/static/scripts/viz/visualization.js

define( ["libs/underscore", "mvc/data", "viz/trackster/util", "utils/config"], 
        function(_, data_mod, util_mod, config_mod) {

/**
 * Model, view, and controller objects for Galaxy visualization framework.
 *
 * Models have no references to views, instead using events to indicate state 
 * changes; this is advantageous because multiple views can use the same object 
 * and models can be used without views.
 */

/**
 * Use a popup grid to select datasets from histories or libraries. After datasets are selected,
 * track definitions are obtained from the server and the success_fn is called with the list of
 * definitions for selected datasets.
 */
var select_datasets = function(dataset_url, add_track_async_url, filters, success_fn) {
    $.ajax({
        url: dataset_url,
        data: filters,
        error: function() { alert( "Grid failed" ); },
        success: function(table_html) {
            show_modal(
                "Select datasets for new tracks",
                table_html, {
                    "Cancel": function() {
                        hide_modal();
                    },
                    "Add": function() {
                       var requests = [];
                        $('input[name=id]:checked,input[name=ldda_ids]:checked').each(function() {
                            var data = {
                                    data_type: 'track_config',
                                   'hda_ldda': 'hda'
                                },
                                id = $(this).val();
                               if ($(this).attr("name") !== "id") {
                                    data.hda_ldda = 'ldda';
                                }
                                requests[requests.length] = $.ajax({
                                   url: add_track_async_url + "/" + id,
                                    data: data,
                                    dataType: "json"
                                });
                        });
                        // To preserve order, wait until there are definitions for all tracks and then add 
                        // them sequentially.
                        $.when.apply($, requests).then(function() {
                            // jQuery always returns an Array for arguments, so need to look at first element
                            // to determine whether multiple requests were made and consequently how to 
                            // map arguments to track definitions.
                            var track_defs = (arguments[0] instanceof Array ?  
                                               $.map(arguments, function(arg) { return arg[0]; }) :
                                               [ arguments[0] ]
                                               );
                            success_fn(track_defs);
                        });
                        hide_modal();
                    }
               }
            );
        }
    });
};


/**
 * Helper to determine if object is jQuery deferred.
 */
var is_deferred = function ( d ) {
    return ('promise' in d);
};

// --------- Models ---------

/**
 * Canvas manager is used to create canvases, for browsers, this deals with
 * backward comparibility using excanvas, as well as providing a pattern cache
 */
var CanvasManager = function(default_font) {
    this.default_font = default_font !== undefined ? default_font : "9px Monaco, Lucida Console, monospace";
    
    this.dummy_canvas = this.new_canvas();
    this.dummy_context = this.dummy_canvas.getContext('2d');
    this.dummy_context.font = this.default_font;
    
    this.char_width_px = this.dummy_context.measureText("A").width;
    
    this.patterns = {};

    // FIXME: move somewhere to make this more general
    this.load_pattern( 'right_strand', "/visualization/strand_right.png" );
    this.load_pattern( 'left_strand', "/visualization/strand_left.png" );
    this.load_pattern( 'right_strand_inv', "/visualization/strand_right_inv.png" );
    this.load_pattern( 'left_strand_inv', "/visualization/strand_left_inv.png" );
};

_.extend( CanvasManager.prototype, {
    load_pattern: function( key, path ) {
        var patterns = this.patterns,
            dummy_context = this.dummy_context,
            image = new Image();
        image.src = galaxy_paths.attributes.image_path + path;
        image.onload = function() {
            patterns[key] = dummy_context.createPattern( image, "repeat" );
        };
    },
    get_pattern: function( key ) {
        return this.patterns[key];
    },
    new_canvas: function() {
        var canvas = $("<canvas/>")[0];
        // If using excanvas in IE, we need to explicately attach the canvas
        // methods to the DOM element
        if (window.G_vmlCanvasManager) { G_vmlCanvasManager.initElement(canvas); }
        // Keep a reference back to the manager
        canvas.manager = this;
        return canvas;
    }
});

/**
 * Generic cache that handles key/value pairs. Keys can be any object that can be 
 * converted to a String and compared.
 */ 
var Cache = Backbone.Model.extend({
    defaults: {
        num_elements: 20,
        // Objects in cache; indexes into cache are strings of keys. 
        obj_cache: null,
        // key_ary contains keys for objects in cache.
        key_ary: null
    },

    initialize: function(options) {
        this.clear();
    },

    /**
     * Get an element from the cache using its key.
     */    
    get_elt: function(key) {
        var obj_cache = this.attributes.obj_cache,
            key_ary = this.attributes.key_ary,
            key_str = key.toString(),
            index = _.indexOf(key_ary, function(k) {
                return k.toString() === key_str;
            });

        // Update cache.
        if (index !== -1) {
            // Object is in cache, so update it.
            if (obj_cache[key_str].stale) {
                // Object is stale: remove key and object.
                key_ary.splice(index, 1);
                delete obj_cache[key_str];
            }
            else {
                // Move key to back because it is most recently used.
                this.move_key_to_end(key, index);
            }
        }

        return obj_cache[key_str];
    },
    
    /**
     * Put an element into the cache.
     */
    set_elt: function(key, value) {
        var obj_cache = this.attributes.obj_cache,
            key_ary = this.attributes.key_ary,
            key_str = key.toString(),
            num_elements = this.attributes.num_elements;

        // Update keys, objects.
        if (!obj_cache[key_str]) {
            // Add object to cache.

            if (key_ary.length >= num_elements) {
                // Cache full, so remove first element.
                var deleted_key = key_ary.shift();
                delete obj_cache[deleted_key.toString()];
            }

            // Add key.
            key_ary.push(key);
        }

        // Add object.
        obj_cache[key_str] = value;
        return value;
    },
    
    /** 
     * Move key to end of cache. Keys are removed from the front, so moving a key to the end 
     * delays the key's removal.
     */
    move_key_to_end: function(key, index) {
        this.attributes.key_ary.splice(index, 1);
        this.attributes.key_ary.push(key);
    },
    
    /**
     * Clear all elements from the cache.
     */
    clear: function() {
        this.attributes.obj_cache = {};
        this.attributes.key_ary = [];
    },
    
    /** Returns the number of elements in the cache. */
    size: function() {
        return this.attributes.key_ary.length;
    },

    /** Returns key most recently added to cache. */
    most_recently_added: function() {
        return this.size() === 0 ? null : 
               // Most recent key is at the end of key array. 
               this.attributes.key_ary[this.attributes.key_ary.length - 1];
    }
});

/**
 * Data manager for genomic data. Data is connected to and queryable by genomic regions.
 */
var GenomeDataManager = Cache.extend({
    defaults: _.extend({}, Cache.prototype.defaults, {
        dataset: null,
        genome: null,
        init_data: null,
        min_region_size: 200,
        filters_manager: null,
        data_type: "data",
        data_mode_compatible: function(entry, mode) { return true; },
        can_subset: function(entry) { return false; }
    }),

    /**
     * Initialization.
     */
    initialize: function(options) {
        Cache.prototype.initialize.call(this);

        // Set initial entries in data manager.
        var initial_entries = this.get('init_data');
        if (initial_entries) {
            this.add_data(initial_entries);
        }
    },

    /**
     * Add data entries to manager; each entry should be a dict with attributes region (key), data, and data_type.
     * If necessary, manager size is increased to hold all data.
     */
    add_data: function(entries) {
        // Increase size to accomodate all entries.
        if (this.get('num_elements') < entries.length) {
            this.set('num_elements', entries.length);
        }

        // Put data into manager.
        var self = this;
        _.each(entries, function(entry) {
            self.set_data(entry.region, entry);
        });
    },

    /**
     * Returns deferred that resolves to true when dataset is ready (or false if dataset
     * cannot be used).
     */
    data_is_ready: function() {
        var dataset = this.get('dataset'),
            ready_deferred = $.Deferred(),
            // If requesting raw data, query dataset state; if requesting (converted) data, 
            // need to query converted datasets state.
            query_type = (this.get('data_type') === 'raw_data' ? 'state' : 
                          this.get('data_type') === 'data' ? 'converted_datasets_state' : "error" ),
            ss_deferred = new util_mod.ServerStateDeferred({
                ajax_settings: {
                    url: this.get('dataset').url(),
                    data: {
                        hda_ldda: dataset.get('hda_ldda'),
                        data_type: query_type
                    },
                    dataType: "json"
                },
                interval: 5000,
                success_fn: function(response) { return response !== "pending"; }
            });

        $.when(ss_deferred.go()).then(function(response) {
            ready_deferred.resolve(response === "ok" || response === "data" );
        });
        return ready_deferred;
    },

    /**
     * Perform a feature search from server; returns Deferred object that resolves when data is available.
     */
    search_features: function(query) {
        var dataset = this.get('dataset'),
            params = {
                query: query,
                hda_ldda: dataset.get('hda_ldda'),
                data_type: 'features'
            };
        return $.getJSON(dataset.url(), params);
    },
    
    /**
     * Load data from server and manages data entries. Adds a Deferred to manager
     * for region; when data becomes available, replaces Deferred with data.
     * Returns the Deferred that resolves when data is available.
     */
    load_data: function(region, mode, resolution, extra_params) {
        // Setup data request params.
        var dataset = this.get('dataset'),
            params = {
                        "data_type": this.get('data_type'),
                        "chrom": region.get('chrom'), 
                        "low": region.get('start'), 
                        "high": region.get('end'), 
                        "mode": mode,
                        "resolution": resolution,
                        "hda_ldda": dataset.get('hda_ldda')
                     };

        $.extend(params, extra_params);
        
        // Add track filters to params.
        var filters_manager = this.get('filters_manager');
        if (filters_manager) {
            var filter_names = [];
            var filters = filters_manager.filters;
            for (var i = 0; i < filters.length; i++) {
                filter_names.push(filters[i].name);
            }
            params.filter_cols = JSON.stringify(filter_names);
        }
                        
        // Do request.
        var manager = this,
            entry = $.getJSON(dataset.url(), params, function (result) {
                // Add region to the result.
                result.region = region;
                manager.set_data(region, result);
            });

        this.set_data(region, entry);
        return entry;
    },
    
    /**
     * Get data from dataset.
     */
    get_data: function(region, mode, resolution, extra_params) {
                
        // Look for entry and return if it's a deferred or if data available is compatible with mode.
        var entry = this.get_elt(region);
        if ( entry && 
             ( is_deferred(entry) || this.get('data_mode_compatible')(entry, mode) ) ) {
            return entry;
        }

        //
        // Look in cache for data that can be used.
        // TODO: this logic could be improved if the visualization knew whether
        // the data was "index" or "data."
        //
        var key_ary = this.get('key_ary'),
            obj_cache = this.get('obj_cache'),
            entry_region, is_subregion;
        for (var i = 0; i < key_ary.length; i++) {
            entry_region = key_ary[i];
            
            if (entry_region.contains(region)) {
                is_subregion = true;

                // This entry has data in the requested range. Return if data
                // is compatible and can be subsetted.
                entry = obj_cache[entry_region.toString()];
                if ( is_deferred(entry) || 
                    ( this.get('data_mode_compatible')(entry, mode) && this.get('can_subset')(entry) ) ) {
                    this.move_key_to_end(entry_region, i);

                    // If there's data, subset it.
                    if ( !is_deferred(entry) ) {
                        var subset_entry = this.subset_entry(entry, region);
                        this.set(region, subset_entry);
                        entry = subset_entry;
                    }

                    return entry;
                }
            }
        }

        // FIXME: There _may_ be instances where region is a subregion of another entry but cannot be 
        // subsetted. For these cases, do not increase length because region will never be found (and
        // an infinite loop will occur.)
        // If needed, extend region to make it minimum size.
        if (!is_subregion && region.length() < this.attributes.min_region_size) {
            // IDEA: alternative heuristic is to find adjacent cache entry to region and use that to extend.
            // This would prevent bad extensions when zooming in/out while still preserving the behavior
            // below.

            // Use heuristic to extend region: extend relative to last data request.
            var last_request = this.most_recently_added();
            if (!last_request || (region.get('start') > last_request.get('start'))) {
                // This request is after the last request, so extend right.
                region.set('end', region.get('start') + this.attributes.min_region_size);
            }
            else {
                // This request is after the last request, so extend left.
                region.set('start', region.get('end') - this.attributes.min_region_size);
            }

            // Trim region to avoid invalid coordinates.
            region.set('genome', this.attributes.genome);
            region.trim();
        }

        return this.load_data(region, mode, resolution, extra_params);
    },
    
    /**
     * Alias for set_elt for readbility.
     */
    set_data: function(region, entry) {
        this.set_elt(region, entry);  
    },
    
    /** "Deep" data request; used as a parameter for DataManager.get_more_data() */
    DEEP_DATA_REQ: "deep",
    
    /** "Broad" data request; used as a parameter for DataManager.get_more_data() */
    BROAD_DATA_REQ: "breadth",
    
    /**
     * Gets more data for a region using either a depth-first or a breadth-first approach.
     */
    get_more_data: function(region, mode, resolution, extra_params, req_type) {
        var cur_data = this._mark_stale(region);
        if (!(cur_data && this.get('data_mode_compatible')(cur_data, mode))) {
            console.log('ERROR: problem with getting more data: current data is not compatible');
            return;
        }
        
        //
        // Set parameters based on request type.
        //
        var query_low = region.get('start');
        if (req_type === this.DEEP_DATA_REQ) {
            // Use same interval but set start_val to skip data that's already in cur_data.
            $.extend(extra_params, {start_val: cur_data.data.length + 1});
        }
        else if (req_type === this.BROAD_DATA_REQ) {
            // To get past an area of extreme feature depth, set query low to be after either
            // (a) the maximum high or HACK/FIXME (b) the end of the last feature returned.
            query_low = (cur_data.max_high ? cur_data.max_high : cur_data.data[cur_data.data.length - 1][2]) + 1;
        }
        var query_region = region.copy().set('start', query_low);
        
        //
        // Get additional data, append to current data, and set new data. Use a custom deferred object
        // to signal when new data is available.
        //
        var data_manager = this,
            new_data_request = this.load_data(query_region, mode, resolution, extra_params),
            new_data_available = $.Deferred();
        // load_data sets cache to new_data_request, but use custom deferred object so that signal and data
        // is all data, not just new data.
        this.set_data(region, new_data_available);
        $.when(new_data_request).then(function(result) {
            // Update data and message.
            if (result.data) {
                result.data = cur_data.data.concat(result.data);
                if (result.max_low) {
                    result.max_low = cur_data.max_low;
                }
                if (result.message) {
                    // HACK: replace number in message with current data length. Works but is ugly.
                    result.message = result.message.replace(/[0-9]+/, result.data.length);
                }
            }
            data_manager.set_data(region, result);
            new_data_available.resolve(result);
        });
        return new_data_available;
    },

    /**
     * Returns true if more detailed data can be obtained for entry.
     */
    can_get_more_detailed_data: function(region) {
        var cur_data = this.get_elt(region);

        // Can only get more detailed data for bigwig data that has less than 8000 data points.
        // Summary tree returns *way* too much data, and 8000 data points ~ 500KB.
        return (cur_data.dataset_type === 'bigwig' && cur_data.data.length < 8000);
    },

    /**
     * Returns more detailed data for an entry.
     */
    get_more_detailed_data: function(region, mode, resolution, detail_multiplier, extra_params) {
        // Mark current entry as stale.
        var cur_data = this._mark_stale(region);
        if (!cur_data) {
            console.log("ERROR getting more detailed data: no current data");
            return;
        }

        if (!extra_params) { extra_params = {}; }

        // Use additional parameters to get more detailed data.
        if (cur_data.dataset_type === 'bigwig') {
            // FIXME: constant should go somewhere.
            extra_params.num_samples = 1000 * detail_multiplier;
        }

        return this.load_data(region, mode, resolution, extra_params);
    },

    /**
     * Marks cache data as stale.
     */
    _mark_stale: function(region) {
        var entry = this.get_elt(region);
        if (!entry) {
            console.log("ERROR: no data to mark as stale: ", this.get('dataset'), region.toString());
        }
        entry.stale = true;
        return entry;
    },

    /**
     * Returns an array of data with each entry representing one chromosome/contig
     * of data or, if data is not available, returns a Deferred that resolves to the
     * data when it becomes available.
     */
    get_genome_wide_data: function(genome) {
        // -- Get all data. --

        var self = this,
            all_data_available = true,

            //  Map chromosome info into genome data.
            gw_data = _.map(genome.get('chroms_info').chrom_info, function(chrom_info) {
                var chrom_data = self.get_elt(
                    new GenomeRegion({
                        chrom: chrom_info.chrom,
                        start: 0,
                        end: chrom_info.len
                    })
                );

                // Set flag if data is not available.
                if (!chrom_data) { all_data_available = false; }

                return chrom_data;
            });

        // -- If all data is available, return it. --
        if (all_data_available) {
            return gw_data;
        }

        // -- All data is not available, so load from server. --

        var deferred = $.Deferred();
        $.getJSON(this.get('dataset').url(), { data_type: 'genome_data' }, function(genome_wide_data) {
            self.add_data(genome_wide_data.data);
            deferred.resolve(genome_wide_data.data);
        });

        return deferred;
    },

    /**
     * Returns entry with only data in the subregion.
     */
    subset_entry: function(entry, subregion) {
        // Dictionary from entry type to function for subsetting data.
        var subset_fns = {
            bigwig: function(data, subregion) {
                return _.filter(data, function(data_point) {
                    return data_point[0] >= subregion.get('start') && 
                           data_point[0] <= subregion.get('end');
                });
            },
            refseq: function(data, subregion) {
                var seq_start = subregion.get('start') - entry.region.get('start'),
                    seq_end = entry.data.length - ( entry.region.get('end') - subregion.get('end') );
                return entry.data.slice(seq_start, seq_end);
            }
        };

        // Subset entry if there is a function for subsetting and regions are not the same.
        var subregion_data = entry.data;
        if (!entry.region.same(subregion) && entry.dataset_type in subset_fns) {
            subregion_data = subset_fns[entry.dataset_type](entry.data, subregion);
        }

        // Return entry with subregion's data.
        return {
            region: subregion,
            data: subregion_data,
            dataset_type: entry.dataset_type
        };
    }
});

var GenomeReferenceDataManager = GenomeDataManager.extend({
    initialize: function(options) {
        // Use generic object in place of dataset and set urlRoot to fetch data.
        var dataset_placeholder = new Backbone.Model();
        dataset_placeholder.urlRoot = options.data_url;
        this.set('dataset', dataset_placeholder);
    },

    load_data: function(region, mode, resolution, extra_params) {
        // Fetch data if region is not too large.
        return ( region.length() <= 100000 ? 
                 GenomeDataManager.prototype.load_data.call(this, region, mode, resolution, extra_params) :
                 { data: null, region: region } );
    }
});
 
/**
 * A genome build.
 */
var Genome = Backbone.Model.extend({
    defaults: {
        name: null,
        key: null,
        chroms_info: null
    },

    initialize: function(options) {
        this.id = options.dbkey;
    },
    
    /**
     * Shorthand for getting to chromosome information.
     */
    get_chroms_info: function() {
        return this.attributes.chroms_info.chrom_info;  
    },

    /** 
     * Returns a GenomeRegion object denoting a complete chromosome.
     */
    get_chrom_region: function(chr_name) {
        // FIXME: use findWhere in underscore 1.4
        var chrom_info = _.find(this.get_chroms_info(), function(chrom_info) { 
            return chrom_info.chrom === chr_name;
        });
        return new GenomeRegion({
            chrom: chrom_info.chrom,
            end: chrom_info.len
        });
    },

    /** Returns the length of a chromosome. */
    get_chrom_len: function(chr_name) {
        // FIXME: use findWhere in underscore 1.4
        return _.find(this.get_chroms_info(), function(chrom_info) { 
            return chrom_info.chrom === chr_name;
        }).len;
    }
});

/**
 * A genomic region.
 */
var GenomeRegion = Backbone.RelationalModel.extend({
    defaults: {
        chrom: null,
        start: 0,
        end: 0,
        str_val: null,
        genome: null
    },

    /**
     * Returns true if this region is the same as a given region.
     * It does not test the genome right now.
     */
    same: function(region) {
        return this.attributes.chrom === region.get('chrom') &&
               this.attributes.start === region.get('start') &&
               this.attributes.end === region.get('end');
    },
    
    /**
     * If from_str specified, use it to initialize attributes.
     */
    initialize: function(options) {
        if (options.from_str) {
            var pieces = options.from_str.split(':'),
                chrom = pieces[0],
                start_end = pieces[1].split('-');
            this.set({
                chrom: chrom,
                start: parseInt(start_end[0], 10),
                end: parseInt(start_end[1], 10)
            });
        }

        // Keep a copy of region's string value for fast lookup.
        this.attributes.str_val = this.get('chrom') + ":" + this.get('start') + "-" + this.get('end');
    },
    
    copy: function() {
        return new GenomeRegion({
            chrom: this.get('chrom'),
            start: this.get('start'),
            end: this.get('end') 
        });
    },

    length: function() {
        return this.get('end') - this.get('start');
    },
    
    /** Returns region in canonical form chrom:start-end */
    toString: function() {
        return this.attributes.str_val;
    },
    
    toJSON: function() {
        return {
            chrom: this.get('chrom'),
            start: this.get('start'),
            end: this.get('end')
        };
    },
    
    /**
     * Compute the type of overlap between this region and another region. The overlap is computed relative to the given/second region; 
     * hence, OVERLAP_START indicates that the first region overlaps the start (but not the end) of the second region.
     */
    compute_overlap: function(a_region) {
        var first_chrom = this.get('chrom'), second_chrom = a_region.get('chrom'),
            first_start = this.get('start'), second_start = a_region.get('start'),
            first_end = this.get('end'), second_end = a_region.get('end'),
            overlap;
            
        // Compare chroms.
        if (first_chrom && second_chrom && first_chrom !== second_chrom) {
            return GenomeRegion.overlap_results.DIF_CHROMS;
        }
        
        // Compare regions.
        if (first_start < second_start) {
            if (first_end < second_start) {
                overlap = GenomeRegion.overlap_results.BEFORE;
            }
            else if (first_end < second_end) {
                overlap = GenomeRegion.overlap_results.OVERLAP_START;
            }
            else { // first_end >= second_end
                overlap = GenomeRegion.overlap_results.CONTAINS;
            }
        }
        else if (first_start > second_start) {
            if (first_start > second_end) {
                overlap = GenomeRegion.overlap_results.AFTER;
            }
            else if (first_end <= second_end) {
                overlap = GenomeRegion.overlap_results.CONTAINED_BY;
            }
            else {
                overlap = GenomeRegion.overlap_results.OVERLAP_END;
            }
        }
        else { // first_start === second_start
            overlap = (first_end >= second_end ? 
                       GenomeRegion.overlap_results.CONTAINS : 
                       GenomeRegion.overlap_results.CONTAINED_BY);
        }

        return overlap;
    },

    /**
     * Trim a region to match genome's constraints.
     */
    trim: function(genome) {
        // Assume that all chromosome/contigs start at 0.
        if (this.attributes.start < 0) {
            this.attributes.start = 0;
        }

        // Only try to trim the end if genome is set.
        if (this.attributes.genome) {
            var chrom_len = this.attributes.genome.get_chrom_len(this.attributes.chrom);
            if (this.attributes.end > chrom_len) {
                this.attributes.end = chrom_len - 1;
            }
        }

        return this;
    },
    
    /**
     * Returns true if this region contains a given region.
     */
    contains: function(a_region) {
        return this.compute_overlap(a_region) === GenomeRegion.overlap_results.CONTAINS;
    },

    /**
     * Returns true if regions overlap.
     */
    overlaps: function(a_region) {
        return _.intersection( [this.compute_overlap(a_region)], 
                               [GenomeRegion.overlap_results.DIF_CHROMS, GenomeRegion.overlap_results.BEFORE, GenomeRegion.overlap_results.AFTER] ).length === 0;  
    }
},
{
    overlap_results: {
        DIF_CHROMS: 1000,
        BEFORE: 1001, 
        CONTAINS: 1002, 
        OVERLAP_START: 1003, 
        OVERLAP_END: 1004, 
        CONTAINED_BY: 1005, 
        AFTER: 1006
    }
});

var GenomeRegionCollection = Backbone.Collection.extend({
    model: GenomeRegion
});

/**
 * A genome browser bookmark.
 */
var BrowserBookmark = Backbone.RelationalModel.extend({
    defaults: {
        region: null,
        note: ''
    },

    relations: [
        {
            type: Backbone.HasOne,
            key: 'region',
            relatedModel: GenomeRegion
        }
    ]
});

/**
 * Bookmarks collection.
 */
var BrowserBookmarkCollection = Backbone.Collection.extend({
    model: BrowserBookmark
});

/**
 * A track of data in a genome visualization.
 */
// TODO: rename to Track and merge with Trackster's Track object.
var BackboneTrack = Backbone.RelationalModel.extend({

    relations: [
        {
            type: Backbone.HasOne,
            key: 'dataset',
            relatedModel: data_mod.Dataset
        }
    ],

    initialize: function(options) {

        // -- Set up config settings. -- 

        this.set('config', config_mod.ConfigSettingCollection.from_config_dict(options.prefs));

        // Set up some minimal config.
        this.get('config').add( [
            { key: 'name', value: this.get('name') },
            { key: 'color' }
        ] );

        // -- Set up data manager. --
        var preloaded_data = this.get('preloaded_data');
        if (preloaded_data) {
            preloaded_data = preloaded_data.data;
        }
        else {
            preloaded_data = [];
        }
        this.set('data_manager', new GenomeDataManager({
            dataset: this.get('dataset'),
            init_data: preloaded_data
        }));
    }
});

/**
 * A visualization.
 */
var Visualization = Backbone.RelationalModel.extend({
    defaults: {
        title: '',
        type: ''
    },

    // No API to create/save visualization yet, so use this path:
    url: galaxy_paths.get("visualization_url"),
    
    /**
     * POSTs visualization's JSON to its URL using the parameter 'vis_json'
     * Note: This is necessary because (a) Galaxy requires keyword args and 
     * (b) Galaxy does not handle PUT now.
     */
    save: function() {
        return $.ajax({
            url: this.url(),
            type: "POST",
            dataType: "json",
            data: { 
                vis_json: JSON.stringify(this)
            }
        });
    }
});

/**
 * A visualization of genome data.
 */
var GenomeVisualization = Visualization.extend({
    defaults: _.extend({}, Visualization.prototype.defaults, {
        dbkey: '',
        tracks: null,
        bookmarks: null,
        viewport: null
    }),

    relations: [
        {
            type: Backbone.HasMany,
            key: 'tracks',
            relatedModel: BackboneTrack
        }
    ],

    /**
     * Add a track or array of tracks to the visualization.
     */
    add_tracks: function(tracks) {
        this.get('tracks').add(tracks);
    }
});

/**
 * Configuration data for a Trackster track.
 */
var TrackConfig = Backbone.Model.extend({
    
});

/**
 * -- Routers --
 */

/**
 * Router for track browser.
 */
var TrackBrowserRouter = Backbone.Router.extend({    
    initialize: function(options) {
        this.view = options.view;
        
        // Can't put regular expression in routes dictionary.
        // NOTE: parentheses are used to denote parameters returned to callback.
        this.route(/([\w]+)$/, 'change_location');
        this.route(/([\w]+\:[\d,]+-[\d,]+)$/, 'change_location');
        
        // Handle navigate events from view.
        var self = this;
        self.view.on("navigate", function(new_loc) {
            self.navigate(new_loc);
        });
    },
    
    change_location: function(new_loc) {
        this.view.go_to(new_loc);
    }
});

return {
    BackboneTrack: BackboneTrack,
    BrowserBookmark: BrowserBookmark,
    BrowserBookmarkCollection: BrowserBookmarkCollection,
    Cache: Cache,
    CanvasManager: CanvasManager,
    Genome: Genome,
    GenomeDataManager: GenomeDataManager,
    GenomeRegion: GenomeRegion,
    GenomeRegionCollection: GenomeRegionCollection,
    GenomeVisualization: GenomeVisualization,
    GenomeReferenceDataManager: GenomeReferenceDataManager,
    TrackBrowserRouter: TrackBrowserRouter,
    TrackConfig: TrackConfig,
    Visualization: Visualization,
    select_datasets: select_datasets
};

});