From 849d50be8edbc84a49fc421543b3f9852cf5956e Mon Sep 17 00:00:00 2001
From: Gary Talent <gary@drinkingtea.net>
Date: Wed, 8 Jan 2025 21:34:01 -0600
Subject: [PATCH] [nostalgia/core] Make getTileIdx return an Optional

---
 .../core/include/nostalgia/core/tilesheet.hpp        |  8 +++++++-
 src/nostalgia/modules/core/src/tilesheet.cpp         | 12 +++++++-----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp b/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
index bbb7aca7..7561e196 100644
--- a/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
+++ b/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
@@ -212,6 +212,10 @@ struct TileSheetV4 {
 				pixels(std::move(pPixels)) {
 		}
 
+		/**
+		 *
+		 * @return the dimensional size of the SubSheet (e.g. width * height)
+		 */
 		[[nodiscard]]
 		constexpr std::size_t size() const noexcept {
 			return static_cast<std::size_t>(columns) * static_cast<std::size_t>(rows);
@@ -273,7 +277,7 @@ size_t getTileCnt(TileSheet const&ts) noexcept;
 TileSheet::SubSheet const*getSubsheet(TileSheet const&ts, SubSheetId id) noexcept;
 
 [[nodiscard]]
-size_t getTileIdx(TileSheet const&ts, SubSheetId id) noexcept;
+ox::Optional<size_t> getTileIdx(TileSheet const&ts, SubSheetId id) noexcept;
 
 [[nodiscard]]
 uint8_t getPixel4Bpp(TileSheet::SubSheet const&ss, std::size_t idx) noexcept;
@@ -392,6 +396,8 @@ ox::Result<SubSheetId> getIdFor(TileSheet const&ts, ox::StringViewCR path) noexc
 
 ox::Result<unsigned> getTileOffset(TileSheet const&ts, ox::StringViewCR pNamePath) noexcept;
 
+ox::Result<uint32_t> getTileOffset(TileSheet const&ts, SubSheetId pId) noexcept;
+
 ox::Result<ox::StringView> getNameFor(TileSheet::SubSheet const&ss, SubSheetId pId) noexcept;
 
 ox::Result<ox::StringView> getNameFor(TileSheet const&ts, SubSheetId pId) noexcept;
diff --git a/src/nostalgia/modules/core/src/tilesheet.cpp b/src/nostalgia/modules/core/src/tilesheet.cpp
index 6a113935..d82ac5f3 100644
--- a/src/nostalgia/modules/core/src/tilesheet.cpp
+++ b/src/nostalgia/modules/core/src/tilesheet.cpp
@@ -66,10 +66,10 @@ static ox::Optional<size_t> getPixelIdx(
 	return ox::Optional<size_t>{};
 }
 
-size_t getTileIdx(TileSheet const&ts, SubSheetId const id) noexcept {
+ox::Optional<size_t> getTileIdx(TileSheet const&ts, SubSheetId const id) noexcept {
 	size_t idx{};
 	auto const out = getPixelIdx(ts.subsheet, id, idx, ts.bpp);
-	return out.or_value(0) / PixelsPerTile;
+	return out ? ox::Optional<size_t>{ox::in_place, *out / PixelsPerTile} : out;
 }
 
 uint8_t getPixel4Bpp(TileSheet::SubSheet const&ss, std::size_t idx) noexcept {
@@ -355,12 +355,12 @@ ox::Result<SubSheetId> getIdFor(TileSheet const&ts, ox::StringViewCR path) noexc
 /**
  * Gets the offset in tiles of the desired subsheet.
  */
-static ox::Result<unsigned> getTileOffset(
+static ox::Result<uint32_t> getTileOffset(
 		TileSheet::SubSheet const&ss,
 		ox::SpanView<ox::StringView> const&pNamePath,
 		int8_t pBpp,
 		std::size_t pIt = 0,
-		unsigned pCurrentTotal = 0) noexcept {
+		uint32_t pCurrentTotal = 0) noexcept {
 	// pIt == pNamePath.size() - 1 &&
 	if (ss.name != pNamePath[pIt]) {
 		return ox::Error(2, "Wrong branch");
@@ -374,12 +374,14 @@ static ox::Result<unsigned> getTileOffset(
 		if (!err) {
 			return offset;
 		}
+		// Possible bug? Shoud this be usinga a recursive version of
+		// pixelCnt will count pixels in subsheets of sub as well.
 		pCurrentTotal += pixelCnt(sub, pBpp) / PixelsPerTile;
 	}
 	return ox::Error(1, "SubSheet not found");
 }
 
-ox::Result<unsigned> getTileOffset(TileSheet const&ts, ox::StringViewCR pNamePath) noexcept {
+ox::Result<uint32_t> getTileOffset(TileSheet const&ts, ox::StringViewCR pNamePath) noexcept {
 	return core::getTileOffset(ts.subsheet, ox::split<8>(pNamePath, '.'), ts.bpp);
 }