/*!
 * walletdb.js - storage for wallets
 * Copyright (c) 2014-2015, Fedor Indutny (MIT License)
 * Copyright (c) 2014-2016, Christopher Jeffrey (MIT License).
 * https://github.com/bcoin-org/bcoin
 */

'use strict';

var bcoin = require('../env');
var AsyncObject = require('../utils/async');
var utils = require('../utils/utils');
var crypto = require('../crypto/crypto');
var assert = utils.assert;
var constants = bcoin.constants;
var BufferReader = require('../utils/reader');
var BufferWriter = require('../utils/writer');
var Path = require('./path');
var MAX_POINT = String.fromCharCode(0xdbff, 0xdfff); // U+10FFFF

/*
 * Database Layout:
 *  p[addr-hash] -> path data
 *  w[wid] -> wallet
 *  l[id] -> wid
 *  a[wid][index] -> account
 *  i[wid][name] -> account index
 *  t[wid]* -> txdb
 *  R -> tip
 *  b[hash] -> wallet block
 *  e[hash] -> tx->wid map
 */

var layout = {
  p: function(hash) {
    var key = new Buffer(1 + (hash.length / 2));
    key[0] = 0x70;
    key.write(hash, 1, 'hex');
    return key;
  },
  pp: function(key) {
    return key.toString('hex', 1);
  },
  w: function(wid) {
    var key = new Buffer(5);
    key[0] = 0x77;
    key.writeUInt32BE(wid, 1, true);
    return key;
  },
  ww: function(key) {
    return key.readUInt32BE(1, true);
  },
  l: function(id) {
    var len = Buffer.byteLength(id, 'utf8');
    var key = new Buffer(1 + len);
    key[0] = 0x6c;
    if (len > 0)
      key.write(id, 1, 'utf8');
    return key;
  },
  ll: function(key) {
    return key.toString('utf8', 1);
  },
  a: function a(wid, index) {
    var key = new Buffer(9);
    key[0] = 0x61;
    key.writeUInt32BE(wid, 1, true);
    key.writeUInt32BE(index, 5, true);
    return key;
  },
  i: function i(wid, name) {
    var len = Buffer.byteLength(name, 'utf8');
    var key = new Buffer(5 + len);
    key[0] = 0x69;
    key.writeUInt32BE(wid, 1, true);
    if (len > 0)
      key.write(name, 5, 'utf8');
    return key;
  },
  ii: function ii(key) {
    return [key.readUInt32BE(1, true), key.toString('utf8', 5)];
  },
  R: new Buffer([0x52]),
  b: function b(hash) {
    var key = new Buffer(33);
    key[0] = 0x62;
    key.write(hash, 1, 'hex');
    return key;
  },
  e: function e(hash) {
    var key = new Buffer(33);
    key[0] = 0x65;
    key.write(hash, 1, 'hex');
    return key;
  }
};

if (utils.isBrowser)
  layout = require('./browser').walletdb;

/**
 * WalletDB
 * @exports WalletDB
 * @constructor
 * @param {Object} options
 * @param {String?} options.name - Database name.
 * @param {String?} options.location - Database file location.
 * @param {String?} options.db - Database backend (`"leveldb"` by default).
 * @param {Boolean?} options.verify - Verify transactions as they
 * come in (note that this will not happen on the worker pool).
 * @property {Boolean} loaded
 */

function WalletDB(options) {
  if (!(this instanceof WalletDB))
    return new WalletDB(options);

  if (!options)
    options = {};

  AsyncObject.call(this);

  this.options = options;
  this.network = bcoin.network.get(options.network);
  this.fees = options.fees;
  this.logger = options.logger || bcoin.defaultLogger;
  this.batches = {};
  this.wallets = {};
  this.workerPool = null;

  this.tip = this.network.genesis.hash;
  this.height = 0;
  this.depth = 0;

  // We need one read lock for `get` and `create`.
  // It will hold locks specific to wallet ids.
  this.readLock = new bcoin.locker.mapped(this);
  this.writeLock = new bcoin.locker.mapped(this);
  this.txLock = new bcoin.locker(this);

  this.walletCache = new bcoin.lru(10000);
  this.accountCache = new bcoin.lru(10000);
  this.pathCache = new bcoin.lru(100000);

  // Try to optimize for up to 1m addresses.
  // We use a regular bloom filter here
  // because we never want members to
  // lose membership, even if quality
  // degrades.
  // Memory used: 1.7mb
  this.filter = this.options.useFilter !== false
    ? bcoin.bloom.fromRate(1000000, 0.001, -1)
    : null;

  this.db = bcoin.ldb({
    location: this.options.location,
    db: this.options.db,
    maxOpenFiles: this.options.maxFiles,
    cacheSize: 8 << 20,
    writeBufferSize: 4 << 20,
    bufferKeys: !utils.isBrowser
  });

  if (bcoin.useWorkers)
    this.workerPool = new bcoin.workers();

  this._init();
}

utils.inherits(WalletDB, AsyncObject);

/**
 * Database layout.
 * @type {Object}
 */

WalletDB.layout = layout;

/**
 * Initialize wallet db.
 * @private
 */

WalletDB.prototype._init = function _init() {
  var self = this;

  if (bcoin.useWorkers) {
    this.workerPool.on('error', function(err) {
      self.emit('error', err);
    });
  }
};

/**
 * Invoke wallet read mutex lock.
 * @private
 */

WalletDB.prototype._lockRead = function _lockRead(key, func, args, force) {
  return this.readLock.lock(key, func, args, force);
};

/**
 * Invoke wallet write mutex lock.
 * @private
 */

WalletDB.prototype._lockWrite = function _lockWrite(key, func, args, force) {
  return this.writeLock.lock(key, func, args, force);
};

/**
 * Invoke tx handling mutex lock.
 * @private
 */

WalletDB.prototype._lockTX = function _lockTX(func, args, force) {
  return this.txLock.lock(func, args, force);
};

/**
 * Open the walletdb, wait for the database to load.
 * @alias WalletDB#open
 * @param {Function} callback
 */

WalletDB.prototype._open = function open(callback) {
  var self = this;

  this.db.open(function(err) {
    if (err)
      return callback(err);

    self.db.checkVersion('V', 2, function(err) {
      if (err)
        return callback(err);

      self.writeGenesis(function(err) {
        if (err)
          return callback(err);

        self.getDepth(function(err, depth) {
          if (err)
            return callback(err);

          self.depth = depth;

          self.logger.info(
            'WalletDB loaded (depth=%d, height=%d).',
            depth, self.height);

          self.loadFilter(callback);
        });
      });
    });
  });
};

/**
 * Close the walletdb, wait for the database to close.
 * @alias WalletDB#close
 * @param {Function} callback
 */

WalletDB.prototype._close = function close(callback) {
  var self = this;
  var keys = Object.keys(this.wallets);
  var wallet;

  utils.forEachSerial(keys, function(key, next) {
    wallet = self.wallets[key];
    wallet.destroy(next);
  }, function(err) {
    if (err)
      return callback(err);

    self.db.close(callback);
  });
};

/**
 * Backup the wallet db.
 * @param {String} path
 * @param {Function} callback
 */

WalletDB.prototype.backup = function backup(path, callback) {
  this.db.backup(path, callback);
};

/**
 * Get current wallet wid depth.
 * @private
 * @param {Function} callback
 */

WalletDB.prototype.getDepth = function getDepth(callback) {
  var iter, depth;

  // This may seem like a strange way to do
  // this, but updating a global state when
  // creating a new wallet is actually pretty
  // damn tricky. There would be major atomicity
  // issues if updating a global state inside
  // a "scoped" state. So, we avoid all the
  // nonsense of adding a global lock to
  // walletdb.create by simply seeking to the
  // highest wallet wid.
  iter = this.db.iterator({
    gte: layout.w(0x00000000),
    lte: layout.w(0xffffffff),
    reverse: true
  });

  iter.next(function(err, key, value) {
    if (err) {
      return iter.end(function() {
        callback(err);
      });
    }

    iter.end(function(err) {
      if (err)
        return callback(err);

      if (key === undefined)
        return callback(null, 1);

      depth = layout.ww(key);

      callback(null, depth + 1);
    });
  });
};

/**
 * Start batch.
 * @private
 * @param {WalletID} wid
 */

WalletDB.prototype.start = function start(wid) {
  assert(utils.isNumber(wid), 'Bad ID for batch.');
  assert(!this.batches[wid], 'Batch already started.');
  this.batches[wid] = this.db.batch();
};

/**
 * Drop batch.
 * @private
 * @param {WalletID} wid
 */

WalletDB.prototype.drop = function drop(wid) {
  var batch = this.batch(wid);
  batch.clear();
  delete this.batches[wid];
};

/**
 * Get batch.
 * @private
 * @param {WalletID} wid
 * @returns {Leveldown.Batch}
 */

WalletDB.prototype.batch = function batch(wid) {
  var batch;
  assert(utils.isNumber(wid), 'Bad ID for batch.');
  batch = this.batches[wid];
  assert(batch, 'Batch does not exist.');
  return batch;
};

/**
 * Save batch.
 * @private
 * @param {WalletID} wid
 * @param {Function} callback
 */

WalletDB.prototype.commit = function commit(wid, callback) {
  var batch = this.batch(wid);
  delete this.batches[wid];
  batch.write(callback);
};

/**
 * Load the bloom filter into memory.
 * @private
 * @param {Function} callback
 */

WalletDB.prototype.loadFilter = function loadFilter(callback) {
  var self = this;

  if (!this.filter)
    return callback();

  this.db.iterate({
    gte: layout.p(constants.NULL_HASH),
    lte: layout.p(constants.HIGH_HASH),
    parse: function(key) {
      var hash = layout.pp(key);
      self.filter.add(hash, 'hex');
    }
  }, callback);
};

/**
 * Test the bloom filter against an array of address hashes.
 * @private
 * @param {Hash[]} hashes
 * @returns {Boolean}
 */

WalletDB.prototype.testFilter = function testFilter(hashes) {
  var i;

  if (!this.filter)
    return true;

  for (i = 0; i < hashes.length; i++) {
    if (this.filter.test(hashes[i], 'hex'))
      return true;
  }

  return false;
};

/**
 * Dump database (for debugging).
 * @param {Function} callback - Returns [Error, Object].
 */

WalletDB.prototype.dump = function dump(callback) {
  var records = {};
  this.db.each({
    gte: ' ',
    lte: '~',
    values: true
  }, function(key, value, next) {
    records[key] = value;
    next();
  }, function(err) {
    if (err)
      return callback(err);
    callback(null, records);
  });
};

/**
 * Register an object with the walletdb.
 * @param {Object} object
 */

WalletDB.prototype.register = function register(wallet) {
  assert(!this.wallets[wallet.wid]);
  this.wallets[wallet.wid] = wallet;
};

/**
 * Unregister a object with the walletdb.
 * @param {Object} object
 * @returns {Boolean}
 */

WalletDB.prototype.unregister = function unregister(wallet) {
  assert(this.wallets[wallet.wid]);
  delete this.wallets[wallet.wid];
};

/**
 * Map wallet label to wallet id.
 * @param {String} label
 * @param {Function} callback
 */

WalletDB.prototype.getWalletID = function getWalletID(id, callback) {
  var self = this;
  var wid;

  if (!id)
    return callback();

  if (typeof id === 'number')
    return callback(null, id);

  wid = this.walletCache.get(id);

  if (wid)
    return callback(null, wid);

  this.db.fetch(layout.l(id), function(data) {
    wid = data.readUInt32LE(0, true);
    self.walletCache.set(id, wid);
    return wid;
  }, callback);
};

/**
 * Get a wallet from the database, setup watcher.
 * @param {WalletID} wid
 * @param {Function} callback - Returns [Error, {@link Wallet}].
 */

WalletDB.prototype.get = function get(wid, callback) {
  var self = this;

  this.getWalletID(wid, function(err, wid) {
    if (err)
      return callback(err);

    if (!wid)
      return callback();

    self._get(wid, function(err, wallet, watched) {
      if (err)
        return callback(err);

      if (!wallet)
        return callback();

      if (watched)
        return callback(null, wallet);

      try {
        self.register(wallet);
      } catch (e) {
        return callback(e);
      }

      wallet.open(function(err) {
        if (err)
          return callback(err);

        callback(null, wallet);
      });
    });
  });
};

/**
 * Get a wallet from the database, do not setup watcher.
 * @private
 * @param {WalletID} wid
 * @param {Function} callback - Returns [Error, {@link Wallet}].
 */

WalletDB.prototype._get = function get(wid, callback) {
  var self = this;
  var wallet;

  callback = this._lockRead(wid, get, [wid, callback]);

  if (!callback)
    return;

  wallet = this.wallets[wid];

  if (wallet)
    return callback(null, wallet, true);

  this.db.fetch(layout.w(wid), function(data) {
    return bcoin.wallet.fromRaw(self, data);
  }, callback);
};

/**
 * Save a wallet to the database.
 * @param {Wallet} wallet
 * @param {Function} callback
 */

WalletDB.prototype.save = function save(wallet) {
  var batch = this.batch(wallet.wid);
  var wid = new Buffer(4);
  this.walletCache.set(wallet.id, wallet.wid);
  batch.put(layout.w(wallet.wid), wallet.toRaw());
  wid.writeUInt32LE(wallet.wid, 0, true);
  batch.put(layout.l(wallet.id), wid);
};

/**
 * Test an api key against a wallet's api key.
 * @param {WalletID} wid
 * @param {String} token
 * @param {Function} callback
 */

WalletDB.prototype.auth = function auth(wid, token, callback) {
  this.get(wid, function(err, wallet) {
    if (err)
      return callback(err);

    if (!wallet)
      return callback();

    if (typeof token === 'string') {
      if (!utils.isHex(token))
        return callback(new Error('Authentication error.'));
      token = new Buffer(token, 'hex');
    }

    // Compare in constant time:
    if (!crypto.ccmp(token, wallet.token))
      return callback(new Error('Authentication error.'));

    callback(null, wallet);
  });
};

/**
 * Create a new wallet, save to database, setup watcher.
 * @param {Object} options - See {@link Wallet}.
 * @param {Function} callback - Returns [Error, {@link Wallet}].
 */

WalletDB.prototype.create = function create(options, callback) {
  var self = this;
  var wallet;

  if (typeof options === 'function') {
    callback = options;
    options = {};
  }

  callback = this._lockWrite(options.id, create, [options, callback]);

  if (!callback)
    return;

  this.has(options.id, function(err, exists) {
    if (err)
      return callback(err);

    if (err)
      return callback(err);

    if (exists)
      return callback(new Error('Wallet already exists.'));

    try {
      wallet = bcoin.wallet.fromOptions(self, options);
      wallet.wid = self.depth++;
    } catch (e) {
      return callback(e);
    }

    try {
      self.register(wallet);
    } catch (e) {
      return callback(e);
    }

    wallet.init(options, function(err) {
      if (err)
        return callback(err);

      self.logger.info('Created wallet %s.', wallet.id);

      callback(null, wallet);
    });
  });
};

/**
 * Test for the existence of a wallet.
 * @param {WalletID} id
 * @param {Function} callback
 */

WalletDB.prototype.has = function has(id, callback) {
  this.getWalletID(id, function(err, wid) {
    if (err)
      return callback(err);
    callback(null, wid != null);
  });
};

/**
 * Attempt to create wallet, return wallet if already exists.
 * @param {Object} options - See {@link Wallet}.
 * @param {Function} callback
 */

WalletDB.prototype.ensure = function ensure(options, callback) {
  var self = this;

  this.get(options.id, function(err, wallet) {
    if (err)
      return callback(err);

    if (wallet)
      return callback(null, wallet);

    self.create(options, callback);
  });
};

/**
 * Get an account from the database.
 * @param {WalletID} wid
 * @param {String|Number} name - Account name/index.
 * @param {Function} callback - Returns [Error, {@link Wallet}].
 */

WalletDB.prototype.getAccount = function getAccount(wid, name, callback) {
  var self = this;

  this.getAccountIndex(wid, name, function(err, index) {
    if (err)
      return callback(err);

    if (index === -1)
      return callback();

    self._getAccount(wid, index, function(err, account) {
      if (err)
        return callback(err);

      if (!account)
        return callback();

      account.open(function(err) {
        if (err)
          return callback(err);

        callback(null, account);
      });
    });
  });
};

/**
 * Get an account from the database. Do not setup watcher.
 * @private
 * @param {WalletID} wid
 * @param {Number} index - Account index.
 * @param {Function} callback - Returns [Error, {@link Wallet}].
 */

WalletDB.prototype._getAccount = function getAccount(wid, index, callback) {
  var self = this;
  var key = wid + '/' + index;
  var account = this.accountCache.get(key);

  if (account)
    return callback(null, account);

  this.db.fetch(layout.a(wid, index), function(data) {
    account = bcoin.account.fromRaw(self, data);
    self.accountCache.set(key, account);
    return account;
  }, callback);
};

/**
 * List account names and indexes from the db.
 * @param {WalletID} wid
 * @param {Function} callback - Returns [Error, Array].
 */

WalletDB.prototype.getAccounts = function getAccounts(wid, callback) {
  var map = [];
  var i, accounts;

  this.db.iterate({
    gte: layout.i(wid, ''),
    lte: layout.i(wid, MAX_POINT),
    values: true,
    parse: function(key, value) {
      var name = layout.ii(key)[1];
      var index = value.readUInt32LE(0, true);
      map[index] = name;
    }
  }, function(err) {
    if (err)
      return callback(err);

    // Get it out of hash table mode.
    accounts = [];

    for (i = 0; i < map.length; i++) {
      assert(map[i] != null);
      accounts.push(map[i]);
    }

    callback(null, accounts);
  });
};

/**
 * Lookup the corresponding account name's index.
 * @param {WalletID} wid
 * @param {String|Number} name - Account name/index.
 * @param {Function} callback - Returns [Error, Number].
 */

WalletDB.prototype.getAccountIndex = function getAccountIndex(wid, name, callback) {
  if (!wid)
    return callback(null, -1);

  if (name == null)
    return callback(null, -1);

  if (typeof name === 'number')
    return callback(null, name);

  this.db.get(layout.i(wid, name), function(err, index) {
    if (err)
      return callback(err);

    if (!index)
      return callback(null, -1);

    callback(null, index.readUInt32LE(0, true));
  });
};

/**
 * Save an account to the database.
 * @param {Account} account
 * @param {Function} callback
 */

WalletDB.prototype.saveAccount = function saveAccount(account) {
  var batch = this.batch(account.wid);
  var index = new Buffer(4);
  var key = account.wid + '/' + account.accountIndex;

  index.writeUInt32LE(account.accountIndex, 0, true);

  batch.put(layout.a(account.wid, account.accountIndex), account.toRaw());
  batch.put(layout.i(account.wid, account.name), index);

  this.accountCache.set(key, account);
};

/**
 * Create an account.
 * @param {Object} options - See {@link Account} options.
 * @param {Function} callback - Returns [Error, {@link Account}].
 */

WalletDB.prototype.createAccount = function createAccount(options, callback) {
  var self = this;
  var account;

  this.hasAccount(options.wid, options.name, function(err, exists) {
    if (err)
      return callback(err);

    if (err)
      return callback(err);

    if (exists)
      return callback(new Error('Account already exists.'));

    try {
      account = bcoin.account.fromOptions(self, options);
    } catch (e) {
      return callback(e);
    }

    account.init(function(err) {
      if (err)
        return callback(err);

      self.logger.info('Created account %s/%s/%d.',
        account.id,
        account.name,
        account.accountIndex);

      callback(null, account);
    });
  });
};

/**
 * Test for the existence of an account.
 * @param {WalletID} wid
 * @param {String|Number} account
 * @param {Function} callback - Returns [Error, Boolean].
 */

WalletDB.prototype.hasAccount = function hasAccount(wid, account, callback) {
  var self = this;
  var key;

  if (!wid)
    return callback(null, false);

  this.getAccountIndex(wid, account, function(err, index) {
    if (err)
      return callback(err);

    if (index === -1)
      return callback(null, false);

    key = wid + '/' + index;

    if (self.accountCache.has(key))
      return callback(null, true);

    self.db.has(layout.a(wid, index), callback);
  });
};

/**
 * Save addresses to the path map.
 * The path map exists in the form of:
 * `p/[address-hash] -> {walletid1=path1, walletid2=path2, ...}`
 * @param {WalletID} wid
 * @param {KeyRing[]} rings
 * @param {Function} callback
 */

WalletDB.prototype.saveAddress = function saveAddress(wid, rings, callback) {
  var self = this;
  var items = [];
  var i, ring, path;

  for (i = 0; i < rings.length; i++) {
    ring = rings[i];
    path = ring.path;

    items.push([ring.getAddress(), path]);

    if (ring.witness) {
      path = path.clone();
      path.hash = ring.getProgramHash('hex');
      items.push([ring.getProgramAddress(), path]);
    }
  }

  utils.forEachSerial(items, function(item, next) {
    self.writeAddress(wid, item[0], item[1], next);
  }, callback);
};

/**
 * Save a single address to the path map.
 * @param {WalletID} wid
 * @param {KeyRing} rings
 * @param {Path} path
 * @param {Function} callback
 */

WalletDB.prototype.writeAddress = function writeAddress(wid, address, path, callback) {
  var self = this;
  var hash = address.getHash('hex');
  var batch = this.batch(wid);

  if (this.filter)
    this.filter.add(hash, 'hex');

  this.emit('save address', address, path);

  this.getAddressPaths(hash, function(err, paths) {
    if (err)
      return callback(err);

    if (!paths)
      paths = {};

    if (paths[wid])
      return callback();

    paths[wid] = path;

    self.pathCache.set(hash, paths);

    batch.put(layout.p(hash), serializePaths(paths));

    callback();
  });
};

/**
 * Retrieve paths by hash.
 * @param {Hash} hash
 * @param {Function} callback
 */

WalletDB.prototype.getAddressPaths = function getAddressPaths(hash, callback) {
  var self = this;
  var paths;

  if (!hash)
    return callback();

  paths = this.pathCache.get(hash);

  if (paths)
    return callback(null, paths);

  this.db.fetch(layout.p(hash), function(value) {
    return parsePaths(value, hash);
  }, function(err, paths) {
    if (err)
      return callback(err);

    if (!paths)
      return callback();

    self.pathCache.set(hash, paths);

    callback(null, paths);
  });
};

/**
 * Test whether an address hash exists in the
 * path map and is relevant to the wallet id.
 * @param {WalletID} wid
 * @param {Hash} hash
 * @param {Function} callback
 */

WalletDB.prototype.hasAddress = function hasAddress(wid, hash, callback) {
  this.getAddressPaths(hash, function(err, paths) {
    if (err)
      return callback(err);

    if (!paths || !paths[wid])
      return callback(null, false);

    callback(null, true);
  });
};

/**
 * Get all address hashes.
 * @param {WalletID} wid
 * @param {Function} callback
 */

WalletDB.prototype.getAddressHashes = function getAddressHashes(wid, callback) {
  if (!callback) {
    callback = wid;
    wid = null;
  }

  this.db.iterate({
    gte: layout.p(constants.NULL_HASH),
    lte: layout.p(constants.HIGH_HASH),
    values: true,
    parse: function(key, value) {
      var paths = parsePaths(value);

      if (wid && !paths[wid])
        return;

      return layout.pp(key);
    }
  }, callback);
};

/**
 * Get all paths for a wallet.
 * @param {WalletID} wid
 * @param {Function} callback
 */

WalletDB.prototype.getWalletPaths = function getWalletPaths(wid, callback) {
  this.db.iterate({
    gte: layout.p(constants.NULL_HASH),
    lte: layout.p(constants.HIGH_HASH),
    values: true,
    parse: function(key, value) {
      var hash = layout.pp(key);
      var paths = parsePaths(value, hash);
      var path = paths[wid];

      if (!path)
        return;

      return path;
    }
  }, callback);
};

/**
 * Get all wallet ids.
 * @param {Function} callback
 */

WalletDB.prototype.getWallets = function getWallets(callback) {
  this.db.iterate({
    gte: layout.l(''),
    lte: layout.l(MAX_POINT),
    parse: function(key) {
      return layout.ll(key);
    }
  }, callback);
};

/**
 * Rescan the blockchain.
 * @param {ChainDB} chaindb
 * @param {Function} callback
 */

WalletDB.prototype.rescan = function rescan(chaindb, height, callback) {
  var self = this;

  if (typeof height === 'function') {
    callback = height;
    height = null;
  }

  if (height == null)
    height = this.height;

  callback = this._lockTX(rescan, [chaindb, height, callback]);

  if (!callback)
    return;

  this.getAddressHashes(function(err, hashes) {
    if (err)
      return callback(err);

    self.logger.info('Scanning for %d addresses.', hashes.length);

    chaindb.scan(height, hashes, function(block, txs, next) {
      self.addBlock(block, txs, next, true);
    }, callback);
  });
};

/**
 * Get keys of all pending transactions
 * in the wallet db (for resending).
 * @param {Function} callback
 */

WalletDB.prototype.getPendingKeys = function getPendingKeys(callback) {
  var layout = require('./txdb').layout;
  var uniq = {};

  this.db.iterate({
    gte: layout.prefix(0x00000000, layout.p(constants.NULL_HASH)),
    lte: layout.prefix(0xffffffff, layout.p(constants.HIGH_HASH)),
    keys: true,
    parse: function(key) {
      var wid = layout.pre(key);
      var hash = layout.pp(key);

      if (uniq[hash])
        return;

      uniq[hash] = true;

      return layout.prefix(wid, layout.t(hash));
    }
  }, callback);
};

/**
 * Resend all pending transactions.
 * @param {Function} callback
 */

WalletDB.prototype.resend = function resend(callback) {
  var self = this;

  this.getPendingKeys(function(err, keys) {
    if (err)
      return callback(err);

    if (keys.length > 0)
      self.logger.info('Rebroadcasting %d transactions.', keys.length);

    utils.forEachSerial(keys, function(key, next) {
      self.db.fetch(key, function(data) {
        return bcoin.tx.fromExtended(data);
      }, function(err, tx) {
        if (err)
          return next(err);

        if (!tx)
          return next();

        self.emit('send', tx);

        next();
      });
    }, callback);
  });
};

/**
 * Helper function to get a wallet.
 * @private
 * @param {WalletID} wid
 * @param {Function} callback
 * @param {Function} handler
 */

WalletDB.prototype.fetchWallet = function fetchWallet(wid, callback, handler) {
  this.get(wid, function(err, wallet) {
    if (err)
      return callback(err);

    if (!wallet)
      return callback(new Error('No wallet.'));

    handler(wallet, function(err, res1, res2) {
      if (err)
        return callback(err);

      callback(null, res1, res2);
    });
  });
};

/**
 * Map a transactions' addresses to wallet IDs.
 * @param {TX} tx
 * @param {Function} callback - Returns [Error, {@link PathInfo[]}].
 */

WalletDB.prototype.mapWallets = function mapWallets(tx, callback) {
  var self = this;
  var hashes = tx.getHashes('hex');
  var wallets;

  if (!this.testFilter(hashes))
    return callback();

  this.getTable(hashes, function(err, table) {
    if (err)
      return callback(err);

    if (!table)
      return callback();

    wallets = PathInfo.map(self, tx, table);

    callback(null, wallets);
  });
};

/**
 * Map a transactions' addresses to wallet IDs.
 * @param {TX} tx
 * @param {Function} callback - Returns [Error, {@link PathInfo}].
 */

WalletDB.prototype.getPathInfo = function getPathInfo(wallet, tx, callback) {
  var self = this;
  var hashes = tx.getHashes('hex');
  var info;

  this.getTable(hashes, function(err, table) {
    if (err)
      return callback(err);

    if (!table)
      return callback();

    info = new PathInfo(self, wallet.wid, tx, table);
    info.id = wallet.id;

    callback(null, info);
  });
};

/**
 * Map address hashes to paths.
 * @param {Hash[]} hashes - Address hashes.
 * @param {Function} callback - Returns [Error, {@link AddressTable}].
 */

WalletDB.prototype.getTable = function getTable(hashes, callback) {
  var self = this;
  var table = {};
  var count = 0;
  var i, keys, values;

  utils.forEachSerial(hashes, function(hash, next) {
    self.getAddressPaths(hash, function(err, paths) {
      if (err)
        return next(err);

      if (!paths) {
        assert(!table[hash]);
        table[hash] = [];
        return next();
      }

      keys = Object.keys(paths);
      values = [];

      for (i = 0; i < keys.length; i++)
        values.push(paths[keys[i]]);

      assert(!table[hash]);
      table[hash] = values;
      count += values.length;

      next();
    });
  }, function(err) {
    if (err)
      return callback(err);

    if (count === 0)
      return callback();

    callback(null, table);
  });
};

/**
 * Write the genesis block as the best hash.
 * @param {Function} callback
 */

WalletDB.prototype.writeGenesis = function writeGenesis(callback) {
  var self = this;

  this.getTip(function(err, block) {
    if (err)
      return callback(err);

    if (block) {
      self.tip = block.hash;
      self.height = block.height;
      return callback();
    }

    self.setTip(self.network.genesis.hash, 0, callback);
  });
};

/**
 * Get the best block hash.
 * @param {Function} callback
 */

WalletDB.prototype.getTip = function getTip(callback) {
  this.db.fetch(layout.R, function(data) {
    return WalletBlock.fromTip(data);
  }, callback);
};

/**
 * Write the best block hash.
 * @param {Hash} hash
 * @param {Number} height
 * @param {Function} callback
 */

WalletDB.prototype.setTip = function setTip(hash, height, callback) {
  var self = this;
  var block = new WalletBlock(hash, height);
  this.db.put(layout.R, block.toTip(), function(err) {
    if (err)
      return callback(err);

    self.tip = block.hash;
    self.height = block.height;

    callback();
  });
};

/**
 * Connect a block.
 * @param {WalletBlock} block
 * @param {Function} callback
 */

WalletDB.prototype.writeBlock = function writeBlock(block, matches, callback) {
  var batch = this.db.batch();
  var i, hash, wallets;

  batch.put(layout.R, block.toTip());

  if (block.hashes.length > 0) {
    batch.put(layout.b(block.hash), block.toRaw());

    for (i = 0; i < block.hashes.length; i++) {
      hash = block.hashes[i];
      wallets = matches[i];
      batch.put(layout.e(hash), serializeWallets(wallets));
    }
  }

  batch.write(callback);
};

/**
 * Disconnect a block.
 * @param {WalletBlock} block
 * @param {Function} callback
 */

WalletDB.prototype.unwriteBlock = function unwriteBlock(block, callback) {
  var batch = this.db.batch();
  var prev = new WalletBlock(block.prevBlock, block.height - 1);

  batch.put(layout.R, prev.toTip());
  batch.del(layout.b(block.hash));

  batch.write(callback);
};

/**
 * Get a wallet block (with hashes).
 * @param {Hash} hash
 * @param {Function} callback
 */

WalletDB.prototype.getBlock = function getBlock(hash, callback) {
  this.db.fetch(layout.b(hash), function(data) {
    return WalletBlock.fromRaw(hash, data);
  }, callback);
};

/**
 * Get a TX->Wallet map.
 * @param {Hash} hash
 * @param {Function} callback
 */

WalletDB.prototype.getWalletsByTX = function getWalletsByTX(hash, callback) {
  this.db.fetch(layout.e(hash), parseWallets, callback);
};

/**
 * Add a block's transactions and write the new best hash.
 * @param {ChainEntry} entry
 * @param {Function} callback
 */

WalletDB.prototype.addBlock = function addBlock(entry, txs, callback, force) {
  var self = this;
  var block, matches, hash;

  callback = this._lockTX(addBlock, [entry, txs, callback], force);

  if (!callback)
    return;

  if (this.options.useCheckpoints) {
    if (entry.height <= this.network.checkpoints.lastHeight)
      return this.setTip(entry.hash, entry.height, callback);
  }

  block = WalletBlock.fromEntry(entry);
  matches = [];

  // Update these early so transactions
  // get correct confirmation calculations.
  this.tip = block.hash;
  this.height = block.height;

  // NOTE: Atomicity doesn't matter here. If we crash
  // during this loop, the automatic rescan will get
  // the database back into the correct state.
  utils.forEachSerial(txs, function(tx, next) {
    self.addTX(tx, function(err, wallets) {
      if (err)
        return next(err);

      if (!wallets)
        return next();

      hash = tx.hash('hex');
      block.hashes.push(hash);
      matches.push(wallets);

      next();
    }, true);
  }, function(err) {
    if (err)
      return callback(err);

    if (block.hashes.length > 0) {
      self.logger.info('Connecting block %s (%d txs).',
        utils.revHex(block.hash), block.hashes.length);
    }

    self.writeBlock(block, matches, callback);
  });
};

/**
 * Unconfirm a block's transactions
 * and write the new best hash (SPV version).
 * @param {ChainEntry} entry
 * @param {Function} callback
 */

WalletDB.prototype.removeBlock = function removeBlock(entry, callback) {
  var self = this;
  var block;

  callback = this._lockTX(removeBlock, [entry, callback]);

  if (!callback)
    return;

  block = WalletBlock.fromEntry(entry);

  // Note:
  // If we crash during a reorg, there's not much to do.
  // Reorgs cannot be rescanned. The database will be
  // in an odd state, with some txs being confirmed
  // when they shouldn't be. That being said, this
  // should eventually resolve itself when a new block
  // comes in.
  this.getBlock(block.hash, function(err, data) {
    if (err)
      return callback(err);

    if (data)
      block.hashes = data.hashes;

    if (block.hashes.length > 0) {
      self.logger.warning('Disconnecting block %s (%d txs).',
        utils.revHex(block.hash), block.hashes.length);
    }

    // Unwrite the tip as fast as we can.
    self.unwriteBlock(block, function(err) {
      if (err)
        return callback(err);

      utils.forEachSerial(block.hashes, function(hash, next) {
        self.getWalletsByTX(hash, function(err, wallets) {
          if (err)
            return next(err);

          if (!wallets)
            return next();

          utils.forEachSerial(wallets, function(wid, next) {
            self.get(wid, function(err, wallet) {
              if (err)
                return next(err);

              if (!wallet)
                return next();

              wallet.tx.unconfirm(hash, next);
            });
          }, function(err) {
            if (err)
              return callback(err);

            self.tip = block.hash;
            self.height = block.height;

            next();
          });
        });
      }, callback);
    });
  });
};

/**
 * Add a transaction to the database, map addresses
 * to wallet IDs, potentially store orphans, resolve
 * orphans, or confirm a transaction.
 * @param {TX} tx
 * @param {Function} callback - Returns [Error].
 */

WalletDB.prototype.addTX = function addTX(tx, callback, force) {
  var self = this;

  callback = this._lockTX(addTX, [tx, callback], force);

  if (!callback)
    return;

  assert(!tx.mutable, 'Cannot add mutable TX to wallet.');

  // Note:
  // Atomicity doesn't matter here. If we crash,
  // the automatic rescan will get the database
  // back in the correct state.
  this.mapWallets(tx, function(err, wallets) {
    if (err)
      return callback(err);

    if (!wallets)
      return callback();

    self.logger.info(
      'Incoming transaction for %d wallets (%s).',
      wallets.length, tx.rhash);

    utils.forEachSerial(wallets, function(info, next) {
      self.get(info.wid, function(err, wallet) {
        if (err)
          return next(err);

        if (!wallet)
          return next();

        self.logger.debug('Adding tx to wallet: %s', wallet.id);

        info.id = wallet.id;

        wallet.tx.add(tx, info, function(err) {
          if (err)
            return next(err);

          wallet.handleTX(info, next);
        });
      });
    }, function(err) {
      if (err)
        return callback(err);
      callback(null, wallets);
    });
  });
};

/**
 * Get the corresponding path for an address hash.
 * @param {WalletID} wid
 * @param {Hash} hash
 * @param {Function} callback
 */

WalletDB.prototype.getAddressPath = function getAddressPath(wid, hash, callback) {
  var path;
  this.getAddressPaths(hash, function(err, paths) {
    if (err)
      return callback(err);

    if (!paths)
      return callback();

    path = paths[wid];

    if (!path)
      return callback();

    callback(null, path);
  });
};

/**
 * Path Info
 * @constructor
 */

function PathInfo(db, wid, tx, table) {
  if (!(this instanceof PathInfo))
    return new PathInfo(db, wid, tx, table);

  // Reference to the walletdb.
  this.db = db;

  // All relevant Accounts for
  // inputs and outputs (for database indexing).
  this.accounts = [];

  // All output paths (for deriving during sync).
  this.paths = [];

  // Wallet ID
  this.wid = wid;

  // Wallet Label (passed in by caller).
  this.id = null;

  // Map of address hashes->paths (for everything).
  this.table = null;

  // Map of address hashes->paths (specific to wallet).
  this.pathMap = {};

  // Current transaction.
  this.tx = null;

  // Wallet-specific details cache.
  this._details = null;
  this._json = null;

  if (tx)
    this.fromTX(tx, table);
}

PathInfo.map = function map(db, tx, table) {
  var hashes = Object.keys(table);
  var wallets = [];
  var info = [];
  var uniq = {};
  var i, j, hash, paths, path, wid;

  for (i = 0; i < hashes.length; i++) {
    hash = hashes[i];
    paths = table[hash];
    for (j = 0; j < paths.length; j++) {
      path = paths[j];
      if (!uniq[path.wid]) {
        uniq[path.wid] = true;
        wallets.push(path.wid);
      }
    }
  }

  if (wallets.length === 0)
    return;

  for (i = 0; i < wallets.length; i++) {
    wid = wallets[i];
    info.push(new PathInfo(db, wid, tx, table));
  }

  return info;
};

PathInfo.prototype.fromTX = function fromTX(tx, table) {
  var uniq = {};
  var i, j, hashes, hash, paths, path;

  this.tx = tx;
  this.table = table;

  hashes = Object.keys(table);

  for (i = 0; i < hashes.length; i++) {
    hash = hashes[i];
    paths = table[hash];
    for (j = 0; j < paths.length; j++) {
      path = paths[j];
      if (path.wid !== this.wid)
        continue;
      this.pathMap[hash] = path;
      if (!uniq[path.account]) {
        uniq[path.account] = true;
        this.accounts.push(path.account);
      }
    }
  }

  hashes = tx.getOutputHashes('hex');

  for (i = 0; i < hashes.length; i++) {
    hash = hashes[i];
    paths = table[hash];
    for (j = 0; j < paths.length; j++) {
      path = paths[j];
      if (path.wid !== this.wid)
        continue;
      this.paths.push(path);
    }
  }

  return this;
};

PathInfo.fromTX = function fromTX(db, wid, tx, table) {
  return new PathInfo(db, wid).fromTX(tx, table);
};

/**
 * Test whether the map has paths
 * for a given address hash.
 * @param {Hash} hash
 * @returns {Boolean}
 */

PathInfo.prototype.hasPath = function hasPath(hash) {
  if (!hash)
    return false;

  return this.pathMap[hash] != null;
};

/**
 * Get paths for a given address hash.
 * @param {Hash} hash
 * @returns {Path[]|null}
 */

PathInfo.prototype.getPath = function getPath(hash) {
  if (!hash)
    return;

  return this.pathMap[hash];
};

PathInfo.prototype.toDetails = function toDetails() {
  var details = this._details;

  if (!details) {
    details = new Details(this);
    this._details = details;
  }

  return details;
};

PathInfo.prototype.toJSON = function toJSON() {
  var json = this._json;

  if (!json) {
    json = this.toDetails().toJSON();
    this._json = json;
  }

  return json;
};

/**
 * Details
 * @constructor
 */

function Details(info) {
  if (!(this instanceof Details))
    return new Details(info);

  this.db = info.db;
  this.network = info.db.network;
  this.wid = info.wid;
  this.id = info.id;
  this.hash = info.tx.hash('hex');
  this.height = info.tx.height;
  this.block = info.tx.block;
  this.index = info.tx.index;
  this.confirmations = info.tx.getConfirmations(this.db.height);
  this.fee = info.tx.getFee();
  this.ts = info.tx.ts;
  this.ps = info.tx.ps;
  this.tx = info.tx;
  this.inputs = [];
  this.outputs = [];

  this.init(info.table);
}

Details.prototype.init = function init(table) {
  this._insert(this.tx.inputs, this.inputs, table);
  this._insert(this.tx.outputs, this.outputs, table);
};

Details.prototype._insert = function _insert(vector, target, table) {
  var i, j, io, address, hash, paths, path, member;

  for (i = 0; i < vector.length; i++) {
    io = vector[i];
    member = new DetailsMember();

    if (io instanceof bcoin.input)
      member.value = io.coin ? io.coin.value : 0;
    else
      member.value = io.value;

    address = io.getAddress();

    if (address) {
      member.address = address;

      hash = address.getHash('hex');
      paths = table[hash];

      for (j = 0; j < paths.length; j++) {
        path = paths[j];
        if (path.wid === this.wid) {
          path.id = this.id;
          member.path = path;
          break;
        }
      }
    }

    target.push(member);
  }
};

Details.prototype.toJSON = function toJSON() {
  var self = this;
  return {
    wid: this.wid,
    id: this.id,
    hash: utils.revHex(this.hash),
    height: this.height,
    block: this.block ? utils.revHex(this.block) : null,
    ts: this.ts,
    ps: this.ps,
    index: this.index,
    fee: utils.btc(this.fee),
    confirmations: this.confirmations,
    inputs: this.inputs.map(function(input) {
      return input.toJSON(self.network);
    }),
    outputs: this.outputs.map(function(output) {
      return output.toJSON(self.network);
    }),
    tx: this.tx.toRaw().toString('hex')
  };
};

/**
 * DetailsMember
 * @constructor
 */

function DetailsMember() {
  if (!(this instanceof DetailsMember))
    return new DetailsMember();

  this.value = 0;
  this.address = null;
  this.path = null;
}

DetailsMember.prototype.toJSON = function toJSON(network) {
  return {
    value: utils.btc(this.value),
    address: this.address
      ? this.address.toBase58(network)
      : null,
    path: this.path
      ? this.path.toJSON()
      : null
  };
};

/**
 * Wallet Block
 * @constructor
 */

function WalletBlock(hash, height) {
  if (!(this instanceof WalletBlock))
    return new WalletBlock(hash, height);

  this.hash = hash || constants.NULL_HASH;
  this.height = height != null ? height : -1;
  this.prevBlock = constants.NULL_HASH;
  this.hashes = [];
}

WalletBlock.prototype.fromEntry = function fromEntry(entry) {
  this.hash = entry.hash;
  this.height = entry.height;
  this.prevBlock = entry.prevBlock;
  return this;
};

WalletBlock.prototype.fromJSON = function fromJSON(json) {
  this.hash = utils.revHex(json.hash);
  this.height = json.height;
  if (json.prevBlock)
    this.prevBlock = utils.revHex(json.prevBlock);
  return this;
};

WalletBlock.prototype.fromRaw = function fromRaw(hash, data) {
  var p = new BufferReader(data);
  this.hash = hash;
  this.height = p.readU32();
  while (p.left())
    this.hashes.push(p.readHash('hex'));
  return this;
};

WalletBlock.prototype.fromTip = function fromTip(data) {
  var p = new BufferReader(data);
  this.hash = p.readHash('hex');
  this.height = p.readU32();
  return this;
};

WalletBlock.fromEntry = function fromEntry(entry) {
  return new WalletBlock().fromEntry(entry);
};

WalletBlock.fromJSON = function fromJSON(json) {
  return new WalletBlock().fromJSON(json);
};

WalletBlock.fromRaw = function fromRaw(hash, data) {
  return new WalletBlock().fromRaw(hash, data);
};

WalletBlock.fromTip = function fromTip(data) {
  return new WalletBlock().fromTip(data);
};

WalletBlock.prototype.toTip = function toTip() {
  var p = new BufferWriter();
  p.writeHash(this.hash);
  p.writeU32(this.height);
  return p.render();
};

WalletBlock.prototype.toRaw = function toRaw() {
  var p = new BufferWriter();
  var i;

  p.writeU32(this.height);

  for (i = 0; i < this.hashes.length; i++)
    p.writeHash(this.hashes[i]);

  return p.render();
};

WalletBlock.prototype.toJSON = function toJSON() {
  return {
    hash: utils.revHex(this.hash),
    height: this.height
  };
};

/*
 * Helpers
 */

function parsePaths(data, hash) {
  var p = new BufferReader(data);
  var out = {};
  var path;

  while (p.left()) {
    path = Path.fromRaw(p);
    out[path.wid] = path;
    if (hash)
      path.hash = hash;
  }

  return out;
}

function serializePaths(out) {
  var p = new BufferWriter();
  var keys = Object.keys(out);
  var i, wid, path;

  for (i = 0; i < keys.length; i++) {
    wid = keys[i];
    path = out[wid];
    path.toRaw(p);
  }

  return p.render();
}

function parseWallets(data) {
  var p = new BufferReader(data);
  var wallets = [];
  while (p.left())
    wallets.push(p.readU32());
  return wallets;
}

function serializeWallets(wallets) {
  var p = new BufferWriter();
  var i, info;

  for (i = 0; i < wallets.length; i++) {
    info = wallets[i];
    p.writeU32(info.wid);
  }

  return p.render();
}

/*
 * Expose
 */

module.exports = WalletDB;