Text_After.cs

using System;
using static System.StringComparison;

namespace ToSic.Razor.Blade
{
    public static partial class Text
    {

        /// <summary>
        /// Get string value after the (first occurrence) key.
        /// Case insensitive by default. 
        /// Will return null in various cases which don't make sense or if not found.
        /// Very safe and robust, fully tested. 
        /// </summary>
        /// <param name="value">The initial string. If null, will always return null</param>
        /// <param name="key">The key to find. If null, will always return null</param>
        /// <param name="caseSensitive">Set to true if you need case-sensitive compare</param>
        /// <returns></returns>
        /// <remarks>New in v3.09</remarks>
        public static string After(this string value, string key, bool caseSensitive = false)
            => value.AfterInternal(key, caseSensitive ? Ordinal : InvariantCultureIgnoreCase);

        /// <summary>
        /// Get string value after the last occurrence of a key.
        /// Will return null in various cases which don't make sense or if not found.
        /// Case insensitive by default. 
        /// Very safe and robust, fully tested.
        /// </summary>
        /// <param name="value">The initial string. If null, will always return null</param>
        /// <param name="key">The key to find. If null, will always return null</param>
        /// <param name="caseSensitive">Set to true if you need case-sensitive compare</param>
        /// <returns></returns>
        /// <remarks>New in v3.09</remarks>
        public static string AfterLast(this string value, string key, bool caseSensitive = false)
            => value.AfterInternal(key, caseSensitive ? Ordinal : InvariantCultureIgnoreCase, true);

        private static string AfterInternal(this string value,
            string key,
            StringComparison comparison,
            bool findLast = false,
            string fallback = null)
        {
            if (value == null || key == null) return fallback;
            var posA = findLast ? value.LastIndexOf(key, comparison) : value.IndexOf(key, comparison);
            if (posA == -1) return fallback;
            var adjustedPosA = posA + key.Length;
            // If found but nothing left, return "" which is correct
            if (adjustedPosA >= value.Length) return "";
            return value.Substring(adjustedPosA);
        }
    }
}