Feat: Add a Nix flake for reproducible development environments

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -39,3 +39,6 @@ TM-CE/
 
 # Mac files
 .DS_Store
+
+# Direnv folder
+.direnv/

DEVELOPMENT.md

@@ -26,6 +26,13 @@ If you have any other questions, feel free to ping me (Aitch) in the dev-discuss
     - If the provided binaries fail (possibly due to libc issues), you can compile your own binaries from my repos:
 [gc_fst](https://github.com/AlexanderHarrison/gc_fst), [hmex](https://github.com/AlexanderHarrison/cdat), [hgecko](https://github.com/AlexanderHarrison/hgecko)
 
+### NixOS
+1. Make sure you have the [Flakes](https://nixos.wiki/wiki/Flakes) feature enabled.
+2. Enter the development shell by running `nix develop` to load all the necessary dependencies.
+3. Run the command `./build.sh path-to-melee.iso` in the console.
+
+Alternatively, if you have [Direnv](https://nixos.wiki/wiki/Direnv) installed, you can run `direnv allow` to enter the development shell automatically when you enter this project directory.
+
 ### Build Mode
 The build script takes an optional additional mode argument called the mode - `build.sh iso [mode]`.
 This allows building an optimized release, or fine-grained recompilation.

build.sh

@@ -32,9 +32,18 @@ elif [[ "$(uname)" == "Darwin" && "$(uname -m)" == "arm64" ]]; then
     hmex="bin/hmex_macos_arm64"
     xdelta="xdelta3"
 else
-    gc_fst="bin/gc_fst"
-    hgecko="bin/hgecko"
-    hmex="bin/hmex"
+    gc_fst="gc_fst"
+    if ! command -v gc_fst > /dev/null; then
+        gc_fst="bin/gc_fst"
+    fi
+    hgecko="hgecko"
+    if ! command -v hgecko > /dev/null; then
+        hgecko="bin/hgecko"
+    fi
+    hmex="hmex"
+    if ! command -v hmex > /dev/null; then
+        hmex="bin/hmex"
+    fi
     xdelta="xdelta3"
 fi