using System.Text;
using System.Text.RegularExpressions;

namespace Core.Blueprint.Caching.Helpers
{
    /// <summary>
    /// Helper class for generating consistent and normalized cache keys.
    /// </summary>
    public static class CacheKeyHelper
    {
        /// <summary>
        /// Generates a cache key based on the instance, method name, and parameters.
        /// </summary>
        /// <param name="instance">The instance of the class.</param>
        /// <param name="methodName">The method name related to the cache key.</param>
        /// <param name="parameters">The parameters used to generate the key.</param>
        /// <returns>A normalized cache key string.</returns>
        public static string GenerateCacheKey(object instance, string methodName, params object[] parameters)
        {
            var className = instance.GetType().Name;
            var keyBuilder = new StringBuilder($"{className}.{methodName}");

            foreach (var param in parameters)
            {
                string normalizedParam = NormalizeParameter(param);
                keyBuilder.Append($".{normalizedParam}");
            }

            return keyBuilder.ToString();
        }

        /// <summary>
        /// Normalizes a parameter value for use in a cache key.
        /// </summary>
        /// <param name="param">The parameter to normalize.</param>
        /// <returns>A normalized string representation of the parameter.</returns>
        private static string NormalizeParameter(object param)
        {
            if (param == null)
            {
                return "null";
            }

            string paramString;

            if (param is DateTime dateTime)
            {
                paramString = dateTime.ToString("yyyyMMdd");
            }
            else
            {
                paramString = param.ToString();
            }

            // Replace special characters with an underscore.
            return Regex.Replace(paramString, @"[^a-zA-Z0-9]", "_");
        }
    }
}