'use strict';

module.exports.create = function (opts) {
  // opts = { filepath };
  var engine = { db: null };

  var db = require(opts.filepath);
  var crypto = require('crypto');
  db.primaryNameservers.forEach(function (ns) {
    if (!ns.id) {
      ns.id = crypto.randomBytes(16).toString('hex');
    }
  });
  db.zones.forEach(function (zone) {
    if (!zone.name) {
      zone.name = zone.id;
      zone.id = null;
    }
    if (!zone.id) {
      zone.id = crypto.randomBytes(16).toString('hex');
    }
  });
  db.records.forEach(function (record) {
    if (!record.id) {
      record.id = crypto.randomBytes(16).toString('hex');
    }
  });
  db.save = function (cb) {
    if (db.save._saving) {
      console.log('make pending');
      db.save._pending.push(cb);
      return;
    }

    db.save._saving = true;
    require('fs').writeFile(opts.filepath, JSON.stringify(db, null, 2), function (err) {
      console.log('done writing');
      var pending = db.save._pending.splice(0);
      db.save._saving = false;
      cb(err);
      if (!pending.length) {
        return;
      }
      db.save(function (err) {
        console.log('double save');
        pending.forEach(function (cb) { cb(err); });
      });
    });
  };
  db.save._pending = [];
  require('fs').writeFileSync(opts.filepath, JSON.stringify(db, null, 2));

  engine.primaryNameservers = db.primaryNameservers;
  engine.zoneToSoa = function (domain) {
    var nameservers = domain.vanityNs || engine.primaryNameservers.map(function (n) { return n.name; });

    var index = Math.floor(Math.random() * nameservers.length) % nameservers.length;
    var nameserver = nameservers[index];
    return {
      name: domain.name
    , 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.name)
    , email_addr: domain.admin || ('admin.' + domain.name)

      // 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
    };
  };
  engine.peers = {
    all: function (cb) {
      process.nextTick(function () {
        cb(null, db.primaryNameservers);
      });
    }
  };
  engine.zones = {
    all: function (cb) {
      process.nextTick(function () {
        cb(null, db.zones.slice(0));
      });
    }
  , get: function (queries, cb) {
      if (!Array.isArray(queries)) {
        queries = queries.names.map(function (n) {
          return { name: n };
        });
      }
      var myDomains = db.zones.filter(function (d) {
        return queries.some(function (q) {
          return d.name.toLowerCase() === q.name;
        });
      });
      process.nextTick(function () {
        cb(null, myDomains);
      });
    }
  };
  engine.records = {
    all: function (cb) {
      process.nextTick(function () {
        cb(null, db.records.slice(0));
      });
    }
  , get: function (query, cb) {
      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 (query.name === r.name || ('*.' + query.name.split('.').slice(1).join('.')) === r.name) {
          return true;
        }
      });
      process.nextTick(function () {
        cb(null, myRecords);
      });
    }
  , save: function (record, cb) {
      if (record.id) {
        console.log('update record!');
        engine.records.update(record, cb);
      } else {
        engine.records.create(record, cb);
      }
    }
  , update: function (record, cb) {
      var existing;
      var dirty;

      db.records.some(function (r) {
        if (r.id === record.id) {
          existing = r;
          return true;
        }
      });

      if (!existing) {
        console.log('no existing record');
        cb(new Error("record for '" + record.id + "' does not exist"), null);
        return;
      }

      console.log('found existing record');
      console.log(existing);
      console.log(record);
      Object.keys(record).forEach(function (key) {
        if (existing[key] !== record[key]) {
          dirty = true;
          console.log(existing[key], record[key]);
          existing[key] = record[key];
        }
      });

      record.updatedAt = new Date().toISOString(); // Math.round(Date.now() / 1000);
      if (dirty) {
        record.changedAt = record.updatedAt;
      }

      console.log('saving...');
      db.save(function (err) {
        cb(err, !err && existing || null);
      });
    }
  };

  return engine;
};