qdr.fnd/qdr.fnd.core/Value/Extensions/TimeSpanExt.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Quadarax.Foundation.Core.Value.Formatters;

namespace Quadarax.Foundation.Core.Value.Extensions
{
    public static class TimeSpanExt
    {
        public static string ToReadableString(this TimeSpan owner)
        {
            // formats and its cutoffs based on TotalSeconds
            var cutoff = new SortedList<long, string> { 
                {59, "{3:S}" }, 
                {60, "{2:M}" },
                {60*60-1, "{2:M}, {3:S}"},
                {60*60, "{1:H}"},
                {24*60*60-1, "{1:H}, {2:M}"},
                {24*60*60, "{0:D}"},
                {Int64.MaxValue , "{0:D}, {1:H}"}
            };

            // find nearest best match
            var find = cutoff.Keys.ToList()
                .BinarySearch((long)owner.TotalSeconds);
            // negative values indicate a nearest match
            var near = find<0?Math.Abs(find)-1:find;
            // use custom formatter to get the string
            return String.Format(
                new HmsFormatter(), 
                cutoff[cutoff.Keys[near]], 
                owner.Days, 
                owner.Hours, 
                owner.Minutes, 
                owner.Seconds);
        }
    }
}