#!/usr/bin/env bash
set -euo pipefail

# backup-modifications: Detect user-modified plugin files and back them up
# Output: BACKED_UP | NO_MODIFICATIONS | NO_CHECKSUMS

PLUGIN_ROOT="${1:-$(cd "$(dirname "$0")/.." && pwd)}"
WORK_DIR="$PWD"
CHECKSUMS_FILE="$PLUGIN_ROOT/.mindrian-checksums"

# Check for checksums file (generated at install time)
if [[ ! -f "$CHECKSUMS_FILE" ]]; then
  echo "NO_CHECKSUMS"
  echo "Cannot detect modifications without install checksums."
  exit 0
fi

# Read current version via platform.cjs (plan 85-06 sweep).
PLUGIN_VERSION=$(node -e "try{process.stdout.write(require('$PLUGIN_ROOT/lib/core/platform.cjs').readPluginJsonVersion('$PLUGIN_ROOT'))}catch(e){process.stdout.write('unknown')}" 2>/dev/null || echo "unknown")

# Compare current checksums against stored ones
MODIFIED_FILES=()

while IFS='  ' read -r stored_hash file_path; do
  # Skip empty lines and comments
  [[ -z "$stored_hash" || "$stored_hash" == \#* ]] && continue

  full_path="$PLUGIN_ROOT/$file_path"
  if [[ -f "$full_path" ]]; then
    current_hash=$(md5sum "$full_path" | cut -d' ' -f1)
    if [[ "$current_hash" != "$stored_hash" ]]; then
      MODIFIED_FILES+=("$file_path")
    fi
  fi
done < "$CHECKSUMS_FILE"

# No modifications found
if [[ ${#MODIFIED_FILES[@]} -eq 0 ]]; then
  echo "NO_MODIFICATIONS"
  echo "All files match install checksums."
  exit 0
fi

# Back up modified files preserving directory structure
BACKUP_DIR="$WORK_DIR/mindrian-patches"
mkdir -p "$BACKUP_DIR"

for file_path in "${MODIFIED_FILES[@]}"; do
  src="$PLUGIN_ROOT/$file_path"
  dest="$BACKUP_DIR/$file_path"
  mkdir -p "$(dirname "$dest")"
  cp "$src" "$dest"
done

# Create backup metadata
BACKUP_DATE=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
FILES_JSON=$(printf '%s\n' "${MODIFIED_FILES[@]}" | python3 -c "import sys,json; print(json.dumps([l.strip() for l in sys.stdin if l.strip()]))")

cat > "$BACKUP_DIR/backup-meta.json" <<EOF
{
  "backup_date": "$BACKUP_DATE",
  "plugin_version": "$PLUGIN_VERSION",
  "modified_files": $FILES_JSON
}
EOF

echo "BACKED_UP"
echo "${#MODIFIED_FILES[@]} files backed up to mindrian-patches/"