using System;
using System.Collections.Generic;

namespace Quadarax.Foundation.Core.Exceptions
{
    public static class ExceptionExc
    {
        public static int GetCode(this Exception e)
        {
            if (!e.Data.Contains("Code"))
                return -1;

            return int.Parse(e.Data["Code"]?.ToString() ?? "-1");
        }

        public static void SetCode(this Exception e, int code)
        {
            e.Data.Add("Code", code);
        }

        public static string Dump(this Exception e)
        {
            var level = 0;
            var sb = new System.Text.StringBuilder();
            sb.Append("[#").Append(level).Append("]:").AppendLine(e.Message);
            var inner = e.InnerException;
            while (inner != null)
            {
                sb.Append("[#").Append(level).Append("]:").AppendLine(inner.Message);
                inner = inner.InnerException;
            }

            if (e.StackTrace != null)
            {
                sb.AppendLine("[#0] Stack list:");
                sb.AppendLine(e.StackTrace);
            }
            return sb.ToString();
        }


        /// <summary>
        /// Converts an Exception and its inner exceptions to an AggregateException.
        /// Flattens the exception hierarchy into a single AggregateException containing all exceptions.
        /// </summary>
        /// <param name="exception">The exception to convert</param>
        /// <returns>An AggregateException containing the original exception and all inner exceptions</returns>
        public static AggregateException ToAggregateException(this Exception exception)
        {
            if (exception == null)
                throw new ArgumentNullException(nameof(exception));

            // If it's already an AggregateException, flatten it to avoid nested AggregateExceptions
            if (exception is AggregateException aggregateException)
            {
                return aggregateException.Flatten();
            }

            var exceptions = new List<Exception>();
            FlattenExceptions(exception, exceptions);

            return new AggregateException(exceptions);
        }

        /// <summary>
        /// Recursively flattens exception hierarchy into a list
        /// </summary>
        /// <param name="exception">Current exception to process</param>
        /// <param name="exceptions">List to accumulate flattened exceptions</param>
        private static void FlattenExceptions(Exception exception, List<Exception> exceptions)
        {
            if (exception == null)
                return;

            // Handle AggregateException specially to avoid deep nesting
            if (exception is AggregateException aggEx)
            {
                foreach (var innerEx in aggEx.InnerExceptions)
                {
                    FlattenExceptions(innerEx, exceptions);
                }
            }
            else
            {
                // Add the current exception
                exceptions.Add(exception);

                // Recursively process inner exception
                if (exception.InnerException != null)
                {
                    FlattenExceptions(exception.InnerException, exceptions);
                }
            }
        }
    }
}