/**
 * Build a ship depot.
 * @param tile tile where ship depot is built
 * @param flags type of operation
 * @param p1 bit 0 depot orientation (Axis)
 * @param p2 unused
 * @param text unused
 * @return the cost of this operation or an error
 */
CommandCost CmdBuildShipDepot(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
{
	Axis axis = Extract<Axis, 0, 1>(p1);

	TileIndex tile2 = tile + (axis == AXIS_X ? TileDiffXY(1, 0) : TileDiffXY(0, 1));

	if (!HasTileWaterGround(tile) || !HasTileWaterGround(tile2)) {
		return_cmd_error(STR_ERROR_MUST_BE_BUILT_ON_WATER);
	}

	if (IsBridgeAbove(tile) || IsBridgeAbove(tile2)) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);

	if (!IsTileFlat(tile) || !IsTileFlat(tile2)) {
		/* Prevent depots on rapids */
		return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
	}

	if (!Depot::CanAllocateItem()) return CMD_ERROR;

	CommandCost cost = CommandCost(EXPENSES_CONSTRUCTION, _price[PR_BUILD_DEPOT_SHIP]);

	WaterClass wc1 = GetWaterClass(tile);
	WaterClass wc2 = GetWaterClass(tile2);
	bool river1 = HasTileCanalOnRiver(tile);
	bool river2 = HasTileCanalOnRiver(tile2);
	Owner oc1 = wc1 == WATER_CLASS_CANAL ? GetCanalOwner(tile) : INVALID_OWNER;
	Owner oc2 = wc2 == WATER_CLASS_CANAL ? GetCanalOwner(tile2) : INVALID_OWNER;

	bool add_cost;
	CommandCost ret;
	/* At this point we got a flat tile with water at the ground and no bridge over it. Check for ownership */
	if (IsWaterTile(tile) && IsCanal(tile)) {
		ret = EnsureNoVehicleOnGround(tile);
		if (ret.Failed()) return ret;
		if (oc1 != OWNER_NONE) {
			ret = CheckTileOwnership(tile);
			if (ret.Failed() && !_settings_game.construction.build_on_competitor_canal) return ret;
		}
	} else {
		add_cost = !IsWaterTile(tile);
		ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (ret.Failed()) return ret;
		if (add_cost) {
			cost.AddCost(ret);
		}
	}

	/* At this point we got a flat tile2 with water at the ground and no bridge over it. Check for ownership */
	if (IsWaterTile(tile2) && IsCanal(tile2)) {
		ret = EnsureNoVehicleOnGround(tile2);
		if (ret.Failed()) return ret;
		if (oc2 != OWNER_NONE) {
			ret = CheckTileOwnership(tile2);
			if (ret.Failed() && !_settings_game.construction.build_on_competitor_canal) return ret;
		}
	} else {
		add_cost = !IsWaterTile(tile2);
		ret = DoCommand(tile2, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (ret.Failed()) return ret;
		if (add_cost) {
			cost.AddCost(ret);
		}
	}

	if (flags & DC_EXEC) {
		Depot *depot = new Depot(tile);
		depot->build_date = _date;

		Company::Get(_current_company)->infrastructure.water += 2 * LOCK_DEPOT_TILE_FACTOR;
		DirtyCompanyInfrastructureWindows(_current_company);

		MakeShipDepot(tile, _current_company, oc1, depot->index, DEPOT_PART_NORTH, axis, wc1);
		MakeShipDepot(tile2, _current_company, oc2, depot->index, DEPOT_PART_SOUTH, axis, wc2);
		if (river1) SetCanalOnRiver(tile);
		if (river2) SetCanalOnRiver(tile2);
		MarkTileDirtyByTile(tile);
		MarkTileDirtyByTile(tile2);
		MakeDefaultName(depot);
	}

	return cost;
}