Improvements to prettify

scripts/devshell/prettify

@@ -6,30 +6,33 @@ show_help() {
     echo "Format Haskell source files using fourmolu and stylish-haskell."
     echo ""
     echo "Options:"
-    echo "  -t, --tracked     Format all tracked Haskell (*.hs) files in the repository"
-    echo "  -s, --staged      Format all staged Haskell (*.hs) files"
-    echo "  -m, --modified    Format all modified Haskell (*.hs) files, including staged and unstaged"
-    echo "  -n, --not-staged  Format all non-staged modified Haskell (*.hs) files"
-    echo "  -h, --help        Show this help message"
+    echo "  -t, --tracked           Format all tracked Haskell (*.hs) files in the repository"
+    echo "  -s, --staged            Format all staged Haskell (*.hs) files"
+    echo "  -m, --modified          Format all modified Haskell (*.hs) files, including staged and unstaged"
+    echo "  -n, --not-staged        Format all non-staged modified Haskell (*.hs) files"
+    echo "  -p, --previous-commit   Format all Haskell (*.hs) files modified before the last commit (HEAD~1)"
+    echo "  -h, --help              Show this help message"
 }
 
 # Function to run the formatting commands
 run_format() {
+    top_level=$(git rev-parse --show-toplevel) 
     for file in "$@"; do
         if [[ $file == *.hs ]]; then
-            if grep -qE '^#' "$file"; then
+            if grep -qE '^#' "$top_level/$file"; then
               echo "$file contains CPP.  Skipping."
             else
               echo "Formatting: $file"
-              fourmolu -q -i "$file"
-              fourmolu -q -i "$file"
-              stylish-haskell -i "$file"
+              fourmolu -q -i "$top_level/$file"
+              fourmolu -q -i "$top_level/$file"
+              stylish-haskell -i "$top_level/$file"
             fi
-
         fi
     done
 }
 
+flag_passed="true"
+
 # Parse command line arguments
 case $1 in
     -t|--tracked)
@@ -44,31 +47,47 @@ case $1 in
     -n|--not-staged)
         files=$(git diff --name-only --diff-filter=ACM '*.hs')
         ;;
+    -p|--previous-commit)
+        files=$(git diff --name-only --diff-filter=ACM HEAD~1 '*.hs')
+        ;;
     -h|--help)
         show_help
         exit 0
         ;;
     *)
         files="$@"
+        flag_passed="false"
         ;;
 esac
 
-if !(which stylish-haskell > /dev/null 2>&1); then
-    echo "ERROR: stylish-haskell is not available!"
-    echo -e
-    echo "Try entering the development shell with:"
-    echo "  nix develop"
-    exit 1
+if [[ $flag_passed == "true" ]] && [[ $# -gt 1 ]]; then
+  echo "ERROR: only one flag is allowed!"
+  echo -e
+  show_help
+  exit 1
 fi
 
-if !(which fourmolu > /dev/null 2>&1); then
-    echo "ERROR: fourmolu is not available!"
+for file in $files; do
+  if [[ ! -a $file ]]; then
+    echo "ERROR: $file does not exist"
+    exit 1
+    if ![[ -f $file ]]; then
+      echo "ERROR: $file is not a regular file"
+      exit
+    fi
+  fi
+done
+
+for tool in stylish-haskell fourmolu
+do
+  if !(which $tool > /dev/null 2>&1); then
+    echo "ERROR: $tool is not available!"
     echo -e
     echo "Try entering the development shell with:"
     echo "  nix develop"
     exit 1
-fi
-
+  fi
+done
 
 if [[ -z $files ]]; then
     echo "No files to format!"