using EAIAdminBLL.Sync;
using EAIAdminDAL.CustomCode;
using EAIAdminDAL.DTO;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.Resource.Response;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;

namespace EAIAdminBLL.EAIBotAdmin
{
    public class EAIBotAdminBLL : IEAIBotAdminBLL
    {
        private static readonly Regex BotCodePattern =
            new(@"^[A-Za-z0-9_]{1,50}$", RegexOptions.Compiled);

        private readonly IEAIBotAdminDAL _dal;
        private readonly IEAISyncClient _syncClient;
        private readonly ILogger<EAIBotAdminBLL> _logger;

        public EAIBotAdminBLL(
            IEAIBotAdminDAL dal,
            IEAISyncClient syncClient,
            ILogger<EAIBotAdminBLL> logger)
        {
            _dal        = dal        ?? throw new ArgumentNullException(nameof(dal));
            _syncClient = syncClient ?? throw new ArgumentNullException(nameof(syncClient));
            _logger     = logger     ?? throw new ArgumentNullException(nameof(logger));
        }

        public async Task<IEnumerable<EAIBotAdminDTO>> GetBotListAsync(
            string? search, LoginDTO login, CancellationToken ct = default)
        {
            try
            {
                return await _dal.GetBotListAsync(search, login, ct).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "BLL | GetBotList | Error | Tenant={TenantId}", login.ClientId);
                throw;
            }
        }

        public async Task<EAIBotAdminDTO?> GetBotAsync(
            int botId, LoginDTO login, CancellationToken ct = default)
        {
            try
            {
                return await _dal.GetBotAsync(botId, login, ct).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "BLL | GetBot | Error | BotId={Id}", botId);
                throw;
            }
        }

        public async Task<string> SaveBotAsync(
            EAIBotAdminDTO dto, LoginDTO login, CancellationToken ct = default)
        {
            try
            {
                ValidateBotCode(dto.BotCode);

                if (string.IsNullOrWhiteSpace(dto.Name))
                    throw new ArgumentException("Name is required.");

                if (string.IsNullOrWhiteSpace(dto.InitiativeCode))
                    throw new ArgumentException("InitiativeCode is required.");

                // BOTCODE is globally unique — matches gbEAI's unique=True on aibotcode, not
                // per-tenant.
                bool codeExists = await _dal.BotCodeExistsAsync(
                    dto.BotCode, dto.BotId, login, ct).ConfigureAwait(false);

                if (codeExists)
                    throw new InvalidOperationException(
                        $"BotCode '{dto.BotCode}' already exists.");

                dto.TenantId = login.ClientId;

                var isNew = dto.BotId == 0;

                if (isNew)
                {
                    var newId = await _dal.InsertBotAsync(dto, login, ct).ConfigureAwait(false);
                    dto.BotId = newId;
                }
                else
                {
                    await _dal.UpdateBotAsync(dto, login, ct).ConfigureAwait(false);
                }

                // Push to gbEAI AFTER the local commit — never inside a transaction. A failed push
                // does not roll back the local save; GB5 stays system-of-record.
                var syncResult = await _syncClient.PushBotAsync(dto, login, ct).ConfigureAwait(false);

                if (syncResult.Success && syncResult.EAIRemoteId is { } remoteId)
                {
                    await _dal.UpdateEAIRemoteIdAsync(dto.BotId, remoteId, login, ct).ConfigureAwait(false);
                }

                var baseMessage = isNew
                    ? $"{SuccessResponse.SaveSuccessMessage} {dto.BotId}"
                    : SuccessResponse.UpdateSuccess;

                return syncResult.Success
                    ? baseMessage
                    : $"{baseMessage} Sync to AI-Enterprise-v1.0 failed: {syncResult.Message} — retry from this screen.";
            }
            catch (Exception ex)
            {
                _logger.LogError(ex,
                    "BLL | SaveBot | Error | Tenant={TenantId} | BotCode={Code}",
                    login.ClientId, dto.BotCode);
                throw;
            }
        }

        public async Task<string> DeleteBotAsync(
            int botId, LoginDTO login, CancellationToken ct = default)
        {
            try
            {
                if (botId == 0)
                    throw new ArgumentException("BotId must be a positive integer.");

                var existing = await _dal.GetBotAsync(botId, login, ct).ConfigureAwait(false)
                    ?? throw new InvalidOperationException($"Bot {botId} not found.");

                await _dal.DeleteBotAsync(botId, login, ct).ConfigureAwait(false);

                var syncResult = await _syncClient.DeleteBotAsync(existing, login, ct).ConfigureAwait(false);

                return syncResult.Success
                    ? SuccessResponse.DeleteSuccessMessage
                    : $"{SuccessResponse.DeleteSuccessMessage} Sync to AI-Enterprise-v1.0 failed: {syncResult.Message} — retry from this screen.";
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "BLL | DeleteBot | Error | BotId={Id}", botId);
                throw;
            }
        }

        private static void ValidateBotCode(string botCode)
        {
            if (string.IsNullOrWhiteSpace(botCode))
                throw new ArgumentException("BotCode is required.");

            if (!BotCodePattern.IsMatch(botCode))
                throw new ArgumentException(
                    "BotCode must contain only alphanumeric characters and underscores (max 50 chars).");
        }
    }
}