define(["command"], function(command) {

  var defaults = {};
  var local = {};
  
  //put this here because Settings is pretty early in load process
  chrome.version = window.navigator.appVersion.match(/Chrome\/(\d+)/)[1] || 0;
  
  var SyncFile = function(name, c) {
    this.entry = {};
    if (name) {
      this.open(name, c);
    }
    this.virtual = true;
  };
  SyncFile.prototype = {
    name: "",
    open: function(name, c) {
      this.name = name;
      this.entry.name = name;
      if (c) {
        c(this);
      }
    },
    read: function(c) {
      var name = this.name;
      chrome.storage.sync.get(this.name, function(data) {
        c(null, data[name]);
      });
    },
    write: function(content, c) {
      var data = {};
      data[this.name] = content;
      var self = this;
      chrome.storage.sync.set(data, function() {
        command.fire("settings:change-local");
        if (c) c(null, self);
      });
    },
    retain: function() { return false; }
  };
  
  var clone = function(item) {
    var cloneArray = function(a) {
      var n = [];
      for (var i = 0; i < a.length; i++) {
        if (a[i] instanceof Array) {
          n[i] = cloneArray(a[i]);
        } else if (typeof a[i] == "object") {
          n[i] = cloneObject(a[i]);
        } else {
          n[i] = a[i];
        }
      }
      return n;
    };
    var cloneObject = function(o) {
      var n = {};
      for (var key in o) {
        if (o[key] instanceof Array) {
          n[key] = cloneArray(o[key]);
        } else if (typeof o[key] == "object") {
          n[key] = cloneObject(o[key]);
        } else {
          n[key] = o[key];
        }
      }
      return n;
    };
    if (item instanceof Array) {
      return cloneArray(item);
    }
    return cloneObject(item);
  };
  
  //track transfers to prevent multiple requests
  var pending = {};

  var Settings = {
    get: function(name) {
      name = name + ".json";
      var comments = /\/\*[\s\S]*?\*\/|\/\/.*$/gm;
      var original = clone(JSON.parse(defaults[name].replace(comments, "")));
      var custom = {};
      try {
        custom = JSON.parse(local[name].replace(comments, ""));
      } catch (e) {
        //parse failed
      }
      //flat arrays (like menus.json) just get returned, not merged
      if (custom && custom instanceof Array) {
        return custom;
      }
      for (var key in custom) {
        original[key] = custom[key];
      }
      return original;
    },
    getAsString: function(name, original) {
      name = name + ".json";
      if (original) {
        return defaults[name];
      }
      return local[name] || defaults[name];
    },
    getAsFile: function(name) {
      return new SyncFile(name + ".json");
    },
    load: function(name, c) {
      name = name + ".json";
      if (local[name] || defaults[name]) {
        return c();
      }
      
      //if a request is out, tag along with it
      if (pending[name]) {
        pending[name].push(c);
        return;
      }
      
      var onload = function() {
        var raw = this.responseText.replace();
        defaults[name] = raw;
        chrome.storage.sync.get(name, function(data) {
          if (data[name]) {
            local[name] = data[name];
          } else {
            local[name] = defaults[name];
          }
          for (var i = 0; i < pending[name].length; i++) {
            pending[name][i]();
          }
          delete pending[name]
        });
      };
      
      pending[name] = [c]
      
      var xhr = new XMLHttpRequest();
      xhr.open("GET", "config/" + name);
      xhr.onload = onload;
      xhr.send();
    }
  };

  command.on("settings:delete-local", function(key) {
    key += ".json";
    local[key] = defaults[key];
    chrome.storage.sync.remove(key);
    command.fire("init:restart");
  });

  command.on("settings:change-local", function() {
    //reload anything that's been used
    var keys = Object.keys(defaults).map(function(n) { return n.replace(".json", "")});
    local = {};
    defaults = {};
    var completed = 0;
    keys.forEach(function(key) {
      Settings.load(key, function() {
        completed++;
        if (completed == keys.length) {
          command.fire("init:restart");
        }
      });
    });
  });
  
  return {
    load: function(name, parentRequire, onLoad, config) {
      if (name.length == 0) {
        return onLoad(Settings);
      }
      
      var files = name.split(",");
      var completed = 0;
      
      files.forEach(function(file) {
        Settings.load(file, function() {
          completed++;
          if (completed == files.length) {
            onLoad(Settings);
          }
        })
      });
    }
  }

});