using CanonSharp.Combinator.Abstractions;
using CanonSharp.Combinator.Extensions;
using CanonSharp.Combinator.Parsers;

namespace CanonSharp.Combinator.Text;

/// <summary>
/// 字符串解析器
/// </summary>
/// <param name="except">期望的字符串</param>
/// <param name="comparison">字符串比较模式</param>
public class StringParser(string except, StringComparison comparison) : PrimitiveParser<char, string>
{
    protected override IParseResult<char, string> Run<TState>(TState state)
    {
        TState[] states = state.AsEnumerable<char, TState>().Take(except.Length).ToArray();
        string actual = new(states.Select(x => x.Current).ToArray());
        return string.Equals(except, actual, comparison)
            ? ParseResultBuilder.Succeed<char, TState, string>(actual, states.Length == 0 ? state : states.Last().Next)
            : ParseResultBuilder.Fail<char, TState, string>($"Except '{except}' but found '{actual}.", state);
    }
}