using System;
using System.Collections.Generic;
using System.Reflection;
using System.Threading.Tasks;
using F4SD.ActionConnector.Enumerations;
using F4SD.ActionConnector.Events;
using F4SD.ActionConnector.Execution;
using F4SD.ActionConnector.Models;
using F4SD.ActionConnector.Payloads;
using static C4IT.Logging.cLogManager;

namespace F4SD.ActionConnector.Bus
{
    /// <summary>
    /// Entry point for the ActionConnector.
    /// Subscribes to <see cref="ActionConnectorEvents"/>, reads the configuration once,
    /// and dispatches actions whenever a trigger event fires.
    ///
    /// Usage from the host application:
    /// <code>
    ///   var bus = new ActionBus(new ActionBusOptions
    ///   {
    ///       ConfigurationFilePath = @"C:\Config\F4SD-ExternalCommunication-Configuration.xml",
    ///       QuickActionExecutor   = async request =>
    ///       {
    ///           await myJiraClient.CreateTicketAsync(request.QuickActionRef, request.Parameters);
    ///           return ActionResult.Ok(request.ActionId);
    ///       }
    ///   });
    ///
    ///   bus.Start();
    ///   // later:
    ///   bus.Stop();
    /// </code>
    /// </summary>
    public sealed class ActionBus : IDisposable
    {
        private readonly ActionBusOptions _options;
        private readonly ActionDispatcher _dispatcher;
        private ExternalCommunicationConfiguration _configuration;
        private bool _running;

        public ActionBus(ActionBusOptions options)
        {
            _options = options ?? throw new ArgumentNullException(nameof(options));
            _dispatcher = new ActionDispatcher(options.QuickActionExecutor);
        }

        /// <summary>
        /// Loads the configuration and subscribes to all trigger events.
        /// Call once during application startup.
        /// </summary>
        public void Start()
        {
            var CM = MethodBase.GetCurrentMethod();
            LogMethodBegin(CM);
            try
            {
                _configuration = new ExternalCommunicationConfiguration();
                _configuration.Initiate(_options.ConfigRootElement, _options.Parser);

                ActionConnectorEvents.CaseClosed += OnCaseClosed;
                ActionConnectorEvents.CaseCreated += OnCaseCreated;
                ActionConnectorEvents.ApplicationStartup += OnApplicationStartup;

                _running = true;
                LogEntry("ActionBus started.", C4IT.Logging.LogLevels.Info);
            }
            catch (Exception ex)
            {
                LogException(ex);
            }
            finally
            {
                LogMethodEnd(CM);
            }
        }

        /// <summary>
        /// Unsubscribes from all trigger events.
        /// Call during application shutdown.
        /// </summary>
        public void Stop()
        {
            ActionConnectorEvents.CaseClosed -= OnCaseClosed;
            ActionConnectorEvents.CaseCreated -= OnCaseCreated;
            ActionConnectorEvents.ApplicationStartup -= OnApplicationStartup;

            _running = false;
            LogEntry("ActionBus stopped.", C4IT.Logging.LogLevels.Info);
        }

        public void Dispose() => Stop();

        // ──────────────────────────────────────────────────────────────────────────
        // Event handlers — each one creates a typed ActionContext and fires dispatch
        // ──────────────────────────────────────────────────────────────────────────

        private void OnCaseClosed(object sender, TriggerEventArgs<CaseClosedPayload> args)
            => DispatchTrigger(TriggerEvent.CaseClosed, args.Payload, sender);

        private void OnCaseCreated(object sender, TriggerEventArgs<CaseCreatedPayload> args)
            => DispatchTrigger(TriggerEvent.CaseCreated, args.Payload, sender);

        private void OnApplicationStartup(object sender, TriggerEventArgs<ApplicationStartupPayload> args)
            => DispatchTrigger(TriggerEvent.ApplicationStartup, args.Payload, sender);

        // ──────────────────────────────────────────────────────────────────────────
        // Core dispatch — fire-and-forget wrapper that surfaces results via events
        // ──────────────────────────────────────────────────────────────────────────

        private void DispatchTrigger(TriggerEvent triggerEvent, PayloadBase payload, object sender)
        {
            if (!_running) return;
            if (!_configuration.Triggers.TryGetValue(triggerEvent, out Trigger trigger)) return;

            // Run async dispatch on the thread pool; do not block the caller.
            Task.Run(() => DispatchActionsAsync(trigger.Actions, triggerEvent, payload, sender));
        }

        private async Task DispatchActionsAsync(
            IDictionary<string, ActionDefinitionBase> actions,
            TriggerEvent triggerEvent,
            PayloadBase payload,
            object sender)
        {
            foreach (var pair in actions)
            {
                ActionDefinitionBase action = pair.Value;

                var context = new ActionContext
                {
                    TriggerEvent = triggerEvent,
                    AwaitResult = action.AwaitResult,
                    Payload = payload,
                };

                ActionResult result = await ExecuteSafeAsync(action, context);

                ActionConnectorEvents.RaiseActionCompleted(
                    sender,
                    new ActionCompletedEventArgs(result, context));
            }
        }

        private async Task<ActionResult> ExecuteSafeAsync(ActionDefinitionBase action, ActionContext context)
        {
            try
            {
                return await _dispatcher.DispatchAsync(action, context);
            }
            catch (Exception ex)
            {
                LogException(ex);
                return ActionResult.Fail(action.Id, ex.Message);
            }
        }
    }
}