.toString())
          console.error(error.stderr?.toString())
          throw error
        }
      }

      return await testCallback(context)
    },
  )
}
test.only = (name: string, config: TestConfig, testCallback: TestCallback) => {
  return test(name, config, testCallback, { only: true })
}
test.skip = (name: string, config: TestConfig, testCallback: TestCallback) => {
  return test(name, config, testCallback, { skip: true })
}
test.concurrent = (name: string, config: TestConfig, testCallback: TestCallback) => {
  return test(name, config, testCallback, { concurrent: true })
}
test.debug = (name: string, config: TestConfig, testCallback: TestCallback) => {
  return test(name, config, testCallback, { debug: true })
}

// Maps package names to their tarball filenames. See scripts/pack-packages.ts
// for more details.
function pkgToFilename(name: string) {
  return `${name.replace('@', '').replace('/', '-')}.tgz`
}

async function overwriteVersionsInPackageJson(content: string): Promise<string> {
  let json = JSON.parse(content)

  // Resolve all workspace:^ versions to local tarballs
  for (let key of ['dependencies', 'devDependencies', 'peerDependencies', 'optionalDependencies']) {
    let dependencies = json[key] || {}
    for (let dependency in dependencies) {
      if (dependencies[dependency] === 'workspace:^') {
        dependencies[dependency] = resolveVersion(dependency)
      }
    }
  }

  return JSON.stringify(json, null, 2)
}

function overwriteVersionsInPnpmWorkspace(content: string): string {
  let workspace = content.trim() === '' ? {} : Yaml.parse(content)

  // Inherit information from the root workspace
  workspace.allowBuilds = {
    ...ROOT_PNPM_WORKSPACE.allowBuilds,
    ...workspace.allowBuilds,
  }

  // Inject transitive dependency overwrite. This is necessary because
  // @tailwindcss/vite internally depends on a specific version of
  // @tailwindcss/oxide and we instead want to resolve it to the locally built
  // version.
  //
  // As of pnpm v10, the `pnpm.overrides` field in `package.json` is no longer
  // read. Overrides have to be defined in `pnpm-workspace.yaml` instead.
  workspace.overrides ||= {}
  for (let pkg of PUBLIC_PACKAGES) {
    if (pkg === 'tailwindcss') {
      // We want to be explicit about the `tailwindcss` package so our tests can
      // also import v3 without conflicting v4 tarballs.
      workspace.overrides['@tailwindcss/node>tailwindcss'] = resolveVersion(pkg)
      workspace.overrides['@tailwindcss/upgrade>tailwindcss'] = resolveVersion(pkg)
      workspace.overrides['@tailwindcss/cli>tailwindcss'] = resolveVersion(pkg)
      workspace.overrides['@tailwindcss/postcss>tailwindcss'] = resolveVersion(pkg)
      workspace.overrides['@tailwindcss/vite>tailwindcss'] = resolveVersion(pkg)
      workspace.overrides['@tailwindcss/webpack>tailwindcss'] = resolveVersion(pkg)
    } else {
      workspace.overrides[pkg] = resolveVersion(pkg)
    }
  }

  return Yaml.stringify(workspace)
}

function resolveVersion(dependency: string) {
  let tarball = path.join(REPO_ROOT, 'dist', pkgToFilename(dependency))
  return `file:${tarball}`
}

export function stripTailwindComment(content: string) {
  return content.replace(/\/\*! tailwindcss .*? \*\//g, '').trim()
}

export let svg = dedent
export let css = dedent
export let html = dedent
export let ts = dedent
export let js = dedent
export let jsx = dedent
export let json = dedent
export let yaml = dedent
export let txt = dedent

export function binary(str: string | TemplateStringsArray, ...values: unknown[]): Uint8Array {
  let base64 = typeof str === 'string' ? str : String.raw(str, ...values)

  return Uint8Array.from(atob(base64), (c) => c.charCodeAt(0))
}

export function candidate(strings: TemplateStringsArray, ...values: any[]) {
  let output: string[] = []
  for (let i = 0; i < strings.length; i++) {
    output.push(strings[i])
    if (i < values.length) {
      output.push(values[i])
    }
  }

  return `.${escape(output.join('').trim())}`
}

export async function retryAssertion<T>(
  fn: () => Promise<T>,
  { timeout = ASSERTION_TIMEOUT, delay = 5 }: { timeout?: number; delay?: number } = {},
) {
  let end = Date.now() + timeout
  let error: any
  while (Date.now() < end) {
    try {
      return await fn()
    } catch (err) {
      Error.captureStackTrace(err, retryAssertion)
      error = err
      await new Promise((resolve) => setTimeout(resolve, delay))
    }
  }
  throw error
}

export async function fetchStyles(base: string, path = '/'): Promise<string> {
  while (base.endsWith('/')) {
    base = base.slice(0, -1)
  }

  let index = await fetch(`${base}${path}`)
  let html = await index.text()

  let linkRegex = /<link rel="stylesheet" href="([a-zA-Z0-9/_.?=%-]+)"/gi
  let styleRegex = /<style\b[^>]*>([\s\S]*?)<\/style>/gi

  let stylesheets: string[] = []

  let paths: string[] = []
  for (let match of html.matchAll(linkRegex)) {
    let path: string = match[1]
    if (path.startsWith('./')) {
      path = path.slice(1)
    }
    paths.push(path)
  }
  stylesheets.push(
    ...(await Promise.all(
      paths.map(async (path) => {
        let css = await fetch(`${base}${path}`, {
          headers: {
            Accept: 'text/css',
          },
        })
        return await css.text()
      }),
    )),
  )

  for (let match of html.matchAll(styleRegex)) {
    stylesheets.push(match[1])
  }

  return stylesheets.reduce((acc, css) => {
    if (acc.length > 0) acc += '\n'
    acc += css
    return acc
  }, '')
}

export async function getRandomPort() {
  return new Promise<number>((resolve, reject) => {
    let server = createServer()
    server.unref()
    server.on('error', reject)
    server.listen(0, '127.0.0.1', () => {
      let address = server.address()
      server.close(() => {
        if (address && typeof address === 'object') {
          resolve(address.port)
        } else {
          reject(new Error('Unable to allocate random port'))
        }
      })
    })
  })
}

async function killProcessTree(child: ChildProcess) {
  if (child.exitCode !== null || child.signalCode !== null || child.pid === undefined) {
    return
  }

  if (IS_WINDOWS) {
    await execFileAsync('taskkill', ['/pid', String(child.pid), '/T', '/F'], {
      timeout: ASSERTION_TIMEOUT,
      windowsHide: true,
    }).catch(() => {})
    return
  }

  try {
    process.kill(-child.pid, 'SIGTERM')
  } catch (error: any) {
    if (error?.code !== 'ESRCH') {
      child.kill()
    }
  }
}

function forceKillProcessTree(child: ChildProcess) {
  if (child.exitCode !== null || child.signalCode !== null || child.pid === undefined) {
    return
  }

  if (IS_WINDOWS) {
    execFile('taskkill', ['/pid', String(child.pid), '/T', '/F'], { windowsHide: true }, () => {})
    return
  }

  try {
    process.kill(-child.pid, 'SIGKILL')
  } catch (error: any) {
    if (error?.code !== 'ESRCH') {
      child.kill('SIGKILL')
    }
  }
}

async function gracefullyRemove(dir: string) {
  // Skip removing the directory in CI because it can stall on Windows
  if (!process.env.CI) {
    await fs.rm(dir, { recursive: true, force: true }).catch((error) => {
      console.log(`Failed to remove ${dir}`, error)
    })
  }
}

const SOURCE_MAP_COMMENT = /^\/\*# sourceMappingURL=data:application\/json;base64,(.*) \*\/$/

export interface SourceMap {
  at(
    line: number,
    column: number,
  ): {
    source: string | null
    original: string
    generated: string
  }
}

interface SourceMapOptions {
  /**
   * A raw source map
   *
   * This may be a string or an object. Strings will be decoded.
   */
  map: string | object

  /**
   * The content of the generated file the source map is for
   */
  content: string

  /**
   * The encoding of the source map
   *
   * Can be used to decode a base64 map (e.g. an inline source map URI)
   */
  encoding?: BufferEncoding
}

function parseSourceMap(opts: string | SourceMapOptions): SourceMap {
  if (typeof opts === 'string') {
    let lines = opts.trimEnd().split('\n')
    let comment = lines.at(-1) ?? ''
    let map = String(comment).match(SOURCE_MAP_COMMENT)?.[1] ?? null
    if (!map) throw new Error('No source map comment found')

    return parseSourceMap({
      map,
      content: lines.slice(0, -1).join('\n'),
      encoding: 'base64',
    })
  }

  let rawMap: RawSourceMap
  let content = opts.content

  if (typeof opts.map === 'object') {
    rawMap = opts.map as RawSourceMap
  } else {
    rawMap = JSON.parse(Buffer.from(opts.map, opts.encoding ?? 'utf-8').toString())
  }

  let map = new SourceMapConsumer(rawMap)
  let generatedTable = createLineTable(content)

  return {
    at(line: number, column: number) {
      let pos = map.originalPositionFor({ line, column })
      let source = pos.source ? map.sourceContentFor(pos.source) : null
      let originalTable = createLineTable(source ?? '')
      let originalOffset = originalTable.findOffset(pos)
      let generatedOffset = generatedTable.findOffset({ line, column })

      return {
        source: pos.source,
        original: source
          ? source.slice(originalOffset, originalOffset + 10).trim() + '...'
          : '(none)',
        generated: content.slice(generatedOffset, generatedOffset + 10).trim() + '...',
      }
    },
  }
}