mfgames-toolbuilder-cil/src/MfGames.ToolBuilder/Extensions/StringCliExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;

using FluentResults;

namespace MfGames.ToolBuilder.Extensions
{
    public static class StringCliExtensions
    {
        /// <summary>
        /// Parses a string and converts it into an enumeration while ignoring
        /// case and allow only prefix values. If the value cannot be
        /// determined, it will report it and throw an exception.
        /// </summary>
        /// <typeparam name="TEnum">The enumeration to parse.</typeparam>
        /// <param name="input">The input value to parse.</param>
        /// <param name="logger">The logger to report issues.</param>
        /// <param name="label">The name of the variable or label.</param>
        /// <returns></returns>
        public static TEnum GetEnumFuzzy<TEnum>(
            this string input,
            string label)
            where TEnum : struct
        {
            if (input.TryParseEnumFuzzy(out TEnum value))
            {
                return value;
            }

            throw new InvalidOperationException(
                string.Format(
                    "Cannot parse unknown value {0} for {1}: {2}",
                    input,
                    label,
                    Enum.GetNames(typeof(TEnum))));
        }

        /// <summary>
        /// Searches for possible list of values for a given one, handling
        /// case-insensitive searching and substring searches.
        /// </summary>
        /// <param name="value">The value to search for.</param>
        /// <param name="possible">A collection of all possible values.</param>
        /// <returns>A tuple with the selected value or an error message.</returns>
        public static Result<string> GetFuzzy(
            this string value,
            ICollection<string> possible)
        {
            // Look for a direct match.
            var found = possible
                .Where(
                    x => string.Equals(
                        x,
                        value,
                        StringComparison.InvariantCultureIgnoreCase))
                .ToList();

            if (found.Count == 1)
            {
                return Result.Ok(found[0]);
            }

            // Look for substrings in the values.
            found = possible
                .Where(
                    x => x.Contains(
                        value,
                        StringComparison.InvariantCultureIgnoreCase))
                .ToList();

            return found.Count switch
            {
                1 => Result.Ok(found[0]),
                0 => Result.Fail<string>(
                    string.Format(
                        "Cannot find \"{0}\" from possible options: {1}.",
                        value,
                        string.Join(", ", possible))),
                _ => Result.Fail<string>(
                    string.Format(
                        "Found multiple matches for \"{0}\" from possible options: {1}.",
                        value,
                        string.Join(", ", found))),
            };
        }

        /// <summary>
        /// Parses a string and converts it into an enumeration while ignoring
        /// case and allowing only prefix
        /// values.
        /// </summary>
        /// <typeparam name="TEnum">The enumeration to parse.</typeparam>
        /// <param name="input">The input value to parse.</param>
        /// <param name="value">
        /// The resulting value if parsed or default if not.
        /// </param>
        /// <returns>The resulting enum.</returns>
        public static bool TryParseEnumFuzzy<TEnum>(
            this string input,
            out TEnum value)
            where TEnum : struct
        {
            // If we have a blank, then we don't know what to do.
            if (string.IsNullOrWhiteSpace(input))
            {
                value = default;

                return false;
            }

            // See if we have an exact match first.
            if (Enum.TryParse(input, true, out value))
            {
                return true;
            }

            // Attempt a fuzzy search.
            var possible = Enum.GetNames(typeof(TEnum))
                .Select(e => e.ToLower())
                .Where(e => e.StartsWith(input.ToLower()))
                .ToList();

            if (possible.Count == 1)
            {
                value = (TEnum)Enum.Parse(typeof(TEnum), possible[0], true);

                return true;
            }

            // Fall back to not allowing the value.
            value = default;

            return false;
        }
    }
}