'use strict';

module.exports.create = function (deps, conf) {
  var network = deps.PromiseA.promisifyAll(deps.recase.camelCopy(require('network')));
  var loopback = require('./loopback').create(deps, conf);
  var dnsCtrl = require('./dns-ctrl').create(deps, conf);

  var loopbackDomain;
  function updateConf() {
    loopbackDomain = 'oauth3.org';
    if (conf.ddns && conf.ddns.loopback) {
      if (conf.ddns.loopback.type === 'tunnel@oauth3.org' && conf.ddns.loopback.domain) {
        loopbackDomain = conf.ddns.loopback.domain;
      } else {
        console.error('invalid loopback configuration: bad type or missing domain');
      }
    }
  }
  updateConf();

  function iterateAllModules(action) {
    var promises = conf.ddns.modules.map(function (mod) {
      return action(mod, mod.domains);
    });

    conf.domains.forEach(function (dom) {
      if (!dom.modules || !Array.isArray(dom.modules.ddns) || !dom.modules.ddns.length) {
        return null;
      }

      // For the time being all of our things should only be tried once (regardless if it succeeded)
      // TODO: revisit this behavior when we support multiple ways of setting records, and/or
      // if we want to allow later modules to run if early modules fail.
      promises.push(dom.modules.ddns.reduce(function (prom, mod) {
        if (prom) { return prom; }
        return action(mod, dom.names);
      }, null));
    });

    return deps.PromiseA.all(promises.filter(Boolean));
  }

  var tunnelActive = false;
  async function connectTunnel() {
    var sessionCache = {};
    var sessionOverride;
    if (conf.ddns.tunnel) {
      sessionOverride = await deps.storage.tokens.get(conf.ddns.tunnel.tokenId);
    }
    async function getSession(id) {
      if (sessionOverride) {
        return sessionOverride;
      }
      if (!sessionCache.hasOwnProperty(id)) {
        sessionCache[id] = await deps.storage.tokens.get(conf.ddns.tunnel.tokenId);
      }
      if (!sessionCache[id]) {
        throw new Error('no user token with ID "'+id+'"');
      }
      return sessionCache[id];
    }

    await iterateAllModules(function startTunnel(mod, domainsList) {
      if (mod.type !== 'dns@oauth3.org') { return null; }

      return getSession(mod.token_id).then(function (session) {
        return deps.tunnelClients.start(session, domainsList);
      }).catch(function (err) {
        console.log('error starting tunnel for', domainsList.join(', '));
        console.log(err);
      });
    });

    tunnelActive = true;
  }
  async function disconnectTunnel() {
    deps.tunnelClients.disconnect();
    tunnelActive = false;
  }

  var localAddr, gateway;
  async function checkNetworkEnv() {
    // Since we can't detect the OS level events when a user plugs in an ethernet cable to recheck
    // what network environment we are in we check our local network address and the gateway to
    // determine if we need to run the loopback check and router configuration again.
    var gw = await network.getGatewayIpAsync();
    var addr = await network.getPrivateIpAsync();
    if (localAddr === addr && gateway === gw) {
      return;
    }

    localAddr = addr;
    gateway = gw;
    var loopResult = await loopback(loopbackDomain);
    var notLooped = Object.keys(loopResult.ports).filter(function (port) {
      return !loopResult.ports[port];
    });

    // if (notLooped.length) {
    //   // TODO: try to automatically configure router to forward ports to us.
    // }

    // If we are on a public address or all ports we are listening on are forwarded to us then
    // we don't need the tunnel and we can set the DNS records for all our domains to our public
    // address. Otherwise we need to use the tunnel to accept traffic.
    if (!notLooped.length) {
      if (tunnelActive) {
        await disconnectTunnel();
      }
    } else {
      if (!tunnelActive) {
        await connectTunnel();
      }
    }
  }

  var publicAddress;
  async function recheckPubAddr() {
    await checkNetworkEnv();
    if (tunnelActive) {
      return;
    }

    var addr = await loopback.checkPublicAddr(loopbackDomain);
    if (publicAddress === addr) {
      return;
    }

    if (conf.debug) {
      console.log('previous public address',publicAddress, 'does not match current public address', addr);
    }
    publicAddress = addr;

    var sessionCache = {};
    async function getSession(id) {
      if (!sessionCache.hasOwnProperty(id)) {
        sessionCache[id] = await deps.storage.tokens.get(conf.ddns.tunnel.tokenId);
      }
      if (!sessionCache[id]) {
        throw new Error('no user token with ID "'+id+'"');
      }
      return sessionCache[id];
    }

    await iterateAllModules(function setModuleDNS(mod, domainsList) {
      if (mod.type !== 'dns@oauth3.org' || mod.disabled) { return null; }

      return getSession(mod.token_id).then(function (session) {
        return dnsCtrl.setDeviceAddress(session, addr, domainsList);
      }).catch(function (err) {
        console.log('error setting DNS records for', domainsList.join(', '));
        console.log(err);
      });
    });
  }

  recheckPubAddr();
  setInterval(recheckPubAddr, 5*60*1000);

  return {
    loopbackServer:     loopback.server
  , setDeviceAddress:   dnsCtrl.setDeviceAddress
  , getDeviceAddresses: dnsCtrl.getDeviceAddresses
  , recheckPubAddr:     recheckPubAddr
  , updateConf:         updateConf
  };
};