var NotFoundError = require('./error').NotFound;
var utils = require('./utils');

var assign = utils.assign;
var isFunction = utils.isFunction;
var isRegExp = utils.isRegExp;
var isString = utils.isString;
var noop = utils.noop;

function RouteNode () {
  this._children = Object.create(null);
  this._funcs = Object.create(null);
  this._regExs = Object.create(null);
}

assign(RouteNode.prototype, {
  handler: null,

  add: function add(parts, handler, context) {
    parts = parts || [];
    handler = handler || noop;
    context = context || null;

    if (parts.length === 0) {
      this.handler = handler;
      this.context = context;
      return this;
    }
    var part = parts.shift();
    var node = null;

    if (isString(part)) {
      node = this._children[part];
    } else if (isRegExp(part)) {
      this._regExs[part] = part;
    } else if (isFunction(part)) {
      this._funcs[part] = part;
    }

    if (node == null) {
      node = new RouteNode();
      this._children[part] = node;
    }
    return node.add(parts, handler, context);
  },

  get: function get(parts, args, done) {
    parts = parts || [];
    args = args || [];
    if (parts.length === 0) {
      return done(null, this.handler, this.context, args);
    }

    var part = parts.shift();

    // Check exact matches
    if (this._children[part]) {
      return this._children[part].get(parts, args, done);
    }

    // Check regex matches
    var results = this._getRegexChild(part);
    if (results && results.node) {
      return results.node.get(parts, args.concat(results.args), done);
    }

    // Check function matches
    results = this._getFunctionChild(part);
    if (results && results.node) {
      return results.node.get(parts, args.concat(results.args), done);
    }

    return done(new NotFoundError('not found', {location: parts}));
  },

  _getRegexChild: function _getRegexChild(part) {
    var self = this;

    return Object.keys(this._regExs).reduce(function checkRegex(memo, key) {
      if (memo) {
        return memo;
      }
      var regex = self._regExs[key];
      var results = regex.exec(part);
      if (!results) {
        return null;
      }

      var lastIndex = null;
      var args = [];
      while (results && results.index !== lastIndex) {
        args = args.concat(results[0]);
        lastIndex = results.index;
        results = regex.exec(part);
      }
      return {args: args, key: key, node: self._children[key]};
    }, null);
  },

  _getFunctionChild: function _getFunctionChild(part) {
    var self = this;
    return Object.keys(self._funcs).reduce(function checkFunc(memo, key) {
      if (memo) {
        return memo;
      }
      var func = self._funcs[key];
      var result = func(part);
      if (result) {
        return {args: [result], key: key, node: self._children[key]};
      } else {
        return null;
      }
    }, null);
  }
});

module.exports = RouteNode;