app.service( 'API',
             [ '$http',
               function( $http ) {
                   let API = this;

                   API.balance = function( params ) {
                       return $http.get( '/api/ledger/balance', {
                           params: {
                               period: params.period,
                               categories: params.categories,
                               depth: params.depth
                           }
                       } );
                   };

                   API.register = function( params ) {
                       return $http.get( '/api/ledger/register', {
                           params: {
                               period: params.period,
                               categories: params.categories
                           }
                       } );
                   };

                   API.graph_values = function( params ) {
                       return $http.get( '/api/ledger/graph_values', {
                           params: {
                               period: params.period,
                               categories: params.categories
                           }
                       } );
                   };

                   API.budget = function( params ) {
                       return $http.get( '/api/ledger/budget', {
                           params: {
                               period: params.period,
                               categories: params.categories
                           }
                       } );
                   };

                   API.dates_salaries = function(  ) {
                       return $http.get( '/api/ledger/dates_salaries' );
                   };

                   API.accounts = function(  ) {
                       return $http.get( '/api/ledger/accounts' );
                   };

                   API.cleared = function(  ) {
                       return $http.get( '/api/ledger/cleared' );
                   };
               } ] );