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 string? SupplierPriceId { get; init; }
    public string? Barcode { 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();

    public bool IsDraft { get; init; }
    public string? DraftId { get; init; }
    public string? LocationId { get; init; }
    public string? Comment { get; init; }
}

/// <summary>
/// Заказы: локальные черновики (статус «Не отправлен») + серверные заказы (из /api/buyer/report).
/// Черновик можно отправить (создать реальный заказ) или удалить.
/// </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;
            Orders.Clear();

            // 1) Локальные черновики — вверху, статус «Не отправлен»
            foreach (var d in DraftStore.All)
            {
                var items = new ObservableCollection<OrderItemRow>(
                    d.Items.Select(i => new OrderItemRow
                    {
                        Name = i.Name, Qty = i.Qty, Price = i.Price, Sum = i.LineSum,
                        SupplierPriceId = i.SupplierPriceId, Barcode = i.Barcode
                    }));
                Orders.Add(new OrderSummary
                {
                    Date = d.CreatedAt.ToString("dd.MM.yyyy"),
                    Number = d.Number,
                    Supplier = string.Join(", ", d.Items.Select(i => i.Supplier).Where(s => !string.IsNullOrWhiteSpace(s)).Distinct()),
                    Location = d.LocationAddress ?? "",
                    Status = "Не отправлен",
                    ItemsCount = d.ItemsCount,
                    Sum = d.Total,
                    Items = items,
                    IsDraft = true,
                    DraftId = d.Id,
                    LocationId = d.LocationId,
                    Comment = d.Comment
                });
            }

            // 2) Серверные заказы
            var to = DateTime.Today;
            var from = to.AddMonths(-24);
            var lines = await _api.GetBuyerReportAsync(from, to);
            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();
        }
        catch (Exception ex) { Status = ex.Message; }
        finally { Busy = false; }
    }

    [RelayCommand]
    private async Task SendDraftAsync()
    {
        if (SelectedOrder is not { IsDraft: true } d) return;
        Status = null;
        try
        {
            Busy = true;
            var req = new BuyerOrderCreateRequest
            {
                GlobalSign = d.Number.StartsWith("EX-", StringComparison.OrdinalIgnoreCase) ? d.Number : null,
                LocationId = d.LocationId,
                Comment = d.Comment,
                Items = d.Items.Select(i => new BuyerOrderItemReq
                {
                    SupplierPriceId = i.SupplierPriceId ?? "",
                    Qty = (double)i.Qty,
                    ItemName = i.Name,
                    Barcode = i.Barcode
                }).ToList()
            };
            var resp = await _api.CreateOrderAsync(req);
            if (d.DraftId is { } id) DraftStore.Remove(id);
            Status = $"✓ Заказ {resp.GlobalSign ?? resp.OrderId} отправлен ({resp.ItemsCount} поз., {resp.TotalAmount:N2}).";
            await LoadAsync();
        }
        catch (Exception ex) { Status = "Ошибка отправки: " + ex.Message; }
        finally { Busy = false; }
    }

    [RelayCommand]
    private async Task DeleteDraftAsync()
    {
        if (SelectedOrder is not { IsDraft: true } d || d.DraftId is not { } id) return;
        DraftStore.Remove(id);
        await LoadAsync();
        Status = "Черновик удалён.";
    }
}