DateRangeHelper

using System;

namespace System {
    /// <summary>
    /// The class provides routines to make it easy to work with dates.
    /// </summary>
    ///
    [System.Diagnostics.DebuggerStepThrough()]
    public class DateRangeHelper {
        /// <summary>
        /// Defines a list of date ranges, useful for creating a start and end date on reports.
        /// </summary>
        private static string[] iDateRangeNames =
            {
                /* 0  */ "All",
                /* 1  */ "Today",
                /* 2  */ "This Week",
                /* 3  */ "This Week-to-date",
                /* 4  */ "This Month",
                /* 5  */ "This Month-to-date",
                /* 6  */ "This Quarter",
                /* 7  */ "This Quarter-to-date",
                /* 8  */ "This Year",
                /* 9  */ "This Year-to-date",
                /* 10 */ "Yesterday",
                /* 11 */ "Last Week",
                /* 12 */ "Last Month",
                /* 13 */ "Last Quarter",
                /* 14 */ "Last Year"
                /* 15 */
            };

        private static bool _CalculateDatesWithTime = false;
        public static bool CalculateDatesWithTime {
            get { return _CalculateDatesWithTime; }
            set { _CalculateDatesWithTime = value; }
        }
        public static bool GetDates(string dateRangeName,out DateTime startDate,out DateTime stopDate) {
            bool results = GetDates(dateRangeName,DateTime.Today,out startDate,out stopDate);
            if(results == false)
                return results;
            if(CalculateDatesWithTime == true)
                return results;
            stopDate = stopDate.AddDays(1);
            return results;
        }
        private static bool _GetDates(string dateRangeName,out DateTime startDate,out DateTime stopDate) {
            return GetDates(dateRangeName,DateTime.Today,out startDate,out stopDate);
        }
        /// <summary>
        /// Based on iDateRangeName, returns 2 dates the are set to the correct start and stop dates.
        /// </summary>
        /// <param name="dateRangeName">
        /// Specifies the date range to set to the dates for. Must be one of the DateRangeNames elements.
        /// </param>
        /// <param name="startDate">
        /// On function return, set to the starting date based on dateRangeName.
        /// </param>
        /// <param name="stopDate">
        /// On function return, set to the stopping date based on dateRangeName.
        /// </param>
        public static bool GetDates(string dateRangeName,DateTime todayDate,out DateTime startDate,out DateTime stopDate) {
            DateTime StartDate = todayDate;
            DateTime StopDate = todayDate;
            bool result = true;

            // All.
            if(dateRangeName == DateRangeNames[0]) {
                StartDate = new DateTime(1900,1,1);
                StopDate = new DateTime(2100,12,31);
            }

            // Today.
            if(dateRangeName == DateRangeNames[1]) {
                StartDate = DateTime.Today;
                StopDate = DateTime.Today;
            }

            // This Week.
            if(dateRangeName == DateRangeNames[2]) {
                // Set StartDate to most recent Sunday, first day of the current week.
                DateTime Dt = DateTime.Today;
                while(Dt.DayOfWeek != DayOfWeek.Sunday)
                    Dt = Dt.AddDays(-1);
                StartDate = Dt;

                // Set StopDate to the last day of this week, which is Saturday.
                Dt = DateTime.Today;
                while(Dt.DayOfWeek != DayOfWeek.Saturday)
                    Dt = Dt.AddDays(1);
                StopDate = Dt;
            }

            // This Week-to-date.
            if(dateRangeName == DateRangeNames[3]) {
                // Set StartDate to most recent Sunday, first day of the current week.
                DateTime Dt = DateTime.Today;
                while(Dt.DayOfWeek != DayOfWeek.Sunday)
                    Dt = Dt.AddDays(-1);
                StartDate = Dt;

                // Set StopDate to today.
                StopDate = DateTime.Today;
            }

            // This Month.
            if(dateRangeName == DateRangeNames[4]) {
                // Set StartDate to first of current month.
                StartDate = new DateTime(DateTime.Today.Year,DateTime.Today.Month,1);

                // Set StopDate to last date of current month.
                DateTime Dt = new DateTime(DateTime.Today.Year,DateTime.Today.AddMonths(1).Month,1).AddDays(-1);
                StopDate = new DateTime(DateTime.Today.Year,DateTime.Today.Month,Dt.Day);
            }

            // This Month-to-date.
            if(dateRangeName == DateRangeNames[5]) {
                // Set StartDate to first of current month.
                StartDate = new DateTime(DateTime.Today.Year,DateTime.Today.Month,1);

                // Set StopDate to today.
                StopDate = DateTime.Today;
            }

            // This Quarter.
            if(dateRangeName == DateRangeNames[6]) {
                // Set StartDate to first day of the 1st month of this quarter.
                int CurrentMonth = DateTime.Today.Month;
                DateTime Dt = DateTime.Today;
                while((CurrentMonth % 3) != 0) {
                    Dt = Dt.AddMonths(-1);
                    CurrentMonth--;
                }
                StartDate = new DateTime(Dt.Year,Dt.Month,1);

                // Set StopDate to last date of current month.
                Dt = StartDate.AddMonths(4).AddDays(-1);
                StopDate = Dt;
            }

            // This Quarter-to-date.
            if(dateRangeName == DateRangeNames[7]) {
                // Set StartDate to first day of the 1st month of this quarter.
                int CurrentMonth = DateTime.Today.Month;
                DateTime Dt = DateTime.Today;
                while((CurrentMonth % 3) != 0) {
                    Dt = Dt.AddMonths(-1);
                    CurrentMonth--;
                }
                StartDate = new DateTime(Dt.Year,Dt.Month,1);

                // Set StopDate to today.
                StopDate = DateTime.Today;
            }

            // This Year.
            if(dateRangeName == DateRangeNames[8]) {
                // Set StartDate to first day of the year.
                StartDate = new DateTime(DateTime.Today.Year,1,1);

                // Set StopDate to last day of the year.
                StopDate = new DateTime(StartDate.AddYears(1).Year,1,1).AddDays(-1);
            }

            // This Year-to-date.
            if(dateRangeName == DateRangeNames[9]) {
                // Set StartDate to first day of the year.
                StartDate = new DateTime(DateTime.Today.Year,1,1);

                // Set StopDate to today.
                StopDate = DateTime.Today;
            }

            // Yesterday.
            if(dateRangeName == DateRangeNames[10]) {
                // Set StartDate to yesterday.
                StartDate = DateTime.Today.AddDays(-1);

                // Set StopDate to yesterday.
                StopDate = DateTime.Today.AddDays(-1);
            }

            // Last Week.
            if(dateRangeName == DateRangeNames[11]) {
                // Set StartDate to the first day of last week.
                StartDate = DateTime.Today.AddDays(-7);
                while(StartDate.DayOfWeek != System.DayOfWeek.Sunday)
                    StartDate = StartDate.AddDays(-1);

                // Set StopDate to the last day of last week, which was last Saturday.
                // If the current day is Saturday, then go to the previous Saturday.
                StopDate = DateTime.Today.AddDays(-1);
                while(StopDate.DayOfWeek != System.DayOfWeek.Saturday)
                    StopDate = StopDate.AddDays(-1);
            }

            // Last Month.
            if(dateRangeName == DateRangeNames[12]) {
                // Set StartDate to the first day of last month.
                StartDate = new DateTime(DateTime.Today.AddMonths(-1).Year,DateTime.Today.AddMonths(-1).Month,1);

                // Set StopDate to the last day of last month.
                StopDate = new DateTime(DateTime.Today.Year,DateTime.Today.Month,1).AddDays(-1);
            }

            // Last Quarter.
            if(dateRangeName == DateRangeNames[13]) {
                // Set StartDate to the first day of the first month of the previous quarter.
                int CurrentMonth = DateTime.Today.Month;
                DateTime Dt = DateTime.Today;
                while((CurrentMonth % 3) != 0) {
                    Dt = Dt.AddMonths(-1);
                    CurrentMonth--;
                }
                StartDate = Dt.AddMonths(-3);

                // Set StopDate to the last day of last month.
                StopDate = StartDate.AddMonths(4).AddDays(-1);
            }

            // Last Year.
            if(dateRangeName == DateRangeNames[14]) {
                // Set StartDate to first day of the last year.
                StartDate = new DateTime(DateTime.Today.AddYears(-1).Year,1,1);

                // Set StopDate to the last day of the last year.
                StopDate = StartDate.AddYears(1).AddDays(-1);
            }

            //// Custom.
            //if (dateRangeName == DateRangeNames[15])
            //{
            //    // Don't return anything.
            //    result = false;
            //}

            startDate = StartDate;
            stopDate = StopDate;

            return result;
        }

        /// <summary>
        /// Defines a list of date ranges, useful for creating a start and end date on reports.
        /// </summary>
        public static string[] DateRangeNames {
            get {
                return iDateRangeNames;
            }
        }

        /// <summary>
        /// Returns a starting date based on today's date, for the dateRangeName.
        /// </summary>
        public static DateTime GetStartDate(string dateRangeName) {
            DateTime StartDate;
            DateTime StopDate;
            GetDates(dateRangeName,out StartDate,out StopDate);

            return StartDate;
        }

        /// <summary>
        /// Returns a stopping date based on today's date, for the dateRangeName.
        /// </summary>
        public static DateTime GetStopDate(string dateRangeName) {
            DateTime StartDate;
            DateTime StopDate;
            GetDates(dateRangeName,out StartDate,out StopDate);

            return StopDate;
        }
    }
}