#!/usr/bin/env bash
# Pre-commit hook: format staged Haskell files with fourmolu.
# Installed by: scripts/install-hooks
set -euo pipefail

PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"

# Get staged .hs files (handles filenames with spaces)
staged=$(git -C "$PROJECT_DIR" diff --cached --name-only --diff-filter=ACM -- '*.hs')
if [ -z "$staged" ]; then
    exit 0
fi

# Collect the files into an array
mapfile -t files <<< "$staged"

echo "--- Formatting staged Haskell files with fourmolu..."
if ! "$PROJECT_DIR/hs" fourmolu --mode inplace "${files[@]}"; then
    echo "ERROR: fourmolu formatting failed" >&2
    exit 1
fi

# Re-stage any files that were modified by formatting
changed=0
for f in "${files[@]}"; do
    if ! git -C "$PROJECT_DIR" diff --quiet "$f"; then
        git -C "$PROJECT_DIR" add "$f"
        changed=$((changed + 1))
    fi
done

if [ "$changed" -gt 0 ]; then
    echo "--- Formatted $changed file(s) — re-staged automatically"
fi