using MediatR;
using System.Security.Cryptography;
using TakeoutSaaS.Application.App.Stores.Commands;
using TakeoutSaaS.Application.App.Stores.Enums;
using TakeoutSaaS.Application.App.Stores.Services;
using TakeoutSaaS.Domain.Stores.Entities;
using TakeoutSaaS.Domain.Stores.Enums;
using TakeoutSaaS.Domain.Stores.Repositories;
using TakeoutSaaS.Shared.Abstractions.Constants;
using TakeoutSaaS.Shared.Abstractions.Exceptions;

namespace TakeoutSaaS.Application.App.Stores.Handlers;

/// <summary>
/// 租户端创建门店命令处理器。
/// </summary>
public sealed class CreateStoreCommandHandler(
    StoreContextService storeContextService,
    IStoreRepository storeRepository)
    : IRequestHandler<CreateStoreCommand>
{
    /// <inheritdoc />
    public async Task Handle(CreateStoreCommand request, CancellationToken cancellationToken)
    {
        // 1. 解析上下文
        var context = storeContextService.GetRequiredContext();

        // 2. 生成唯一门店编码
        var existingStores = await storeRepository.SearchAsync(
            context.TenantId,
            context.MerchantId,
            status: null,
            auditStatus: null,
            businessStatus: null,
            ownershipType: null,
            keyword: null,
            includeDeleted: false,
            cancellationToken: cancellationToken);
        var generatedCode = GenerateUniqueStoreCode(existingStores);

        // 3. 组装门店实体
        var serviceTypes = request.ServiceTypes?.Count > 0
            ? request.ServiceTypes
            : [ServiceType.Delivery];
        var store = new Store
        {
            TenantId = context.TenantId,
            MerchantId = context.MerchantId,
            Code = generatedCode,
            Name = request.Name.Trim(),
            Phone = request.ContactPhone.Trim(),
            ManagerName = request.ManagerName.Trim(),
            Address = request.Address.Trim(),
            CoverImageUrl = request.CoverImage?.Trim(),
            SignboardImageUrl = request.CoverImage?.Trim(),
            OwnershipType = StoreOwnershipType.SameEntity,
            AuditStatus = StoreAuditStatus.Draft,
            BusinessStatus = request.BusinessStatus ?? StoreBusinessStatus.Open,
            Status = StoreStatus.Operating
        };
        StoreListMapping.ApplyServiceTypes(store, serviceTypes);

        // 4. 持久化
        await storeRepository.AddStoreAsync(store, cancellationToken);
        await storeRepository.SaveChangesAsync(cancellationToken);
    }

    /// <summary>
    /// 生成当前租户商户内唯一的门店编码。
    /// </summary>
    private static string GenerateUniqueStoreCode(IReadOnlyList<Store> existingStores)
    {
        var existingCodeSet = existingStores
            .Select(store => store.Code.Trim())
            .Where(code => !string.IsNullOrWhiteSpace(code))
            .ToHashSet(StringComparer.OrdinalIgnoreCase);

        const int maxRetryCount = 20;
        for (var attempt = 0; attempt < maxRetryCount; attempt++)
        {
            var candidate = $"ST{DateTime.UtcNow:yyMMddHHmmss}{RandomNumberGenerator.GetInt32(100, 1000)}";
            if (existingCodeSet.Add(candidate))
            {
                return candidate;
            }
        }

        throw new BusinessException(ErrorCodes.Conflict, "门店编码生成失败，请稍后重试");
    }
}