using System.Diagnostics.CodeAnalysis;
using System.IO;

namespace v2rayN.Base
{
    internal static class StringEx
    {
        public static bool IsNullOrEmpty([NotNullWhen(false)] this string? value)
        {
            return string.IsNullOrEmpty(value);
        }

        public static bool IsNullOrWhiteSpace([NotNullWhen(false)] this string? value)
        {
            return string.IsNullOrWhiteSpace(value);
        }

        public static bool BeginWithAny(this string s, IEnumerable<char> chars)
        {
            if (s.IsNullOrEmpty()) return false;
            return chars.Contains(s[0]);
        }

        public static bool IsWhiteSpace(this string value)
        {
            foreach (char c in value)
            {
                if (char.IsWhiteSpace(c)) continue;

                return false;
            }
            return true;
        }

        public static IEnumerable<string> NonWhiteSpaceLines(this TextReader reader)
        {
            string? line;
            while ((line = reader.ReadLine()) != null)
            {
                if (line.IsWhiteSpace()) continue;
                yield return line;
            }
        }

        public static string TrimEx(this string? value)
        {
            return value == null ? string.Empty : value.Trim();
        }

        public static string RemovePrefix(this string value, char prefix)
        {
            if (value.StartsWith(prefix))
            {
                return value.Substring(1);
            }
            else
            {
                return value;
            }
        }

        public static string RemovePrefix(this string value, string prefix)
        {
            if (value.StartsWith(prefix))
            {
                return value.Substring(prefix.Length);
            }
            else
            {
                return value;
            }
        }

        public static string UpperFirstChar(this string value)
        {
            if (string.IsNullOrEmpty(value))
            {
                return string.Empty;
            }

            return char.ToUpper(value[0]) + value.Substring(1);
        }
    }
}