using MediatR;
using System.Security.Cryptography;
using TakeoutSaaS.Application.App.Tenants.Commands;
using TakeoutSaaS.Application.App.Tenants.Dto;
using TakeoutSaaS.Domain.Merchants.Entities;
using TakeoutSaaS.Domain.Merchants.Enums;
using TakeoutSaaS.Domain.Merchants.Repositories;
using TakeoutSaaS.Domain.Tenants.Enums;
using TakeoutSaaS.Domain.Tenants.Repositories;
using TakeoutSaaS.Shared.Abstractions.Constants;
using TakeoutSaaS.Shared.Abstractions.Exceptions;
using TakeoutSaaS.Shared.Abstractions.Ids;
using TakeoutSaaS.Shared.Abstractions.Security;

namespace TakeoutSaaS.Application.App.Tenants.Handlers;

/// <summary>
/// 租户审核处理器。
/// </summary>
public sealed class ReviewTenantCommandHandler(
    ITenantRepository tenantRepository,
    IMerchantRepository merchantRepository,
    ICurrentUserAccessor currentUserAccessor,
    IIdGenerator idGenerator)
    : IRequestHandler<ReviewTenantCommand, TenantDto>
{
    /// <inheritdoc />
    public async Task<TenantDto> Handle(ReviewTenantCommand request, CancellationToken cancellationToken)
    {
        // 1. 获取租户与认证资料
        var tenant = await tenantRepository.FindByIdAsync(request.TenantId, cancellationToken)
            ?? throw new BusinessException(ErrorCodes.NotFound, "租户不存在");

        var reviewClaim = await tenantRepository.FindActiveReviewClaimAsync(request.TenantId, cancellationToken)
            ?? throw new BusinessException(ErrorCodes.Conflict, "请先领取审核");

        if (reviewClaim.ClaimedBy != currentUserAccessor.UserId)
        {
            throw new BusinessException(ErrorCodes.Conflict, $"该审核已被 {reviewClaim.ClaimedByName} 领取");
        }

        var verification = await tenantRepository.GetVerificationProfileAsync(request.TenantId, cancellationToken)
            ?? throw new BusinessException(ErrorCodes.BadRequest, "请先提交实名认证资料");

        var subscription = await tenantRepository.GetActiveSubscriptionAsync(request.TenantId, cancellationToken);

        // 2. 记录审核人
        var actorName = currentUserAccessor.IsAuthenticated
            ? $"user:{currentUserAccessor.UserId}"
            : "system";

        // 3. 写入审核信息
        verification.ReviewedAt = DateTime.UtcNow;
        verification.ReviewedBy = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId;
        verification.ReviewedByName = actorName;
        verification.ReviewRemarks = request.Reason;

        var previousStatus = tenant.Status;

        // 4. 更新租户与订阅状态
        if (request.Approve)
        {
            if (!request.OperatingMode.HasValue)
            {
                throw new BusinessException(ErrorCodes.ValidationFailed, "审核通过时必须选择经营模式");
            }

            var renewMonths = request.RenewMonths ?? 0;
            if (renewMonths <= 0)
            {
                throw new BusinessException(ErrorCodes.ValidationFailed, "续费时长必须为正整数（月）");
            }

            var now = DateTime.UtcNow;
            verification.Status = TenantVerificationStatus.Approved;
            tenant.Status = TenantStatus.Active;
            tenant.OperatingMode = request.OperatingMode;
            if (subscription != null)
            {
                subscription.Status = SubscriptionStatus.Active;

                if (subscription.EffectiveFrom == default || subscription.EffectiveFrom > now)
                {
                    subscription.EffectiveFrom = now;
                }

                var previousEffectiveTo = subscription.EffectiveTo;
                var baseEffectiveTo = subscription.EffectiveTo > now ? subscription.EffectiveTo : now;
                subscription.EffectiveTo = baseEffectiveTo.AddMonths(renewMonths);
                subscription.NextBillingDate = subscription.EffectiveTo;

                await tenantRepository.AddAuditLogAsync(new Domain.Tenants.Entities.TenantAuditLog
                {
                    TenantId = tenant.Id,
                    Action = TenantAuditAction.SubscriptionUpdated,
                    Title = "订阅续费",
                    Description = $"续费 {renewMonths} 月，到期时间：{previousEffectiveTo:yyyy-MM-dd HH:mm:ss} -> {subscription.EffectiveTo:yyyy-MM-dd HH:mm:ss}",
                    OperatorId = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
                    OperatorName = actorName,
                    PreviousStatus = previousStatus,
                    CurrentStatus = tenant.Status
                }, cancellationToken);
            }
            else
            {
                throw new BusinessException(ErrorCodes.BadRequest, "订阅不存在，无法续费");
            }

            var existingMerchant = await merchantRepository.FindByTenantIdAsync(tenant.Id, cancellationToken);
            if (existingMerchant == null)
            {
                var merchant = new Merchant
                {
                    Id = idGenerator.NextId(),
                    TenantId = tenant.Id,
                    BrandName = tenant.Name,
                    BrandAlias = tenant.ShortName,
                    Category = tenant.Industry,
                    ContactPhone = tenant.ContactPhone ?? string.Empty,
                    ContactEmail = tenant.ContactEmail,
                    BusinessLicenseNumber = verification.BusinessLicenseNumber,
                    BusinessLicenseImageUrl = verification.BusinessLicenseUrl,
                    LegalPerson = verification.LegalPersonName,
                    Province = tenant.Province,
                    City = tenant.City,
                    Address = tenant.Address,
                    Status = MerchantStatus.Approved,
                    OperatingMode = request.OperatingMode,
                    ApprovedAt = now,
                    ApprovedBy = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
                    JoinedAt = now,
                    LastReviewedAt = now,
                    LastReviewedBy = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
                    IsFrozen = false,
                    RowVersion = RandomNumberGenerator.GetBytes(16)
                };

                await merchantRepository.AddMerchantAsync(merchant, cancellationToken);
                await merchantRepository.AddAuditLogAsync(new MerchantAuditLog
                {
                    TenantId = tenant.Id,
                    MerchantId = merchant.Id,
                    Action = MerchantAuditAction.ReviewApproved,
                    Title = "商户审核通过",
                    Description = request.Reason,
                    OperatorId = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
                    OperatorName = actorName
                }, cancellationToken);
            }
            else
            {
                existingMerchant.Status = MerchantStatus.Approved;
                existingMerchant.OperatingMode = request.OperatingMode;
                existingMerchant.ApprovedAt = now;
                existingMerchant.ApprovedBy = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId;
                existingMerchant.LastReviewedAt = now;
                existingMerchant.LastReviewedBy = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId;
                existingMerchant.IsFrozen = false;
                existingMerchant.FrozenReason = null;
                existingMerchant.FrozenAt = null;
                await merchantRepository.UpdateMerchantAsync(existingMerchant, cancellationToken);
                await merchantRepository.AddAuditLogAsync(new MerchantAuditLog
                {
                    TenantId = tenant.Id,
                    MerchantId = existingMerchant.Id,
                    Action = MerchantAuditAction.ReviewApproved,
                    Title = "商户审核通过",
                    Description = request.Reason,
                    OperatorId = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
                    OperatorName = actorName
                }, cancellationToken);
            }
        }
        else
        {
            verification.Status = TenantVerificationStatus.Rejected;
            tenant.Status = TenantStatus.PendingReview;
            if (subscription != null)
            {
                subscription.Status = SubscriptionStatus.Suspended;
            }
        }

        // 5. 持久化租户与认证资料
        await tenantRepository.UpdateTenantAsync(tenant, cancellationToken);
        await tenantRepository.UpsertVerificationProfileAsync(verification, cancellationToken);
        if (subscription != null)
        {
            await tenantRepository.UpdateSubscriptionAsync(subscription, cancellationToken);
        }

        // 6. 记录审核日志
        await tenantRepository.AddAuditLogAsync(new Domain.Tenants.Entities.TenantAuditLog
        {
            TenantId = tenant.Id,
            Action = request.Approve ? TenantAuditAction.VerificationApproved : TenantAuditAction.VerificationRejected,
            Title = request.Approve ? "审核通过" : "审核驳回",
            Description = request.Reason,
            OperatorId = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
            OperatorName = actorName,
            PreviousStatus = previousStatus,
            CurrentStatus = tenant.Status
        }, cancellationToken);

        // 7. (空行后) 审核完成自动释放领取
        reviewClaim.ReleasedAt = DateTime.UtcNow;
        await tenantRepository.UpdateReviewClaimAsync(reviewClaim, cancellationToken);
        await tenantRepository.AddAuditLogAsync(new Domain.Tenants.Entities.TenantAuditLog
        {
            TenantId = tenant.Id,
            Action = TenantAuditAction.ReviewClaimReleased,
            Title = "审核完成释放",
            Description = $"释放人：{actorName}",
            OperatorId = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
            OperatorName = actorName,
            PreviousStatus = tenant.Status,
            CurrentStatus = tenant.Status
        }, cancellationToken);

        // 8. 保存并返回 DTO
        await tenantRepository.SaveChangesAsync(cancellationToken);
        await merchantRepository.SaveChangesAsync(cancellationToken);

        return TenantMapping.ToDto(tenant, subscription, verification);
    }
}