flight-manifest-plugin.ts

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import { webpack, sources } from 'next/dist/compiled/webpack/webpack'
import { FLIGHT_MANIFEST } from '../../../shared/lib/constants'
import { clientComponentRegex } from '../loaders/utils'
import { relative } from 'path'
import type { webpack5 } from 'next/dist/compiled/webpack/webpack'

// This is the module that will be used to anchor all client references to.
// I.e. it will have all the client files as async deps from this point on.
// We use the Flight client implementation because you can't get to these
// without the client runtime so it's the first time in the loading sequence
// you might want them.
// const clientFileName = require.resolve('../');

interface Options {
  dev: boolean
  appDir: boolean
  pageExtensions: string[]
}

type ModuleId = string | number

type ManifestChunks = Array<`${string}:${string}` | string>

interface ManifestNode {
  [moduleExport: string]: {
    /**
     * Webpack module id
     */
    id: ModuleId
    /**
     * Export name
     */
    name: string
    /**
     * Chunks for the module. JS and CSS.
     */
    chunks: ManifestChunks
  }
}

type FlightManifest = {
  __ssr_module_mapping__: {
    [moduleId: string]: ManifestNode
  }
} & {
  [modulePath: string]: ManifestNode
}

const PLUGIN_NAME = 'FlightManifestPlugin'

export class FlightManifestPlugin {
  dev: Options['dev'] = false
  pageExtensions: Options['pageExtensions']
  appDir: Options['appDir'] = false

  constructor(options: Options) {
    this.dev = options.dev
    this.appDir = options.appDir
    this.pageExtensions = options.pageExtensions
  }

  apply(compiler: webpack5.Compiler) {
    compiler.hooks.compilation.tap(
      PLUGIN_NAME,
      (compilation, { normalModuleFactory }) => {
        compilation.dependencyFactories.set(
          (webpack as any).dependencies.ModuleDependency,
          normalModuleFactory
        )
        compilation.dependencyTemplates.set(
          (webpack as any).dependencies.ModuleDependency,
          new (webpack as any).dependencies.NullDependency.Template()
        )
      }
    )

    compiler.hooks.make.tap(PLUGIN_NAME, (compilation) => {
      compilation.hooks.processAssets.tap(
        {
          name: PLUGIN_NAME,
          // Have to be in the optimize stage to run after updating the CSS
          // asset hash via extract mini css plugin.
          // @ts-ignore TODO: Remove ignore when webpack 5 is stable
          stage: webpack.Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_HASH,
        },
        (assets) => this.createAsset(assets, compilation, compiler.context)
      )
    })
  }

  createAsset(
    assets: webpack5.Compilation['assets'],
    compilation: webpack5.Compilation,
    context: string
  ) {
    const manifest: FlightManifest = {
      __ssr_module_mapping__: {},
    }
    const appDir = this.appDir
    const dev = this.dev

    compilation.chunkGroups.forEach((chunkGroup) => {
      function recordModule(
        chunk: webpack5.Chunk,
        id: ModuleId,
        mod: webpack5.NormalModule
      ) {
        // if appDir is enabled we shouldn't process chunks from
        // the pages dir
        if (chunk.name?.startsWith('pages/') && appDir) {
          return
        }

        const isCSSModule =
          mod.type === 'css/mini-extract' ||
          (mod.loaders &&
            (dev
              ? mod.loaders.some((item) =>
                  item.loader.includes('next-style-loader/index.js')
                )
              : mod.loaders.some((item) =>
                  item.loader.includes('mini-css-extract-plugin/loader.js')
                )))

        const resource =
          mod.type === 'css/mini-extract'
            ? // @ts-expect-error TODO: use `identifier()` instead.
              mod._identifier.slice(mod._identifier.lastIndexOf('!') + 1)
            : mod.resource

        if (!resource) return

        const moduleExports = manifest[resource] || {}
        const moduleIdMapping = manifest.__ssr_module_mapping__
        moduleIdMapping[id] = moduleIdMapping[id] || {}

        // Note that this isn't that reliable as webpack is still possible to assign
        // additional queries to make sure there's no conflict even using the `named`
        // module ID strategy.
        let ssrNamedModuleId = relative(
          context,
          mod.resourceResolveData?.path || resource
        )
        if (!ssrNamedModuleId.startsWith('.'))
          ssrNamedModuleId = `./${ssrNamedModuleId}`

        if (isCSSModule) {
          if (!manifest[resource]) {
            const chunks = [...chunk.files].filter((f) => f.endsWith('.css'))
            manifest[resource] = {
              default: {
                id,
                name: 'default',
                chunks,
              },
            }
            moduleIdMapping[id]['default'] = {
              id: ssrNamedModuleId,
              name: 'default',
              chunks,
            }
            manifest.__ssr_module_mapping__ = moduleIdMapping
          }
          return
        }

        // TODO: Hook into deps instead of the target module.
        // That way we know by the type of dep whether to include.
        // It also resolves conflicts when the same module is in multiple chunks.
        if (!clientComponentRegex.test(resource)) {
          return
        }

        const exportsInfo = compilation.moduleGraph.getExportsInfo(mod)
        const cjsExports = [
          ...new Set([
            ...mod.dependencies.map((dep) => {
              // Match CommonJsSelfReferenceDependency
              if (dep.type === 'cjs self exports reference') {
                // `module.exports = ...`
                // @ts-expect-error: TODO: Fix Dependency type
                if (dep.base === 'module.exports') {
                  return 'default'
                }

                // `exports.foo = ...`, `exports.default = ...`
                // @ts-expect-error: TODO: Fix Dependency type
                if (dep.base === 'exports') {
                  // @ts-expect-error: TODO: Fix Dependency type
                  return dep.names.filter((name: any) => name !== '__esModule')
                }
              }
              return null
            }),
          ]),
        ]

        const moduleExportedKeys = ['', '*']
          .concat(
            [...exportsInfo.exports]
              .filter((exportInfo) => exportInfo.provided)
              .map((exportInfo) => exportInfo.name),
            ...cjsExports
          )
          .filter((name) => name !== null)

        // Get all CSS files imported from the module's dependencies.
        const visitedModule = new Set()
        const cssChunks: Set<string> = new Set()

        function collectClientImportedCss(module: any) {
          if (!module) return

          const modRequest = module.userRequest
          if (visitedModule.has(modRequest)) return
          visitedModule.add(modRequest)

          if (/\.css$/.test(modRequest)) {
            // collect relative imported css chunks
            compilation.chunkGraph.getModuleChunks(module).forEach((c) => {
              ;[...c.files]
                .filter((file) => file.endsWith('.css'))
                .forEach((file) => cssChunks.add(file))
            })
          }

          const connections = Array.from(
            compilation.moduleGraph.getOutgoingConnections(module)
          )
          connections.forEach((connection) => {
            collectClientImportedCss(
              compilation.moduleGraph.getResolvedModule(connection.dependency!)
            )
          })
        }
        collectClientImportedCss(mod)

        moduleExportedKeys.forEach((name) => {
          let requiredChunks: ManifestChunks = []
          if (!moduleExports[name]) {
            const isRelatedChunk = (c: webpack5.Chunk) =>
              // If current chunk is a page, it should require the related page chunk;
              // If current chunk is a component, it should filter out the related page chunk;
              chunk.name?.startsWith('pages/') || !c.name?.startsWith('pages/')

            if (appDir) {
              requiredChunks = chunkGroup.chunks
                .filter(isRelatedChunk)
                .map((requiredChunk: webpack5.Chunk) => {
                  return (
                    requiredChunk.id +
                    ':' +
                    (requiredChunk.name || requiredChunk.id) +
                    (dev ? '' : '-' + requiredChunk.hash)
                  )
                })
            }

            moduleExports[name] = {
              id,
              name,
              chunks: requiredChunks.concat([...cssChunks]),
            }
          }
          if (!moduleIdMapping[id][name]) {
            moduleIdMapping[id][name] = {
              ...moduleExports[name],
              id: ssrNamedModuleId,
            }
          }
        })

        manifest[resource] = moduleExports
        manifest.__ssr_module_mapping__ = moduleIdMapping
      }

      chunkGroup.chunks.forEach((chunk: webpack5.Chunk) => {
        const chunkModules = compilation.chunkGraph.getChunkModulesIterable(
          chunk
          // TODO: Update type so that it doesn't have to be cast.
        ) as Iterable<webpack5.NormalModule>
        for (const mod of chunkModules) {
          const modId = compilation.chunkGraph.getModuleId(mod)

          recordModule(chunk, modId, mod)

          // If this is a concatenation, register each child to the parent ID.
          // TODO: remove any
          const anyModule = mod as any
          if (anyModule.modules) {
            anyModule.modules.forEach((concatenatedMod: any) => {
              recordModule(chunk, modId, concatenatedMod)
            })
          }
        }
      })
    })

    const file = 'server/' + FLIGHT_MANIFEST
    const json = JSON.stringify(manifest)

    assets[file + '.js'] = new sources.RawSource(
      'self.__RSC_MANIFEST=' + json
      // Work around webpack 4 type of RawSource being used
      // TODO: use webpack 5 type by default
    ) as unknown as webpack5.sources.RawSource
    assets[file + '.json'] = new sources.RawSource(
      json
      // Work around webpack 4 type of RawSource being used
      // TODO: use webpack 5 type by default
    ) as unknown as webpack5.sources.RawSource
  }
}