using TransportMauiApp.Models;
using TransportMauiApp.Services;
using Microsoft.Maui.Controls.Shapes;

namespace TransportMauiApp;

public partial class MainPage : ContentPage
{
    private readonly DatabaseService _database = new();
    private readonly VerticalStackLayout _content = new() { Spacing = 14 };
    private readonly List<Button> _sectionButtons = [];

    private UserSession? _session;
    private bool CanEdit => _session?.IsAdministrator == true;

    private List<Driver> _drivers = [];
    private List<AppTransport> _transports = [];
    private List<TransitRoute> _routes = [];
    private List<TransportFlight> _flights = [];

    public MainPage()
    {
        InitializeComponent();
        Title = "Учет транспорта";
        ShowLogin();
    }

    private void ShowLogin()
    {
        var loginEntry = CreateEntry("Логин");
        var passwordEntry = CreateEntry("Пароль");
        passwordEntry.IsPassword = true;

        var statusLabel = new Label
        {
            TextColor = Colors.Firebrick,
            FontSize = 14,
            IsVisible = false
        };

        var loginButton = new Button
        {
            Text = "Войти",
            HeightRequest = 46,
            BackgroundColor = Color.FromArgb("#1D4ED8"),
            TextColor = Colors.White,
            CornerRadius = 8
        };

        loginButton.Clicked += async (_, _) =>
        {
            statusLabel.IsVisible = false;
            loginButton.IsEnabled = false;

            try
            {
                var login = loginEntry.Text?.Trim() ?? string.Empty;
                var password = passwordEntry.Text ?? string.Empty;
                var session = await _database.AuthenticateAsync(login, password);

                if (session is null)
                {
                    statusLabel.Text = "Неверный логин или пароль.";
                    statusLabel.IsVisible = true;
                    return;
                }

                _session = session;
                await LoadLookupsAsync();
                ShowWorkspace();
            }
            catch (Exception ex)
            {
                statusLabel.Text = $"Ошибка подключения: {ex.Message}";
                statusLabel.IsVisible = true;
            }
            finally
            {
                loginButton.IsEnabled = true;
            }
        };

        Content = new Grid
        {
            Padding = new Thickness(22),
            Children =
            {
                new Border
                {
                    StrokeThickness = 1,
                    Stroke = Color.FromArgb("#D7DEE8"),
                    BackgroundColor = Colors.White,
                    StrokeShape = new RoundRectangle { CornerRadius = 8 },
                    MaximumWidthRequest = 460,
                    VerticalOptions = LayoutOptions.Center,
                    HorizontalOptions = LayoutOptions.Center,
                    Padding = new Thickness(24),
                    Content = new VerticalStackLayout
                    {
                        Spacing = 14,
                        Children =
                        {
                            new Label
                            {
                                Text = "Авторизация",
                                FontSize = 26,
                                FontAttributes = FontAttributes.Bold,
                                TextColor = Color.FromArgb("#172033")
                            },
                            loginEntry,
                            passwordEntry,
                            loginButton,
                            statusLabel
                        }
                    }
                }
            }
        };
    }

    private void ShowWorkspace()
    {
        _sectionButtons.Clear();
        _content.Children.Clear();

        var header = new Grid
        {
            ColumnDefinitions =
            {
                new ColumnDefinition(GridLength.Star),
                new ColumnDefinition(GridLength.Auto)
            },
            RowDefinitions =
            {
                new RowDefinition(GridLength.Auto),
                new RowDefinition(GridLength.Auto)
            },
            ColumnSpacing = 12
        };

        header.Add(new Label
        {
            Text = "Учет транспорта",
            FontSize = 26,
            FontAttributes = FontAttributes.Bold,
            TextColor = Color.FromArgb("#172033")
        }, 0, 0);

        var logoutButton = new Button
        {
            Text = "Выйти",
            BackgroundColor = Color.FromArgb("#EEF2F7"),
            TextColor = Color.FromArgb("#172033"),
            CornerRadius = 8
        };
        logoutButton.Clicked += (_, _) =>
        {
            _session = null;
            ShowLogin();
        };
        header.Add(logoutButton, 1, 0);

        header.Add(new Label
        {
            Text = $"Пользователь: {_session?.Login} | Роль: {_session?.DisplayRole} | Режим: {(CanEdit ? "полный доступ" : "только чтение")}",
            FontSize = 14,
            TextColor = Color.FromArgb("#526070")
        }, 0, 1);

        var tabs = new HorizontalStackLayout
        {
            Spacing = 8,
            Children =
            {
                CreateSectionButton("Водители", ShowDriversSection),
                CreateSectionButton("Транспорт", ShowTransportsSection),
                CreateSectionButton("Маршруты", ShowRoutesSection),
                CreateSectionButton("Рейсы", ShowFlightsSection),
                CreateSectionButton("Информация о рейсах", ShowFlightInfoSection)
            }
        };

        Content = new ScrollView
        {
            Content = new VerticalStackLayout
            {
                Padding = new Thickness(20),
                Spacing = 16,
                Children =
                {
                    header,
                    new ScrollView { Orientation = ScrollOrientation.Horizontal, Content = tabs },
                    _content
                }
            }
        };

        ShowDriversSection();
    }

    private Button CreateSectionButton(string text, Action action)
    {
        var button = new Button
        {
            Text = text,
            CornerRadius = 8,
            Padding = new Thickness(14, 8),
            BackgroundColor = Colors.White,
            BorderColor = Color.FromArgb("#D7DEE8"),
            BorderWidth = 1,
            TextColor = Color.FromArgb("#172033")
        };

        button.Clicked += (_, _) =>
        {
            foreach (var tab in _sectionButtons)
            {
                tab.BackgroundColor = Colors.White;
                tab.TextColor = Color.FromArgb("#172033");
            }

            button.BackgroundColor = Color.FromArgb("#1D4ED8");
            button.TextColor = Colors.White;
            action();
        };

        _sectionButtons.Add(button);
        return button;
    }

    private async Task LoadLookupsAsync()
    {
        _drivers = [.. await _database.GetDriversAsync()];
        _transports = [.. await _database.GetTransportsAsync()];
        _routes = [.. await _database.GetRoutesAsync()];
        _flights = [.. await _database.GetFlightsAsync()];
    }

    private async void ShowDriversSection()
    {
        await LoadDriversSectionAsync();
    }

    private async Task LoadDriversSectionAsync()
    {
        _content.Children.Clear();
        await RunSafelyAsync(async () =>
        {
            _drivers = [.. await _database.GetDriversAsync()];
            var recordsCount = await _database.GetDriversCountAsync();
            var list = CreateCollectionView(_drivers);

            var nameEntry = CreateEntry("Имя");
            var surnameEntry = CreateEntry("Фамилия");
            var patronimicEntry = CreateEntry("Отчество");
            Driver? selected = null;

            list.SelectionChanged += (_, e) =>
            {
                selected = e.CurrentSelection.FirstOrDefault() as Driver;
                if (selected is null)
                {
                    return;
                }

                nameEntry.Text = selected.Name;
                surnameEntry.Text = selected.Surname;
                patronimicEntry.Text = selected.Patronimic;
            };

            _content.Children.Add(CreateSectionTitle("Водители", recordsCount));
            _content.Children.Add(list);
            if (CanEdit)
            {
                _content.Children.Add(CreateForm(
                    [nameEntry, surnameEntry, patronimicEntry],
                    CreateCrudButtons(
                        add: async () =>
                        {
                            if (!ValidateRequired(nameEntry, surnameEntry, patronimicEntry))
                            {
                                await DisplayAlertAsync("Проверка", "Заполните все поля.", "OK");
                                return;
                            }

                            await _database.AddDriverAsync(new Driver
                            {
                                Name = nameEntry.Text!.Trim(),
                                Surname = surnameEntry.Text!.Trim(),
                                Patronimic = patronimicEntry.Text!.Trim()
                            });
                            ClearEntries(nameEntry, surnameEntry, patronimicEntry);
                            await LoadDriversSectionAsync();
                        },
                        update: async () =>
                        {
                            if (selected is null || !ValidateRequired(nameEntry, surnameEntry, patronimicEntry))
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись и заполните все поля.", "OK");
                                return;
                            }

                            selected.Name = nameEntry.Text!.Trim();
                            selected.Surname = surnameEntry.Text!.Trim();
                            selected.Patronimic = patronimicEntry.Text!.Trim();
                            await _database.UpdateDriverAsync(selected);
                            await LoadDriversSectionAsync();
                        },
                        delete: async () =>
                        {
                            if (selected is null)
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись.", "OK");
                                return;
                            }

                            await _database.DeleteDriverAsync(selected.DriverId);
                            await LoadDriversSectionAsync();
                        })));
            }
        });
    }

    private async void ShowTransportsSection()
    {
        await LoadTransportsSectionAsync();
    }

    private async Task LoadTransportsSectionAsync()
    {
        _content.Children.Clear();
        await RunSafelyAsync(async () =>
        {
            await LoadLookupsAsync();
            var recordsCount = await _database.GetTransportsCountAsync();
            var list = CreateCollectionView(_transports);
            var branchEntry = CreateEntry("Филиал");
            var modelEntry = CreateEntry("Модель");
            var plateEntry = CreateEntry("Госномер");
            var driverPicker = CreatePicker("Водитель", _drivers);
            AppTransport? selected = null;

            list.SelectionChanged += (_, e) =>
            {
                selected = e.CurrentSelection.FirstOrDefault() as AppTransport;
                if (selected is null)
                {
                    return;
                }

                branchEntry.Text = selected.Branch;
                modelEntry.Text = selected.Model;
                plateEntry.Text = selected.LicensePlateNumber;
                driverPicker.SelectedItem = _drivers.FirstOrDefault(driver => driver.DriverId == selected.DriverId);
            };

            _content.Children.Add(CreateSectionTitle("Транспорт", recordsCount));
            _content.Children.Add(list);
            if (CanEdit)
            {
                var assignButton = new Button
                {
                    Text = "Назначить водителя процедурой",
                    BackgroundColor = Color.FromArgb("#0F766E"),
                    TextColor = Colors.White,
                    CornerRadius = 8
                };
                assignButton.Clicked += async (_, _) =>
                {
                    if (selected is null || driverPicker.SelectedItem is not Driver driver)
                    {
                        await DisplayAlertAsync("Проверка", "Выберите транспорт и водителя.", "OK");
                        return;
                    }

                    await RunSafelyAsync(async () =>
                    {
                        await _database.AssignDriverToTransportAsync(selected.TransportId, driver.DriverId);
                        await LoadTransportsSectionAsync();
                    });
                };

                _content.Children.Add(CreateForm(
                    [branchEntry, modelEntry, plateEntry, driverPicker],
                    CreateCrudButtons(
                        add: async () =>
                        {
                            if (!ValidateRequired(branchEntry, modelEntry, plateEntry))
                            {
                                await DisplayAlertAsync("Проверка", "Заполните филиал, модель и госномер.", "OK");
                                return;
                            }

                            await _database.AddTransportAsync(new AppTransport
                            {
                                Branch = branchEntry.Text!.Trim(),
                                Model = modelEntry.Text!.Trim(),
                                LicensePlateNumber = plateEntry.Text!.Trim(),
                                DriverId = (driverPicker.SelectedItem as Driver)?.DriverId
                            });
                            await LoadTransportsSectionAsync();
                        },
                        update: async () =>
                        {
                            if (selected is null || !ValidateRequired(branchEntry, modelEntry, plateEntry))
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись и заполните обязательные поля.", "OK");
                                return;
                            }

                            selected.Branch = branchEntry.Text!.Trim();
                            selected.Model = modelEntry.Text!.Trim();
                            selected.LicensePlateNumber = plateEntry.Text!.Trim();
                            selected.DriverId = (driverPicker.SelectedItem as Driver)?.DriverId;
                            await _database.UpdateTransportAsync(selected);
                            await LoadTransportsSectionAsync();
                        },
                        delete: async () =>
                        {
                            if (selected is null)
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись.", "OK");
                                return;
                            }

                            await _database.DeleteTransportAsync(selected.TransportId);
                            await LoadTransportsSectionAsync();
                        },
                        extra: assignButton)));
            }
        });
    }

    private async void ShowRoutesSection()
    {
        await LoadRoutesSectionAsync();
    }

    private async Task LoadRoutesSectionAsync()
    {
        _content.Children.Clear();
        await RunSafelyAsync(async () =>
        {
            _routes = [.. await _database.GetRoutesAsync()];
            var recordsCount = await _database.GetRoutesCountAsync();
            var list = CreateCollectionView(_routes);
            var routeNameEntry = CreateEntry("Название маршрута");
            TransitRoute? selected = null;

            list.SelectionChanged += (_, e) =>
            {
                selected = e.CurrentSelection.FirstOrDefault() as TransitRoute;
                routeNameEntry.Text = selected?.RouteName;
            };

            _content.Children.Add(CreateSectionTitle("Маршруты", recordsCount));
            _content.Children.Add(list);
            if (CanEdit)
            {
                _content.Children.Add(CreateForm(
                    [routeNameEntry],
                    CreateCrudButtons(
                        add: async () =>
                        {
                            if (!ValidateRequired(routeNameEntry))
                            {
                                await DisplayAlertAsync("Проверка", "Введите название маршрута.", "OK");
                                return;
                            }

                            await _database.AddRouteAsync(new TransitRoute { RouteName = routeNameEntry.Text!.Trim() });
                            await LoadRoutesSectionAsync();
                        },
                        update: async () =>
                        {
                            if (selected is null || !ValidateRequired(routeNameEntry))
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись и заполните название.", "OK");
                                return;
                            }

                            selected.RouteName = routeNameEntry.Text!.Trim();
                            await _database.UpdateRouteAsync(selected);
                            await LoadRoutesSectionAsync();
                        },
                        delete: async () =>
                        {
                            if (selected is null)
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись.", "OK");
                                return;
                            }

                            await _database.DeleteRouteAsync(selected.RouteId);
                            await LoadRoutesSectionAsync();
                        })));
            }
        });
    }

    private async void ShowFlightsSection()
    {
        await LoadFlightsSectionAsync();
    }

    private async Task LoadFlightsSectionAsync()
    {
        _content.Children.Clear();
        await RunSafelyAsync(async () =>
        {
            await LoadLookupsAsync();
            var recordsCount = await _database.GetFlightsCountAsync();
            var list = CreateCollectionView(_flights);
            var durationEntry = CreateEntry("Длительность HH:mm:ss");
            var transportPicker = CreatePicker("Транспорт", _transports);
            var routePicker = CreatePicker("Маршрут", _routes);
            TransportFlight? selected = null;

            list.SelectionChanged += (_, e) =>
            {
                selected = e.CurrentSelection.FirstOrDefault() as TransportFlight;
                if (selected is null)
                {
                    return;
                }

                durationEntry.Text = selected.Duration.ToString(@"hh\:mm\:ss");
                transportPicker.SelectedItem = _transports.FirstOrDefault(transport => transport.TransportId == selected.TransportId);
                routePicker.SelectedItem = _routes.FirstOrDefault(route => route.RouteId == selected.RouteId);
            };

            _content.Children.Add(CreateSectionTitle("Рейсы", recordsCount));
            _content.Children.Add(list);
            if (CanEdit)
            {
                _content.Children.Add(CreateForm(
                    [durationEntry, transportPicker, routePicker],
                    CreateCrudButtons(
                        add: async () =>
                        {
                            var flight = await CreateFlightFromFormAsync(durationEntry, transportPicker, routePicker);
                            if (flight is null)
                            {
                                return;
                            }

                            await _database.AddFlightAsync(flight);
                            await LoadFlightsSectionAsync();
                        },
                        update: async () =>
                        {
                            var flight = await CreateFlightFromFormAsync(durationEntry, transportPicker, routePicker);
                            if (selected is null || flight is null)
                            {
                                await DisplayAlertAsync("Проверка", "Выберите рейс и заполните поля.", "OK");
                                return;
                            }

                            flight.FlightId = selected.FlightId;
                            await _database.UpdateFlightAsync(flight);
                            await LoadFlightsSectionAsync();
                        },
                        delete: async () =>
                        {
                            if (selected is null)
                            {
                                await DisplayAlertAsync("Проверка", "Выберите запись.", "OK");
                                return;
                            }

                            await _database.DeleteFlightAsync(selected.FlightId);
                            await LoadFlightsSectionAsync();
                        })));
            }
        });
    }

    private async void ShowFlightInfoSection()
    {
        _content.Children.Clear();
        await RunSafelyAsync(async () =>
        {
            await LoadLookupsAsync();
            var routePicker = CreatePicker("Фильтр по маршруту", _routes);
            var flightInfo = await _database.GetFlightInfoAsync();
            var recordsCount = await _database.GetFlightInfoCountAsync();
            var list = CreateCollectionView(flightInfo);

            var allButton = new Button
            {
                Text = "Все рейсы",
                BackgroundColor = Color.FromArgb("#1D4ED8"),
                TextColor = Colors.White,
                CornerRadius = 8
            };
            allButton.Clicked += async (_, _) =>
            {
                await RunSafelyAsync(async () => list.ItemsSource = await _database.GetFlightInfoAsync());
            };

            var byRouteButton = new Button
            {
                Text = "По выбранному маршруту",
                BackgroundColor = Color.FromArgb("#0F766E"),
                TextColor = Colors.White,
                CornerRadius = 8
            };
            byRouteButton.Clicked += async (_, _) =>
            {
                if (routePicker.SelectedItem is not TransitRoute route)
                {
                    await DisplayAlertAsync("Проверка", "Выберите маршрут.", "OK");
                    return;
                }

                await RunSafelyAsync(async () => list.ItemsSource = await _database.GetFlightsByRouteAsync(route.RouteId));
            };

            _content.Children.Add(CreateSectionTitle("Информация о рейсах", recordsCount));
            _content.Children.Add(new Border
            {
                StrokeThickness = 1,
                Stroke = Color.FromArgb("#D7DEE8"),
                BackgroundColor = Colors.White,
                StrokeShape = new RoundRectangle { CornerRadius = 8 },
                Padding = new Thickness(12),
                Content = new VerticalStackLayout
                {
                    Spacing = 10,
                    Children =
                    {
                        routePicker,
                        new HorizontalStackLayout
                        {
                            Spacing = 8,
                            Children = { allButton, byRouteButton }
                        }
                    }
                }
            });
            _content.Children.Add(list);
        });
    }

    private async Task<TransportFlight?> CreateFlightFromFormAsync(Entry durationEntry, Picker transportPicker, Picker routePicker)
    {
        if (!TimeSpan.TryParse(durationEntry.Text, out var duration) || duration <= TimeSpan.Zero)
        {
            await DisplayAlertAsync("Проверка", "Длительность должна быть больше 00:00:00 в формате HH:mm:ss.", "OK");
            return null;
        }

        if (transportPicker.SelectedItem is not AppTransport transport || routePicker.SelectedItem is not TransitRoute route)
        {
            await DisplayAlertAsync("Проверка", "Выберите транспорт и маршрут.", "OK");
            return null;
        }

        return new TransportFlight
        {
            Duration = duration,
            TransportId = transport.TransportId,
            RouteId = route.RouteId
        };
    }

    private static Border CreateSectionTitle(string text, int recordsCount)
    {
        return new Border
        {
            StrokeThickness = 0,
            BackgroundColor = Color.FromArgb("#E8EEF6"),
            StrokeShape = new RoundRectangle { CornerRadius = 8 },
            Padding = new Thickness(14, 10),
            Content = new Label
            {
                Text = $"{text}: {recordsCount} {GetRecordsWord(recordsCount)}",
                FontSize = 20,
                FontAttributes = FontAttributes.Bold,
                TextColor = Color.FromArgb("#172033")
            }
        };
    }

    private static string GetRecordsWord(int count)
    {
        var lastTwoDigits = count % 100;
        if (lastTwoDigits is >= 11 and <= 14)
        {
            return "записей";
        }

        return (count % 10) switch
        {
            1 => "запись",
            >= 2 and <= 4 => "записи",
            _ => "записей"
        };
    }

    private static Entry CreateEntry(string placeholder)
    {
        return new Entry
        {
            Placeholder = placeholder,
            BackgroundColor = Colors.White,
            TextColor = Color.FromArgb("#172033"),
            PlaceholderColor = Color.FromArgb("#7B8794")
        };
    }

    private static Picker CreatePicker<T>(string title, IReadOnlyList<T> items)
    {
        return new Picker
        {
            Title = title,
            ItemsSource = items.ToList(),
            BackgroundColor = Colors.White,
            TextColor = Color.FromArgb("#172033"),
            TitleColor = Color.FromArgb("#7B8794")
        };
    }

    private static CollectionView CreateCollectionView<T>(IEnumerable<T> items)
    {
        return new CollectionView
        {
            ItemsSource = items.ToList(),
            SelectionMode = SelectionMode.Single,
            EmptyView = "Нет данных",
            MinimumHeightRequest = 220,
            ItemTemplate = new DataTemplate(() =>
            {
                var label = new Label
                {
                    FontSize = 15,
                    TextColor = Color.FromArgb("#172033"),
                    LineBreakMode = LineBreakMode.WordWrap
                };
                label.SetBinding(Label.TextProperty, ".");

                return new Border
                {
                    StrokeThickness = 1,
                    Stroke = Color.FromArgb("#D7DEE8"),
                    BackgroundColor = Colors.White,
                    StrokeShape = new RoundRectangle { CornerRadius = 8 },
                    Margin = new Thickness(0, 0, 0, 8),
                    Padding = new Thickness(12),
                    Content = label
                };
            })
        };
    }

    private static Border CreateForm(IReadOnlyList<View> fields, HorizontalStackLayout buttons)
    {
        var stack = new VerticalStackLayout { Spacing = 10 };
        foreach (var field in fields)
        {
            stack.Children.Add(field);
        }

        stack.Children.Add(buttons);

        return new Border
        {
            StrokeThickness = 1,
            Stroke = Color.FromArgb("#D7DEE8"),
            BackgroundColor = Colors.White,
            StrokeShape = new RoundRectangle { CornerRadius = 8 },
            Padding = new Thickness(12),
            Content = stack
        };
    }

    private HorizontalStackLayout CreateCrudButtons(Func<Task> add, Func<Task> update, Func<Task> delete, Button? extra = null)
    {
        var layout = new HorizontalStackLayout { Spacing = 8 };
        layout.Children.Add(CreateActionButton("Добавить", "#1D4ED8", add));
        layout.Children.Add(CreateActionButton("Сохранить", "#0F766E", update));
        layout.Children.Add(CreateActionButton("Удалить", "#B42318", delete));

        if (extra is not null)
        {
            layout.Children.Add(extra);
        }

        return layout;
    }

    private Button CreateActionButton(string text, string color, Func<Task> action)
    {
        var button = new Button
        {
            Text = text,
            BackgroundColor = Color.FromArgb(color),
            TextColor = Colors.White,
            CornerRadius = 8
        };

        button.Clicked += async (_, _) =>
        {
            if (!CanEdit)
            {
                await DisplayAlertAsync("Доступ запрещен", "Менеджер может только читать данные.", "OK");
                return;
            }

            await RunSafelyAsync(action);
        };

        return button;
    }

    private static bool ValidateRequired(params Entry[] entries)
    {
        foreach (var entry in entries)
        {
            if (string.IsNullOrWhiteSpace(entry.Text))
            {
                return false;
            }
        }

        return true;
    }

    private static void ClearEntries(params Entry[] entries)
    {
        foreach (var entry in entries)
        {
            entry.Text = string.Empty;
        }
    }

    private async Task RunSafelyAsync(Func<Task> action)
    {
        try
        {
            await action();
        }
        catch (Exception ex)
        {
            await DisplayAlertAsync("Ошибка", ex.Message, "OK");
        }
    }
}