'use strict';

const JSONStream = require('JSONStream');
const Error = require('http-errors');
const request = require('request');
const Stream = require('readable-stream');
const URL = require('url');
const parse_interval = require('./config').parse_interval;
const Logger = require('./logger');
const MyStreams = require('./streams');
const Utils = require('./utils');
const encode = function(thing) {
  return encodeURIComponent(thing).replace(/^%40/, '@');
};

const _setupProxy = function(hostname, config, mainconfig, isHTTPS) {
  let no_proxy;
  let proxy_key = isHTTPS ? 'https_proxy' : 'http_proxy';

  // get http_proxy and no_proxy configs
  if (proxy_key in config) {
    this.proxy = config[proxy_key];
  } else if (proxy_key in mainconfig) {
    this.proxy = mainconfig[proxy_key];
  }
  if ('no_proxy' in config) {
    no_proxy = config.no_proxy;
  } else if ('no_proxy' in mainconfig) {
    no_proxy = mainconfig.no_proxy;
  }

  // use wget-like algorithm to determine if proxy shouldn't be used
  if (hostname[0] !== '.') {
    hostname = '.' + hostname;
  }
  if (typeof(no_proxy) === 'string' && no_proxy.length) {
    no_proxy = no_proxy.split(',');
  }
  if (Array.isArray(no_proxy)) {
    for (let i=0; i<no_proxy.length; i++) {
      let no_proxy_item = no_proxy[i];
      if (no_proxy_item[0] !== '.') no_proxy_item = '.' + no_proxy_item;
      if (hostname.lastIndexOf(no_proxy_item) === hostname.length - no_proxy_item.length) {
        if (this.proxy) {
          this.logger.debug({url: this.url.href, rule: no_proxy_item},
            'not using proxy for @{url}, excluded by @{rule} rule');
          this.proxy = false;
        }
        break;
      }
    }
  }

  // if it's non-string (i.e. "false"), don't use it
  if (typeof(this.proxy) !== 'string') {
    delete this.proxy;
  } else {
    this.logger.debug( {url: this.url.href, proxy: this.proxy}
                     , 'using proxy @{proxy} for @{url}' );
  }
};

//
// Implements Storage interface
// (same for storage.js, local-storage.js, up-storage.js)
//
class Storage {

  /**
   *
   * @param {*} config
   * @param {*} mainconfig
   */
  constructor(config, mainconfig) {
    this.config = config;
    this.failed_requests = 0;
    this.userAgent = mainconfig.user_agent;
    this.ca = config.ca;
    this.logger = Logger.logger.child({sub: 'out'});
    this.server_id = mainconfig.server_id;

    this.url = URL.parse(this.config.url);

    _setupProxy.call(this, this.url.hostname, config, mainconfig, this.url.protocol === 'https:');

    this.config.url = this.config.url.replace(/\/$/, '');
    if (Number(this.config.timeout) >= 1000) {
      this.logger.warn(['Too big timeout value: ' + this.config.timeout,
                        'We changed time format to nginx-like one',
                        '(see http://wiki.nginx.org/ConfigNotation)',
                        'so please update your config accordingly'].join('\n'));
    }

    // a bunch of different configurable timers
    this.maxage = parse_interval(config_get('maxage', '2m' ));
    this.timeout = parse_interval(config_get('timeout', '30s'));
    this.max_fails = Number(config_get('max_fails', 2 ));
    this.fail_timeout = parse_interval(config_get('fail_timeout', '5m' ));
    return this;

    // just a helper (`config[key] || default` doesn't work because of zeroes)
    function config_get(key, def) {
      return config[key] != null ? config[key] : def;
    }
  }
}


Storage.prototype.request = function(options, cb) {
  if (!this.status_check()) {
    var req = new Stream.Readable();
    process.nextTick(function() {
      if (typeof(cb) === 'function') cb(Error('uplink is offline'));
      req.emit('error', Error('uplink is offline'));
    });
    req._read = function() {};
    // preventing 'Uncaught, unspecified "error" event'
    req.on('error', function() {});
    return req;
  }

  let self = this;
  let headers = options.headers || {};
  headers['Accept'] = headers['Accept'] || 'application/json';
  headers['Accept-Encoding'] = headers['Accept-Encoding'] || 'gzip';
  // registry.npmjs.org will only return search result if user-agent include string 'npm'
  headers['User-Agent'] = headers['User-Agent'] || `npm (${this.userAgent})`;
  this._add_proxy_headers(options.req, headers);

  // add/override headers specified in the config
  for (let key in this.config.headers) {
    headers[key] = this.config.headers[key];
  }

  let method = options.method || 'GET';
  let uri = options.uri_full || (this.config.url + options.uri);

  self.logger.info({
    method: method,
    headers: headers,
    uri: uri,
  }, 'making request: \'@{method} @{uri}\'');

  if (Utils.is_object(options.json)) {
    var json = JSON.stringify(options.json);
    headers['Content-Type'] = headers['Content-Type'] || 'application/json';
  }

  let request_callback = cb ? (function(err, res, body) {
    let error;
    let res_length = err ? 0 : body.length;

    do_decode();
    do_log();
    cb(err, res, body);

    function do_decode() {
      if (err) {
        error = err.message;
        return;
      }

      if (options.json && res.statusCode < 300) {
        try {
          body = JSON.parse(body.toString('utf8'));
        } catch(_err) {
          body = {};
          err = _err;
          error = err.message;
        }
      }

      if (!err && Utils.is_object(body)) {
        if (typeof(body.error) === 'string') {
          error = body.error;
        }
      }
    }

    function do_log() {
      let message = '@{!status}, req: \'@{request.method} @{request.url}\'';
      message += error
               ? ', error: @{!error}'
               : ', bytes: @{bytes.in}/@{bytes.out}';
      self.logger.warn({
        err: err,
        request: {method: method, url: uri},
        level: 35, // http
        status: res != null ? res.statusCode : 'ERR',
        error: error,
        bytes: {
          in: json ? json.length : 0,
          out: res_length || 0,
        },
      }, message);
    }
  }) : undefined;

  var req = request({
    url: uri,
    method: method,
    headers: headers,
    body: json,
    ca: this.ca,
    proxy: this.proxy,
    encoding: null,
    gzip: true,
    timeout: this.timeout,
  }, request_callback);

  let status_called = false;
  req.on('response', function(res) {
    if (!req._verdaccio_aborted && !status_called) {
      status_called = true;
      self.status_check(true);
    }

    if (!request_callback) {
      (function do_log() {
        let message = '@{!status}, req: \'@{request.method} @{request.url}\' (streaming)';
        self.logger.warn({
          request: {method: method, url: uri},
          level: 35, // http
          status: res != null ? res.statusCode : 'ERR',
        }, message);
      })();
    }
  });
  req.on('error', function(_err) {
    if (!req._verdaccio_aborted && !status_called) {
      status_called = true;
      self.status_check(false);
    }
  });
  return req;
};

Storage.prototype.status_check = function(alive) {
  if (arguments.length === 0) {
    if (this.failed_requests >= this.max_fails
     && Math.abs(Date.now() - this.last_request_time) < this.fail_timeout) {
      return false;
    } else {
      return true;
    }
  } else {
    if (alive) {
      if (this.failed_requests >= this.max_fails) {
        this.logger.warn({host: this.url.host}, 'host @{host} is back online');
      }
      this.failed_requests = 0;
    } else {
      this.failed_requests++;
      if (this.failed_requests === this.max_fails) {
        this.logger.warn({host: this.url.host}, 'host @{host} is now offline');
      }
    }
    this.last_request_time = Date.now();
  }
};

Storage.prototype.can_fetch_url = function(url) {
  url = URL.parse(url);

  return url.protocol === this.url.protocol
      && url.host === this.url.host
      && url.path.indexOf(this.url.path) === 0;
};

Storage.prototype.get_package = function(name, options, callback) {
  if (typeof(options) === 'function') callback = options, options = {};

  let headers = {};
  if (options.etag) {
    headers['If-None-Match'] = options.etag;
    headers['Accept'] = 'application/octet-stream';
  }

  this.request({
    uri: '/' + encode(name),
    json: true,
    headers: headers,
    req: options.req,
  }, function(err, res, body) {
    if (err) return callback(err);
    if (res.statusCode === 404) {
      return callback( Error[404]('package doesn\'t exist on uplink') );
    }
    if (!(res.statusCode >= 200 && res.statusCode < 300)) {
      let error = Error('bad status code: ' + res.statusCode);
      error.remoteStatus = res.statusCode;
      return callback(error);
    }
    callback(null, body, res.headers.etag);
  });
};

Storage.prototype.get_tarball = function(name, options, filename) {
  if (!options) options = {};
  return this.get_url(this.config.url + '/' + name + '/-/' + filename);
};

Storage.prototype.get_url = function(url) {
  let stream = MyStreams.ReadTarballStream();
  stream.abort = function() {};
  let current_length = 0, expected_length;

  let rstream = this.request({
    uri_full: url,
    encoding: null,
    headers: {Accept: 'application/octet-stream'},
  });

  rstream.on('response', function(res) {
    if (res.statusCode === 404) {
      return stream.emit('error', Error[404]('file doesn\'t exist on uplink'));
    }
    if (!(res.statusCode >= 200 && res.statusCode < 300)) {
      return stream.emit('error', Error('bad uplink status code: ' + res.statusCode));
    }
    if (res.headers['content-length']) {
      expected_length = res.headers['content-length'];
      stream.emit('content-length', res.headers['content-length']);
    }

    rstream.pipe(stream);
  });

  rstream.on('error', function(err) {
    stream.emit('error', err);
  });
  rstream.on('data', function(d) {
    current_length += d.length;
  });
  rstream.on('end', function(d) {
    if (d) current_length += d.length;
    if (expected_length && current_length != expected_length)
      stream.emit('error', Error('content length mismatch'));
  });
  return stream;
};

Storage.prototype.search = function(startkey, options) {
  let self = this;

  let stream = new Stream.PassThrough({objectMode: true});

  let req = self.request({
    uri: options.req.url,
    req: options.req,
    headers: {
      referer: options.req.headers.referer,
    },
  });

  req.on('response', (res) => {
    if (!String(res.statusCode).match(/^2\d\d$/)) {
      return stream.emit('error', Error('bad status code ' + res.statusCode + ' from uplink'));
    }

    res.pipe(JSONStream.parse('*')).on('data', (pkg) => {
      if (Utils.is_object(pkg)) {
        stream.emit('data', pkg);
      }
    });
    res.on('end', () => {
      stream.emit('end');
    });
  });

  req.on('error', (err) => {
    stream.emit('error', err);
  });

  stream.abort = () => {
    req.abort();
    stream.emit('end');
  };


  return stream;
};

Storage.prototype._add_proxy_headers = function(req, headers) {
  if (req) {
    // Only submit X-Forwarded-For field if we don't have a proxy selected
    // in the config file.
    //
    // Otherwise misconfigured proxy could return 407:
    // https://github.com/rlidwka/sinopia/issues/254
    //
    if (!this.proxy) {
      headers['X-Forwarded-For'] = (
        req && req.headers['x-forwarded-for']
        ? req.headers['x-forwarded-for'] + ', '
        : ''
      ) + req.connection.remoteAddress;
    }
  }

  // always attach Via header to avoid loops, even if we're not proxying
  headers['Via'] =
    req && req.headers['via']
    ? req.headers['via'] + ', '
    : '';

  headers['Via'] += '1.1 ' + this.server_id + ' (Verdaccio)';
};


module.exports = Storage;