namespace CanonSharp.Combinator.Abstractions;

/// <summary>
/// 成功解析结果基类
/// </summary>
/// <param name="value">实际的解析结果</param>
/// <typeparam name="TToken">输入流类型</typeparam>
/// <typeparam name="T">实际的解析结果类型</typeparam>
public abstract class SuccessfulResult<TToken, T>(T value) : ParseResult<TToken, T>
{
    public override T Value => value;

    /// <summary>
    /// 运行下一个解析器
    /// </summary>
    /// <param name="parser">下一个解析器</param>
    /// <param name="continuation">处理解析结果的后继函数</param>
    /// <typeparam name="TNext">下一个解析器返回的结果类型</typeparam>
    /// <typeparam name="TResult">最终的结果类型</typeparam>
    /// <returns>最终的结果</returns>
    protected abstract ParseResult<TToken, TResult> RunNext<TNext, TResult>(Parser<TToken, TNext> parser,
        Func<ParseResult<TToken, TNext>, ParseResult<TToken, TResult>> continuation);

    internal override ParseResult<TToken, TResult> Next<TNext, TResult>(Func<T, Parser<TToken, TNext>> nextParser,
        Func<ParseResult<TToken, TNext>, ParseResult<TToken, TResult>> continuation)
        => RunNext(nextParser(Value), continuation);

    public override TResult CaseOf<TResult>(Func<SuccessfulResult<TToken, T>, TResult> successfulHandler,
        Func<FailedResult<TToken, T>, TResult> failedHandler)
        => successfulHandler(this);

    public override string ToString() => Value?.ToString() ?? string.Empty;
}