// commands for packing and unpacking tarballs
// this file is used by lib/cache.js

var fs = require('graceful-fs')
var path = require('path')
var writeFileAtomic = require('write-file-atomic')
var writeStreamAtomic = require('fs-write-stream-atomic')
var log = require('npmlog')
var uidNumber = require('uid-number')
var readJson = require('read-package-json')
var tar = require('tar')
var zlib = require('zlib')
var fstream = require('fstream')
var Packer = require('fstream-npm')
var iferr = require('iferr')
var inherits = require('inherits')
var npm = require('../npm.js')
var rm = require('./gently-rm.js')
var myUid = process.getuid && process.getuid()
var myGid = process.getgid && process.getgid()
var readPackageTree = require('read-package-tree')
var union = require('lodash.union')

if (process.env.SUDO_UID && myUid === 0) {
  if (!isNaN(process.env.SUDO_UID)) myUid = +process.env.SUDO_UID
  if (!isNaN(process.env.SUDO_GID)) myGid = +process.env.SUDO_GID
}

exports.pack = pack
exports.unpack = unpack

function pack (tarball, folder, pkg, cb) {
  log.verbose('tar pack', [tarball, folder])

  log.verbose('tarball', tarball)
  log.verbose('folder', folder)

  var recalculateMetadata = require('../install/deps.js').recalculateMetadata
  readPackageTree(folder, iferr(cb, function (tree) {
    recalculateMetadata(tree, log.newGroup('pack:' + pkg), iferr(cb, function () {
      pack_(tarball, folder, tree, pkg, cb)
    }))
  }))
}

function BundledPacker (props) {
  Packer.call(this, props)
  this.tree = props.tree
  var flattenTree = require('../install/flatten-tree.js')
  this.flatTree = props.flatTree || flattenTree(props.tree)
}
inherits(BundledPacker, Packer)

BundledPacker.prototype.getChildProps = function (stat) {
  var props = Packer.prototype.getChildProps.call(this, stat)
  props.tree = this.tree
  props.flatTree = this.flatTree
  return props
}

BundledPacker.prototype.applyIgnores = function (entry, partial, entryObj) {
  // package.json files can never be ignored.
  if (entry === 'package.json') return true

  // readme files should never be ignored.
  if (entry.match(/^readme(\.[^\.]*)$/i)) return true

  // license files should never be ignored.
  if (entry.match(/^(license|licence)(\.[^\.]*)?$/i)) return true

  // changelogs should never be ignored.
  if (entry.match(/^(changes|changelog|history)(\.[^\.]*)?$/i)) return true

  // special rules.  see below.
  if (entry === 'node_modules' && this.packageRoot) return true

  // some files are *never* allowed under any circumstances
  if (entry === '.git' ||
      entry === '.lock-wscript' ||
      entry.match(/^\.wafpickle-[0-9]+$/) ||
      entry === 'CVS' ||
      entry === '.svn' ||
      entry === '.hg' ||
      entry.match(/^\..*\.swp$/) ||
      entry === '.DS_Store' ||
      entry.match(/^\._/) ||
      entry === 'npm-debug.log'
    ) {
    return false
  }

  // in a node_modules folder, we only include bundled dependencies
  // also, prevent packages in node_modules from being affected
  // by rules set in the containing package, so that
  // bundles don't get busted.
  // Also, once in a bundle, everything is installed as-is
  // To prevent infinite cycles in the case of cyclic deps that are
  // linked with npm link, even in a bundle, deps are only bundled
  // if they're not already present at a higher level.
  if (this.bundleMagic) {
    // bubbling up.  stop here and allow anything the bundled pkg allows
    if (entry.indexOf('/') !== -1) return true

    // never include the .bin.  It's typically full of platform-specific
    // stuff like symlinks and .cmd files anyway.
    if (entry === '.bin') return false

    // the package root.
    var p = this.parent
    // the package before this one.
    var pp = p && p.parent

    // if this entry has already been bundled, and is a symlink,
    // and it is the *same* symlink as this one, then exclude it.
    if (pp && pp.bundleLinks && this.bundleLinks &&
        pp.bundleLinks[entry] &&
        pp.bundleLinks[entry] === this.bundleLinks[entry]) {
      return false
    }

    // since it's *not* a symbolic link, if we're *already* in a bundle,
    // then we should include everything.
    if (pp && pp.package && pp.basename === 'node_modules') {
      return true
    }

    // only include it at this point if it's a bundleDependency
    return this.isBundled(entry)
  }
  // if (this.bundled) return true

  return Packer.prototype.applyIgnores.call(this, entry, partial, entryObj)
}

function nameMatch (name) { return function (other) { return name === other.package.name } }

BundledPacker.prototype.isBundled = function (name) {
  var bd = this.package && this.package.bundleDependencies
  if (!bd) return false

  if (!Array.isArray(bd)) {
    throw new Error(this.package.name + '\'s `bundledDependencies` should ' +
                    'be an array')
  }

  if (bd.indexOf(name) !== -1) return true
  var pkg = this.tree.children.filter(nameMatch(name))[0]
  if (!pkg) return false
  var requiredBy = union([], pkg.package._requiredBy)
  var seen = {}
  while (requiredBy.length) {
    var req = requiredBy.shift()
    if (seen[req]) continue
    seen[req] = true
    var reqPkg = this.flatTree[req]
    if (!reqPkg) continue
    if (reqPkg.parent === this.tree && bd.indexOf(reqPkg.package.name) !== -1) {
      return true
    }
    requiredBy = union(requiredBy, reqPkg.package._requiredBy)
  }
  return false
}

function pack_ (tarball, folder, tree, pkg, cb) {
  new BundledPacker({ path: folder, tree: tree, type: 'Directory', isDirectory: true })
    .on('error', function (er) {
      if (er) log.error('tar pack', 'Error reading ' + folder)
      return cb(er)
    })

    // By default, npm includes some proprietary attributes in the
    // package tarball.  This is sane, and allowed by the spec.
    // However, npm *itself* excludes these from its own package,
    // so that it can be more easily bootstrapped using old and
    // non-compliant tar implementations.
    .pipe(tar.Pack({ noProprietary: !npm.config.get('proprietary-attribs') }))
    .on('error', function (er) {
      if (er) log.error('tar.pack', 'tar creation error', tarball)
      cb(er)
    })
    .pipe(zlib.Gzip())
    .on('error', function (er) {
      if (er) log.error('tar.pack', 'gzip error ' + tarball)
      cb(er)
    })
    .pipe(writeStreamAtomic(tarball))
    .on('error', function (er) {
      if (er) log.error('tar.pack', 'Could not write ' + tarball)
      cb(er)
    })
    .on('close', cb)
}

function unpack (tarball, unpackTarget, dMode, fMode, uid, gid, cb) {
  log.verbose('tar', 'unpack', tarball)
  log.verbose('tar', 'unpacking to', unpackTarget)
  if (typeof cb !== 'function') {
    cb = gid
    gid = null
  }
  if (typeof cb !== 'function') {
    cb = uid
    uid = null
  }
  if (typeof cb !== 'function') {
    cb = fMode
    fMode = npm.modes.file
  }
  if (typeof cb !== 'function') {
    cb = dMode
    dMode = npm.modes.exec
  }

  uidNumber(uid, gid, function (er, uid, gid) {
    if (er) return cb(er)
    unpack_(tarball, unpackTarget, dMode, fMode, uid, gid, cb)
  })
}

function unpack_ (tarball, unpackTarget, dMode, fMode, uid, gid, cb) {
  rm(unpackTarget, function (er) {
    if (er) return cb(er)
    // gzip {tarball} --decompress --stdout \
    //   | tar -mvxpf - --strip-components=1 -C {unpackTarget}
    gunzTarPerm(tarball, unpackTarget,
                dMode, fMode,
                uid, gid,
                function (er, folder) {
      if (er) return cb(er)
      readJson(path.resolve(folder, 'package.json'), cb)
    })
  })
}

function gunzTarPerm (tarball, target, dMode, fMode, uid, gid, cb_) {
  if (!dMode) dMode = npm.modes.exec
  if (!fMode) fMode = npm.modes.file
  log.silly('gunzTarPerm', 'modes', [dMode.toString(8), fMode.toString(8)])

  var cbCalled = false
  function cb (er) {
    if (cbCalled) return
    cbCalled = true
    cb_(er, target)
  }

  var fst = fs.createReadStream(tarball)

  fst.on('open', function (fd) {
    fs.fstat(fd, function (er, st) {
      if (er) return fst.emit('error', er)
      if (st.size === 0) {
        er = new Error('0-byte tarball\n' +
                       'Please run `npm cache clean`')
        fst.emit('error', er)
      }
    })
  })

  // figure out who we're supposed to be, if we're not pretending
  // to be a specific user.
  if (npm.config.get('unsafe-perm') && process.platform !== 'win32') {
    uid = myUid
    gid = myGid
  }

  function extractEntry (entry) {
    log.silly('gunzTarPerm', 'extractEntry', entry.path)
    // never create things that are user-unreadable,
    // or dirs that are user-un-listable. Only leads to headaches.
    var originalMode = entry.mode = entry.mode || entry.props.mode
    entry.mode = entry.mode | (entry.type === 'Directory' ? dMode : fMode)
    entry.mode = entry.mode & (~npm.modes.umask)
    entry.props.mode = entry.mode
    if (originalMode !== entry.mode) {
      log.silly('gunzTarPerm', 'modified mode',
                [entry.path, originalMode, entry.mode])
    }

    // if there's a specific owner uid/gid that we want, then set that
    if (process.platform !== 'win32' &&
        typeof uid === 'number' &&
        typeof gid === 'number') {
      entry.props.uid = entry.uid = uid
      entry.props.gid = entry.gid = gid
    }
  }

  var extractOpts = { type: 'Directory', path: target, strip: 1 }

  if (process.platform !== 'win32' &&
      typeof uid === 'number' &&
      typeof gid === 'number') {
    extractOpts.uid = uid
    extractOpts.gid = gid
  }

  var sawIgnores = {}
  extractOpts.filter = function () {
    // symbolic links are not allowed in packages.
    if (this.type.match(/^.*Link$/)) {
      log.warn('excluding symbolic link',
               this.path.substr(target.length + 1) +
               ' -> ' + this.linkpath)
      return false
    }

    // Note: This mirrors logic in the fs read operations that are
    // employed during tarball creation, in the fstream-npm module.
    // It is duplicated here to handle tarballs that are created
    // using other means, such as system tar or git archive.
    if (this.type === 'File') {
      var base = path.basename(this.path)
      if (base === '.npmignore') {
        sawIgnores[ this.path ] = true
      } else if (base === '.gitignore') {
        var npmignore = this.path.replace(/\.gitignore$/, '.npmignore')
        if (sawIgnores[npmignore]) {
          // Skip this one, already seen.
          return false
        } else {
          // Rename, may be clobbered later.
          this.path = npmignore
          this._path = npmignore
        }
      }
    }

    return true
  }

  fst
    .on('error', function (er) {
      if (er) log.error('tar.unpack', 'error reading ' + tarball)
      cb(er)
    })
    .on('data', function OD (c) {
      // detect what it is.
      // Then, depending on that, we'll figure out whether it's
      // a single-file module, gzipped tarball, or naked tarball.
      // gzipped files all start with 1f8b08
      if (c[0] === 0x1F &&
          c[1] === 0x8B &&
          c[2] === 0x08) {
        fst
          .pipe(zlib.Unzip())
          .on('error', function (er) {
            if (er) log.error('tar.unpack', 'unzip error ' + tarball)
            cb(er)
          })
          .pipe(tar.Extract(extractOpts))
          .on('entry', extractEntry)
          .on('error', function (er) {
            if (er) log.error('tar.unpack', 'untar error ' + tarball)
            cb(er)
          })
          .on('close', cb)
      } else if (hasTarHeader(c)) {
        // naked tar
        fst
          .pipe(tar.Extract(extractOpts))
          .on('entry', extractEntry)
          .on('error', function (er) {
            if (er) log.error('tar.unpack', 'untar error ' + tarball)
            cb(er)
          })
          .on('close', cb)
      } else {
        // naked js file
        var jsOpts = { path: path.resolve(target, 'index.js') }

        if (process.platform !== 'win32' &&
            typeof uid === 'number' &&
            typeof gid === 'number') {
          jsOpts.uid = uid
          jsOpts.gid = gid
        }

        fst
          .pipe(fstream.Writer(jsOpts))
          .on('error', function (er) {
            if (er) log.error('tar.unpack', 'copy error ' + tarball)
            cb(er)
          })
          .on('close', function () {
            var j = path.resolve(target, 'package.json')
            readJson(j, function (er, d) {
              if (er) {
                log.error('not a package', tarball)
                return cb(er)
              }
              writeFileAtomic(j, JSON.stringify(d) + '\n', cb)
            })
          })
      }

      // now un-hook, and re-emit the chunk
      fst.removeListener('data', OD)
      fst.emit('data', c)
    })
}

function hasTarHeader (c) {
  return c[257] === 0x75 && // tar archives have 7573746172 at position
         c[258] === 0x73 && // 257 and 003030 or 202000 at position 262
         c[259] === 0x74 &&
         c[260] === 0x61 &&
         c[261] === 0x72 &&

       ((c[262] === 0x00 &&
         c[263] === 0x30 &&
         c[264] === 0x30) ||

        (c[262] === 0x20 &&
         c[263] === 0x20 &&
         c[264] === 0x00))
}