using FrameworkBLL.EIPConversation.EIPHandlers.EIPEngine.ActionHandler;
using FrameworkDAL.DTO.EIPConversation;
using GB5Shared.DTO.Framework.Login;
using Microsoft.Extensions.Logging;

namespace FrameworkBLL.EIPConversation.EIPHandlers.EIPActionExecutor
{
    public class EIPActionExecutor : IEIPActionExecutor
    {
        private readonly IReadOnlyDictionary<string, IEIPActionHandler> _handlerMap;
        private readonly IReadOnlyList<IEIPActionHandler> _wildcardHandlers;
        private readonly ILogger<EIPActionExecutor> _logger;

        public EIPActionExecutor(IEnumerable<IEIPActionHandler> handlers, ILogger<EIPActionExecutor> logger)
        {
            if (handlers == null) throw new ArgumentNullException(nameof(handlers));
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));

            // Separate exact-match handlers from wildcard handlers (ActionCode = "")
            var exactHandlers    = handlers.Where(h => !string.IsNullOrEmpty(h.ActionCode)).ToList();
            var wildcardHandlers = handlers.Where(h =>  string.IsNullOrEmpty(h.ActionCode)).ToList();

            // Detect duplicate exact-match ActionCodes
            var grouped = exactHandlers
                .GroupBy(h => h.ActionCode, StringComparer.OrdinalIgnoreCase)
                .ToList();
            var duplicates = grouped.Where(g => g.Count() > 1).Select(g => g.Key).ToList();
            if (duplicates.Any())
            {
                var dupList = string.Join(", ", duplicates);
                _logger.LogError("Duplicate IEIPActionHandler implementations detected for ActionCodes: {Duplicates}", dupList);
                throw new InvalidOperationException($"Duplicate IEIPActionHandler implementations found for ActionCodes: {dupList}");
            }

            _handlerMap      = grouped.ToDictionary(g => g.Key, g => g.First(), StringComparer.OrdinalIgnoreCase);
            _wildcardHandlers = wildcardHandlers.AsReadOnly();
            _logger.LogInformation("EIPActionExecutor initialized with {Exact} exact + {Wild} wildcard handlers.",
                _handlerMap.Count, _wildcardHandlers.Count);
        }

        public async Task<EIPActionResultDTO> ExecuteAsync(
            string actionName,
            EIPActionContextDTO context,
            LoginDTO loginDTO,
            CancellationToken ct = default)
        {
            if (string.IsNullOrWhiteSpace(actionName))
                throw new ArgumentException("Action name cannot be empty.", nameof(actionName));

            if (context == null) throw new ArgumentNullException(nameof(context));
            if (loginDTO == null) throw new ArgumentNullException(nameof(loginDTO));

            try
            {
                _logger.LogInformation("Executing EIP Action: {ActionName}", actionName);

                if (!_handlerMap.TryGetValue(actionName, out var handler))
                {
                    handler = _wildcardHandlers.FirstOrDefault(h => h.CanHandle(actionName));
                    if (handler == null)
                        throw new InvalidOperationException($"No action handler found for action: {actionName}");
                }

                return await handler.HandleAsync(context, loginDTO, ct);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error executing action: {ActionName}", actionName);
                throw;
            }
        }
    }
}