Replace MPQ runtime with loose file asset system

Extract assets from MPQ archives into organized loose files indexed by
manifest.json, enabling fully parallel reads without StormLib serialization.
Add asset_extract and blp_convert tools, PNG texture override support.

tools/asset_extract/path_mapper.cpp

@@ -0,0 +1,207 @@
+#include "path_mapper.hpp"
+#include <algorithm>
+#include <cctype>
+
+namespace wowee {
+namespace tools {
+
+std::string PathMapper::toLower(const std::string& str) {
+    std::string result = str;
+    std::transform(result.begin(), result.end(), result.begin(),
+                   [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
+    return result;
+}
+
+std::string PathMapper::toForwardSlash(const std::string& str) {
+    std::string result = str;
+    std::replace(result.begin(), result.end(), '\\', '/');
+    return result;
+}
+
+bool PathMapper::startsWithCI(const std::string& str, const std::string& prefix) {
+    if (str.size() < prefix.size()) return false;
+    for (size_t i = 0; i < prefix.size(); ++i) {
+        if (std::tolower(static_cast<unsigned char>(str[i])) !=
+            std::tolower(static_cast<unsigned char>(prefix[i]))) {
+            return false;
+        }
+    }
+    return true;
+}
+
+std::string PathMapper::extractAfterPrefix(const std::string& path, size_t prefixLen) {
+    if (prefixLen >= path.size()) return {};
+    return path.substr(prefixLen);
+}
+
+std::string PathMapper::mapPath(const std::string& wowPath) {
+    // Preserve original casing in the remainder for filesystem readability
+    std::string rest;
+
+    // DBFilesClient\ → db/
+    if (startsWithCI(wowPath, "DBFilesClient\\")) {
+        rest = extractAfterPrefix(wowPath, 14);
+        return "db/" + toForwardSlash(rest);
+    }
+
+    // Character\{Race}\{Gender}\ → character/{race}/{gender}/
+    if (startsWithCI(wowPath, "Character\\")) {
+        rest = extractAfterPrefix(wowPath, 10);
+        std::string lowered = toLower(rest);
+        return "character/" + toForwardSlash(lowered);
+    }
+
+    // Creature\{Name}\ → creature/{name}/
+    if (startsWithCI(wowPath, "Creature\\")) {
+        rest = extractAfterPrefix(wowPath, 9);
+        // Keep first component lowercase for directory, preserve filename case
+        std::string fwd = toForwardSlash(rest);
+        auto slash = fwd.find('/');
+        if (slash != std::string::npos) {
+            return "creature/" + toLower(fwd.substr(0, slash)) + "/" + fwd.substr(slash + 1);
+        }
+        return "creature/" + fwd;
+    }
+
+    // Item\ObjectComponents\{Type}\ → item/{type}/
+    if (startsWithCI(wowPath, "Item\\ObjectComponents\\")) {
+        rest = extractAfterPrefix(wowPath, 22);
+        std::string fwd = toForwardSlash(rest);
+        auto slash = fwd.find('/');
+        if (slash != std::string::npos) {
+            return "item/" + toLower(fwd.substr(0, slash)) + "/" + fwd.substr(slash + 1);
+        }
+        return "item/" + fwd;
+    }
+
+    // Item\TextureComponents\ → item/texture/
+    if (startsWithCI(wowPath, "Item\\TextureComponents\\")) {
+        rest = extractAfterPrefix(wowPath, 23);
+        return "item/texture/" + toForwardSlash(rest);
+    }
+
+    // Interface\Icons\ → interface/icons/
+    if (startsWithCI(wowPath, "Interface\\Icons\\")) {
+        rest = extractAfterPrefix(wowPath, 16);
+        return "interface/icons/" + toForwardSlash(rest);
+    }
+
+    // Interface\GossipFrame\ → interface/gossip/
+    if (startsWithCI(wowPath, "Interface\\GossipFrame\\")) {
+        rest = extractAfterPrefix(wowPath, 21);
+        return "interface/gossip/" + toForwardSlash(rest);
+    }
+
+    // Interface\{rest} → interface/{rest}/
+    if (startsWithCI(wowPath, "Interface\\")) {
+        rest = extractAfterPrefix(wowPath, 10);
+        return "interface/" + toForwardSlash(rest);
+    }
+
+    // Textures\Minimap\ → terrain/minimap/
+    if (startsWithCI(wowPath, "Textures\\Minimap\\")) {
+        rest = extractAfterPrefix(wowPath, 17);
+        return "terrain/minimap/" + toForwardSlash(rest);
+    }
+
+    // Textures\BakedNpcTextures\ → creature/baked/
+    if (startsWithCI(wowPath, "Textures\\BakedNpcTextures\\")) {
+        rest = extractAfterPrefix(wowPath, 25);
+        return "creature/baked/" + toForwardSlash(rest);
+    }
+
+    // Textures\{rest} → terrain/textures/{rest}
+    if (startsWithCI(wowPath, "Textures\\")) {
+        rest = extractAfterPrefix(wowPath, 9);
+        return "terrain/textures/" + toForwardSlash(rest);
+    }
+
+    // World\Maps\{Map}\ → terrain/maps/{map}/
+    if (startsWithCI(wowPath, "World\\Maps\\")) {
+        rest = extractAfterPrefix(wowPath, 11);
+        std::string fwd = toForwardSlash(rest);
+        auto slash = fwd.find('/');
+        if (slash != std::string::npos) {
+            return "terrain/maps/" + toLower(fwd.substr(0, slash)) + "/" + fwd.substr(slash + 1);
+        }
+        return "terrain/maps/" + fwd;
+    }
+
+    // World\wmo\ → world/wmo/ (preserve subpath)
+    if (startsWithCI(wowPath, "World\\wmo\\")) {
+        rest = extractAfterPrefix(wowPath, 10);
+        return "world/wmo/" + toForwardSlash(rest);
+    }
+
+    // World\Doodads\ → world/doodads/
+    if (startsWithCI(wowPath, "World\\Doodads\\")) {
+        rest = extractAfterPrefix(wowPath, 14);
+        return "world/doodads/" + toForwardSlash(rest);
+    }
+
+    // World\{rest} → world/{rest}/
+    if (startsWithCI(wowPath, "World\\")) {
+        rest = extractAfterPrefix(wowPath, 6);
+        return "world/" + toForwardSlash(rest);
+    }
+
+    // Environments\ → environment/
+    if (startsWithCI(wowPath, "Environments\\")) {
+        rest = extractAfterPrefix(wowPath, 13);
+        return "environment/" + toForwardSlash(rest);
+    }
+
+    // Sound\Ambience\ → sound/ambient/
+    if (startsWithCI(wowPath, "Sound\\Ambience\\")) {
+        rest = extractAfterPrefix(wowPath, 15);
+        return "sound/ambient/" + toForwardSlash(rest);
+    }
+
+    // Sound\Character\ → sound/character/
+    if (startsWithCI(wowPath, "Sound\\Character\\")) {
+        rest = extractAfterPrefix(wowPath, 16);
+        return "sound/character/" + toForwardSlash(rest);
+    }
+
+    // Sound\Doodad\ → sound/doodad/
+    if (startsWithCI(wowPath, "Sound\\Doodad\\")) {
+        rest = extractAfterPrefix(wowPath, 13);
+        return "sound/doodad/" + toForwardSlash(rest);
+    }
+
+    // Sound\Creature\ → sound/creature/
+    if (startsWithCI(wowPath, "Sound\\Creature\\")) {
+        rest = extractAfterPrefix(wowPath, 15);
+        return "sound/creature/" + toForwardSlash(rest);
+    }
+
+    // Sound\Spells\ → sound/spell/
+    if (startsWithCI(wowPath, "Sound\\Spells\\")) {
+        rest = extractAfterPrefix(wowPath, 13);
+        return "sound/spell/" + toForwardSlash(rest);
+    }
+
+    // Sound\Music\ → sound/music/
+    if (startsWithCI(wowPath, "Sound\\Music\\")) {
+        rest = extractAfterPrefix(wowPath, 12);
+        return "sound/music/" + toForwardSlash(rest);
+    }
+
+    // Sound\{rest} → sound/{rest}/
+    if (startsWithCI(wowPath, "Sound\\")) {
+        rest = extractAfterPrefix(wowPath, 6);
+        return "sound/" + toForwardSlash(rest);
+    }
+
+    // Spells\ → spell/
+    if (startsWithCI(wowPath, "Spells\\")) {
+        rest = extractAfterPrefix(wowPath, 7);
+        return "spell/" + toForwardSlash(rest);
+    }
+
+    // Everything else → misc/{original_path}
+    return "misc/" + toForwardSlash(wowPath);
+}
+
+} // namespace tools
+} // namespace wowee