import {
  forEach
} from 'min-dash';

import {
  closest as domClosest
} from 'min-dom';

var LOW_PRIORITY = 250;

/**
 * The tool manager acts as middle-man between the available tool's and the Palette,
 * it takes care of making sure that the correct active state is set.
 *
 * @param  {Object}    eventBus
 * @param  {Object}    dragging
 */
export default function ToolManager(eventBus, dragging) {
  this._eventBus = eventBus;
  this._dragging = dragging;

  this._tools = [];
  this._active = null;
}

ToolManager.$inject = [ 'eventBus', 'dragging' ];

ToolManager.prototype.registerTool = function(name, events) {
  var tools = this._tools;

  if (!events) {
    throw new Error('A tool has to be registered with it\'s "events"');
  }

  tools.push(name);

  this.bindEvents(name, events);
};

ToolManager.prototype.isActive = function(tool) {
  return tool && this._active === tool;
};

ToolManager.prototype.length = function(tool) {
  return this._tools.length;
};

ToolManager.prototype.setActive = function(tool) {
  var eventBus = this._eventBus;

  if (this._active !== tool) {
    this._active = tool;

    eventBus.fire('tool-manager.update', { tool: tool });
  }
};

ToolManager.prototype.bindEvents = function(name, events) {
  var eventBus = this._eventBus,
      dragging = this._dragging;

  var eventsToRegister = [];

  eventBus.on(events.tool + '.init', function(event) {
    var context = event.context;

    // Active tools that want to reactivate themselves must do this explicitly
    if (!context.reactivate && this.isActive(name)) {
      this.setActive(null);

      dragging.cancel();
      return;
    }

    this.setActive(name);

  }, this);

  // Todo[ricardo]: add test cases
  forEach(events, function(event) {
    eventsToRegister.push(event + '.ended');
    eventsToRegister.push(event + '.canceled');
  });

  eventBus.on(eventsToRegister, LOW_PRIORITY, function(event) {
    var originalEvent = event.originalEvent;

    // We defer the de-activation of the tool to the .activate phase,
    // so we're able to check if we want to toggle off the current
    // active tool or switch to a new one
    if (!this._active) {
      return;
    }

    if (originalEvent && domClosest(originalEvent.target, '.group[data-group="tools"]')) {
      return;
    }

    this.setActive(null);
  }, this);
};