#!/usr/bin/env node

var http = require('http')
var fs = require('fs')
var proc = require('child_process')
var path = require('path')
var URL = require('url')
var http = require('http')
var https = require('https')
var crypto = require('crypto')
var Transform = require('stream').Transform
var SsbNpmRegistry = require('../')
var pullFile = require('pull-file')
var lru = require('hashlru')
var memo = require('asyncmemo')

var ssbAppname = process.env.ssb_appname || 'ssb'
var ssbPath = process.env.ssb_path || path.join(process.env.HOME, '.' + ssbAppname)
var blobsPath = path.join(ssbPath, 'blobs')
var configPath = path.join(ssbPath, 'config')
var blobsTmpPath = path.join(blobsPath, 'tmp')
var numTmpBlobs = 0

var host = null
var port = null
var msgsUrl = null
var blobsUrl = null
var server
var listenHostname
var branches = []

function shift(args) {
  if (!args.length) return usage(1)
  return args.shift()
}

function version() {
  var pkg = require('./package')
  console.log(pkg.name + ' ' + pkg.version)
}

function usage(code) {
  console.error(fs.readFileSync(path.join(__dirname, 'usage.txt')))
  process.exit(code)
}

function main(args) {
  var viewerUrl = null
  var wsUrl = null

  var cmdArgs = []
  while (args.length) {
    var arg = args.shift()
    switch (arg) {
      case '--help': return usage(0)
      case '--version': return version()
      case '--host': host = shift(args); break
      case '--port': port = shift(args); break
      case '--msgs-url': msgsUrl = shift(args); break
      case '--blobs-url': blobsUrl = shift(args); break
      case '--ws-url': wsUrl = shift(args); break
      case '--viewer-url': viewerUrl = shift(args); break
      case '--branch': branches.push(shift(args)); break
      case '--': cmdArgs.push.apply(cmdArgs, args.splice(0)); break
      default: cmdArgs.push(arg); break
    }
  }

  if (wsUrl && viewerUrl) {
    throw '--ws-url and --viewer-url options conflict'
  }
  if (wsUrl && (msgsUrl || blobsUrl)) {
    throw '--ws-url option conflicts with --msgs-url and --blobs-url'
  }
  if (viewerUrl && (msgsUrl || blobsUrl)) {
    throw '--viewer-url option conflicts with --msgs-url and --blobs-url'
  }

  if (wsUrl) {
    wsUrl = wsUrl.replace(/\/+$/, '')
    blobsUrl = wsUrl + '/blobs/get/%s'
    msgsUrl = wsUrl + '/msg/%s'
  }

  if (viewerUrl) {
    viewerUrl = viewerUrl.replace(/\/+$/, '')
    blobsUrl = viewerUrl + '/%s'
    msgsUrl = viewerUrl + '/%s.json'
  }

  if (!port && !cmdArgs.length) {
    port = 8989
  }

  server = http.createServer(serve)
  server.listen(port, host, function () {
    if (cmdArgs.length) {
      var cmd = cmdArgs.shift()
      port = server.address().port
      var registryUrl = 'http://' + (host || 'localhost') + ':' + port
        + '/npm/' + branches.map(encodeURIComponent).join(',') + '/'
      var env = {}
      for (var k in process.env) env[k] = process.env[k]
      env.npm_config_registry = registryUrl
      if (cmd === 'npm') {
        cmdArgs.unshift('--no-update-notifier')
        cmdArgs.unshift('--fetch-retries=0')
        cmdArgs.unshift('--download=' + registryUrl + '-/prebuild/{name}-v{version}-{runtime}-v{abi}-{platform}{libc}-{arch}.tar.gz')
      }
      cmdArgs.forEach(function (arg, i) {
        cmdArgs[i] = arg.replace(/\{registry\}/g, registryUrl)
      })
      var child = proc.spawn(cmd, cmdArgs, {
        env: env,
        stdio: 'inherit'
      })
      child.on('exit', process.exit)
      process.on('SIGINT', function () { child.kill('SIGINT') })
      process.on('SIGTERM', function () { child.kill('SIGTERM') })
      process.on('uncaughtException', function (e) {
        console.error(e)
        child.kill('SIGKILL')
        process.exit(1)
      })
    } else {
      printServerListening()
    }
  })
}

function printServerListening() {
  var addr = server.address()
  listenHostname = typeof addr === 'string' ? 'unix:' + addr
    : addr.family === 'IPv6' ? '[' + addr.address + ']:' + addr.port
    : addr.address + ':' + addr.port
  console.log('Listening on http://' + listenHostname)
}

function serveStatus(res, code, message) {
  res.writeHead(code, message)
  res.end(message)
}

var blobIdRegex = /^&([A-Za-z0-9\/+]{43}=)\.sha256$/

function idToBuf(id) {
  var m = blobIdRegex.exec(id)
  if (!m) return null
  return new Buffer(m[1], 'base64')
}

function blobFilename(buf) {
  if (!buf) return null
  var str = buf.toString('hex')
  return path.join(blobsPath, 'sha256', str.slice(0, 2), str.slice(2))
}

function getRemoteBlob(id, cb) {
  var url = blobsUrl.replace('%s', id)
  return /^https:\/\//.test(url) ? https.get(url, cb) : http.get(url, cb)
}

function getRemoteMsg(id, cb) {
  var url = msgsUrl.replace('%s', encodeURIComponent(id))
  return /^https:\/\//.test(url) ? https.get(url, cb) : http.get(url, cb)
}

function mkdirp(dir, cb) {
  fs.stat(dir, function (err, stats) {
    if (!err) return cb()
    fs.mkdir(dir, function (err) {
      if (!err) return cb()
      mkdirp(path.dirname(dir), function (err) {
        if (err) return cb(err)
        fs.mkdir(dir, cb)
      })
    })
  })
}

function rename(src, dest, cb) {
  mkdirp(path.dirname(dest), function (err) {
    if (err) return cb(err)
    fs.rename(src, dest, cb)
  })
}

function hash(arr) {
  return arr.reduce(function (hash, item) {
    return hash.update(String(item))
  }, crypto.createHash('sha256')).digest('base64')
}

function fetchAddBlob(id, hash, filename, opts, cb) {
  opts = opts || {}
  var readIt = opts.readIt !== false
  if (!blobsUrl) return cb(new Error('Missing blobs URL'))
  var req = getRemoteBlob(id, function (res) {
    req.removeListener('error', cb)
    if (res.statusCode !== 200) return cb(new Error(res.statusMessage))
    mkdirp(blobsTmpPath, function (err) {
      if (err) return res.destroy(), cb(err)
      var blobTmpPath = path.join(blobsTmpPath, Date.now() + '-' + numTmpBlobs++)
      fs.open(blobTmpPath, 'w+', function (err, fd) {
        if (err) return res.destroy(), cb(err)
        var writeStream = fs.createWriteStream(null, {
          fd: fd, flags: 'w+', autoClose: false})
        var hasher = crypto.createHash('sha256')
        var hashThrough = new Transform({
          transform: function (data, encoding, cb) {
            hasher.update(data)
            cb(null, data)
          }
        })
        res.pipe(hashThrough).pipe(writeStream, {end: false})
        res.on('error', function (err) {
          writeStream.end(function (err1) {
            fs.unlink(blobTmpPath, function (err2) {
              cb(err || err1 || err2)
            })
          })
        })
        hashThrough.on('end', function () {
          var receivedHash = hasher.digest()
          if (receivedHash.compare(hash)) {
            writeStream.end(function (err) {
              fs.unlink(blobTmpPath, function (err1) {
                cb(err1 || err || new Error('mismatched hash'))
              })
            })
          } else {
            res.unpipe(hashThrough)
            rename(blobTmpPath, filename, function (err) {
              if (err) return console.error(err)
              if (readIt) cb(null, fs.createReadStream(null, {fd: fd, start: 0}))
              else fs.close(fd, function (err) {
                if (err) return cb(err)
                cb(null)
              })
            })
          }
        })
      })
    })
  })
  req.on('error', cb)
}

function getAddBlob(id, hash, filename, cb) {
  fs.access(filename, fs.constants.R_OK, function (err) {
    if (err && err.code === 'ENOENT') return fetchAddBlob(id, hash, filename, {}, cb)
    if (err) return cb(err)
    cb(null, fs.createReadStream(filename))
  })
}

function serveBlobsGet(req, res, id) {
  try { id = decodeURIComponent(id) }
  catch (e) {}
  var hash = idToBuf(id)
  var filename = blobFilename(hash)
  getAddBlob(id, hash, filename, function (err, stream) {
    if (err) return serveStatus(res, 500, err.message)
    if (!stream) return serveStatus(res, 404, 'Blob Not Found')
    res.writeHead(200)
    stream.pipe(res)
  })
}

function serveMsg(req, res, id) {
  try { id = decodeURIComponent(id) }
  catch (e) {}
  ssbGet(id, function (err, value) {
    if (err) return serveStatus(res, 400, err.message)
    if (!msg) return serveStatus(res, 404, 'Msg Not Found')
    res.writeHead(200, {'Content-Type': 'application/json'})
    res.end(JSON.stringify({key: id, value: msg}))
  })
}

function whoami(cb) {
  cb(null, {id: 'foo'})
}

var ssbGet = memo({
  cache: lru(1000)
}, function (id, cb) {
  if (!msgsUrl) return cb(new Error('Missing msgs URL'))
  var req = getRemoteMsg(id, function (res) {
    req.removeListener('error', cb)
    if (res.statusCode !== 200)
      return cb(new Error('unable to get msg ' + id + ': ' + res.statusMessage))
    var bufs = []
    res.on('data', function (buf) {
      bufs.push(buf)
    })
    res.on('error', onError)
    function onError(err) {
      cb(err)
      cb = null
    }
    res.on('end', function () {
      if (!cb) return
      res.removeListener('error', onError)
      var buf = Buffer.concat(bufs)
      try {
        var obj = JSON.parse(buf.toString('utf8'))
        if (Array.isArray(obj)) obj = obj[0]
        if (!obj) return cb(new Error('empty message'))
        if (obj.value) obj = obj.value
        gotMsg(obj, cb)
      } catch(e) {
        return cb(e)
      }
    })
  })
  req.removeListener('error', cb)
  function gotMsg(value, cb) {
    var encoded = new Buffer(JSON.stringify(value, null, 2), 'binary')
    var hash = crypto.createHash('sha256').update(encoded).digest('base64')
    var id1 = '%' + hash + '.sha256'
    if (id !== id1) return cb(new Error('mismatched hash ' + id + ' ' + id1))
    cb(null, value)
  }
})

function blobsSize(id, cb) {
  var filename = blobFilename(idToBuf(id))
  if (!filename) return cb(new Error('bad id'))
  fs.stat(filename, function (err, stats) {
    if (err) return cb(err)
    cb(null, stats.size)
  })
}

function blobsWant(id, cb) {
  var hash = idToBuf(id)
  var filename = blobFilename(hash)
  fetchAddBlob(id, hash, filename, {readIt: false}, function (err) {
    if (err) return cb(err)
    cb(null, true)
  })
}

function blobsGet(id) {
  var filename = blobFilename(idToBuf(id))
  if (!filename) return cb(new Error('bad id'))
  return pullFile(filename)
}

var ssbNpmConfig
try {
  ssbNpmConfig = JSON.stringify(fs.readFileSync(configPath)).npm
} catch(e) {
}

var serveNpm1 = SsbNpmRegistry.respond({
  whoami: whoami,
  get: ssbGet,
  blobs: {
    size: blobsSize,
    want: blobsWant,
    get: blobsGet,
  }
}, {
  ws: {
    port: port,
    host: host,
  },
  npm: ssbNpmConfig
})

function serveNpm(req, res, url) {
  req.url = url
  serveNpm1(req, res)
}

function serve(req, res) {
  var p = URL.parse(req.url)
  if (p.pathname.startsWith('/npm/')) return serveNpm(req, res, p.pathname.substr(4))
  if (p.pathname.startsWith('/msg/')) return serveMsg(req, res, p.pathname.substr(5))
  if (p.pathname.startsWith('/blobs/get/')) return serveBlobsGet(req, res, p.pathname.substr(11))
  return serveStatus(res, 404, 'Not Found')
}

main(process.argv.slice(2))