define({
  get: function (url) {
    return new Promise(function (resolve, reject) {
      var req = new XMLHttpRequest();
      req.open("GET", url);

      req.onload = function () {
        if (req.status == 200) {
          resolve(req.response);
        }
        else {
          reject(Error(req.statusText));
        }
      };

      req.onerror = function () {
        reject(Error("Network Error"));
      };

      req.send();
    });
  },

  getJSON: function (url) {
    return require("helper").get(url).then(JSON.parse);
  },

  sortByKey: function (key, d) {
    return d.slice().sort(function (a, b) {
      return a[key] - b[key];
    }).reverse();
  },

  limit: function (key, m, d) {
    return d.filter(function (d) {
      return d[key].isAfter(m);
    });
  },

  sum: function (a) {
    return a.reduce(function (a, b) {
      return a + b;
    }, 0);
  },

  one: function () {
    return 1;
  },

  trueDefault: function (d) {
    return d === undefined ? true : d;
  },

  dictGet: function (dict, key) {
    var k = key.shift();

    if (!(k in dict)) {
      return null;
    }

    if (key.length == 0) {
      return dict[k];
    }

    return this.dictGet(dict[k], key);
  },

  localStorageTest: function () {
    var test = "test";
    try {
      localStorage.setItem(test, test);
      localStorage.removeItem(test);
      return true;
    } catch (e) {
      return false;
    }
  },

  listReplace: function (s, subst) {
    for (key in subst) {
      var re = new RegExp(key, "g");
      s = s.replace(re, subst[key]);
    }
    return s;
  },

  /* Helpers working with nodes */

  offline: function (d) {
    return !d.flags.online;
  },

  online: function (d) {
    return d.flags.online;
  },

  hasLocation: function (d) {
    return "location" in d.nodeinfo &&
      Math.abs(d.nodeinfo.location.latitude) < 90 &&
      Math.abs(d.nodeinfo.location.longitude) < 180;
  },

  subtract: function (a, b) {
    var ids = {};

    b.forEach(function (d) {
      ids[d.nodeinfo.node_id] = true;
    });

    return a.filter(function (d) {
      return !(d.nodeinfo.node_id in ids);
    });
  },

  /* Helpers working with links */

  showDistance: function (d) {
    if (isNaN(d.distance)) {
      return;
    }

    return d.distance.toFixed(0) + " m";
  },

  showTq: function (d) {
    return (1 / d.tq * 100).toFixed(0) + "%";
  },

  attributeEntry: function (el, label, value) {
    if (value === null || value == undefined) {
      return;
    }

    var tr = document.createElement("tr");
    var th = document.createElement("th");
    th.textContent = label;
    tr.appendChild(th);

    var td = document.createElement("td");

    if (typeof value == "function") {
      value(td);
    } else {
      td.appendChild(document.createTextNode(value));
    }

    tr.appendChild(td);

    el.appendChild(tr);

    return td;
  },

  createIframe: function (opt, width, height) {
    var el = document.createElement("iframe");
    width = typeof width !== "undefined" ? width : "525px";
    height = typeof height !== "undefined" ? height : "350px";

    if (opt.src) {
      el.src = opt.src;
    } else {
      el.src = opt;
    }

    if (opt.frameBorder) {
      el.frameBorder = opt.frameBorder;
    } else {
      el.frameBorder = 1;
    }

    if (opt.width) {
      el.width = opt.width;
    } else {
      el.width = width;
    }

    if (opt.height) {
      el.height = opt.height;
    } else {
      el.height = height;
    }

    el.scrolling = "no";
    el.seamless = "seamless";

    return el;
  },

  showStat: function (o, subst) {
    var content, caption;
    subst = typeof subst !== "undefined" ? subst : {};

    if (o.thumbnail) {
      content = document.createElement("img");
      content.src = require("helper").listReplace(o.thumbnail, subst);
    }

    if (o.caption) {
      caption = require("helper").listReplace(o.caption, subst);

      if (!content) {
        content = document.createTextNode(caption);
      }
    }

    if (o.iframe) {
      content = require("helper").createIframe(o.iframe, o.width, o.height);
      if (o.iframe.src) {
        content.src = require("helper").listReplace(o.iframe.src, subst);
      } else {
        content.src = require("helper").listReplace(o.iframe, subst);
      }
    }

    var p = document.createElement("p");

    if (o.href) {
      var link = document.createElement("a");
      link.target = "_blank";
      link.href = require("helper").listReplace(o.href, subst);
      link.appendChild(content);

      if (caption && o.thumbnail) {
        link.title = caption;
      }

      p.appendChild(link);
    } else {
      p.appendChild(content);
    }

    return p;
  }
});