'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 equal = require('deep-equal');

  var loopbackDomain;

  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));
  }

  async function getSession(id) {
    var session = await deps.storage.tokens.get(id);
    if (!session) {
      throw new Error('no user token with ID "'+id+'"');
    }
    return session;
  }

  var tunnelActive = false;
  async function connectTunnel() {
    var tunnelSession;
    if (conf.ddns.tunnel) {
      // In the case of a non-existant token, I'm not sure if we want to throw here and prevent
      // any tunnel connections, or if we  want to ignore it and fall back to the DNS tokens
      tunnelSession = await deps.storage.tokens.get(conf.ddns.tunnel.tokenId);
    }

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

      return getSession(mod.tokenId).then(function (dnsSession) {
        return deps.tunnelClients.start(tunnelSession || dnsSession, domainList);
      }).catch(function (err) {
        console.log('error starting tunnel for', domainList.join(', '));
        console.log(err);
      });
    });

    tunnelActive = true;
  }
  async function disconnectTunnel() {
    deps.tunnelClients.disconnect();
    tunnelActive = false;
    await Promise.resolve();
  }
  async function checkTunnelTokens() {
    var oldTokens = deps.tunnelClients.current();

    var newTokens = await iterateAllModules(function checkTokens(mod, domainList) {
      if (mod.type !== 'dns@oauth3.org') { return null; }

      var domainStr = domainList.slice().sort().join(',');
      // If there is already a token handling exactly the domains this modules
      // needs handled remove it from the list of tokens to be removed. Otherwise
      // return the module and domain list so we can get new tokens.
      if (oldTokens[domainStr]) {
        delete oldTokens[domainStr];
      } else {
        return Promise.resolve({ mod, domainList });
      }
    });

    await Promise.all(Object.values(oldTokens).map(deps.tunnelClients.remove));

    if (!newTokens.length) { return; }

    var tunnelSession;
    if (conf.ddns.tunnel) {
      // In the case of a non-existant token, I'm not sure if we want to throw here and prevent
      // any tunnel connections, or if we  want to ignore it and fall back to the DNS tokens
      tunnelSession = await deps.storage.tokens.get(conf.ddns.tunnel.tokenId);
    }

    await Promise.all(newTokens.map(function startTunnel({mod, domainList}) {
      return getSession(mod.tokenId).then(function (dnsSession) {
        return deps.tunnelClients.start(tunnelSession || dnsSession, domainList);
      }).catch(function (err) {
        console.log('error starting tunnel for', domainList.join(', '));
        console.log(err);
      });
    }));
  }

  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;

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

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

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

  var curConf;
  function updateConf() {
    if (curConf && equal(curConf.ddns, conf.ddns) && equal(curConf.domains, conf.domains)) {
      // We could update curConf, but since everything we care about is the same...
      return;
    }

    if (!curConf || !equal(curConf.ddns.loopback, conf.ddns.loopback)) {
      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');
        }
      }
    }

    if (tunnelActive) {
      if (!curConf || !equal(curConf.ddns.tunnel, conf.ddns.tunnel)) {
        disconnectTunnel().then(connectTunnel);
      } else {
        checkTunnelTokens();
      }
    }

    // We need to make a deep copy of the config so we can use it next time to
    // compare and see what setup/cleanup is needed to adapt to the changes.
    curConf = JSON.parse(JSON.stringify(conf));
  }
  updateConf();

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