build_report.js

map = function(){
    customer = this;
    
    function fresh_data(){
        return {
            'order_value'           : 0,
            'order_sales'           : 0,
            'order_count'           : 0, 
            'customer_count'        : 1,
            'item_count'            : 0, 
            'sku_count'             : 0,
            'orders/customer'       : 0,
            'value/order'           : 0,
            'value/customer'        : 0,
            'sale/order'            : 0,
            'sale/customer'         : 0,
            'item_count/customer'   : 0,
            'item_count/order'      : 0,
            'sku_count/order'       : 0
        };
    }
    
    function add_data (arr, field, value) {
        arr[field] += value;
    }
    
    var customer = this,
        first_year = 100000;
    
    //merged data is not identical to the original so we account for it. 
    if ("value" in customer) {
        customer = customer.value;
    };
        
    for ( var i in customer.years ){
        if( customer.years.hasOwnProperty( i ) && parseInt(i, 10) < first_year){
            first_year = parseInt( i, 10);
        }
    };
    data = {};
    all_data = fresh_data();
    
    for ( var year in customer.years ){
        if( customer.years.hasOwnProperty( year ) ){
            year_orders = customer.years[ year ];
            offset    = parseInt( year, 10) - first_year;
            year_data = fresh_data();
            for (var on = year_orders.length - 1; on >= 0; on--){
                order = customer.orders[year_orders[on]];
                quant = 0;
                for (var li = order.line_items.length - 1; li >= 0; li--){
                    quant += order.line_items[li].quantity;
                };
                add_data( year_data, "order_value", Math.round(order.total * 100));
                add_data( year_data, "order_sales", Math.round(order.line_total * 100));
                add_data( year_data, "order_count", 1);
                add_data( year_data, "sku_count", order.line_items.length);
                add_data( year_data, "item_count", quant);
                
                add_data( all_data, "order_value", Math.round(order.total * 100));
                add_data( all_data, "order_sales", Math.round(order.line_total * 100));
                add_data( all_data, "order_count", 1);
                add_data( all_data, "sku_count", order.line_items.length);
                add_data( all_data, "item_count", quant);
            };
            data[offset] = year_data;
        }
    };
    data["all time"] = all_data;
    emit( 'all', data );
    emit( first_year, data);
};

reduce = function( first_year, report_data ){
    function fresh_data() { 
        return {
            'order_value'           : 0,
            'order_sales'           : 0,
            'order_count'           : 0, 
            'customer_count'        : 0,
            'item_count'            : 0, 
            'sku_count'             : 0,
            'orders/customer'       : 0,
            'value/order'           : 0,
            'value/customer'        : 0,
            'sale/order'            : 0,
            'sale/customer'         : 0,
            'item_count/customer'   : 0,
            'item_count/order'      : 0,
            'sku_count/order'       : 0
        };
    }
    function add_field( dst, src, fld ){
        dst[fld] += src[fld];
    }
    merged_report = {};

    for (var i = report_data.length - 1; i >= 0; i--){
        report = report_data[i];
        for ( var offset in report ){
            if( report.hasOwnProperty( offset ) ){
                merged_report[ offset ] = merged_report[ offset ] || fresh_data();
                mr = merged_report[ offset ];
                or = report[ offset ];
                add_field( mr, or,'order_value');
                add_field( mr, or,'order_sales');
                add_field( mr, or,'order_count');
                add_field( mr, or,'customer_count');
                add_field( mr, or,'item_count');
                add_field( mr, or,'sku_count');
            }
        };
    };
    for ( var offet in merged_report ){
        if( merged_report.hasOwnProperty( offet ) ){
            mr = merged_report[ offet ];
            orders = mr[ 'order_count' ];
            customers = mr[ 'customer_count' ];
             mr[ 'orders/customer' ]     = orders/customers;
             mr[ 'value/order' ]         = Math.round( mr[ 'order_value' ]/orders );
             mr[ 'value/customer' ]      = Math.round( mr[ 'order_value' ]/customers );
             mr[ 'sale/order' ]          = Math.round( mr[ 'order_sales' ]/orders );
             mr[ 'sale/customer' ]       = Math.round( mr[ 'order_sales' ]/customers );
             mr[ 'item_count/customer' ] = mr[ 'item_count' ]/customers;
             mr[ 'item_count/order' ]    = mr[ 'item_count' ]/orders;
             mr[ 'sku_count/order' ]     = mr[ 'sku_count' ]/orders;
             mr[ 'items/sku' ] =  mr[ 'item_count'] / mr[ 'sku_count' ];
        } 
    };
    
    
    return merged_report;
};

db.nwb_old.mapReduce( map, reduce, {out: 'nwb_old_ltv'} );
db.pwb_old.mapReduce( map, reduce, {out: 'pwb_old_ltv'} );
db.all_old.mapReduce( map, reduce, {out: 'all_old_ltv'} );