/**
 * 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);

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

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

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

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

	WaterClass wc1 = IsWaterTile(tile) ? GetWaterClass(tile) : WATER_CLASS_CANAL;
	Owner oc1 = HasTileWaterGround(tile) && GetWaterClass(tile) == WATER_CLASS_CANAL ? GetCanalOwner(tile) : _current_company;
	bool add_cost1 = !IsWaterTile(tile);

	/* At this point we got a tile with 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 {
		ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (ret.Failed()) return ret;
		if (add_cost1) {
			cost.AddCost(ret);
			if (wc1 == WATER_CLASS_CANAL) cost.AddCost(_price[PR_BUILD_CANAL]);
		}
	}

	WaterClass wc2 = IsWaterTile(tile2) ? GetWaterClass(tile2) : WATER_CLASS_CANAL;
	Owner oc2 = HasTileWaterGround(tile2) && GetWaterClass(tile2) == WATER_CLASS_CANAL ? GetCanalOwner(tile2) : _current_company;
	bool add_cost2 = !IsWaterTile(tile2);

	/* At this point we got a tile2 with 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 {
		ret = DoCommand(tile2, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (ret.Failed()) return ret;
		if (add_cost2) {
			cost.AddCost(ret);
			if (wc2 == WATER_CLASS_CANAL) cost.AddCost(_price[PR_BUILD_CANAL]);
		}
	}

	if (!IsTileFlat(tile) || !IsTileFlat(tile2)) {
		Slope slope1 = GetTileSlope(tile);
		Slope slope2 = GetTileSlope(tile2);

		if (IsSteepSlope(slope1) || IsSteepSlope(slope2)) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

		int h_north_corner_n = TileHeight(tile);
		int h_north_corner_s = TileHeight(TileAddByDiagDir(tile, AxisToDiagDir(OtherAxis(axis))));
		int h_middle_corner_n = TileHeight(tile2);
		int h_middle_corner_s = TileHeight(TileAddByDiagDir(tile2, AxisToDiagDir(OtherAxis(axis))));
		int h_south_corner_n = TileHeight(tile2 + diff);
		int h_south_corner_s = TileHeight(TileAddByDiagDir(tile2 + diff, AxisToDiagDir(OtherAxis(axis))));

		int corners[] = { h_north_corner_n, h_north_corner_s, h_middle_corner_n, h_middle_corner_s, h_south_corner_n, h_south_corner_s };

		int min_h = MAX_TILE_HEIGHT;
		int max_h = 0;
		for (int i = 0; i < lengthof(corners); i++) {
			min_h = min(min_h, corners[i]);
			max_h = max(max_h, corners[i]);
		}

		int best_h = INT_MAX;
		int second_best_h = INT_MAX;
		int best_sum = INT_MAX;
		int second_best_sum = INT_MAX;
		for (int h = min_h; h <= max_h; h++) {
			int sum = 0;
			for (int c = 0; c < lengthof(corners); c++) {
				sum += abs(h - corners[c]);
			}
			if (sum <= best_sum) {
				second_best_sum = best_sum;
				best_sum = sum;
				second_best_h = best_h;
				best_h = h;
			}
		}
		if (best_sum != second_best_sum) {
			int command1p2 = -1;
			Slope tileh1 = SLOPE_FLAT;
			if (h_north_corner_n > best_h) {
				command1p2 = 0;
				tileh1 |= SLOPE_N;
			} else if (h_north_corner_n < best_h) {
				command1p2 = 1;
				tileh1 |= SLOPE_N;
			}
			if (h_north_corner_s > best_h) {
				command1p2 = 0;
				tileh1 |= axis == AXIS_X ? SLOPE_E : SLOPE_W;
			} else if (h_north_corner_s < best_h) {
				command1p2 = 1;
				tileh1 |= axis == AXIS_X ? SLOPE_E : SLOPE_W;
			}

			int command2p2 = -1;
			Slope tileh2 = SLOPE_FLAT;
			if (h_south_corner_n > best_h) {
				command2p2 = 0;
				tileh2 |= axis == AXIS_X ? SLOPE_W : SLOPE_E;
			} else if (h_south_corner_n < best_h) {
				command2p2 = 1;
				tileh2 |= axis == AXIS_X ? SLOPE_W : SLOPE_E;
			}
			if (h_south_corner_s > best_h) {
				command2p2 = 0;
				tileh2 |= SLOPE_S;
			} else if (h_south_corner_s < best_h) {
				command2p2 = 1;
				tileh2 |= SLOPE_S;
			}

			if (h_middle_corner_n > best_h) {
				if (tileh1 != SLOPE_FLAT) {
					command1p2 = 0;
					tileh1 |= axis == AXIS_X ? SLOPE_W : SLOPE_E;
				} else {
					command2p2 = 0;
					tileh2 |= SLOPE_N;
				}
			} else if (h_middle_corner_n < best_h) {
				if (tileh1 != SLOPE_FLAT) {
					command1p2 = 1;
					tileh1 |= axis == AXIS_X ? SLOPE_W : SLOPE_E;
				} else {
					command2p2 = 1;
					tileh2 |= SLOPE_N;
				}
			}

			if (h_middle_corner_s > best_h) {
				if (tileh1 != SLOPE_FLAT) {
					command1p2 = 0;
					tileh1 |= SLOPE_S;
				} else {
					command2p2 = 0;
					tileh2 |= axis == AXIS_X ? SLOPE_E : SLOPE_W;
				}
			} else if (h_middle_corner_s < best_h) {
				if (tileh1 != SLOPE_FLAT) {
					command1p2 = 1;
					tileh1 |= SLOPE_S;
				} else {
					command2p2 = 1;
					tileh2 |= axis == AXIS_X ? SLOPE_E : SLOPE_W;
				}
			}
			
			if (tileh1 != SLOPE_FLAT && command1p2 != -1) {
				/* Mark the tile as already cleared for the terraform command. */
				ClearedObjectArea *coa = MakeClearedObjectArea(tile, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
				/* Hide the tile from the terraforming command. */
				TileIndex tile1_before = coa->first_tile;
				coa->first_tile = INVALID_TILE;
				ret = DoCommand(tile, tileh1, command1p2, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
				coa->first_tile = tile1_before;
				if (ret.Failed()) return ret;
				cost.AddCost(ret);

			}

			if (tileh2 != SLOPE_FLAT && command2p2 != -1) {
				/* Mark the tile as already cleared for the terraform command. */
				ClearedObjectArea *coa = MakeClearedObjectArea(tile2, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
				/* Hide the tile from the terraforming command. */
				TileIndex tile2_before = coa->first_tile;
				coa->first_tile = INVALID_TILE;
				ret = DoCommand(tile2, tileh2, command2p2, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
				coa->first_tile = tile2_before;
				if (ret.Failed()) return ret;
				cost.AddCost(ret);
			}
		} else {
			return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
		}
	}

//	int best_h;
//	int max_delta = MAX_TILE_HEIGHT;
//	for (int h = min_h; h <= max_h; h++) {
//		int delta = 0;
//		for (int c = 0; c < lengthof(corners); c++) {
//			delta = max(delta, Delta(h, corners[c]));
//		}
//		if (delta <= max_delta) {
//			max_delta = delta;
//			int c_count = 0;
//			for (int c = 0; c < lengthof(corners); c++) {
//				if (corners[c] == h) {
//					c_count++;
//				}
//			}
//			best_h = h;
//		}
//	}

//	if (!IsTileFlat(tile) || !IsTileFlat(tile2)) {
//		int z_slope1;
//		Slope slope1 = GetTileSlope(tile, &z_slope1);
//		int z_middle_corner_n = TileHeight(tile2);
//		int z_middle_corner_s = TileHeight(TileAddByDiagDir(tile2, AxisToDiagDir(OtherAxis(axis))));
//		int z_slope2;
//		Slope slope2 = GetTileSlope(tile2, &z_slope2);

//		/* Forbid these combinations. */
		/**
		 *       3
		 *      / \
		 *     2   2
		 *    / \ /
		 *   1   1
		 *    \ /
		 *     0
		 */
//		if (IsSteepSlope(slope1) || IsSteepSlope(slope2)) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

		/**
		 *       1         0
		 *      / \       / \
		 *     0   0     1   1
		 *    / \ /     / \ /
		 *   1   1     0   0
		 *    \ /       \ /
		 *     0         1
		 */
//		if (slope1 == SLOPE_NS && slope2 == SLOPE_EW || slope1 == SLOPE_EW && slope2 == SLOPE_NS) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

	    /**
		 *       1
		 *      / \
		 *     0   1
		 *    / \ /
		 *   0   1
		 *    \ /
		 *     0
		 */
//		if (z_middle_corner_n != z_middle_corner_s && (IsSlopeWithThreeCornersRaised(slope1) && IsSlopeWithOneCornerRaised(slope2) || IsSlopeWithOneCornerRaised(slope1) && IsSlopeWithThreeCornersRaised(slope2))) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

		/**
		 *       2         1
		 *      / \       / \
		 *     1   2     1   0
		 *    / \ /     / \ /
		 *   0   1     1   0
		 *    \ /       \ /
		 *     0         0
		 */
//		if (slope1 == slope2 && IsInclinedSlope(slope1)) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

		/**
		 *       1         2         0
		 *      / \       / \       / \
		 *     0   1     1   2     1   0
		 *    / \ /     / \ /     / \ /
		 *   0   0     1   1     1   1
		 *    \ /       \ /       \ /
		 *     1         0         2
		 */
//		if (((IsSlopeWithOneCornerRaised(slope2) || IsSlopeWithThreeCornersRaised(slope2)) && IsInclinedSlope(slope1) && DiagDirToAxis(GetInclinedSlopeDirection(slope1)) == axis) || ((IsSlopeWithOneCornerRaised(slope1) || IsSlopeWithThreeCornersRaised(slope1)) && IsInclinedSlope(slope2) && DiagDirToAxis(GetInclinedSlopeDirection(slope2)) == axis)) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

		/**
		 *       0
		 *      / \
		 *     0   1
		 *    / \ /
		 *   1   1
		 *    \ /
		 *     0
		 */
//		if (((slope2 == SLOPE_EW || slope2 == SLOPE_NS) && IsInclinedSlope(slope1) && DiagDirToAxis(GetInclinedSlopeDirection(slope1)) == OtherAxis(axis)) || ((slope1 == SLOPE_EW || slope1 == SLOPE_NS) && IsInclinedSlope(slope2) && DiagDirToAxis(GetInclinedSlopeDirection(slope2)) == OtherAxis(axis))) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);

//		/* Terraform these combinations. */
//		if (slope1 == SLOPE_FLAT || slope2 == SLOPE_FLAT) {
//			/* Mark the tile as already cleared for the terraform command. */
//			ClearedObjectArea *coa = MakeClearedObjectArea(slope1 == SLOPE_FLAT ? tile2 : tile, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
//			/* Hide the tile from the terraforming command. */
//			TileIndex tile_flat_before = coa->first_tile;
//			coa->first_tile = INVALID_TILE;
//			ret = DoCommand(slope1 == SLOPE_FLAT ? tile2 : tile, slope1 == SLOPE_FLAT ? z_slope1 == z_slope2 ? slope2: ComplementSlope(slope2) : z_slope1 == z_slope2 ? slope1 : ComplementSlope(slope1), z_slope1 == z_slope2 ? 0 : 1, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
//			coa->first_tile = tile_flat_before;
//			if (ret.Failed()) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
//			cost.AddCost(ret);
//		} else {
//			if ((IsSlopeWithThreeCornersRaised(slope1) || IsSlopeWithOneCornerRaised(slope1)) && (IsSlopeWithThreeCornersRaised(slope2) || IsSlopeWithOneCornerRaised(slope2))) {
//				/* Mark the tile as already cleared for the terraform command. */
//				ClearedObjectArea *coa = MakeClearedObjectArea(tile, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
//				/* Hide the tile from the terraforming command. */
//				TileIndex tile_3corner1_before = coa->first_tile;
//				coa->first_tile = INVALID_TILE;
//				ret = DoCommand(tile, IsSlopeWithThreeCornersRaised(slope1) ? ComplementSlope(slope1) : slope1, IsSlopeWithThreeCornersRaised(slope1) ? 1 : 0, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
//				coa->first_tile = tile_3corner1_before;
//				if (ret.Failed()) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
//				cost.AddCost(ret);
//				if (z_middle_corner_n == z_middle_corner_s) {
//					/* Mark the tile as already cleared for the terraform command. */
//					ClearedObjectArea *coa = MakeClearedObjectArea(tile2, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
//					/* Hide the tile from the terraforming command. */
//					TileIndex tile_3corner2_before = coa->first_tile;
//					coa->first_tile = INVALID_TILE;
//					ret = DoCommand(tile2, IsSlopeWithThreeCornersRaised(slope2) ? ComplementSlope(slope2) : slope2, IsSlopeWithThreeCornersRaised(slope2) ? 1 : 0, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
//					coa->first_tile = tile_3corner2_before;
//					if (ret.Failed()) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
//					cost.AddCost(ret);
//				}
//			} else {
//				if ((IsInclinedSlope(slope1) && DiagDirToAxis(GetInclinedSlopeDirection(slope1)) == OtherAxis(axis) && (IsSlopeWithOneCornerRaised(slope2) || IsSlopeWithThreeCornersRaised(slope2))) || (IsInclinedSlope(slope2) && DiagDirToAxis(GetInclinedSlopeDirection(slope2)) == OtherAxis(axis) && (IsSlopeWithOneCornerRaised(slope1) || IsSlopeWithThreeCornersRaised(slope1)))) {
//					/* Mark the tile as already cleared for the terraform command. */
//					ClearedObjectArea *coa = MakeClearedObjectArea(IsInclinedSlope(slope1) ? tile : tile2, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
//					/* Hide the tile from the terraforming command. */
//					TileIndex tile_inclined1_before = coa->first_tile;
//					coa->first_tile = INVALID_TILE;
//					ret = DoCommand(IsInclinedSlope(slope1) ? tile : tile2, IsInclinedSlope(slope1) ? IsSlopeWithThreeCornersRaised(slope2) ? ComplementSlope(slope1) : slope1 : IsSlopeWithThreeCornersRaised(slope1) ? ComplementSlope(slope2) : slope2, IsInclinedSlope(slope1) ? IsSlopeWithThreeCornersRaised(slope2) ? 1 : 0 : IsSlopeWithThreeCornersRaised(slope1) ? 1 : 0, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
//					coa->first_tile = tile_inclined1_before;
//					if (ret.Failed()) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
//					cost.AddCost(ret);
//				} else {
//					if ((slope1 == SLOPE_EW || slope1 == SLOPE_NS) && (IsSlopeWithOneCornerRaised(slope2) || IsSlopeWithThreeCornersRaised(slope2)) || (slope2 == SLOPE_NS || slope2 == SLOPE_EW) && (IsSlopeWithOneCornerRaised(slope1) || IsSlopeWithThreeCornersRaised(slope1))) {
//						/* Mark the tile as already cleared for the terraform command. */
//						ClearedObjectArea *coa = MakeClearedObjectArea((slope1 == SLOPE_EW || slope1 == SLOPE_NS) ? tile : tile2, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
//						/* Hide the tile from the terraforming command. */
//						TileIndex tile_oppositecorners_before = coa->first_tile;
//						coa->first_tile = INVALID_TILE;
//						ret = DoCommand((slope1 == SLOPE_EW || slope1 == SLOPE_NS) ? tile : tile2, (slope1 == SLOPE_EW || slope1 == SLOPE_NS) ? IsSlopeWithOneCornerRaised(slope2) ? slope1 : ComplementSlope(slope1) : IsSlopeWithOneCornerRaised(slope1) ? slope2 : ComplementSlope(slope2), (slope1 == SLOPE_EW || slope1 == SLOPE_NS) ? IsSlopeWithOneCornerRaised(slope2) ? 0 : 1 : IsSlopeWithOneCornerRaised(slope1) ? 0 : 1, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
//						coa->first_tile = tile_oppositecorners_before;
//						if (ret.Failed()) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
//						cost.AddCost(ret);
//					} else {
//						if (slope1 == ComplementSlope(slope2) && IsInclinedSlope(slope1)) {
//							/* Mark the tile as already cleared for the terraform command. */
//							ClearedObjectArea *coa = MakeClearedObjectArea(tile2, tile, axis == AXIS_X ? 2 : 1, axis == AXIS_Y ? 2 : 1);
//							/* Hide the tile from the terraforming command. */
//							TileIndex tile_complement_before = coa->first_tile;
//							coa->first_tile = INVALID_TILE;
//							ret = DoCommand(tile2, z_middle_corner_n > z_slope1 ? slope2 : slope1, z_middle_corner_n > z_slope1 ? 0 : 1, flags | DC_NO_WATER, CMD_TERRAFORM_LAND);
//							coa->first_tile = tile_complement_before;
//							if (ret.Failed()) return_cmd_error(STR_ERROR_SITE_UNSUITABLE);
//							cost.AddCost(ret);
//						} else {
//							/* Shouldn't reach here. */
//							assert(false);
//						}
//					}
//				}
//			}
//		}
//	}

//		if (!IsTileFlat(tile) || !IsTileFlat(tile2)) return_cmd_error(STR_ERROR_FLAT_LAND_REQUIRED);

	DiagDirection dir_rotate = axis == AXIS_X ? DIAGDIR_SE : DIAGDIR_NE;
	TileIndex tc = tile + (axis == AXIS_X ? TileDiffXY(0, -1) : TileDiffXY(1, 0));
	ret = EnsureNoShipFromDiagDir(tc, dir_rotate);
	if (ret.Failed()) return ret;

	tc = tile2 + (axis == AXIS_X ? TileDiffXY(0, -1) : TileDiffXY(1, 0));
	ret = EnsureNoShipFromDiagDir(tc, dir_rotate);
	if (ret.Failed()) return ret;

	dir_rotate = ReverseDiagDir(dir_rotate);
	tc = tile + (axis == AXIS_X ? TileDiffXY(0, 1) : TileDiffXY(-1, 0));
	ret = EnsureNoShipFromDiagDir(tc, dir_rotate);
	if (ret.Failed()) return ret;

	tc = tile2 + (axis == AXIS_X ? TileDiffXY(0, 1) : TileDiffXY(-1, 0));
	ret = EnsureNoShipFromDiagDir(tc, dir_rotate);
	if (ret.Failed()) return ret;

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

		if (add_cost1 && wc1 == WATER_CLASS_CANAL) Company::Get(_current_company)->infrastructure.water++;
		if (add_cost2 && wc2 == WATER_CLASS_CANAL) Company::Get(_current_company)->infrastructure.water++;
		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);
		MarkTileDirtyByTile(tile);
		MarkTileDirtyByTile(tile2);
		MakeDefaultName(depot);
	}

	return cost;
}