(function () {
'use strict';

/*
module.exports.ask = function (query, cb) {
};
*/

var NOERROR = 0;
var NXDOMAIN = 3;
var REFUSED = 5;

function getRecords(db, qname, cb) {
  var delMe = {};
  var dns = require('dns');
  // SECURITY XXX TODO var dig = require('dig.js/dns-request');
  var count;
  var myRecords = db.records.slice(0).filter(function (r) {

    if ('string' !== typeof r.name) {
      return false;
    }

    // TODO use IN in masterquest (or implement OR)
    // Only return single-level wildcard?
    if (qname === r.name || ('*.' + qname.split('.').slice(1).join('.')) === r.name) {
      return true;
    }
  });

  function checkCount() {
    count -= 1;
    if (count <= 0) {
      myRecords = myRecords.filter(function (r) {
        return !delMe[r.id];
      });
      cb(null, myRecords);
    }
  }

  function getRecord(r) {
    // TODO allow multiple records to be returned(?)
    return function (err, addresses) {
      if (err || !addresses.length) {
        r.id = r.id || Math.random();
        delMe[r.id] = true;
      } else if (addresses.length > 1) {
        r._address = addresses[Math.floor(Math.random() * addresses.length)];
      } else {
        r._address = addresses[0];
      }
      checkCount();
    };
  }

  count = myRecords.length;
  myRecords.forEach(function (r) {
    if (r.aname && !r.address) {
      if ('A' === r.type) {
        // SECURITY XXX TODO dig.resolveJson(query, opts);
        dns.resolve4(r.aname, getRecord(r));
        return;
      }
      if ('AAAA' === r.type) {
        // SECURITY XXX TODO dig.resolveJson(query, opts);
        dns.resolve6(r.aname, getRecord(r));
        return;
      }
    }

    checkCount();
  });

  if (!myRecords.length) {
    checkCount();
  }
}

function dbToResourceRecord(r) {
  return {
    name: r.name
  , typeName: r.type // NS
  , className: 'IN'
  , ttl: r.ttl || 300

    // SOA
    /*
  , "primary": "ns1.yahoo.com"
  , "admin": "hostmaster.yahoo-inc.com"
  , "serial": 2017092539
  , "refresh": 3600
  , "retry": 300
  , "expiration": 1814400
  , "minimum": 600
    */

    // A, AAAA
  , address: -1 !== [ 'A', 'AAAA' ].indexOf(r.type) ? (r._address || r.address || r.value) : undefined

    // CNAME, NS, PTR || TXT
  , data: -1 !== [ 'CNAME', 'NS', 'PTR', 'TXT' ].indexOf(r.type) ? (r.data || r.value || r.values) : undefined

    // MX, SRV
  , priority: r.priority

    // MX
  , exchange: r.exchange

    // SRV
  , weight: r.weight
  , port: r.port
  , target: r.target
  };
}

function getNs(db, ds, results, cb) {
  console.log('[DEV] getNs entered');

  var d = ds.shift();

  if (!d) {
    results.header.rcode = NXDOMAIN;
    cb(null, results);
    return;
  }

  var qn = d.id.toLowerCase();

  return getRecords(db, qn, function (err, records) {
    if (err) { cb(err); return; }

    records.forEach(function (r) {
      if ('NS' !== r.type) {
        return;
      }

      var ns = {
        name: r.name
      , typeName: r.type // NS
      , className: r.class || 'IN'
      , ttl: r.ttl || 300
      , data: r.data || r.value || r.address
      };

      console.log('got NS record:');
      console.log(r);
      console.log(ns);

      // TODO what if this NS is one of the NS?
      // return SOA record instead
      results.authority.push(ns);
    });

    if (!results.authority.length) {
      return getNs(db, ds, results, cb);
    }

    // d.vanityNs should only be vanity nameservers (pointing to this same server)
    if (d.vanityNs || results.authority.some(function (ns) {
      console.log('[debug] ns', ns);
      return -1 !== db.primaryNameservers.indexOf(ns.data.toLowerCase());
    })) {
      results.authority.length = 0;
      results.authority.push(domainToSoa(db, d));
      results.header.rcode = NXDOMAIN;
    }
    cb(null, results);
    return;
  });
}

function domainToSoa(db, domain) {
  var nameservers = domain.vanityNs || db.primaryNameservers;

  var index = Math.floor(Math.random() * nameservers.length) % nameservers.length;
  var nameserver = nameservers[index];
  return {
    name: domain.id
  , typeName: 'SOA'
  , className: 'IN'
  , ttl: domain.ttl || 60

    // nameserver -- select an NS at random if they're all in sync
  , primary: nameserver
  , name_server: nameserver

    // admin -- email address or domain for admin
  , admin: domain.admin || ('admin.' + domain.id)
  , email_addr: domain.admin || ('admin.' + domain.id)

    // serial -- the version, for cache-busting of secondary nameservers. suggested format: YYYYMMDDnn
  , serial: domain.serial || Math.round((domain.updatedAt || domain.createdAt || 0) / 1000)
  , sn: domain.serial || Math.round((domain.updatedAt || domain.createdAt || 0) / 1000)

    // refresh -- only used when nameservers following the DNS NOTIFY spec talk
  , refresh: domain.refresh || 1800
  , ref: domain.refresh || 1800

    // retry -- only used when nameservers following the DNS NOTIFY spec talk
  , retry: domain.retry || 600
  , ret: domain.retry || 600

    // expiration -- how long other nameservers should continue when the primary goes down
  , expiration: domain.expiration || 2419200
  , ex: domain.expiration || 2419200

    // minimum -- how long to cache a non-existent domain (also the default ttl for BIND)
  , minimum: domain.minimum || 5
  , nx: domain.minimum || 5
  };
}

function getSoa(db, domain, results, cb, answerSoa) {
  console.log('[DEV] getSoa entered');

  if (!answerSoa) {
    results.authority.push(domainToSoa(db, domain));
  } else {
    results.answer.push(domainToSoa(db, domain));
  }

  cb(null, results);
  return;
}

module.exports.query = function (input, query, cb) {
  /*
  var fs = require('fs');

  fs.readFile(input, 'utf8', function (err, text) {
    if (err) { cb(err); return; }
    var records;
    try {
      records = JSON.parse(text);
    } catch(e) { cb(e); return; }
  });
  */

  var db;
  var qname;
  try {
    db = require(input);
  } catch(e) { cb(e); return; }

  if (!Array.isArray(query.question) || query.question.length < 1) {
    cb(new Error("query is missing question section"));
    return;
  }

  if (1 !== query.question.length) {
    cb(new Error("query should have exactly one question (for now)"));
    return;
  }

  if (!query.question[0] || 'string' !== typeof query.question[0].name) {
    cb(new Error("query's question section should exist and have a String name property"));
    return;
  }

  qname = query.question[0].name.toLowerCase();

  var results = {
    header: {
      id: query.header.id   // same as request
    , qr: 1
    , opcode: 0             // pretty much always 0 QUERY
    , aa: 1                 // TODO right now we assume that if we have the record, we're authoritative
                            // but in reality we could be hitting a cache and then recursing on a cache miss
    , tc: 0
    , rd: query.header.rd   // duh
    , ra: 0                 // will be changed by cli.norecurse
    , rcode: NOERROR        // 0 NOERROR, 3 NXDOMAIN, 5 REFUSED
    }
  , question: [ query.question[0] ], answer: [], authority: [], additional: []
  };

  function getNsAndSoa(getNsAlso, answerSoa) {
    // If the query is www.foo.delegated.example.com
    // and we have been delegated delegated.example.com
    // and delegated.example.com exists
    // but foo.delegated.example.com does not exist
    // what's the best strategy for returning the record?
    //
    // What does PowerDNS do in these situations?
    // https://doc.powerdns.com/md/authoritative/backend-generic-mysql/

    // How to optimize:
    // Assume that if a record is being requested, it probably exists
    // (someone has probably published it somewhere)
    // If the record doesn't exist, then see if any of the domains are managed
    // [ 'www.john.smithfam.net', 'john.smithfam.net', 'smithfam.net', 'net' ]
    // Then if one of those exists, return the SOA record with NXDOMAIN

    var qarr = qname.split('.');
    var qnames = [];
    while (qarr.length) {
      qnames.push(qarr.join('.').toLowerCase());
      qarr.shift(); // first
    }

    var myDomains = db.domains.filter(function (d) {
      return -1 !== qnames.indexOf(d.id.toLowerCase());
    });

    // this should result in a REFUSED status
    if (!myDomains.length) {
      // REFUSED will have no records, so we could still recursion, if enabled
      results.header.rcode = REFUSED;
      cb(null, results);
      return;
    }

    myDomains.sort(function (d1, d2) {
      if (d1.id.length > d2.id.length) {
        return -1;
      }
      if (d1.id.length < d2.id.length) {
        return 1;
      }
      return 0;
    });
    //console.log('sorted domains', myDomains);

    if (!getNsAlso) {
      return getSoa(db, myDomains[0], results, cb, answerSoa);
    }

    return getNs(db, myDomains.slice(0), results, function (err, results) {
      //console.log('[DEV] getNs complete');

      if (err) { cb(err, results); return; }

      // has NS records (or SOA record if NS records match the server itself)
      if (results.authority.length) {
        console.log(results); cb(null, results); return;
      }

      // myDomains was sorted such that the longest was first
      return getSoa(db, myDomains[0], results, cb);

    });
  }

  if ('SOA' === query.question[0].typeName) {
    return getNsAndSoa(false, true);
  }

  //console.log('[DEV] QUERY NAME', qname);
  return getRecords(db, qname, function (err, someRecords) {
    var myRecords;
    var nsRecords = [];

    if (err) { cb(err); return; }

    // filter out NS (delegation) records, unless that is what is intended
    someRecords = someRecords.filter(function (r) {
      // If it's not an NS record, it's a potential result
      if ('NS' !== r.type && 'NS' !== r.typeName) {
        return true;
      }

      // If the query was for NS, it's a potential result
      if ('NS' === query.question[0].typeName) {
        return true;
      }

      // If it's a vanity NS, it's not a valid NS for lookup
      if (-1 !== db.primaryNameservers.indexOf(r.data.toLowerCase())) {
        return false;
      }

      nsRecords.push(r);
      return false;
    });

    // TODO should NS be returned as ANSWER or AUTHORITY in ANY?
    myRecords = someRecords;
    if (255 !== query.question[0].type && 'ANY' !== query.question[0].typeName) {
      myRecords = myRecords.filter(function (r) {

        return ((r.type && r.type === query.question[0].type)
          || (r.type && r.type === query.question[0].typeName)
          || (r.typeName && r.typeName === query.question[0].typeName)
        );
      });
    }

    if (myRecords.length) {
      myRecords.forEach(function (r) {
        results.answer.push(dbToResourceRecord(r));
      });
      results.header.rcode = NOERROR;
      //console.log('[DEV] ANSWER results', results);
      cb(null, results);
      return;
    }
    else if (nsRecords.length) {
      nsRecords.forEach(function (r) {
        results.authority.push(dbToResourceRecord(r));
      });
      results.header.rcode = NOERROR;
      //console.log('[DEV] AUTHORITY results', results);
      cb(null, results);
      return;
    }

    if (!myRecords.length) {
      getNsAndSoa(true);
    }
  });
};

}());