'use strict'

const Buffer = require('./buffer.js')

// A readable tar stream creator
// Technically, this is a transform stream that you write paths into,
// and tar format comes out of.
// The `add()` method is like `write()` but returns this,
// and end() return `this` as well, so you can
// do `new Pack(opt).add('files').add('dir').end().pipe(output)
// You could also do something like:
// streamOfPaths().pipe(new Pack()).pipe(new fs.WriteStream('out.tar'))

class PackJob {
  constructor (path, absolute) {
    this.path = path || './'
    this.absolute = absolute
    this.entry = null
    this.stat = null
    this.readdir = null
    this.pending = false
    this.ignore = false
    this.piped = false
  }
}

const MiniPass = require('minipass')
const zlib = require('minizlib')
const ReadEntry = require('./read-entry.js')
const WriteEntry = require('./write-entry.js')
const WriteEntrySync = WriteEntry.Sync
const WriteEntryTar = WriteEntry.Tar
const Yallist = require('yallist')
const EOF = Buffer.alloc(1024)
const ONSTAT = Symbol('onStat')
const ENDED = Symbol('ended')
const QUEUE = Symbol('queue')
const CURRENT = Symbol('current')
const PROCESS = Symbol('process')
const PROCESSING = Symbol('processing')
const PROCESSJOB = Symbol('processJob')
const JOBS = Symbol('jobs')
const JOBDONE = Symbol('jobDone')
const ADDFSENTRY = Symbol('addFSEntry')
const ADDTARENTRY = Symbol('addTarEntry')
const STAT = Symbol('stat')
const READDIR = Symbol('readdir')
const ONREADDIR = Symbol('onreaddir')
const PIPE = Symbol('pipe')
const ENTRY = Symbol('entry')
const ENTRYOPT = Symbol('entryOpt')
const WRITEENTRYCLASS = Symbol('writeEntryClass')
const WRITE = Symbol('write')
const ONDRAIN = Symbol('ondrain')

const fs = require('fs')
const path = require('path')
const warner = require('./warn-mixin.js')

const Pack = warner(class Pack extends MiniPass {
  constructor (opt) {
    super(opt)
    opt = opt || Object.create(null)
    this.opt = opt
    this.cwd = opt.cwd || process.cwd()
    this.maxReadSize = opt.maxReadSize
    this.preservePaths = !!opt.preservePaths
    this.strict = !!opt.strict
    this.noPax = !!opt.noPax
    this.prefix = (opt.prefix || '').replace(/(\\|\/)+$/, '')
    this.linkCache = opt.linkCache || new Map()
    this.statCache = opt.statCache || new Map()
    this.readdirCache = opt.readdirCache || new Map()

    this[WRITEENTRYCLASS] = WriteEntry
    if (typeof opt.onwarn === 'function')
      this.on('warn', opt.onwarn)

    this.zip = null
    if (opt.gzip) {
      if (typeof opt.gzip !== 'object')
        opt.gzip = {}
      this.zip = new zlib.Gzip(opt.gzip)
      this.zip.on('data', chunk => super.write(chunk))
      this.zip.on('end', _ => super.end())
      this.zip.on('drain', _ => this[ONDRAIN]())
      this.on('resume', _ => this.zip.resume())
    } else
      this.on('drain', this[ONDRAIN])

    this.portable = !!opt.portable
    this.noDirRecurse = !!opt.noDirRecurse
    this.follow = !!opt.follow
    this.noMtime = !!opt.noMtime
    this.mtime = opt.mtime || null

    this.filter = typeof opt.filter === 'function' ? opt.filter : _ => true

    this[QUEUE] = new Yallist
    this[JOBS] = 0
    this.jobs = +opt.jobs || 4
    this[PROCESSING] = false
    this[ENDED] = false
  }

  [WRITE] (chunk) {
    return super.write(chunk)
  }

  add (path) {
    this.write(path)
    return this
  }

  end (path) {
    if (path)
      this.write(path)
    this[ENDED] = true
    this[PROCESS]()
    return this
  }

  write (path) {
    if (this[ENDED])
      throw new Error('write after end')

    if (path instanceof ReadEntry)
      this[ADDTARENTRY](path)
    else
      this[ADDFSENTRY](path)
    return this.flowing
  }

  [ADDTARENTRY] (p) {
    const absolute = path.resolve(this.cwd, p.path)
    if (this.prefix)
      p.path = this.prefix + '/' + p.path.replace(/^\.(\/+|$)/, '')

    // in this case, we don't have to wait for the stat
    if (!this.filter(p.path, p))
      p.resume()
    else {
      const job = new PackJob(p.path, absolute, false)
      job.entry = new WriteEntryTar(p, this[ENTRYOPT](job))
      job.entry.on('end', _ => this[JOBDONE](job))
      this[JOBS] += 1
      this[QUEUE].push(job)
    }

    this[PROCESS]()
  }

  [ADDFSENTRY] (p) {
    const absolute = path.resolve(this.cwd, p)
    if (this.prefix)
      p = this.prefix + '/' + p.replace(/^\.(\/+|$)/, '')

    this[QUEUE].push(new PackJob(p, absolute))
    this[PROCESS]()
  }

  [STAT] (job) {
    job.pending = true
    this[JOBS] += 1
    const stat = this.follow ? 'stat' : 'lstat'
    fs[stat](job.absolute, (er, stat) => {
      job.pending = false
      this[JOBS] -= 1
      if (er)
        this.emit('error', er)
      else
        this[ONSTAT](job, stat)
    })
  }

  [ONSTAT] (job, stat) {
    this.statCache.set(job.absolute, stat)
    job.stat = stat

    // now we have the stat, we can filter it.
    if (!this.filter(job.path, stat))
      job.ignore = true

    this[PROCESS]()
  }

  [READDIR] (job) {
    job.pending = true
    this[JOBS] += 1
    fs.readdir(job.absolute, (er, entries) => {
      job.pending = false
      this[JOBS] -= 1
      if (er)
        return this.emit('error', er)
      this[ONREADDIR](job, entries)
    })
  }

  [ONREADDIR] (job, entries) {
    this.readdirCache.set(job.absolute, entries)
    job.readdir = entries
    this[PROCESS]()
  }

  [PROCESS] () {
    if (this[PROCESSING])
      return

    this[PROCESSING] = true
    for (let w = this[QUEUE].head;
         w !== null && this[JOBS] < this.jobs;
         w = w.next) {
      this[PROCESSJOB](w.value)
      if (w.value.ignore) {
        const p = w.next
        this[QUEUE].removeNode(w)
        w.next = p
      }
    }

    this[PROCESSING] = false

    if (this[ENDED] && !this[QUEUE].length && this[JOBS] === 0) {
      if (this.zip)
        this.zip.end(EOF)
      else {
        super.write(EOF)
        super.end()
      }
    }
  }

  get [CURRENT] () {
    return this[QUEUE] && this[QUEUE].head && this[QUEUE].head.value
  }

  [JOBDONE] (job) {
    this[QUEUE].shift()
    this[JOBS] -= 1
    this[PROCESS]()
  }

  [PROCESSJOB] (job) {
    if (job.pending)
      return

    if (job.entry) {
      if (job === this[CURRENT] && !job.piped)
        this[PIPE](job)
      return
    }

    if (!job.stat) {
      if (this.statCache.has(job.absolute))
        this[ONSTAT](job, this.statCache.get(job.absolute))
      else
        this[STAT](job)
    }
    if (!job.stat)
      return

    // filtered out!
    if (job.ignore)
      return

    if (!this.noDirRecurse && job.stat.isDirectory() && !job.readdir) {
      if (this.readdirCache.has(job.absolute))
        this[ONREADDIR](job, this.readdirCache.get(job.absolute))
      else
        this[READDIR](job)
      if (!job.readdir)
        return
    }

    // we know it doesn't have an entry, because that got checked above
    job.entry = this[ENTRY](job)
    if (!job.entry) {
      job.ignore = true
      return
    }

    if (job === this[CURRENT] && !job.piped)
      this[PIPE](job)
  }

  [ENTRYOPT] (job) {
    return {
      onwarn: (msg, data) => {
        this.warn(msg, data)
      },
      noPax: this.noPax,
      cwd: this.cwd,
      absolute: job.absolute,
      preservePaths: this.preservePaths,
      maxReadSize: this.maxReadSize,
      strict: this.strict,
      portable: this.portable,
      linkCache: this.linkCache,
      statCache: this.statCache,
      noMtime: this.noMtime,
      mtime: this.mtime
    }
  }

  [ENTRY] (job) {
    this[JOBS] += 1
    try {
      return new this[WRITEENTRYCLASS](job.path, this[ENTRYOPT](job))
        .on('end', () => this[JOBDONE](job))
        .on('error', er => this.emit('error', er))
    } catch (er) {
      this.emit('error', er)
    }
  }

  [ONDRAIN] () {
    if (this[CURRENT] && this[CURRENT].entry)
      this[CURRENT].entry.resume()
  }

  // like .pipe() but using super, because our write() is special
  [PIPE] (job) {
    job.piped = true

    if (job.readdir)
      job.readdir.forEach(entry => {
        const p = this.prefix ?
          job.path.slice(this.prefix.length + 1) || './'
          : job.path

        const base = p === './' ? '' : p.replace(/\/*$/, '/')
        this[ADDFSENTRY](base + entry)
      })

    const source = job.entry
    const zip = this.zip

    if (zip)
      source.on('data', chunk => {
        if (!zip.write(chunk))
          source.pause()
      })
    else
      source.on('data', chunk => {
        if (!super.write(chunk))
          source.pause()
      })
  }

  pause () {
    if (this.zip)
      this.zip.pause()
    return super.pause()
  }
})

class PackSync extends Pack {
  constructor (opt) {
    super(opt)
    this[WRITEENTRYCLASS] = WriteEntrySync
  }

  // pause/resume are no-ops in sync streams.
  pause () {}
  resume () {}

  [STAT] (job) {
    const stat = this.follow ? 'statSync' : 'lstatSync'
    this[ONSTAT](job, fs[stat](job.absolute))
  }

  [READDIR] (job, stat) {
    this[ONREADDIR](job, fs.readdirSync(job.absolute))
  }

  // gotta get it all in this tick
  [PIPE] (job) {
    const source = job.entry
    const zip = this.zip

    if (job.readdir)
      job.readdir.forEach(entry => {
        const p = this.prefix ?
          job.path.slice(this.prefix.length + 1) || './'
          : job.path

        const base = p === './' ? '' : p.replace(/\/*$/, '/')
        this[ADDFSENTRY](base + entry)
      })

    if (zip)
      source.on('data', chunk => {
        zip.write(chunk)
      })
    else
      source.on('data', chunk => {
        super[WRITE](chunk)
      })
  }
}

Pack.Sync = PackSync

module.exports = Pack