public function calculate_current_range( $current_range ) {

		switch ( $current_range ) {

			case 'custom':
				$this->start_date = max( strtotime( '-20 years' ), strtotime( sanitize_text_field( $_GET['start_date'] ) ) );

				if ( empty( $_GET['end_date'] ) ) {
					$this->end_date = strtotime( 'midnight', current_time( 'timestamp' ) );
				} else {
					$this->end_date = strtotime( 'midnight', strtotime( sanitize_text_field( $_GET['end_date'] ) ) );
				}

				$interval = 0;
				$min_date = $this->start_date;

				while ( ( $min_date = strtotime( '+1 MONTH', $min_date ) ) <= $this->end_date ) {
					$interval ++;
				}

				// 3 months max for day view
				if ( $interval > 3 ) {
					$this->chart_groupby = 'month';
				} else {
					$this->chart_groupby = 'day';
				}
				break;

			case 'year':
				$this->start_date    = strtotime( date( 'Y-01-01', current_time( 'timestamp' ) ) );
				$this->end_date      = strtotime( 'midnight', current_time( 'timestamp' ) );
				$this->chart_groupby = 'month';
				break;

			case 'last_month':
				$first_day_current_month = strtotime( date( 'Y-m-01', current_time( 'timestamp' ) ) );
				$this->start_date        = strtotime( date( 'Y-m-01', strtotime( '-1 DAY', $first_day_current_month ) ) );
				$this->end_date          = strtotime( date( 'Y-m-t', strtotime( '-1 DAY', $first_day_current_month ) ) );
				$this->chart_groupby     = 'day';
				break;

			case 'month':
				$this->start_date    = strtotime( date( 'Y-m-01', current_time( 'timestamp' ) ) );
				$this->end_date      = strtotime( 'midnight', current_time( 'timestamp' ) );
				$this->chart_groupby = 'day';
				break;

			case '7day':
				$this->start_date    = strtotime( '-6 days', strtotime( 'midnight', current_time( 'timestamp' ) ) );
				$this->end_date      = strtotime( 'midnight', current_time( 'timestamp' ) );
				$this->chart_groupby = 'day';
				break;
		}

		// Group by
		switch ( $this->chart_groupby ) {

			case 'day':
				$this->group_by_query = 'YEAR(posts.post_date), MONTH(posts.post_date), DAY(posts.post_date)';
				$this->chart_interval = absint( ceil( max( 0, ( $this->end_date - $this->start_date ) / ( 60 * 60 * 24 ) ) ) );
				$this->barwidth       = 60 * 60 * 24 * 1000;
				break;

			case 'month':
				$this->group_by_query = 'YEAR(posts.post_date), MONTH(posts.post_date)';
				$this->chart_interval = 0;
				$min_date             = strtotime( date( 'Y-m-01', $this->start_date ) );

				while ( ( $min_date = strtotime( '+1 MONTH', $min_date ) ) <= $this->end_date ) {
					$this->chart_interval ++;
				}

				$this->barwidth = 60 * 60 * 24 * 7 * 4 * 1000;
				break;
		}
	}