importAnalysisBuild.ts

import path from 'node:path'
import MagicString from 'magic-string'
import type { ImportSpecifier } from 'es-module-lexer'
import { init, parse as parseImports } from 'es-module-lexer'
import type { OutputChunk, SourceMap } from 'rollup'
import colors from 'picocolors'
import type { RawSourceMap } from '@ampproject/remapping'
import {
  bareImportRE,
  cleanUrl,
  combineSourcemaps,
  isDataUrl,
  isExternalUrl,
  moduleListContains,
} from '../utils'
import type { Plugin } from '../plugin'
import { getDepOptimizationConfig } from '../config'
import type { ResolvedConfig } from '../config'
import { toOutputFilePathInJS } from '../build'
import { genSourceMapUrl } from '../server/sourcemap'
import { getDepsOptimizer, optimizedDepNeedsInterop } from '../optimizer'
import { isCSSRequest, removedPureCssFilesCache } from './css'
import { interopNamedImports } from './importAnalysis'

/**
 * A flag for injected helpers. This flag will be set to `false` if the output
 * target is not native es - so that injected helper logic can be conditionally
 * dropped.
 */
export const isModernFlag = `__VITE_IS_MODERN__`
export const preloadMethod = `__vitePreload`
export const preloadMarker = `__VITE_PRELOAD__`
export const preloadBaseMarker = `__VITE_PRELOAD_BASE__`

export const preloadHelperId = '\0vite/preload-helper'
const preloadMarkerWithQuote = `"${preloadMarker}"` as const

const dynamicImportPrefixRE = /import\s*\(/

// TODO: abstract
const optimizedDepChunkRE = /\/chunk-[A-Z\d]{8}\.js/
const optimizedDepDynamicRE = /-[A-Z\d]{8}\.js/

function toRelativePath(filename: string, importer: string) {
  const relPath = path.relative(path.dirname(importer), filename)
  return relPath.startsWith('.') ? relPath : `./${relPath}`
}

/**
 * Helper for preloading CSS and direct imports of async chunks in parallel to
 * the async chunk itself.
 */

function detectScriptRel() {
  const relList = document.createElement('link').relList
  return relList && relList.supports && relList.supports('modulepreload')
    ? 'modulepreload'
    : 'preload'
}

declare const scriptRel: string
declare const seen: Record<string, boolean>
function preload(
  baseModule: () => Promise<{}>,
  deps?: string[],
  importerUrl?: string,
) {
  // @ts-expect-error __VITE_IS_MODERN__ will be replaced with boolean later
  if (!__VITE_IS_MODERN__ || !deps || deps.length === 0) {
    return baseModule()
  }

  const links = document.getElementsByTagName('link')

  return Promise.all(
    deps.map((dep) => {
      // @ts-expect-error assetsURL is declared before preload.toString()
      dep = assetsURL(dep, importerUrl)
      if (dep in seen) return
      seen[dep] = true
      const isCss = dep.endsWith('.css')
      const cssSelector = isCss ? '[rel="stylesheet"]' : ''
      const isBaseRelative = !!importerUrl

      // check if the file is already preloaded by SSR markup
      if (isBaseRelative) {
        // When isBaseRelative is true then we have `importerUrl` and `dep` is
        // already converted to an absolute URL by the `assetsURL` function
        for (let i = links.length - 1; i >= 0; i--) {
          const link = links[i]
          // The `links[i].href` is an absolute URL thanks to browser doing the work
          // for us. See https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#reflecting-content-attributes-in-idl-attributes:idl-domstring-5
          if (link.href === dep && (!isCss || link.rel === 'stylesheet')) {
            return
          }
        }
      } else if (document.querySelector(`link[href="${dep}"]${cssSelector}`)) {
        return
      }

      const link = document.createElement('link')
      link.rel = isCss ? 'stylesheet' : scriptRel
      if (!isCss) {
        link.as = 'script'
        link.crossOrigin = ''
      }
      link.href = dep
      document.head.appendChild(link)
      if (isCss) {
        return new Promise((res, rej) => {
          link.addEventListener('load', res)
          link.addEventListener('error', () =>
            rej(new Error(`Unable to preload CSS for ${dep}`)),
          )
        })
      }
    }),
  ).then(() => baseModule())
}

/**
 * Build only. During serve this is performed as part of ./importAnalysis.
 */
export function buildImportAnalysisPlugin(config: ResolvedConfig): Plugin {
  const ssr = !!config.build.ssr
  const isWorker = config.isWorker
  const insertPreload = !(
    ssr ||
    !!config.build.lib ||
    isWorker ||
    config.build.modulePreload === false
  )

  const resolveModulePreloadDependencies =
    config.build.modulePreload && config.build.modulePreload.resolveDependencies
  const renderBuiltUrl = config.experimental.renderBuiltUrl
  const customModulePreloadPaths = !!(
    resolveModulePreloadDependencies || renderBuiltUrl
  )
  const isRelativeBase = config.base === './' || config.base === ''
  const optimizeModulePreloadRelativePaths =
    isRelativeBase && !customModulePreloadPaths

  const { modulePreload } = config.build
  const scriptRel =
    modulePreload && modulePreload.polyfill
      ? `'modulepreload'`
      : `(${detectScriptRel.toString()})()`

  // There are three different cases for the preload list format in __vitePreload
  //
  // __vitePreload(() => import(asyncChunk), [ ...deps... ])
  //
  // This is maintained to keep backwards compatibility as some users developed plugins
  // using regex over this list to workaround the fact that module preload wasn't
  // configurable.
  const assetsURL = customModulePreloadPaths
    ? // If `experimental.renderBuiltUrl` or `build.modulePreload.resolveDependencies` are used
      // the dependencies are already resolved. To avoid the need for `new URL(dep, import.meta.url)`
      // a helper `__vitePreloadRelativeDep` is used to resolve from relative paths which can be minimized.
      `function(dep, importerUrl) { return dep.startsWith('.') ? new URL(dep, importerUrl).href : dep }`
    : optimizeModulePreloadRelativePaths
    ? // If there isn't custom resolvers affecting the deps list, deps in the list are relative
      // to the current chunk and are resolved to absolute URL by the __vitePreload helper itself.
      // The importerUrl is passed as third parameter to __vitePreload in this case
      `function(dep, importerUrl) { return new URL(dep, importerUrl).href }`
    : // If the base isn't relative, then the deps are relative to the projects `outDir` and the base
      // is appendended inside __vitePreload too.
      `function(dep) { return ${JSON.stringify(config.base)}+dep }`
  const preloadCode = `const scriptRel = ${scriptRel};const assetsURL = ${assetsURL};const seen = {};export const ${preloadMethod} = ${preload.toString()}`

  return {
    name: 'vite:build-import-analysis',
    resolveId(id) {
      if (id === preloadHelperId) {
        return id
      }
    },

    load(id) {
      if (id === preloadHelperId) {
        return preloadCode
      }
    },

    async transform(source, importer) {
      if (
        importer.includes('node_modules') &&
        !dynamicImportPrefixRE.test(source)
      ) {
        return
      }

      await init

      let imports: readonly ImportSpecifier[] = []
      try {
        imports = parseImports(source)[0]
      } catch (e: any) {
        this.error(e, e.idx)
      }

      if (!imports.length) {
        return null
      }

      const { root } = config
      const depsOptimizer = getDepsOptimizer(config, ssr)

      const normalizeUrl = async (
        url: string,
        pos: number,
      ): Promise<[string, string]> => {
        let importerFile = importer

        const optimizeDeps = getDepOptimizationConfig(config, ssr)
        if (moduleListContains(optimizeDeps?.exclude, url)) {
          if (depsOptimizer) {
            await depsOptimizer.scanProcessing

            // if the dependency encountered in the optimized file was excluded from the optimization
            // the dependency needs to be resolved starting from the original source location of the optimized file
            // because starting from node_modules/.vite will not find the dependency if it was not hoisted
            // (that is, if it is under node_modules directory in the package source of the optimized file)
            for (const optimizedModule of depsOptimizer.metadata.depInfoList) {
              if (!optimizedModule.src) continue // Ignore chunks
              if (optimizedModule.file === importer) {
                importerFile = optimizedModule.src
              }
            }
          }
        }

        const resolved = await this.resolve(url, importerFile)

        if (!resolved) {
          // in ssr, we should let node handle the missing modules
          if (ssr) {
            return [url, url]
          }
          return this.error(
            `Failed to resolve import "${url}" from "${path.relative(
              process.cwd(),
              importerFile,
            )}". Does the file exist?`,
            pos,
          )
        }

        // normalize all imports into resolved URLs
        // e.g. `import 'foo'` -> `import '/@fs/.../node_modules/foo/index.js'`
        if (resolved.id.startsWith(root + '/')) {
          // in root: infer short absolute path from root
          url = resolved.id.slice(root.length)
        } else {
          url = resolved.id
        }

        if (isExternalUrl(url)) {
          return [url, url]
        }

        return [url, resolved.id]
      }

      let s: MagicString | undefined
      const str = () => s || (s = new MagicString(source))
      let needPreloadHelper = false

      for (let index = 0; index < imports.length; index++) {
        const {
          s: start,
          e: end,
          ss: expStart,
          se: expEnd,
          n: specifier,
          d: dynamicIndex,
          a: assertIndex,
        } = imports[index]

        const isDynamicImport = dynamicIndex > -1

        // strip import assertions as we can process them ourselves
        if (!isDynamicImport && assertIndex > -1) {
          str().remove(end + 1, expEnd)
        }

        if (isDynamicImport && insertPreload) {
          needPreloadHelper = true
          str().prependLeft(expStart, `${preloadMethod}(() => `)
          str().appendRight(
            expEnd,
            `,${isModernFlag}?"${preloadMarker}":void 0${
              optimizeModulePreloadRelativePaths || customModulePreloadPaths
                ? ',import.meta.url'
                : ''
            })`,
          )
        }

        // static import or valid string in dynamic import
        // If resolvable, let's resolve it
        if (depsOptimizer && specifier) {
          // skip external / data uri
          if (isExternalUrl(specifier) || isDataUrl(specifier)) {
            continue
          }

          // normalize
          const [url, resolvedId] = await normalizeUrl(specifier, start)

          if (url !== specifier) {
            if (
              depsOptimizer.isOptimizedDepFile(resolvedId) &&
              !resolvedId.match(optimizedDepChunkRE)
            ) {
              const file = cleanUrl(resolvedId) // Remove ?v={hash}

              const needsInterop = await optimizedDepNeedsInterop(
                depsOptimizer.metadata,
                file,
                config,
                ssr,
              )

              let rewriteDone = false

              if (needsInterop === undefined) {
                // Non-entry dynamic imports from dependencies will reach here as there isn't
                // optimize info for them, but they don't need es interop. If the request isn't
                // a dynamic import, then it is an internal Vite error
                if (!file.match(optimizedDepDynamicRE)) {
                  config.logger.error(
                    colors.red(
                      `Vite Error, ${url} optimized info should be defined`,
                    ),
                  )
                }
              } else if (needsInterop) {
                // config.logger.info(`${url} needs interop`)
                interopNamedImports(str(), imports[index], url, index)
                rewriteDone = true
              }
              if (!rewriteDone) {
                let rewrittenUrl = JSON.stringify(file)
                if (!isDynamicImport) rewrittenUrl = rewrittenUrl.slice(1, -1)
                str().update(start, end, rewrittenUrl)
              }
            }
          }
        }

        // Differentiate CSS imports that use the default export from those that
        // do not by injecting a ?used query - this allows us to avoid including
        // the CSS string when unnecessary (esbuild has trouble tree-shaking
        // them)
        if (
          specifier &&
          isCSSRequest(specifier) &&
          // always inject ?used query when it is a dynamic import
          // because there is no way to check whether the default export is used
          (source.slice(expStart, start).includes('from') || isDynamicImport) &&
          // already has ?used query (by import.meta.glob)
          !specifier.match(/\?used(&|$)/) &&
          // edge case for package names ending with .css (e.g normalize.css)
          !(bareImportRE.test(specifier) && !specifier.includes('/'))
        ) {
          const url = specifier.replace(/\?|$/, (m) => `?used${m ? '&' : ''}`)
          str().update(start, end, isDynamicImport ? `'${url}'` : url)
        }
      }

      if (
        needPreloadHelper &&
        insertPreload &&
        !source.includes(`const ${preloadMethod} =`)
      ) {
        str().prepend(`import { ${preloadMethod} } from "${preloadHelperId}";`)
      }

      if (s) {
        return {
          code: s.toString(),
          map: config.build.sourcemap ? s.generateMap({ hires: true }) : null,
        }
      }
    },

    renderChunk(code, _, { format }) {
      // make sure we only perform the preload logic in modern builds.
      if (code.indexOf(isModernFlag) > -1) {
        const re = new RegExp(isModernFlag, 'g')
        const isModern = String(format === 'es')
        if (config.build.sourcemap) {
          const s = new MagicString(code)
          let match: RegExpExecArray | null
          while ((match = re.exec(code))) {
            s.update(match.index, match.index + isModernFlag.length, isModern)
          }
          return {
            code: s.toString(),
            map: s.generateMap({ hires: true }),
          }
        } else {
          return code.replace(re, isModern)
        }
      }
      return null
    },

    generateBundle({ format }, bundle) {
      if (
        format !== 'es' ||
        ssr ||
        isWorker ||
        config.build.modulePreload === false
      ) {
        return
      }

      for (const file in bundle) {
        const chunk = bundle[file]
        // can't use chunk.dynamicImports.length here since some modules e.g.
        // dynamic import to constant json may get inlined.
        if (chunk.type === 'chunk' && chunk.code.indexOf(preloadMarker) > -1) {
          const code = chunk.code
          let imports!: ImportSpecifier[]
          try {
            imports = parseImports(code)[0].filter((i) => i.d > -1)
          } catch (e: any) {
            this.error(e, e.idx)
          }

          const s = new MagicString(code)
          const rewroteMarkerStartPos = new Set() // position of the leading double quote

          if (imports.length) {
            for (let index = 0; index < imports.length; index++) {
              // To handle escape sequences in specifier strings, the .n field will be provided where possible.
              const {
                n: name,
                s: start,
                e: end,
                ss: expStart,
                se: expEnd,
              } = imports[index]
              // check the chunk being imported
              let url = name
              if (!url) {
                const rawUrl = code.slice(start, end)
                if (rawUrl[0] === `"` && rawUrl[rawUrl.length - 1] === `"`)
                  url = rawUrl.slice(1, -1)
              }
              const deps: Set<string> = new Set()
              let hasRemovedPureCssChunk = false

              let normalizedFile: string | undefined = undefined

              if (url) {
                normalizedFile = path.posix.join(
                  path.posix.dirname(chunk.fileName),
                  url,
                )

                const ownerFilename = chunk.fileName
                // literal import - trace direct imports and add to deps
                const analyzed: Set<string> = new Set<string>()
                const addDeps = (filename: string) => {
                  if (filename === ownerFilename) return
                  if (analyzed.has(filename)) return
                  analyzed.add(filename)
                  const chunk = bundle[filename] as OutputChunk | undefined
                  if (chunk) {
                    deps.add(chunk.fileName)
                    chunk.imports.forEach(addDeps)
                    // Ensure that the css imported by current chunk is loaded after the dependencies.
                    // So the style of current chunk won't be overwritten unexpectedly.
                    chunk.viteMetadata.importedCss.forEach((file) => {
                      deps.add(file)
                    })
                  } else {
                    const removedPureCssFiles =
                      removedPureCssFilesCache.get(config)!
                    const chunk = removedPureCssFiles.get(filename)
                    if (chunk) {
                      if (chunk.viteMetadata.importedCss.size) {
                        chunk.viteMetadata.importedCss.forEach((file) => {
                          deps.add(file)
                        })
                        hasRemovedPureCssChunk = true
                      }

                      s.update(expStart, expEnd, 'Promise.resolve({})')
                    }
                  }
                }
                addDeps(normalizedFile)
              }

              let markerStartPos = code.indexOf(preloadMarkerWithQuote, end)
              // fix issue #3051
              if (markerStartPos === -1 && imports.length === 1) {
                markerStartPos = code.indexOf(preloadMarkerWithQuote)
              }

              if (markerStartPos > 0) {
                // the dep list includes the main chunk, so only need to reload when there are actual other deps.
                const depsArray =
                  deps.size > 1 ||
                  // main chunk is removed
                  (hasRemovedPureCssChunk && deps.size > 0)
                    ? [...deps]
                    : []

                let renderedDeps: string[]
                if (normalizedFile && customModulePreloadPaths) {
                  const { modulePreload } = config.build
                  const resolveDependencies =
                    modulePreload && modulePreload.resolveDependencies
                  let resolvedDeps: string[]
                  if (resolveDependencies) {
                    // We can't let the user remove css deps as these aren't really preloads, they are just using
                    // the same mechanism as module preloads for this chunk
                    const cssDeps: string[] = []
                    const otherDeps: string[] = []
                    for (const dep of depsArray) {
                      ;(dep.endsWith('.css') ? cssDeps : otherDeps).push(dep)
                    }
                    resolvedDeps = [
                      ...resolveDependencies(normalizedFile, otherDeps, {
                        hostId: file,
                        hostType: 'js',
                      }),
                      ...cssDeps,
                    ]
                  } else {
                    resolvedDeps = depsArray
                  }

                  renderedDeps = resolvedDeps.map((dep: string) => {
                    const replacement = toOutputFilePathInJS(
                      dep,
                      'asset',
                      chunk.fileName,
                      'js',
                      config,
                      toRelativePath,
                    )
                    const replacementString =
                      typeof replacement === 'string'
                        ? JSON.stringify(replacement)
                        : replacement.runtime

                    return replacementString
                  })
                } else {
                  renderedDeps = depsArray.map((d) =>
                    // Don't include the assets dir if the default asset file names
                    // are used, the path will be reconstructed by the import preload helper
                    JSON.stringify(
                      optimizeModulePreloadRelativePaths
                        ? toRelativePath(d, file)
                        : d,
                    ),
                  )
                }

                s.update(
                  markerStartPos,
                  markerStartPos + preloadMarkerWithQuote.length,
                  `[${renderedDeps.join(',')}]`,
                )
                rewroteMarkerStartPos.add(markerStartPos)
              }
            }
          }

          // there may still be markers due to inlined dynamic imports, remove
          // all the markers regardless
          let markerStartPos = code.indexOf(preloadMarkerWithQuote)
          while (markerStartPos >= 0) {
            if (!rewroteMarkerStartPos.has(markerStartPos)) {
              s.update(
                markerStartPos,
                markerStartPos + preloadMarkerWithQuote.length,
                'void 0',
              )
            }

            markerStartPos = code.indexOf(
              preloadMarkerWithQuote,
              markerStartPos + preloadMarkerWithQuote.length,
            )
          }

          if (s.hasChanged()) {
            chunk.code = s.toString()
            if (config.build.sourcemap && chunk.map) {
              const nextMap = s.generateMap({
                source: chunk.fileName,
                hires: true,
              })
              const map = combineSourcemaps(
                chunk.fileName,
                [nextMap as RawSourceMap, chunk.map as RawSourceMap],
                false,
              ) as SourceMap
              map.toUrl = () => genSourceMapUrl(map)
              chunk.map = map
            }
          }
        }
      }
    },
  }
}