using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SyncEngine.Configuration
{
    /// <summary>Raised when required configuration is missing or invalid.</summary>
    public sealed class ConfigurationException : Exception
    {
        public ConfigurationException(IEnumerable<string> errors)
            : base(BuildMessage(errors))
        {
            Errors = errors == null ? new List<string>() : new List<string>(errors);
        }

        public ConfigurationException(string message)
            : base(message)
        {
            Errors = new List<string> { message };
        }

        public IList<string> Errors { get; private set; }

        private static string BuildMessage(IEnumerable<string> errors)
        {
            var list = errors == null ? new string[0] : errors.ToArray();
            if (list.Length == 0)
            {
                return "Configuration is invalid.";
            }

            if (list.Length == 1)
            {
                return list[0];
            }

            var sb = new StringBuilder();
            sb.AppendLine("Configuration is invalid:");
            foreach (var error in list)
            {
                sb.AppendLine("  - " + error);
            }

            return sb.ToString().TrimEnd();
        }
    }
}