/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file depot_gui.cpp The GUI for depots. */

#include "stdafx.h"
#include "train.h"
#include "roadveh.h"
#include "ship.h"
#include "aircraft.h"
#include "gui.h"
#include "textbuf_gui.h"
#include "viewport_func.h"
#include "command_func.h"
#include "depot_base.h"
#include "spritecache.h"
#include "strings_func.h"
#include "sound_func.h"
#include "vehicle_func.h"
#include "company_func.h"
#include "tilehighlight_func.h"
#include "window_gui.h"
#include "vehiclelist.h"
#include "vehicle_func.h"
#include "order_backup.h"
#include "zoom_func.h"
#include "error.h"
#include "depot_cmd.h"
#include "train_cmd.h"
#include "vehicle_cmd.h"
#include "core/geometry_func.hpp"

#include "widgets/depot_widget.h"

#include "table/strings.h"

#include "safeguards.h"

/*
 * Since all depot window sizes aren't the same, we need to modify sizes a little.
 * It's done with the following arrays of widget indexes. Each of them tells if a widget side should be moved and in what direction.
 * How long they should be moved and for what window types are controlled in ShowDepotWindow()
 */

/** Nested widget definition for train depots. */
static constexpr NWidgetPart _nested_train_depot_widgets[] = {
	NWidget(NWID_HORIZONTAL),
		NWidget(WWT_CLOSEBOX, COLOUR_GREY),
		NWidget(NWID_SELECTION, INVALID_COLOUR, WID_D_SHOW_RENAME), SetAspect(WidgetDimensions::ASPECT_RENAME), // rename button
			NWidget(WWT_PUSHIMGBTN, COLOUR_GREY, WID_D_RENAME), SetAspect(WidgetDimensions::ASPECT_RENAME), SetSpriteTip(SPR_RENAME, STR_DEPOT_RENAME_TOOLTIP),
		EndContainer(),
		NWidget(WWT_CAPTION, COLOUR_GREY, WID_D_CAPTION),
		NWidget(WWT_PUSHIMGBTN, COLOUR_GREY, WID_D_LOCATION), SetAspect(WidgetDimensions::ASPECT_LOCATION), SetSpriteTip(SPR_GOTO_LOCATION),
		NWidget(WWT_SHADEBOX, COLOUR_GREY),
		NWidget(WWT_DEFSIZEBOX, COLOUR_GREY),
		NWidget(WWT_STICKYBOX, COLOUR_GREY),
	EndContainer(),
	NWidget(NWID_HORIZONTAL),
		NWidget(NWID_VERTICAL),
			NWidget(WWT_MATRIX, COLOUR_GREY, WID_D_MATRIX), SetResize(1, 1), SetScrollbar(WID_D_V_SCROLL),
			NWidget(NWID_SELECTION, INVALID_COLOUR, WID_D_SHOW_H_SCROLL),
				NWidget(NWID_HSCROLLBAR, COLOUR_GREY, WID_D_H_SCROLL),
			EndContainer(),
		EndContainer(),
		NWidget(NWID_VERTICAL),
			NWidget(WWT_IMGBTN, COLOUR_GREY, WID_D_SELL), SetResize(0, 1), SetFill(0, 1),
			NWidget(NWID_SELECTION, INVALID_COLOUR, WID_D_SHOW_SELL_CHAIN),
				NWidget(WWT_IMGBTN, COLOUR_GREY, WID_D_SELL_CHAIN), SetSpriteTip(SPR_SELL_CHAIN_TRAIN, STR_DEPOT_DRAG_WHOLE_TRAIN_TO_SELL_TOOLTIP), SetResize(0, 1), SetFill(0, 1),
			EndContainer(),
			NWidget(WWT_PUSHIMGBTN, COLOUR_GREY, WID_D_SELL_ALL),
			NWidget(WWT_PUSHIMGBTN, COLOUR_GREY, WID_D_AUTOREPLACE),
		EndContainer(),
		NWidget(NWID_VSCROLLBAR, COLOUR_GREY, WID_D_V_SCROLL),
	EndContainer(),
	NWidget(NWID_HORIZONTAL, NWidContainerFlag::EqualSize),
		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_D_BUILD), SetFill(1, 1), SetResize(1, 0),
		NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_D_CLONE), SetFill(1, 1), SetResize(1, 0),
		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_D_VEHICLE_LIST), SetAspect(WidgetDimensions::ASPECT_VEHICLE_ICON), SetFill(0, 1),
		NWidget(WWT_PUSHIMGBTN, COLOUR_GREY, WID_D_STOP_ALL), SetSpriteTip(SPR_FLAG_VEH_STOPPED), SetAspect(WidgetDimensions::ASPECT_VEHICLE_FLAG), SetFill(0, 1),
		NWidget(WWT_PUSHIMGBTN, COLOUR_GREY, WID_D_START_ALL), SetSpriteTip(SPR_FLAG_VEH_RUNNING), SetAspect(WidgetDimensions::ASPECT_VEHICLE_FLAG), SetFill(0, 1),
		NWidget(WWT_RESIZEBOX, COLOUR_GREY),
	EndContainer(),
};

static WindowDesc _train_depot_desc(
	WDP_AUTO, "depot_train", 362, 123,
	WC_VEHICLE_DEPOT, WC_NONE,
	{},
	_nested_train_depot_widgets
);

static WindowDesc _road_depot_desc(
	WDP_AUTO, "depot_roadveh", 316, 97,
	WC_VEHICLE_DEPOT, WC_NONE,
	{},
	_nested_train_depot_widgets
);

static WindowDesc _ship_depot_desc(
	WDP_AUTO, "depot_ship", 306, 99,
	WC_VEHICLE_DEPOT, WC_NONE,
	{},
	_nested_train_depot_widgets
);

static WindowDesc _aircraft_depot_desc(
	WDP_AUTO, "depot_aircraft", 332, 99,
	WC_VEHICLE_DEPOT, WC_NONE,
	{},
	_nested_train_depot_widgets
);

extern void DepotSortList(VehicleList *list);

/**
 * This is the Callback method after the cloning attempt of a vehicle
 * @param result the result of the cloning command
 * @param veh_id cloned vehicle ID
 */
void CcCloneVehicle(Commands, const CommandCost &result, VehicleID veh_id)
{
	if (result.Failed()) return;

	const Vehicle *v = Vehicle::Get(veh_id);

	ShowVehicleViewWindow(v);
}

static void TrainDepotMoveVehicle(const Vehicle *wagon, VehicleID sel, const Vehicle *head)
{
	const Vehicle *v = Vehicle::Get(sel);

	if (v == wagon) return;

	if (wagon == nullptr) {
		if (head != nullptr) wagon = head->Last();
	} else {
		wagon = wagon->Previous();
		if (wagon == nullptr) return;
	}

	if (wagon == v) return;

	Command<CMD_MOVE_RAIL_VEHICLE>::Post(STR_ERROR_CAN_T_MOVE_VEHICLE, v->tile, v->index, wagon == nullptr ? VehicleID::Invalid() : wagon->index, _ctrl_pressed);
}

static VehicleCellSize _base_block_sizes_depot[VEH_COMPANY_END];    ///< Cell size for vehicle images in the depot view.
static VehicleCellSize _base_block_sizes_purchase[VEH_COMPANY_END]; ///< Cell size for vehicle images in the purchase list.
static uint _consistent_train_width;                                ///< Whether trains of all lengths are consistently scaled. Either TRAININFO_DEFAULT_VEHICLE_WIDTH, VEHICLEINFO_FULL_VEHICLE_WIDTH, or 0.

/**
 * Get the GUI cell size for a vehicle image.
 * @param type Vehicle type to get the size for.
 * @param image_type Image type to get size for.
 * @pre image_type == EIT_IN_DEPOT || image_type == EIT_PURCHASE
 * @return Cell dimensions for the vehicle and image type.
 */
VehicleCellSize GetVehicleImageCellSize(VehicleType type, EngineImageType image_type)
{
	switch (image_type) {
		case EIT_IN_DEPOT: return _base_block_sizes_depot[type];
		case EIT_PURCHASE: return _base_block_sizes_purchase[type];
		default: NOT_REACHED();
	}
}

static void InitBlocksizeForVehicles(VehicleType type, EngineImageType image_type)
{
	int max_extend_left  = 0;
	int max_extend_right = 0;
	uint max_height = 0;

	for (const Engine *e : Engine::IterateType(type)) {
		if (!e->IsEnabled()) continue;

		EngineID eid = e->index;
		uint x, y;
		int x_offs, y_offs;

		switch (type) {
			default: NOT_REACHED();
			case VEH_TRAIN:    GetTrainSpriteSize(   eid, x, y, x_offs, y_offs, image_type); break;
			case VEH_ROAD:     GetRoadVehSpriteSize( eid, x, y, x_offs, y_offs, image_type); break;
			case VEH_SHIP:     GetShipSpriteSize(    eid, x, y, x_offs, y_offs, image_type); break;
			case VEH_AIRCRAFT: GetAircraftSpriteSize(eid, x, y, x_offs, y_offs, image_type); break;
		}
		if (y > max_height) max_height = y;
		if (-x_offs > max_extend_left) max_extend_left = -x_offs;
		if ((int)x + x_offs > max_extend_right) max_extend_right = x + x_offs;
	}

	int min_extend = ScaleSpriteTrad(16);
	int max_extend = ScaleSpriteTrad(98);

	switch (image_type) {
		case EIT_IN_DEPOT:
			_base_block_sizes_depot[type].height       = std::max<uint>(ScaleSpriteTrad(GetVehicleHeight(type)), max_height);
			_base_block_sizes_depot[type].extend_left  = Clamp(max_extend_left, min_extend, max_extend);
			_base_block_sizes_depot[type].extend_right = Clamp(max_extend_right, min_extend, max_extend);
			break;
		case EIT_PURCHASE:
			_base_block_sizes_purchase[type].height       = std::max<uint>(ScaleSpriteTrad(GetVehicleHeight(type)), max_height);
			_base_block_sizes_purchase[type].extend_left  = Clamp(max_extend_left, min_extend, max_extend);
			_base_block_sizes_purchase[type].extend_right = Clamp(max_extend_right, min_extend, max_extend);
			break;

		default: NOT_REACHED();
	}
}

/**
 * Set the size of the blocks in the window so we can be sure that they are big enough for the vehicle sprites in the current game.
 * @note Calling this function once for each game is enough.
 */
void InitDepotWindowBlockSizes()
{
	for (VehicleType vt = VEH_BEGIN; vt < VEH_COMPANY_END; vt++) {
		InitBlocksizeForVehicles(vt, EIT_IN_DEPOT);
		InitBlocksizeForVehicles(vt, EIT_PURCHASE);
	}

	_consistent_train_width = TRAININFO_DEFAULT_VEHICLE_WIDTH;
	bool first = true;
	for (const Engine *e : Engine::IterateType(VEH_TRAIN)) {
		if (!e->IsEnabled()) continue;

		uint w = TRAININFO_DEFAULT_VEHICLE_WIDTH;
		if (e->GetGRF() != nullptr && IsCustomVehicleSpriteNum(e->u.rail.image_index)) {
			w = e->GetGRF()->traininfo_vehicle_width;
			if (w != VEHICLEINFO_FULL_VEHICLE_WIDTH) {
				/* Hopeless.
				 * This is a NewGRF vehicle that uses TRAININFO_DEFAULT_VEHICLE_WIDTH.
				 * If the vehicles are shorter than 8/8 we have fractional lengths, which are not consistent after rounding.
				 */
				_consistent_train_width = 0;
				break;
			}
		}

		if (first) {
			_consistent_train_width = w;
			first = false;
		} else if (w != _consistent_train_width) {
			_consistent_train_width = 0;
			break;
		}
	}
}

static void DepotSellAllConfirmationCallback(Window *w, bool confirmed);
const Sprite *GetAircraftSprite(EngineID engine);

struct DepotWindow : Window {
	VehicleID sel = VehicleID::Invalid();
	VehicleID vehicle_over = VehicleID::Invalid(); ///< Rail vehicle over which another one is dragged, \c VehicleID::Invalid() if none.
	VehicleType type = VEH_INVALID;
	bool generate_list = true;
	bool check_unitnumber_digits = true;
	WidgetID hovered_widget = -1; ///< Index of the widget being hovered during drag/drop. -1 if no drag is in progress.
	VehicleList vehicle_list{};
	VehicleList wagon_list{};
	uint unitnumber_digits = 2;
	uint num_columns = 1; ///< Number of columns.
	Scrollbar *hscroll = nullptr; ///< Only for trains.
	Scrollbar *vscroll = nullptr;
	uint count_width = 0; ///< Width of length count, including separator.
	uint header_width = 0; ///< Width of unit number and flag, including separator.
	Dimension flag_size{}; ///< Size of start/stop flag.
	VehicleCellSize cell_size{}; ///< Vehicle sprite cell size.
	bool last_overlay_state = false;

	DepotWindow(WindowDesc &desc, TileIndex tile, VehicleType type) : Window(desc)
	{
		assert(IsCompanyBuildableVehicleType(type)); // ensure that we make the call with a valid type

		this->type = type;

		this->CreateNestedTree();
		this->hscroll = (this->type == VEH_TRAIN ? this->GetScrollbar(WID_D_H_SCROLL) : nullptr);
		this->vscroll = this->GetScrollbar(WID_D_V_SCROLL);
		/* Don't show 'rename button' of aircraft hangar */
		this->GetWidget<NWidgetStacked>(WID_D_SHOW_RENAME)->SetDisplayedPlane(type == VEH_AIRCRAFT ? SZSP_NONE : 0);
		/* Only train depots have a horizontal scrollbar and a 'sell chain' button */
		if (type == VEH_TRAIN) this->GetWidget<NWidgetCore>(WID_D_MATRIX)->SetMatrixDimension(1, 0 /* auto-scale */);
		this->GetWidget<NWidgetStacked>(WID_D_SHOW_H_SCROLL)->SetDisplayedPlane(type == VEH_TRAIN ? 0 : SZSP_HORIZONTAL);
		this->GetWidget<NWidgetStacked>(WID_D_SHOW_SELL_CHAIN)->SetDisplayedPlane(type == VEH_TRAIN ? 0 : SZSP_NONE);
		this->SetupWidgetData(type);
		this->FinishInitNested(tile);

		this->owner = GetTileOwner(tile);
		OrderBackup::Reset();
	}

	void Close([[maybe_unused]] int data = 0) override
	{
		CloseWindowById(WC_BUILD_VEHICLE, this->window_number);
		CloseWindowById(GetWindowClassForVehicleType(this->type), VehicleListIdentifier(VL_DEPOT_LIST, this->type, this->owner, this->GetDestinationIndex()).ToWindowNumber(), false);
		OrderBackup::Reset(TileIndex(this->window_number));
		this->Window::Close();
	}

	/**
	 * Count the dragged selection length if appropriate for the provided train.
	 * @note This ignores potential changes in length due to callback returning different results.
	 * @param t Train being counted.
	 * @return Additional length of dragged selection to add.
	 */
	uint CountDraggedLength(const Train *t) const
	{
		/* Nothing is selected to add. */
		if (this->sel == VehicleID::Invalid()) return 0;

		/* Test if the dragged selection applies to this train. */
		bool add_dragged = false;
		for (const Train *u = t; u != nullptr; u = u->Next()) {
			if (u->index == this->sel) return 0; // Selection is part of this train, so doesn't increase its length.
			if (u->index == this->vehicle_over) add_dragged = true;
		}

		if (!add_dragged) return 0;

		/* Sum the length of the dragged selection. */
		uint length = 0;
		for (Train *u = Train::Get(this->sel); u != nullptr; u = _cursor.vehchain ? u->Next() : (u->HasArticulatedPart() ? u->GetNextArticulatedPart() : nullptr)) {
			length += u->gcache.cached_veh_length;
		}

		return length;
	}

	/**
	 * Draw a vehicle in the depot window in the box with the top left corner at x,y.
	 * @param v     Vehicle to draw.
	 * @param r     Rect to draw in.
	 */
	void DrawVehicleInDepot(const Vehicle *v, const Rect &r) const
	{
		bool free_wagon = false;

		bool rtl = _current_text_dir == TD_RTL;
		Rect text = r.Shrink(RectPadding::zero, WidgetDimensions::scaled.matrix);       /* Ract for text elements, horizontal is already applied. */
		Rect image = r.Indent(this->header_width, rtl).Indent(this->count_width, !rtl); /* Rect for vehicle images */

		switch (v->type) {
			case VEH_TRAIN: {
				const Train *u = Train::From(v);
				free_wagon = u->IsFreeWagon();

				uint x_space = free_wagon ?
						ScaleSpriteTrad(_consistent_train_width != 0 ? _consistent_train_width : TRAININFO_DEFAULT_VEHICLE_WIDTH) :
						0;

				DrawTrainImage(u, image.Indent(x_space, rtl), this->sel, EIT_IN_DEPOT, free_wagon ? 0 : this->hscroll->GetPosition(), this->vehicle_over);

				/* Length of consist in tiles with 1 fractional digit (rounded up) */
				uint length = u->gcache.cached_total_length + this->CountDraggedLength(u);
				Rect count = text.WithWidth(this->count_width - WidgetDimensions::scaled.hsep_normal, !rtl);
				DrawString(count.left, count.right, count.bottom - GetCharacterHeight(FS_SMALL) + 1,
						GetString(STR_JUST_DECIMAL, CeilDiv(length * 10, TILE_SIZE), 1),
						TC_BLACK, SA_RIGHT | SA_FORCE, false, FS_SMALL); // Draw the counter
				break;
			}

			case VEH_ROAD:     DrawRoadVehImage( v, image, this->sel, EIT_IN_DEPOT); break;
			case VEH_SHIP:     DrawShipImage(    v, image, this->sel, EIT_IN_DEPOT); break;
			case VEH_AIRCRAFT: DrawAircraftImage(v, image, this->sel, EIT_IN_DEPOT); break;
			default: NOT_REACHED();
		}

		uint diff_x, diff_y;
		if (v->IsGroundVehicle()) {
			/* Arrange unitnumber and flag horizontally */
			diff_x = this->flag_size.width + WidgetDimensions::scaled.hsep_normal;
			diff_y = WidgetDimensions::scaled.matrix.top;
		} else {
			/* Arrange unitnumber and flag vertically */
			diff_x = 0;
			diff_y = WidgetDimensions::scaled.matrix.top + GetCharacterHeight(FS_NORMAL) + WidgetDimensions::scaled.vsep_normal;
		}

		text = text.WithWidth(this->header_width - WidgetDimensions::scaled.hsep_normal, rtl).WithHeight(GetCharacterHeight(FS_NORMAL)).Indent(diff_x, rtl);
		if (free_wagon) {
			DrawString(text, STR_DEPOT_NO_ENGINE);
		} else {
			Rect flag = r.WithWidth(this->flag_size.width, rtl).WithHeight(this->flag_size.height).Translate(0, diff_y);
			DrawSpriteIgnorePadding((v->vehstatus.Test(VehState::Stopped)) ? SPR_FLAG_VEH_STOPPED : SPR_FLAG_VEH_RUNNING, PAL_NONE, flag, SA_CENTER);

			DrawString(text, GetString(STR_JUST_COMMA, v->unitnumber), (v->max_age - CalendarTime::DAYS_IN_LEAP_YEAR) >= v->age ? TC_BLACK : TC_RED);
		}
	}

	void DrawWidget(const Rect &r, WidgetID widget) const override
	{
		if (widget != WID_D_MATRIX) return;

		bool rtl = _current_text_dir == TD_RTL;

		/* Set the row and number of boxes in each row based on the number of boxes drawn in the matrix */
		const NWidgetCore *wid = this->GetWidget<NWidgetCore>(WID_D_MATRIX);

		/* Set up rect for each cell */
		Rect ir = r.WithHeight(this->resize.step_height);
		if (this->num_columns != 1) ir = ir.WithWidth(this->resize.step_width, rtl);
		ir = ir.Shrink(WidgetDimensions::scaled.framerect, RectPadding::zero);

		/* Draw vertical separators at whole tiles.
		 * This only works in two cases:
		 *  - All vehicles use VEHICLEINFO_FULL_VEHICLE_WIDTH as reference width.
		 *  - All vehicles are 8/8. This cannot be checked for NewGRF, so instead we check for "all vehicles are original vehicles".
		 */
		if (this->type == VEH_TRAIN && _consistent_train_width != 0) {
			int w = ScaleSpriteTrad(2 * _consistent_train_width);
			PixelColour col = GetColourGradient(wid->colour, SHADE_NORMAL);
			Rect image = ir.Indent(this->header_width, rtl).Indent(this->count_width, !rtl);
			int first_line = w + (-this->hscroll->GetPosition()) % w;
			if (rtl) {
				for (int x = image.right - first_line; x >= image.left; x -= w) {
					GfxDrawLine(x, r.top, x, r.bottom, col, ScaleGUITrad(1), ScaleGUITrad(3));
				}
			} else {
				for (int x = image.left + first_line; x <= image.right; x += w) {
					GfxDrawLine(x, r.top, x, r.bottom, col, ScaleGUITrad(1), ScaleGUITrad(3));
				}
			}
		}

		uint16_t rows_in_display = wid->current_y / wid->resize_y;

		uint num = this->vscroll->GetPosition() * this->num_columns;
		uint maxval = static_cast<uint>(std::min<size_t>(this->vehicle_list.size(), num + (rows_in_display * this->num_columns)));
		for (; num < maxval; ir = ir.Translate(0, this->resize.step_height)) { // Draw the rows
			Rect cell = ir; /* Keep track of horizontal cells */
			for (uint i = 0; i < this->num_columns && num < maxval; i++, num++) {
				/* Draw all vehicles in the current row */
				const Vehicle *v = this->vehicle_list[num];
				this->DrawVehicleInDepot(v, cell);
				cell = cell.Translate(rtl ? -(int)this->resize.step_width : (int)this->resize.step_width, 0);
			}
		}

		maxval = static_cast<uint>(std::min<size_t>(this->vehicle_list.size() + this->wagon_list.size(), (this->vscroll->GetPosition() * this->num_columns) + (rows_in_display * this->num_columns)));

		/* Draw the train wagons without an engine in front. */
		for (; num < maxval; num++, ir = ir.Translate(0, this->resize.step_height)) {
			const Vehicle *v = this->wagon_list[num - this->vehicle_list.size()];
			this->DrawVehicleInDepot(v, ir);
		}
	}

	std::string GetWidgetString(WidgetID widget, StringID stringid) const override
	{
		if (widget == WID_D_CAPTION) return GetString(STR_DEPOT_CAPTION, this->type, this->GetDestinationIndex());

		return this->Window::GetWidgetString(widget, stringid);
	}

	struct GetDepotVehiclePtData {
		const Vehicle *head;
		const Vehicle *wagon;
	};

	enum DepotGUIAction : uint8_t {
		MODE_ERROR,
		MODE_DRAG_VEHICLE,
		MODE_SHOW_VEHICLE,
		MODE_START_STOP,
	};

	DepotGUIAction GetVehicleFromDepotWndPt(int x, int y, const Vehicle **veh, GetDepotVehiclePtData *d)
	{
		this->RefreshVehicleList();

		const NWidgetCore *matrix_widget = this->GetWidget<NWidgetCore>(WID_D_MATRIX);
		/* Make X relative to widget. Y is left alone for GetScrolledRowFromWidget(). */
		x -= matrix_widget->pos_x;
		/* In case of RTL the widgets are swapped as a whole */
		if (_current_text_dir == TD_RTL) x = matrix_widget->current_x - x;

		uint xt = 0, xm = 0, ym = 0;
		if (this->type == VEH_TRAIN) {
			xm = x;
		} else {
			xt = x / this->resize.step_width;
			xm = x % this->resize.step_width;
			if (xt >= this->num_columns) return MODE_ERROR;
		}
		ym = (y - matrix_widget->pos_y) % this->resize.step_height;

		int32_t row = this->vscroll->GetScrolledRowFromWidget(y, this, WID_D_MATRIX);
		uint pos = (row * this->num_columns) + xt;

		if (row == INT32_MAX || this->vehicle_list.size() + this->wagon_list.size() <= pos) {
			/* Clicking on 'line' / 'block' without a vehicle */
			if (this->type == VEH_TRAIN) {
				/* End the dragging */
				d->head  = nullptr;
				d->wagon = nullptr;
				return MODE_DRAG_VEHICLE;
			} else {
				return MODE_ERROR; // empty block, so no vehicle is selected
			}
		}

		bool wagon = false;
		if (this->vehicle_list.size() > pos) {
			*veh = this->vehicle_list[pos];
			/* Skip vehicles that are scrolled off the list */
			if (this->type == VEH_TRAIN) x += this->hscroll->GetPosition();
		} else {
			pos -= (uint)this->vehicle_list.size();
			*veh = this->wagon_list[pos];
			/* free wagons don't have an initial loco. */
			x -= ScaleSpriteTrad(VEHICLEINFO_FULL_VEHICLE_WIDTH);
			wagon = true;
		}

		const Train *v = nullptr;
		if (this->type == VEH_TRAIN) {
			v = Train::From(*veh);
			d->head = d->wagon = v;
		}

		if (xm <= this->header_width) {
			switch (this->type) {
				case VEH_TRAIN:
					if (wagon) return MODE_ERROR;
					[[fallthrough]];

				case VEH_ROAD:
					if (xm <= this->flag_size.width) return MODE_START_STOP;
					break;

				case VEH_SHIP:
				case VEH_AIRCRAFT:
					if (xm <= this->flag_size.width && ym >= (uint)(GetCharacterHeight(FS_NORMAL) + WidgetDimensions::scaled.vsep_normal)) return MODE_START_STOP;
					break;

				default: NOT_REACHED();
			}
			return MODE_SHOW_VEHICLE;
		}

		if (this->type != VEH_TRAIN) return MODE_DRAG_VEHICLE;

		/* Clicking on the counter */
		if (xm >= matrix_widget->current_x - this->count_width) return wagon ? MODE_ERROR : MODE_SHOW_VEHICLE;

		/* Account for the header */
		x -= this->header_width;

		/* find the vehicle in this row that was clicked */
		for (; v != nullptr; v = v->Next()) {
			x -= v->GetDisplayImageWidth();
			if (x < 0) break;
		}

		d->wagon = (v != nullptr ? v->GetFirstEnginePart() : nullptr);

		return MODE_DRAG_VEHICLE;
	}

	/**
	 * Handle click in the depot matrix.
	 * @param x Horizontal position in the matrix widget in pixels.
	 * @param y Vertical position in the matrix widget in pixels.
	 */
	void DepotClick(int x, int y)
	{
		GetDepotVehiclePtData gdvp = { nullptr, nullptr };
		const Vehicle *v = nullptr;
		DepotGUIAction mode = this->GetVehicleFromDepotWndPt(x, y, &v, &gdvp);

		if (this->type == VEH_TRAIN) v = gdvp.wagon;

		switch (mode) {
			case MODE_ERROR: // invalid
				return;

			case MODE_DRAG_VEHICLE: { // start dragging of vehicle
				if (v != nullptr && VehicleClicked(v)) return;

				VehicleID sel = this->sel;

				if (this->type == VEH_TRAIN && sel != VehicleID::Invalid()) {
					this->sel = VehicleID::Invalid();
					TrainDepotMoveVehicle(v, sel, gdvp.head);
				} else if (v != nullptr) {
					SetObjectToPlaceWnd(SPR_CURSOR_MOUSE, PAL_NONE, HT_DRAG, this);
					SetMouseCursorVehicle(v, EIT_IN_DEPOT);
					_cursor.vehchain = _ctrl_pressed;

					this->sel = v->index;
					this->SetDirty();
				}
				break;
			}

			case MODE_SHOW_VEHICLE: // show info window
				ShowVehicleViewWindow(v);
				break;

			case MODE_START_STOP: // click start/stop flag
				StartStopVehicle(v, false);
				break;

			default: NOT_REACHED();
		}
	}

	/**
	 * Function to set up vehicle specific widgets (mainly sprites and strings).
	 * Only use this function to if the widget is used for several vehicle types and each has
	 * different text/sprites. If the widget is only used for a single vehicle type, or the same
	 * text/sprites are used every time, use the nested widget array to initialize the widget.
	 */
	void SetupWidgetData(VehicleType type)
	{
		this->GetWidget<NWidgetCore>(WID_D_STOP_ALL)->SetToolTip(STR_DEPOT_MASS_STOP_DEPOT_TRAIN_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_START_ALL)->SetToolTip(STR_DEPOT_MASS_START_DEPOT_TRAIN_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_SELL)->SetToolTip(STR_DEPOT_TRAIN_SELL_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_SELL_ALL)->SetToolTip(STR_DEPOT_SELL_ALL_BUTTON_TRAIN_TOOLTIP + type);

		this->GetWidget<NWidgetCore>(WID_D_BUILD)->SetStringTip(STR_DEPOT_TRAIN_NEW_VEHICLES_BUTTON + type, STR_DEPOT_TRAIN_NEW_VEHICLES_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_CLONE)->SetStringTip(STR_DEPOT_CLONE_TRAIN + type, STR_DEPOT_CLONE_TRAIN_DEPOT_TOOLTIP + type);

		this->GetWidget<NWidgetCore>(WID_D_LOCATION)->SetToolTip(STR_DEPOT_TRAIN_LOCATION_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_VEHICLE_LIST)->SetToolTip(STR_DEPOT_VEHICLE_ORDER_LIST_TRAIN_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_AUTOREPLACE)->SetToolTip(STR_DEPOT_AUTOREPLACE_TRAIN_TOOLTIP + type);
		this->GetWidget<NWidgetCore>(WID_D_MATRIX)->SetToolTip(STR_DEPOT_TRAIN_LIST_TOOLTIP + this->type);

		switch (type) {
			default: NOT_REACHED();

			case VEH_TRAIN:
				this->GetWidget<NWidgetCore>(WID_D_VEHICLE_LIST)->SetString(STR_TRAIN);

				/* Sprites */
				this->GetWidget<NWidgetCore>(WID_D_SELL)->SetSprite(SPR_SELL_TRAIN);
				this->GetWidget<NWidgetCore>(WID_D_SELL_ALL)->SetSprite(SPR_SELL_ALL_TRAIN);
				this->GetWidget<NWidgetCore>(WID_D_AUTOREPLACE)->SetSprite(SPR_REPLACE_TRAIN);
				break;

			case VEH_ROAD:
				this->GetWidget<NWidgetCore>(WID_D_VEHICLE_LIST)->SetString(STR_LORRY);

				/* Sprites */
				this->GetWidget<NWidgetCore>(WID_D_SELL)->SetSprite(SPR_SELL_ROADVEH);
				this->GetWidget<NWidgetCore>(WID_D_SELL_ALL)->SetSprite(SPR_SELL_ALL_ROADVEH);
				this->GetWidget<NWidgetCore>(WID_D_AUTOREPLACE)->SetSprite(SPR_REPLACE_ROADVEH);
				break;

			case VEH_SHIP:
				this->GetWidget<NWidgetCore>(WID_D_VEHICLE_LIST)->SetString(STR_SHIP);

				/* Sprites */
				this->GetWidget<NWidgetCore>(WID_D_SELL)->SetSprite(SPR_SELL_SHIP);
				this->GetWidget<NWidgetCore>(WID_D_SELL_ALL)->SetSprite(SPR_SELL_ALL_SHIP);
				this->GetWidget<NWidgetCore>(WID_D_AUTOREPLACE)->SetSprite(SPR_REPLACE_SHIP);
				break;

			case VEH_AIRCRAFT:
				this->GetWidget<NWidgetCore>(WID_D_VEHICLE_LIST)->SetString(STR_PLANE);

				/* Sprites */
				this->GetWidget<NWidgetCore>(WID_D_SELL)->SetSprite(SPR_SELL_AIRCRAFT);
				this->GetWidget<NWidgetCore>(WID_D_SELL_ALL)->SetSprite(SPR_SELL_ALL_AIRCRAFT);
				this->GetWidget<NWidgetCore>(WID_D_AUTOREPLACE)->SetSprite(SPR_REPLACE_AIRCRAFT);
				break;
		}
	}

	void OnInit() override
	{
		this->cell_size = GetVehicleImageCellSize(this->type, EIT_IN_DEPOT);
		this->flag_size = maxdim(GetScaledSpriteSize(SPR_FLAG_VEH_STOPPED), GetScaledSpriteSize(SPR_FLAG_VEH_RUNNING));
	}

	void UpdateWidgetSize(WidgetID widget, Dimension &size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension &fill, [[maybe_unused]] Dimension &resize) override
	{
		switch (widget) {
			case WID_D_MATRIX: {
				uint min_height = 0;

				if (this->type == VEH_TRAIN) {
					this->count_width = GetStringBoundingBox(GetString(STR_JUST_DECIMAL, GetParamMaxValue(1000, 0, FS_SMALL), 1), FS_SMALL).width + WidgetDimensions::scaled.hsep_normal;
				} else {
					this->count_width = 0;
				}

				Dimension unumber = GetStringBoundingBox(GetString(STR_JUST_COMMA, GetParamMaxDigits(this->unitnumber_digits)));

				if (this->type == VEH_TRAIN || this->type == VEH_ROAD) {
					min_height = std::max<uint>(unumber.height, this->flag_size.height);
					this->header_width = unumber.width + WidgetDimensions::scaled.hsep_normal + this->flag_size.width + WidgetDimensions::scaled.hsep_normal;
				} else {
					min_height = unumber.height + WidgetDimensions::scaled.vsep_normal + this->flag_size.height;
					this->header_width = std::max<uint>(unumber.width, this->flag_size.width) + WidgetDimensions::scaled.hsep_normal;
				}
				int base_width = this->count_width + this->header_width + padding.width;

				resize.height = std::max<uint>(this->cell_size.height, min_height + padding.height);
				if (this->type == VEH_TRAIN) {
					resize.width = 1;
					size.width = base_width + 2 * ScaleSpriteTrad(29); // about 2 parts
					size.height = resize.height * 6;
				} else {
					resize.width = base_width + this->cell_size.extend_left + this->cell_size.extend_right;
					size.width = resize.width * (this->type == VEH_ROAD ? 5 : 3);
					size.height = resize.height * (this->type == VEH_ROAD ? 5 : 3);
				}
				fill.width = resize.width;
				fill.height = resize.height;
				break;
			}
		}
	}

	/**
	 * Some data on this window has become invalid.
	 * @param data Information about the changed data.
	 * @param gui_scope Whether the call is done from GUI scope. You may not do everything when not in GUI scope. See #InvalidateWindowData() for details.
	 */
	void OnInvalidateData([[maybe_unused]] int data = 0, [[maybe_unused]] bool gui_scope = true) override
	{
		this->generate_list = true;
	}

	void RefreshVehicleList()
	{
		if (this->generate_list) {
			/* Generate the vehicle list
			 * It's ok to use the wagon pointers for non-trains as they will be ignored */
			BuildDepotVehicleList(this->type, TileIndex(this->window_number), &this->vehicle_list, &this->wagon_list);
			this->generate_list = false;
			DepotSortList(&this->vehicle_list);

			this->check_unitnumber_digits = true;
		}
	}

	void OnPaint() override
	{
		this->RefreshVehicleList();

		if (this->check_unitnumber_digits) {
			this->check_unitnumber_digits = false;
			uint new_unitnumber_digits = GetUnitNumberDigits(this->vehicle_list);
			/* Only increase the size; do not decrease to prevent constant changes */
			if (this->unitnumber_digits < new_unitnumber_digits) {
				this->unitnumber_digits = new_unitnumber_digits;
				this->ReInit();
			}
		}

		/* determine amount of items for scroller */
		if (this->type == VEH_TRAIN) {
			uint max_width = ScaleSpriteTrad(VEHICLEINFO_FULL_VEHICLE_WIDTH);
			for (uint num = 0; num < this->vehicle_list.size(); num++) {
				uint width = 0;
				for (const Train *v = Train::From(this->vehicle_list[num]); v != nullptr; v = v->Next()) {
					width += v->GetDisplayImageWidth();
				}
				max_width = std::max(max_width, width);
			}
			/* Always have 1 empty row, so people can change the setting of the train */
			this->vscroll->SetCount(this->vehicle_list.size() + this->wagon_list.size() + 1);
			/* Always make it longer than the longest train, so you can attach vehicles at the end, and also see the next vertical tile separator line */
			this->hscroll->SetCount(max_width + ScaleSpriteTrad(2 * VEHICLEINFO_FULL_VEHICLE_WIDTH + 1));
		} else {
			this->vscroll->SetCount(CeilDiv((uint)this->vehicle_list.size(), this->num_columns));
		}

		/* Setup disabled buttons. */
		TileIndex tile(this->window_number);
		this->SetWidgetsDisabledState(!IsTileOwner(tile, _local_company),
			WID_D_STOP_ALL,
			WID_D_START_ALL,
			WID_D_SELL,
			WID_D_SELL_CHAIN,
			WID_D_SELL_ALL,
			WID_D_BUILD,
			WID_D_CLONE,
			WID_D_RENAME,
			WID_D_AUTOREPLACE);

		this->DrawWidgets();
	}

	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
	{
		switch (widget) {
			case WID_D_MATRIX: // List
				this->DepotClick(pt.x, pt.y);
				break;

			case WID_D_BUILD: // Build vehicle
				ResetObjectToPlace();
				ShowBuildVehicleWindow(TileIndex(this->window_number), this->type);
				break;

			case WID_D_CLONE: // Clone button
				this->SetWidgetDirty(WID_D_CLONE);
				this->ToggleWidgetLoweredState(WID_D_CLONE);

				if (this->IsWidgetLowered(WID_D_CLONE)) {
					static const CursorID clone_icons[] = {
						SPR_CURSOR_CLONE_TRAIN, SPR_CURSOR_CLONE_ROADVEH,
						SPR_CURSOR_CLONE_SHIP, SPR_CURSOR_CLONE_AIRPLANE
					};

					SetObjectToPlaceWnd(clone_icons[this->type], PAL_NONE, HT_VEHICLE, this);
				} else {
					ResetObjectToPlace();
				}
				SndClickBeep();
				break;

			case WID_D_LOCATION:
				if (_ctrl_pressed) {
					ShowExtraViewportWindow(TileIndex(this->window_number));
				} else {
					ScrollMainWindowToTile(TileIndex(this->window_number));
				}
				break;

			case WID_D_RENAME: // Rename button
				ShowQueryString(GetString(STR_DEPOT_NAME, this->type, Depot::GetByTile(TileIndex(this->window_number))->index), STR_DEPOT_RENAME_DEPOT_CAPTION,
					MAX_LENGTH_DEPOT_NAME_CHARS, this, CS_ALPHANUMERAL, {QueryStringFlag::EnableDefault, QueryStringFlag::LengthIsInChars});
				break;

			case WID_D_STOP_ALL:
			case WID_D_START_ALL: {
				VehicleListIdentifier vli(VL_DEPOT_LIST, this->type, this->owner);
				Command<CMD_MASS_START_STOP>::Post(TileIndex(this->window_number), widget == WID_D_START_ALL, false, vli);
				break;
			}

			case WID_D_SELL_ALL:
				/* Only open the confirmation window if there are anything to sell */
				if (!this->vehicle_list.empty() || !this->wagon_list.empty()) {
					ShowQuery(
						GetEncodedString(STR_DEPOT_CAPTION, this->type, this->GetDestinationIndex()),
						GetEncodedString(STR_DEPOT_SELL_CONFIRMATION_TEXT),
						this,
						DepotSellAllConfirmationCallback
					);
				}
				break;

			case WID_D_VEHICLE_LIST:
				ShowVehicleListWindow(GetTileOwner(this->window_number), this->type, TileIndex(this->window_number));
				break;

			case WID_D_AUTOREPLACE:
				Command<CMD_DEPOT_MASS_AUTOREPLACE>::Post(GetCmdAutoreplaceVehMsg(this->type), TileIndex(this->window_number), this->type);
				break;

		}
	}

	void OnQueryTextFinished(std::optional<std::string> str) override
	{
		if (!str.has_value()) return;

		/* Do depot renaming */
		Command<CMD_RENAME_DEPOT>::Post(STR_ERROR_CAN_T_RENAME_DEPOT, this->GetDestinationIndex().ToDepotID(), *str);
	}

	bool OnRightClick([[maybe_unused]] Point pt, WidgetID widget) override
	{
		if (widget != WID_D_MATRIX) return false;

		GetDepotVehiclePtData gdvp = { nullptr, nullptr };
		const Vehicle *v = nullptr;
		DepotGUIAction mode = this->GetVehicleFromDepotWndPt(pt.x, pt.y, &v, &gdvp);

		if (this->type == VEH_TRAIN) v = gdvp.wagon;

		if (v == nullptr || mode != MODE_DRAG_VEHICLE) return false;

		CargoArray capacity{}, loaded{};

		/* Display info for single (articulated) vehicle, or for whole chain starting with selected vehicle */
		bool whole_chain = (this->type == VEH_TRAIN && _ctrl_pressed);

		/* loop through vehicle chain and collect cargoes */
		uint num = 0;
		for (const Vehicle *w = v; w != nullptr; w = w->Next()) {
			if (w->cargo_cap > 0 && w->cargo_type < NUM_CARGO) {
				capacity[w->cargo_type] += w->cargo_cap;
				loaded  [w->cargo_type] += w->cargo.StoredCount();
			}

			if (w->type == VEH_TRAIN && !w->HasArticulatedPart()) {
				num++;
				if (!whole_chain) break;
			}
		}

		/* Build tooltipstring */
		static std::string details;
		details.clear();

		for (const CargoSpec *cs : _sorted_cargo_specs) {
			CargoType cargo_type = cs->Index();
			if (capacity[cargo_type] == 0) continue;

			auto params = MakeParameters(cargo_type, loaded[cargo_type], cargo_type, capacity[cargo_type]);
			AppendStringWithArgsInPlace(details, STR_DEPOT_VEHICLE_TOOLTIP_CARGO, params);
		}

		/* Show tooltip window */
		if (whole_chain) {
			GuiShowTooltips(this, GetEncodedString(STR_DEPOT_VEHICLE_TOOLTIP_CHAIN, num, details), TCC_RIGHT_CLICK);
		} else {
			GuiShowTooltips(this, GetEncodedString(STR_DEPOT_VEHICLE_TOOLTIP, v->engine_type, details), TCC_RIGHT_CLICK);
		}

		return true;
	}

	/**
	 * Clones a vehicle
	 * @param v the original vehicle to clone
	 * @return Always true.
	 */
	bool OnVehicleSelect(const Vehicle *v) override
	{
		if (_ctrl_pressed) {
			/* Share-clone, do not open new viewport, and keep tool active */
			Command<CMD_CLONE_VEHICLE>::Post(STR_ERROR_CAN_T_BUY_TRAIN + v->type, TileIndex(this->window_number), v->index, true);
		} else {
			/* Copy-clone, open viewport for new vehicle, and deselect the tool (assume player wants to change things on new vehicle) */
			if (Command<CMD_CLONE_VEHICLE>::Post(STR_ERROR_CAN_T_BUY_TRAIN + v->type, CcCloneVehicle, TileIndex(this->window_number), v->index, false)) {
				ResetObjectToPlace();
			}
		}

		return true;
	}

	/**
	 * Clones a vehicle from a vehicle list.  If this doesn't make sense (because not all vehicles in the list have the same orders), then it displays an error.
	 * @return This always returns true, which indicates that the contextual action handled the mouse click.
	 *         Note that it's correct behaviour to always handle the click even though an error is displayed,
	 *         because users aren't going to expect the default action to be performed just because they overlooked that cloning doesn't make sense.
	 */
	bool OnVehicleSelect(VehicleList::const_iterator begin, VehicleList::const_iterator end) override
	{
		if (!_ctrl_pressed) {
			/* If CTRL is not pressed: If all the vehicles in this list have the same orders, then copy orders */
			if (AllEqual(begin, end, [](const Vehicle *v1, const Vehicle *v2) {
				return VehiclesHaveSameEngineList(v1, v2);
			})) {
				if (AllEqual(begin, end, [](const Vehicle *v1, const Vehicle *v2) {
					return VehiclesHaveSameOrderList(v1, v2);
				})) {
					OnVehicleSelect(*begin);
				} else {
					ShowErrorMessage(GetEncodedString(STR_ERROR_CAN_T_BUY_TRAIN + (*begin)->type),
						GetEncodedString(STR_ERROR_CAN_T_COPY_ORDER_VEHICLE_LIST), WL_INFO);
				}
			} else {
				ShowErrorMessage(GetEncodedString(STR_ERROR_CAN_T_BUY_TRAIN + (*begin)->type),
					GetEncodedString(STR_ERROR_CAN_T_CLONE_VEHICLE_LIST), WL_INFO);
			}
		} else {
			/* If CTRL is pressed: If all the vehicles in this list share orders, then copy orders */
			if (AllEqual(begin, end, [](const Vehicle *v1, const Vehicle *v2) {
				return VehiclesHaveSameEngineList(v1, v2);
			})) {
				if (AllEqual(begin, end, [](const Vehicle *v1, const Vehicle *v2) {
					return v1->FirstShared() == v2->FirstShared();
				})) {
					OnVehicleSelect(*begin);
				} else {
					ShowErrorMessage(GetEncodedString(STR_ERROR_CAN_T_BUY_TRAIN + (*begin)->type),
						GetEncodedString(STR_ERROR_CAN_T_SHARE_ORDER_VEHICLE_LIST), WL_INFO);
				}
			} else {
				ShowErrorMessage(GetEncodedString(STR_ERROR_CAN_T_BUY_TRAIN + (*begin)->type),
					GetEncodedString(STR_ERROR_CAN_T_CLONE_VEHICLE_LIST), WL_INFO);
			}
		}

		return true;
	}

	void OnPlaceObjectAbort() override
	{
		/* abort clone */
		this->RaiseWidget(WID_D_CLONE);
		this->SetWidgetDirty(WID_D_CLONE);

		/* abort drag & drop */
		this->sel = VehicleID::Invalid();
		this->vehicle_over = VehicleID::Invalid();
		this->SetWidgetDirty(WID_D_MATRIX);

		if (this->hovered_widget != -1) {
			this->SetWidgetLoweredState(this->hovered_widget, false);
			this->SetWidgetDirty(this->hovered_widget);
			this->hovered_widget = -1;
		}
	}

	void OnMouseLoop() override
	{
		if (last_overlay_state != ShowCargoIconOverlay()) {
			last_overlay_state = ShowCargoIconOverlay();
			this->SetDirty();
		}
	}

	void OnMouseDrag(Point pt, WidgetID widget) override
	{
		if (this->sel == VehicleID::Invalid()) return;
		if (widget != this->hovered_widget) {
			if (this->hovered_widget == WID_D_SELL || this->hovered_widget == WID_D_SELL_CHAIN) {
				this->SetWidgetLoweredState(this->hovered_widget, false);
				this->SetWidgetDirty(this->hovered_widget);
			}
			this->hovered_widget = widget;
			if (this->hovered_widget == WID_D_SELL || this->hovered_widget == WID_D_SELL_CHAIN) {
				this->SetWidgetLoweredState(this->hovered_widget, true);
				this->SetWidgetDirty(this->hovered_widget);
			}
		}
		if (this->type != VEH_TRAIN) return;

		/* A rail vehicle is dragged.. */
		if (widget != WID_D_MATRIX) { // ..outside of the depot matrix.
			if (this->vehicle_over != VehicleID::Invalid()) {
				this->vehicle_over = VehicleID::Invalid();
				this->SetWidgetDirty(WID_D_MATRIX);
			}
			return;
		}

		const Vehicle *v = nullptr;
		GetDepotVehiclePtData gdvp = {nullptr, nullptr};

		if (this->GetVehicleFromDepotWndPt(pt.x, pt.y, &v, &gdvp) != MODE_DRAG_VEHICLE) return;

		VehicleID new_vehicle_over = VehicleID::Invalid();
		if (gdvp.head != nullptr) {
			if (gdvp.wagon == nullptr && gdvp.head->Last()->index != this->sel) { // ..at the end of the train.
				/* NOTE: As a wagon can't be moved at the begin of a train, head index isn't used to mark a drag-and-drop
				 * destination inside a train. This head index is then used to indicate that a wagon is inserted at
				 * the end of the train.
				 */
				new_vehicle_over = gdvp.head->index;
			} else if (gdvp.wagon != nullptr && gdvp.head != gdvp.wagon &&
					gdvp.wagon->index != this->sel &&
					gdvp.wagon->Previous()->index != this->sel) { // ..over an existing wagon.
				new_vehicle_over = gdvp.wagon->index;
			}
		}

		if (this->vehicle_over == new_vehicle_over) return;

		this->vehicle_over = new_vehicle_over;
		this->SetWidgetDirty(widget);
	}

	void OnDragDrop(Point pt, WidgetID widget) override
	{
		switch (widget) {
			case WID_D_MATRIX: {
				const Vehicle *v = nullptr;
				VehicleID sel = this->sel;

				this->sel = VehicleID::Invalid();
				this->SetDirty();

				if (this->type == VEH_TRAIN) {
					GetDepotVehiclePtData gdvp = { nullptr, nullptr };

					if (this->GetVehicleFromDepotWndPt(pt.x, pt.y, &v, &gdvp) == MODE_DRAG_VEHICLE && sel != VehicleID::Invalid()) {
						if (gdvp.wagon != nullptr && gdvp.wagon->index == sel && _ctrl_pressed) {
							Command<CMD_REVERSE_TRAIN_DIRECTION>::Post(STR_ERROR_CAN_T_REVERSE_DIRECTION_RAIL_VEHICLE, Vehicle::Get(sel)->tile, Vehicle::Get(sel)->index, true);
						} else if (gdvp.wagon == nullptr || gdvp.wagon->index != sel) {
							this->vehicle_over = VehicleID::Invalid();
							TrainDepotMoveVehicle(gdvp.wagon, sel, gdvp.head);
						} else if (gdvp.head != nullptr && gdvp.head->IsFrontEngine()) {
							ShowVehicleViewWindow(gdvp.head);
						}
					}
				} else if (this->GetVehicleFromDepotWndPt(pt.x, pt.y, &v, nullptr) == MODE_DRAG_VEHICLE && v != nullptr && sel == v->index) {
					ShowVehicleViewWindow(v);
				}
				break;
			}

			case WID_D_SELL: case WID_D_SELL_CHAIN: {
				if (this->IsWidgetDisabled(widget)) return;
				if (this->sel == VehicleID::Invalid()) return;

				this->HandleButtonClick(widget);

				const Vehicle *v = Vehicle::Get(this->sel);
				this->sel = VehicleID::Invalid();
				this->SetDirty();

				bool sell_cmd = (v->type == VEH_TRAIN && (widget == WID_D_SELL_CHAIN || _ctrl_pressed));
				Command<CMD_SELL_VEHICLE>::Post(GetCmdSellVehMsg(v->type), v->tile, v->index, sell_cmd, true, INVALID_CLIENT_ID);
				break;
			}

			default:
				this->sel = VehicleID::Invalid();
				this->SetDirty();
				break;
		}
		this->hovered_widget = -1;
		_cursor.vehchain = false;
	}

	void OnTimeout() override
	{
		if (!this->IsWidgetDisabled(WID_D_SELL)) {
			this->RaiseWidget(WID_D_SELL);
			this->SetWidgetDirty(WID_D_SELL);
		}
		if (this->GetWidget<NWidgetBase>(WID_D_SELL) != nullptr && !this->IsWidgetDisabled(WID_D_SELL_CHAIN)) {
			this->RaiseWidget(WID_D_SELL_CHAIN);
			this->SetWidgetDirty(WID_D_SELL_CHAIN);
		}
	}

	void OnResize() override
	{
		this->vscroll->SetCapacityFromWidget(this, WID_D_MATRIX);
		NWidgetCore *nwi = this->GetWidget<NWidgetCore>(WID_D_MATRIX);
		if (this->type == VEH_TRAIN) {
			this->hscroll->SetCapacity(nwi->current_x - this->header_width - this->count_width);
		} else {
			this->num_columns = nwi->current_x / nwi->resize_x;
		}
	}

	EventState OnCTRLStateChange() override
	{
		if (this->sel != VehicleID::Invalid()) {
			_cursor.vehchain = _ctrl_pressed;
			this->SetWidgetDirty(WID_D_MATRIX);
			return ES_HANDLED;
		}

		return ES_NOT_HANDLED;
	}

	/**
	 * Gets the DepotID of the current window.
	 * In the case of airports, this is the station ID.
	 * @return Depot or station ID of this window.
	 */
	inline DestinationID GetDestinationIndex() const
	{
		return GetDepotDestinationIndex(this->window_number);
	}
};

static void DepotSellAllConfirmationCallback(Window *win, bool confirmed)
{
	if (confirmed) {
		DepotWindow *w = (DepotWindow*)win;
		TileIndex tile(w->window_number);
		VehicleType vehtype = w->type;
		Command<CMD_DEPOT_SELL_ALL_VEHICLES>::Post(GetCmdSellAllVehMsg(vehtype), tile, vehtype);
	}
}

/**
 * Opens a depot window
 * @param tile The tile where the depot/hangar is located
 * @param type The type of vehicles in the depot
 */
void ShowDepotWindow(TileIndex tile, VehicleType type)
{
	if (BringWindowToFrontById(WC_VEHICLE_DEPOT, tile) != nullptr) return;

	switch (type) {
		default: NOT_REACHED();
		case VEH_TRAIN:    new DepotWindow(_train_depot_desc, tile, type);    break;
		case VEH_ROAD:     new DepotWindow(_road_depot_desc, tile, type);     break;
		case VEH_SHIP:     new DepotWindow(_ship_depot_desc, tile, type);     break;
		case VEH_AIRCRAFT: new DepotWindow(_aircraft_depot_desc, tile, type); break;
	}
}

/**
 * Removes the highlight of a vehicle in a depot window
 * @param *v Vehicle to remove all highlights from
 */
void DeleteDepotHighlightOfVehicle(const Vehicle *v)
{
	DepotWindow *w;

	/* If we haven't got any vehicles on the mouse pointer, we haven't got any highlighted in any depots either
	 * If that is the case, we can skip looping though the windows and save time
	 */
	if (_special_mouse_mode != WSM_DRAGDROP) return;

	w = dynamic_cast<DepotWindow*>(FindWindowById(WC_VEHICLE_DEPOT, v->tile));
	if (w != nullptr) {
		if (w->sel == v->index) ResetObjectToPlace();
	}
}
