const assert = require('assert');
const CIDRMatcher = require('cidr-matcher');
const {parseUri} = require('drachtio-srf');
const {normalizeDID} = require('./utils');

const sqlSelectSPForAccount = 'SELECT service_provider_sid FROM accounts WHERE account_sid = ?';

const sqlSelectAllCarriersForAccountByRealm =
`SELECT sg.sip_gateway_sid, sg.voip_carrier_sid, vc.name, vc.account_sid,  
vc.application_sid, sg.inbound, sg.outbound, sg.is_active, sg.ipv4, sg.netmask  
FROM sip_gateways sg, voip_carriers vc, accounts acc 
WHERE acc.sip_realm = ? 
AND vc.account_sid = acc.account_sid 
AND vc.is_active = 1 
AND sg.inbound = 1 
AND sg.voip_carrier_sid = vc.voip_carrier_sid`;

const sqlSelectAllCarriersForSPByRealm =
`SELECT sg.sip_gateway_sid, sg.voip_carrier_sid, vc.name, vc.account_sid,  
vc.application_sid, sg.inbound, sg.outbound, sg.is_active, sg.ipv4, sg.netmask  
FROM sip_gateways sg, voip_carriers vc, accounts acc 
WHERE acc.sip_realm = ? 
AND vc.service_provider_sid = acc.service_provider_sid  
AND vc.account_sid IS NULL 
AND vc.is_active = 1 
AND sg.inbound = 1 
AND sg.voip_carrier_sid = vc.voip_carrier_sid`;

const sqlSelectAllGatewaysForSP =
`SELECT sg.sip_gateway_sid, sg.voip_carrier_sid, vc.name, vc.service_provider_sid,  
vc.account_sid, vc.application_sid, sg.inbound, sg.outbound, sg.is_active, sg.ipv4, sg.netmask  
FROM sip_gateways sg, voip_carriers vc
WHERE sg.voip_carrier_sid = vc.voip_carrier_sid 
AND vc.service_provider_sid IS NOT NULL 
AND vc.is_active = 1 
AND sg.inbound = 1`;

const sqlCarriersForAccountBySid =
`SELECT sg.sip_gateway_sid, sg.voip_carrier_sid, vc.name, vc.account_sid,  
vc.application_sid, sg.inbound, sg.outbound, sg.is_active, sg.ipv4, sg.netmask  
FROM sip_gateways sg, voip_carriers vc, accounts acc 
WHERE acc.account_sid = ? 
AND vc.account_sid = acc.account_sid 
AND vc.is_active = 1 
AND sg.inbound = 1 
AND sg.voip_carrier_sid = vc.voip_carrier_sid`;

const sqlAccountByRealm = 'SELECT * from accounts WHERE sip_realm = ?';
const sqlAccountBySid = 'SELECT * from accounts WHERE account_sid = ?';
const sqlApplicationBySid = 'SELECT * from applications WHERE application_sid = ?';

const sqlQueryApplicationByDid = `
SELECT * FROM phone_numbers 
WHERE number = ? 
AND voip_carrier_sid = ?`;

const sqlQueryAllDidsForCarrier = `
SELECT * FROM phone_numbers 
WHERE voip_carrier_sid = ?`;

const sqlSelectOutboundGatewayForCarrier = `
SELECT ipv4, port, e164_leading_plus  
FROM sip_gateways sg, voip_carriers vc 
WHERE sg.voip_carrier_sid = ? 
AND sg.voip_carrier_sid = vc.voip_carrier_sid 
AND outbound = 1`;

const sqlSelectCarrierRequiringRegistration = `
SELECT sg.sip_gateway_sid, sg.voip_carrier_sid, vc.name, vc.service_provider_sid, vc.account_sid, 
vc.application_sid, sg.inbound, sg.outbound, sg.is_active, sg.ipv4, sg.netmask  
FROM sip_gateways sg, voip_carriers vc 
WHERE sg.voip_carrier_sid = vc.voip_carrier_sid 
AND vc.requires_register = 1 
AND vc.is_active = 1 
AND vc.register_sip_realm = ? 
AND vc.register_username = ?`;

const gatewayMatchesSourceAddress = (logger, source_address, gw) => {
  if (32 === gw.netmask && gw.ipv4 === source_address) return true;
  if (gw.netmask < 32) {
    try {
      const matcher = new CIDRMatcher([`${gw.ipv4}/${gw.netmask}`]);
      return matcher.contains(source_address);
    } catch (err) {
      logger.info({err, gw}, 'gatewayMatchesSourceAddress: Error parsing netmask');
    }
  }
  return false;
};

module.exports = (srf, logger) => {
  const {pool}  = srf.locals.dbHelpers;
  const pp = pool.promise();

  const getApplicationBySid = async(application_sid) => {
    const [r] = await pp.query(sqlApplicationBySid, [application_sid]);
    if (0 === r.length) return null;
    return r[0];
  };

  const getSPForAccount = async(account_sid) => {
    const [r] = await pp.query(sqlSelectSPForAccount, [account_sid]);
    if (0 === r.length) return null;
    return r[0].service_provider_sid;
  };

  const getOutboundGatewayForRefer = async(voip_carrier_sid) => {
    try {
      const [r] = await pp.query(sqlSelectOutboundGatewayForCarrier, [voip_carrier_sid]);
      if (0 === r.length) return null;

      /* if multiple, prefer a DNS name */
      const hasDns = r.find((row) => row.ipv4.match(/^[A-Za-z]/));
      return hasDns /* || r[0] */;
    } catch (err) {
      logger.error({err}, 'getOutboundGatewayForRefer');
    }
  };

  const getApplicationForDidAndCarrier = async(req, voip_carrier_sid) => {
    const did = normalizeDID(req.calledNumber) || 'anonymous';

    try {
      /* straight DID match */
      const [r] = await pp.query(sqlQueryApplicationByDid, [did, voip_carrier_sid]);
      if (r.length) return r[0].application_sid;

      /* wildcard / regex match */
      const [r2] = await pp.query(sqlQueryAllDidsForCarrier, [voip_carrier_sid]);
      const match = r2
        .filter((o) => o.number.match(/\D/))                  // look at anything with non-digit characters
        .sort((a, b) => b.number.length - a.number.length)    // prefer longest match
        .find((o) => did.match(new RegExp(o.number.endsWith('*') ? `${o.number.slice(0, -1)}\\d*` : o.number)));
      if (match) return match.application_sid;
      return null;
    } catch (err) {
      logger.error({err}, 'getApplicationForDidAndCarrier');
    }
  };

  const wasOriginatedFromCarrier = async(req) => {
    const failure = {fromCarrier: false};
    const uri = parseUri(req.uri);
    const isDotDecimal = /^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$/.test(uri.host);

    if (!isDotDecimal) {
      /**
       * The host part of the SIP URI is not a dot-decimal IP address,
       * so this can be one of two things:
       * (1) a sip realm value associate with an account, or
       * (2) a carrier name for a carrier that we send outbound registrations to
       *
       * Let's look for case #1 first...
       */

      /* get all the carriers and gateways for the account owning this sip realm */
      const [gwAcc] = await pp.query(sqlSelectAllCarriersForAccountByRealm, [uri.host]);
      const [gwSP] = gwAcc.length ? [[]] : await pp.query(sqlSelectAllCarriersForSPByRealm, uri.host);
      const gw = gwAcc.concat(gwSP);
      const selected = gw.find(gatewayMatchesSourceAddress.bind(null, logger, req.source_address));
      if (selected) {
        const [a] = await pp.query(sqlAccountByRealm, [uri.host]);
        if (0 === a.length) return failure;
        return {
          fromCarrier: true,
          gateway: selected,
          service_provider_sid: a[0].service_provider_sid,
          account_sid: a[0].account_sid,
          application_sid: selected.application_sid,
          account: a[0]
        };
      }

      /* no match, so let's look for case #2 */
      try {
        logger.info({
          host: uri.host,
          user: uri.user
        }, 'sip realm is not associated with an account, checking carriers');
        const [gw] = await pp.query(sqlSelectCarrierRequiringRegistration, [uri.host, uri.user]);
        const matches = gw.filter(gatewayMatchesSourceAddress.bind(null, logger, req.source_address));
        if (1 === matches.length) {
          // bingo
          //TODO: this assumes the carrier is associate to an account, not an SP
          //if the carrier is associated with an SP (which would mean we
          //must see a dialed number in the To header, not the register username),
          //then we need to look up the account based on the dialed number in the To header
          const [a] = await pp.query(sqlAccountBySid, [[matches[0].account_sid]]);
          if (0 === a.length) return failure;
          logger.debug({matches}, `found registration carrier using ${uri.host} and ${uri.user}`);
          return {
            fromCarrier: true,
            gateway: matches[0],
            service_provider_sid: a[0].service_provider_sid,
            account_sid: a[0].account_sid,
            application_sid: matches[0].application_sid,
            account: a[0]
          };
        }
        else if (matches.length > 1) {
          logger.warn({matches, source_address: req.source_address}, 'multiple gateways match source address');
          return {
            fromCarrier: true,
            error: 'Multiple gateways match registration carrier source address'
          };
        }
      } catch (err) {
        logger.info({err, host: uri.host, user: uri.user}, 'Error looking up carrier by host and user');
      }
      /* no match, so fall through  */
    }

    if (isDotDecimal && process.env.JAMBONES_HOSTING) {
      if (!process.env.SBC_ACCOUNT_SID) return failure;

      /* look for carrier only within that account */
      const [r] = await pp.query(sqlCarriersForAccountBySid,
        [process.env.SBC_ACCOUNT_SID, req.source_address, req.source_port]);
      if (0 === r.length) return failure;
      const service_provider_sid = await getSPForAccount(process.env.SBC_ACCOUNT_SID);
      return {
        fromCarrier: true,
        gateway: r[0],
        account_sid: process.env.SBC_ACCOUNT_SID,
        service_provider_sid
      };
    }
    else {
      /* find all carrier entries that have an inbound gateway matching the source IP */
      const [gw] = await pp.query(sqlSelectAllGatewaysForSP);
      let matches = gw
        .filter(gatewayMatchesSourceAddress.bind(null, logger, req.source_address))
        .map((gw) => {
          return {
            voip_carrier_sid: gw.voip_carrier_sid,
            name: gw.name,
            service_provider_sid: gw.service_provider_sid,
            account_sid: gw.account_sid,
            application_sid: gw.application_sid
          };
        });
      /* remove duplicates, winnow down to voip_carriers, not gateways */
      matches = [...new Set(matches.map(JSON.stringify))].map(JSON.parse);
      if (matches.length) {
        /* we have one or more matches.  Now check for one with a provisioned phone number matching the DID */
        const vc_sids = matches.map((m) => `'${m.voip_carrier_sid}'`).join(',');
        const did = normalizeDID(req.calledNumber) || 'anonymous';
        const sql =  `SELECT * FROM phone_numbers WHERE number = '${did}' AND voip_carrier_sid IN (${vc_sids})`;
        logger.debug({matches, sql, did, vc_sids}, 'looking up DID');

        const [r] = await pp.query(sql);
        if (0 === r.length) {
          /* came from a provisioned carrier, but the dialed number is not provisioned.
              check if we have an account with default routing of that carrier to an application
          */
          const accountLevelGateways = matches.filter((m) => m.account_sid && m.application_sid);
          if (accountLevelGateways.length > 1) {
            logger.info({accounts: accountLevelGateways.map((m) => m.account_sid)},
              'multiple accounts have added this carrier with default routing -- cannot determine which to use');
            return {
              fromCarrier: true,
              error: 'Multiple accounts are attempting to default route this carrier'
            };
          }
          else if (accountLevelGateways.length === 1) {
            const [accounts] = await pp.query('SELECT * from accounts where account_sid = ?',
              [accountLevelGateways[0].account_sid]);
            return {
              fromCarrier: true,
              gateway: accountLevelGateways[0],
              service_provider_sid: accountLevelGateways[0].service_provider_sid,
              account_sid: accountLevelGateways[0].account_sid,
              application_sid: accountLevelGateways[0].application_sid,
              account: accounts[0]
            };
          }
          else {
            /* check if we only have a single account, otherwise we have no
-               way of knowing which account this is for
            */
            const [r] = await pp.query('SELECT count(*) as count from accounts where service_provider_sid = ?',
              [matches[0].service_provider_sid]);
            if (r[0].count === 0 || r[0].count > 1) return {fromCarrier: true};
            else {
              const [accounts] = await pp.query('SELECT * from accounts where service_provider_sid = ?',
                [matches[0].service_provider_sid]);
              return {
                fromCarrier: true,
                gateway: matches[0],
                service_provider_sid: accounts[0].service_provider_sid,
                account_sid: accounts[0].account_sid,
                account: accounts[0]
              };
            }
          }
        }
        else if (r.length > 1) {
          logger.info({r},
            'multiple accounts have added this carrier with default routing -- cannot determine which to use');
          return {
            fromCarrier: true,
            error: 'Multiple accounts are attempting to route the same phone number from the same carrier'
          };
        }

        /* we have a route for this phone number and carrier combination */
        const gateway = matches.find((m) => m.voip_carrier_sid === r[0].voip_carrier_sid);
        const [accounts] = await pp.query(sqlAccountBySid, [r[0].account_sid]);
        assert(accounts.length);
        return {
          fromCarrier: true,
          gateway,
          service_provider_sid: accounts[0].service_provider_sid,
          account_sid: r[0].account_sid,
          application_sid: r[0].application_sid,
          account: accounts[0]
        };
      }
    }
    return failure;
  };

  return {
    wasOriginatedFromCarrier,
    getApplicationForDidAndCarrier,
    getOutboundGatewayForRefer,
    getSPForAccount,
    getApplicationBySid
  };
};