/*
 * # Semantic - Colorize
 * http://github.com/semantic-org/semantic-ui/
 *
 *
 * Copyright 2014 Contributor
 * Released under the MIT license
 * http://opensource.org/licenses/MIT
 *
 */

;(function ( $, window, document, undefined ) {

  $.fn.colorize = function(parameters) {
    var
      settings        = $.extend(true, {}, $.fn.colorize.settings, parameters),
      // hoist arguments
      moduleArguments = arguments || false
    ;
    $(this)
      .each(function(instanceIndex) {

        var
          $module         = $(this),

          mainCanvas      = $('<canvas />')[0],
          imageCanvas     = $('<canvas />')[0],
          overlayCanvas   = $('<canvas />')[0],

          backgroundImage = new Image(),

          // defs
          mainContext,
          imageContext,
          overlayContext,

          image,
          imageName,

          width,
          height,

          // shortucts
          colors    = settings.colors,
          paths     = settings.paths,
          namespace = settings.namespace,
          error     = settings.error,

          // boilerplate
          instance   = $module.data('module-' + namespace),
          module
        ;

        module = {

          checkPreconditions: function() {
            module.debug('Checking pre-conditions');

            if( !$.isPlainObject(colors) || $.isEmptyObject(colors) ) {
              module.error(error.undefinedColors);
              return false;
            }
            return true;
          },

          async: function(callback) {
            if(settings.async) {
              setTimeout(callback, 0);
            }
            else {
              callback();
            }
          },

          getMetadata: function() {
            module.debug('Grabbing metadata');
            image     = $module.data('image') || settings.image || undefined;
            imageName = $module.data('name')  || settings.name  || instanceIndex;
            width     = settings.width        || $module.width();
            height    = settings.height       || $module.height();
            if(width === 0 || height === 0) {
              module.error(error.undefinedSize);
            }
          },

          initialize: function() {
            module.debug('Initializing with colors', colors);
            if( module.checkPreconditions() ) {

              module.async(function() {
                module.getMetadata();
                module.canvas.create();

                module.draw.image(function() {
                  module.draw.colors();
                  module.canvas.merge();
                });
                $module
                  .data('module-' + namespace, module)
                ;
              });
            }
          },

          redraw: function() {
            module.debug('Redrawing image');
            module.async(function() {
              module.canvas.clear();
              module.draw.colors();
              module.canvas.merge();
            });
          },

          change: {
            color: function(colorName, color) {
              module.debug('Changing color', colorName);
              if(colors[colorName] === undefined) {
                module.error(error.missingColor);
                return false;
              }
              colors[colorName] = color;
              module.redraw();
            }
          },

          canvas: {
            create: function() {
              module.debug('Creating canvases');

              mainCanvas.width     = width;
              mainCanvas.height    = height;
              imageCanvas.width    = width;
              imageCanvas.height   = height;
              overlayCanvas.width  = width;
              overlayCanvas.height = height;

              mainContext    = mainCanvas.getContext('2d');
              imageContext   = imageCanvas.getContext('2d');
              overlayContext = overlayCanvas.getContext('2d');

              $module
                .append( mainCanvas )
              ;
              mainContext    = $module.children('canvas')[0].getContext('2d');
            },
            clear: function(context) {
              module.debug('Clearing canvas');
              overlayContext.fillStyle = '#FFFFFF';
              overlayContext.fillRect(0, 0, width, height);
            },
            merge: function() {
              if( !$.isFunction(mainContext.blendOnto) ) {
                module.error(error.missingPlugin);
                return;
              }
              mainContext.putImageData( imageContext.getImageData(0, 0, width, height), 0, 0);
              overlayContext.blendOnto(mainContext, 'multiply');
            }
          },

          draw: {

            image: function(callback) {
              module.debug('Drawing image');
              callback = callback || function(){};
              if(image) {
                backgroundImage.src    = image;
                backgroundImage.onload = function() {
                  imageContext.drawImage(backgroundImage, 0, 0);
                  callback();
                };
              }
              else {
                module.error(error.noImage);
                callback();
              }
            },

            colors: function() {
              module.debug('Drawing color overlays', colors);
              $.each(colors, function(colorName, color) {
                settings.onDraw(overlayContext, imageName, colorName, color);
              });
            }

          },

          debug: function(message, variableName) {
            if(settings.debug) {
              if(variableName !== undefined) {
                console.info(settings.name + ': ' + message, variableName);
              }
              else {
                console.info(settings.name + ': ' + message);
              }
            }
          },
          error: function(errorMessage) {
            console.warn(settings.name + ': ' + errorMessage);
          },
          invoke: function(methodName, context, methodArguments) {
            var
              method
            ;
            methodArguments = methodArguments || Array.prototype.slice.call( arguments, 2 );

            if(typeof methodName == 'string' && instance !== undefined) {
              methodName = methodName.split('.');
              $.each(methodName, function(index, name) {
                if( $.isPlainObject( instance[name] ) ) {
                  instance = instance[name];
                  return true;
                }
                else if( $.isFunction( instance[name] ) ) {
                  method = instance[name];
                  return true;
                }
                module.error(settings.error.method);
                return false;
              });
            }
            return ( $.isFunction( method ) )
              ? method.apply(context, methodArguments)
              : false
            ;
          }

        };
        if(instance !== undefined && moduleArguments) {
          // simpler than invoke realizing to invoke itself (and losing scope due prototype.call()
          if(moduleArguments[0] == 'invoke') {
            moduleArguments = Array.prototype.slice.call( moduleArguments, 1 );
          }
          return module.invoke(moduleArguments[0], this, Array.prototype.slice.call( moduleArguments, 1 ) );
        }
        // initializing
        module.initialize();
      })
    ;
    return this;
  };

  $.fn.colorize.settings = {
    name      : 'Image Colorizer',
    debug     : true,
    namespace : 'colorize',

    onDraw    : function(overlayContext, imageName, colorName, color) {},

    // whether to block execution while updating canvas
    async     : true,
    // object containing names and default values of color regions
    colors    : {},

    metadata: {
      image : 'image',
      name  : 'name'
    },

    error: {
      noImage         : 'No tracing image specified',
      undefinedColors : 'No default colors specified.',
      missingColor    : 'Attempted to change color that does not exist',
      missingPlugin   : 'Blend onto plug-in must be included',
      undefinedHeight : 'The width or height of image canvas could not be automatically determined. Please specify a height.'
    }

  };

})( jQuery, window , document );