// EN: Query to get merchant statistics for admin dashboard.
// VI: Query để lấy thống kê merchant cho dashboard admin.

using MediatR;
using Microsoft.EntityFrameworkCore;
using MerchantService.Domain.AggregatesModel.MerchantAggregate;
using MerchantService.Domain.AggregatesModel.ShopAggregate;
using MerchantService.Infrastructure;

namespace MerchantService.API.Application.Queries.Admin;

/// <summary>
/// EN: Query to get merchant statistics (Admin only).
/// VI: Query để lấy thống kê merchant (chỉ Admin).
/// </summary>
public record GetMerchantStatisticsQuery : IRequest<AdminMerchantStatisticsDto>;

/// <summary>
/// EN: Handler for GetMerchantStatisticsQuery.
/// VI: Handler cho GetMerchantStatisticsQuery.
/// </summary>
public class GetMerchantStatisticsQueryHandler : IRequestHandler<GetMerchantStatisticsQuery, AdminMerchantStatisticsDto>
{
    private readonly MerchantServiceContext _context;

    public GetMerchantStatisticsQueryHandler(MerchantServiceContext context)
    {
        _context = context;
    }

    public async Task<AdminMerchantStatisticsDto> Handle(
        GetMerchantStatisticsQuery request,
        CancellationToken cancellationToken)
    {
        var merchantsQuery = _context.Merchants.Where(m => !m.IsDeleted);

        var totalMerchants = await merchantsQuery.CountAsync(cancellationToken);
        
        var pendingApproval = await merchantsQuery
            .CountAsync(m => m.StatusId == MerchantStatus.PendingApproval.Id, cancellationToken);
        
        var active = await merchantsQuery
            .CountAsync(m => m.StatusId == MerchantStatus.Active.Id, cancellationToken);
        
        var suspended = await merchantsQuery
            .CountAsync(m => m.StatusId == MerchantStatus.Suspended.Id, cancellationToken);
        
        var banned = await merchantsQuery
            .CountAsync(m => m.StatusId == MerchantStatus.Banned.Id, cancellationToken);

        var shopsQuery = _context.Shops.Where(s => !s.IsDeleted);
        
        var totalShops = await shopsQuery.CountAsync(cancellationToken);
        
        // EN: Active shops (published/active)
        // VI: Shops đang hoạt động
        var activeShops = await shopsQuery
            .CountAsync(s => s.StatusId == ShopStatus.Active.Id, cancellationToken);

        var totalStaff = await _context.MerchantStaff.CountAsync(cancellationToken);

        return new AdminMerchantStatisticsDto(
            totalMerchants,
            pendingApproval,
            active,
            suspended,
            banned,
            totalShops,
            activeShops,
            totalStaff);
    }
}