// An adaptor for binding Ractive.js views with nested Backbone models and collections via 
// backbone-associations (https://github.com/dhruvaray/backbone-associations)
//
// Based on the original Backbone adaptor for Ractive by Rich Harris:
// https://github.com/Rich-Harris/Ractive/blob/master/src/Ractive/Ractive.adaptors/backbone.js

Ractive.adaptors.backboneAssociatedModel = function ( model, path ) {
  var settingModel, settingView, setModel, setView, pathMatcher, pathLength, prefix, modelChangeEventHandler;

  if ( path ) {
    path += '.';
    pathMatcher = new RegExp( '^' + path.replace( /\./g, '\\.' ) );
    pathLength = path.length;
  }

  modelChangeEventHandler = function ( eventName ) {
    var eventNameSplit, eventType, keypath, value;

    eventNameSplit = eventName.split( ':' );
    eventType = eventNameSplit[0];
    keypath = eventNameSplit[1];

    if ( eventType === 'change' && keypath  ) {
      value = model.get( keypath );

      if ( value && value.toJSON ) {
        value = value.toJSON();
      }

      setView( keypath, value );
    }
  };


  return {
    init: function ( view ) {

      // if no path specified...
      if ( !path ) {
        setView = function ( keypath, value ) {
          if ( !settingModel ) {
            settingView = true;
            view.set( keypath, value );
            settingView = false;
          }
        };

        setModel = function ( keypath, value ) {
          if ( !settingView ) {
            settingModel = true;
            model.set( keypath, value );
            settingModel = false;
          }
        };
      }

      else {
        prefix = function ( attrs ) {
          var attr, result;

          result = {};

          for ( attr in attrs ) {
            if ( ({}).hasOwnProperty.call( attrs, attr ) ) {
              result[ path + attr ] = attrs[ attr ];
            }
          }

          return result;
        };

        setView = function ( keypath, value ) {
          if ( !settingModel ) {
            settingView = true;
            var changed = {};
            changed[keypath] = value;
            view.set( prefix( model.changed ) );
            settingView = false;
          }
        };

        setModel = function ( keypath, value ) {
          if ( !settingView ) {
            if ( pathMatcher.test( keypath ) ) {
              settingModel = true;
              model.set( keypath.substring( pathLength ), value );
              settingModel = false;
            }
          }
        };
      }

      model.on( 'all', modelChangeEventHandler );
      view.on( 'set', setModel );

      // initialise
      view.set( path ? prefix( model.toJSON() ) : model.toJSON() );
    },

    teardown: function ( view ) {
      model.off( 'all', modelChangeEventHandler );
      view.off( 'set', setModel );
    }
  };
};