pnpm/modules-mounter/daemon/src/createFuseHandlers.ts

// cspell:ignore ents
import fs from 'node:fs'

import { type LockfileObject, type PackageSnapshot, readWantedLockfile, type TarballResolution } from '@pnpm/lockfile.fs'
import {
  nameVerFromPkgSnapshot,
} from '@pnpm/lockfile.utils'
import { getFilePathByModeInCafs, type PackageFilesIndex } from '@pnpm/store.cafs'
import { StoreIndex, storeIndexKey } from '@pnpm/store.index'
import type { DepPath } from '@pnpm/types'
import Fuse from 'fuse-native'
import schemas from 'hyperdrive-schemas'

import * as cafsExplorer from './cafsExplorer.js'
import { makeVirtualNodeModules } from './makeVirtualNodeModules.js'

const TIME = new Date()
const STAT_DEFAULT = {
  mtime: TIME,
  atime: TIME,
  ctime: TIME,
  nlink: 1,
  uid: process.getuid ? process.getuid() : 0,
  gid: process.getgid ? process.getgid() : 0,
}

export interface FuseHandlers {
  open: (p: string, flags: string | number, cb: (exitCode: number, fd?: number) => void) => void
  release: (p: string, fd: number, cb: (exitCode: number) => void) => void
  read: (p: string, fd: number, buffer: Buffer, length: number, position: number, cb: (readBytes: number) => void) => void
  readlink: (p: string, cb: (returnCode: number, target?: string) => void) => void
  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
  getattr: (p: string, cb: (returnCode: number, files?: any) => void) => void
  readdir: (p: string, cb: (returnCode: number, files?: string[]) => void) => void
}

export async function createFuseHandlers (lockfileDir: string, storeDir: string): Promise<FuseHandlers> {
  const lockfile = await readWantedLockfile(lockfileDir, { ignoreIncompatible: true })
  if (lockfile == null) throw new Error('Cannot generate a .pnp.cjs without a lockfile')
  return createFuseHandlersFromLockfile(lockfile, storeDir)
}

export function createFuseHandlersFromLockfile (lockfile: LockfileObject, storeDir: string): FuseHandlers {
  const storeIndex = new StoreIndex(storeDir)
  const pkgSnapshotCache = new Map<string, { name: string, version: string, pkgSnapshot: PackageSnapshot, index: PackageFilesIndex }>()
  const virtualNodeModules = makeVirtualNodeModules(lockfile)
  return {
    open (p: string, flags: string | number, cb: (exitCode: number, fd?: number) => void) {
      const dirEnt = getDirEnt(p)
      if (dirEnt?.entryType !== 'index') {
        cb(-1)
        return
      }
      const fileInfo = dirEnt.index.files.get(dirEnt.subPath)
      if (!fileInfo) {
        cb(-1)
        return
      }
      const filePathInStore = getFilePathByModeInCafs(storeDir, fileInfo.digest, fileInfo.mode)
      fs.open(filePathInStore, flags, (err, fd) => {
        if (err != null) {
          cb(-1)
          return
        }
        cb(0, fd)
      })
    },
    release (p: string, fd: number, cb: (exitCode: number) => void) {
      fs.close(fd, (err) => {
        cb((err != null) ? -1 : 0)
      })
    },
    read (p: string, fd: number, buffer: Buffer, length: number, position: number, cb: (readBytes: number) => void) {
      fs.read(fd, buffer, 0, length, position, (err, bytesRead) => {
        if (err != null) {
          cb(-1)
          return
        }
        cb(bytesRead)
      })
    },
    readlink (p: string, cb: (returnCode: number, target?: string) => void) {
      const dirEnt = getDirEnt(p)
      if (dirEnt?.entryType !== 'symlink') {
        cb(Fuse.ENOENT)
        return
      }
      cb(0, dirEnt.target)
    },
    /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
    getattr (p: string, cb: (returnCode: number, files?: any) => void) {
      const dirEnt = getDirEnt(p)
      if (dirEnt == null) {
        cb(Fuse.ENOENT)
        return
      }
      if (dirEnt.entryType === 'directory' || dirEnt.entryType === 'index' && !dirEnt.subPath) {
        cb(0, schemas.Stat.directory({
          ...STAT_DEFAULT,
          size: 1,
        }))
        return
      }
      if (dirEnt.entryType === 'symlink') {
        cb(0, schemas.Stat.symlink({
          ...STAT_DEFAULT,
          size: 1,
        }))
        return
      }
      if (dirEnt.entryType === 'index') {
        switch (cafsExplorer.dirEntityType(dirEnt.index, dirEnt.subPath)) {
          case 'file': {
            const fileInfo = dirEnt.index.files.get(dirEnt.subPath)!
            cb(0, schemas.Stat.file({
              ...STAT_DEFAULT,
              mode: fileInfo.mode,
              size: fileInfo.size,
            }))
            return
          }
          case 'directory':
            cb(0, schemas.Stat.directory({
              ...STAT_DEFAULT,
              size: 1,
            }))
            return
          default:
            cb(Fuse.ENOENT)
            return
        }
      }
      cb(Fuse.ENOENT)
    },
    readdir,
  }
  function readdir (p: string, cb: (returnCode: number, files?: string[]) => void) {
    const dirEnt = getDirEnt(p)
    if (dirEnt?.entryType === 'index') {
      const dirEnts = cafsExplorer.readdir(dirEnt.index, dirEnt.subPath)
      if (dirEnts.length === 0) {
        cb(Fuse.ENOENT)
        return
      }
      cb(0, dirEnts)
      return
    }
    if ((dirEnt == null) || dirEnt.entryType !== 'directory') {
      cb(Fuse.ENOENT)
      return
    }
    cb(0, Object.keys(dirEnt.entries))
  }
  function getDirEnt (p: string) {
    let currentDirEntry = virtualNodeModules
    const parts = p === '/' ? [] : p.split('/')
    parts.shift()
    while ((parts.length > 0) && currentDirEntry && currentDirEntry.entryType === 'directory') {
      currentDirEntry = currentDirEntry.entries[parts.shift()!]
    }
    if (currentDirEntry?.entryType === 'index') {
      const pkg = getPkgInfo(currentDirEntry.depPath)
      if (pkg == null) {
        return null
      }
      return {
        ...currentDirEntry,
        index: pkg.index,
        subPath: parts.join('/'),
      }
    }
    return currentDirEntry
  }
  function getPkgInfo (depPath: string) {
    if (!pkgSnapshotCache.has(depPath)) {
      const pkgSnapshot = lockfile.packages?.[depPath as DepPath]
      if (pkgSnapshot == null) return undefined
      const nameVer = nameVerFromPkgSnapshot(depPath, pkgSnapshot)
      const pkgIndexFilePath = storeIndexKey((pkgSnapshot.resolution as TarballResolution).integrity!, `${nameVer.name}@${nameVer.version}`)
      const pkgIndex = storeIndex.get(pkgIndexFilePath) as PackageFilesIndex
      pkgSnapshotCache.set(depPath, {
        ...nameVer,
        pkgSnapshot,
        index: pkgIndex,
      })
    }
    return pkgSnapshotCache.get(depPath)
  }
}