using System;
using System.Collections.ObjectModel;
using System.Linq;
using System.Threading.Tasks;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using Elfisa.Core;

namespace Elfisa.Avalonia.ViewModels;

public sealed class OrderItemRow
{
    public string Name { get; init; } = "";
    public string Code { get; init; } = "";
    public decimal Qty { get; init; }
    public decimal Price { get; init; }
    public decimal Sum { get; init; }
}

public sealed class OrderSummary
{
    public string Date { get; init; } = "";
    public string Number { get; init; } = "";
    public string Supplier { get; init; } = "";
    public string Location { get; init; } = "";
    public string Status { get; init; } = "";
    public int ItemsCount { get; init; }
    public decimal Sum { get; init; }
    public ObservableCollection<OrderItemRow> Items { get; init; } = new();
}

/// <summary>
/// Заказы: список + состав. Пока строится из /api/buyer/report (он работает);
/// после деплоя фикса /api/buyer/orders можно перейти на «родной» эндпоинт
/// (даст ещё PlacedAt, Comment, отмену/размещение).
/// </summary>
public partial class OrdersViewModel : ViewModelBase
{
    private readonly ApiClient _api = new();

    public ObservableCollection<OrderSummary> Orders { get; } = new();

    [ObservableProperty] private OrderSummary? _selectedOrder;
    [ObservableProperty] private bool _busy;
    [ObservableProperty] private string? _status;

    public OrdersViewModel()
    {
        _api.SetToken(Session.Current.Token);
        if (Session.Current.IsAuthenticated) _ = LoadAsync();
    }

    [RelayCommand]
    private async Task LoadAsync()
    {
        Status = null;
        try
        {
            Busy = true;
            var to = DateTime.Today;
            var from = to.AddMonths(-24);
            var lines = await _api.GetBuyerReportAsync(from, to);

            Orders.Clear();
            foreach (var g in lines.GroupBy(l => l.OrderId)
                         .OrderByDescending(x => x.First().OrderDate ?? DateTime.MinValue))
            {
                var f = g.First();
                var items = new ObservableCollection<OrderItemRow>(
                    g.Select(l => new OrderItemRow
                    {
                        Name = l.ItemName ?? "",
                        Code = l.ItemCode ?? "",
                        Qty = l.Qty,
                        Price = l.UnitPrice,
                        Sum = l.Sum
                    }));

                Orders.Add(new OrderSummary
                {
                    Date = f.OrderDate?.ToLocalTime().ToString("dd.MM.yyyy") ?? "",
                    Number = f.GlobalSign ?? "",
                    Supplier = string.Join(", ", g.Select(x => x.Supplier)
                        .Where(s => !string.IsNullOrWhiteSpace(s)).Distinct()),
                    Location = f.Location ?? "",
                    Status = f.Status ?? "",
                    ItemsCount = g.Count(),
                    Sum = g.Sum(x => x.Sum),
                    Items = items
                });
            }

            SelectedOrder = Orders.FirstOrDefault();
            if (Orders.Count == 0) Status = "Заказов за последние 2 года нет.";
        }
        catch (Exception ex) { Status = ex.Message; }
        finally { Busy = false; }
    }
}