nix: add script to generate nimble dir structure

nix/default.nix

@@ -73,6 +73,8 @@ in stdenv.mkDerivation rec {
   configurePhase = ''
     patchShebangs . vendor/nimbus-build-system > /dev/null
     make nimbus-build-system-paths
+    # Generate ./vendor/.nimble dir structure
+    ./nix/generate-nimble-paths.sh
   '';
 
   preBuild = ''

nix/generate-nimble-paths.sh

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+
+# Output file to store the submodule paths
+output_file="submodule_paths.txt"
+
+# Ensure the output file is empty before we start
+> "$output_file"
+
+# Find all .gitmodules files and process them
+find . -name .gitmodules | while read -r gitmodules_file; do
+    # Get the absolute directory path containing the .gitmodules file
+    module_dir=$(dirname "$(realpath "$gitmodules_file")")
+    
+    # Extract paths from the .gitmodules file
+    while IFS= read -r line; do
+        if [[ $line =~ path[[:space:]]*=[[:space:]]*(.*) ]]; then
+            submodule_path="${BASH_REMATCH[1]}"
+            # Write the absolute path of the submodule to the output file
+            echo "$module_dir/$submodule_path" >> "$output_file"
+        fi
+    done < "$gitmodules_file"
+done
+
+echo "Submodule paths collected in $output_file"
+
+# Base directory for nimble packages
+nimble_pkgs_dir="./vendor/.nimble/pkgs"
+
+# Ensure the base directory exists
+mkdir -p "$nimble_pkgs_dir"
+
+# Read each submodule path and process it
+while IFS= read -r submodule_path; do
+    # Extract the submodule name (last part of the path)
+    submodule_name=$(basename "$submodule_path")
+    
+    # Create the directory for the submodule
+    submodule_dir="$nimble_pkgs_dir/${submodule_name}-#head"
+    mkdir -p "$submodule_dir"
+    
+    # Create the .nimble-link file with the absolute path
+    nimble_link_file="$submodule_dir/${submodule_name}.nimble-link"
+    echo "$submodule_path" > "$nimble_link_file"
+    echo "$submodule_path" >> "$nimble_link_file"
+done < "$output_file"
+
+echo "Nimble packages prepared in $nimble_pkgs_dir"