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

RUNTIME="claude"
APPLY=0
ALL_EMPTY=0

usage() {
  cat <<USAGE
Usage: $(basename "$0") [options]

Remove empty runtime directories created by migration/drift.
Default mode only checks managed legacy surfaces. Use --all-empty for broader cleanup.

Options:
  --runtime <name>   Runtime to clean (default: claude)
  --all-empty        Scan all runtime directories (except protected paths)
  --apply            Perform deletions (default: dry-run)
  -h, --help         Show help
USAGE
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    --runtime)
      [[ $# -lt 2 ]] && { echo "Missing value for --runtime" >&2; exit 1; }
      RUNTIME="$2"
      shift 2
      ;;
    --all-empty)
      ALL_EMPTY=1
      shift
      ;;
    --apply)
      APPLY=1
      shift
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      echo "Unknown argument: $1" >&2
      usage >&2
      exit 1
      ;;
  esac
done

case "$RUNTIME" in
  claude)
    TARGET_ROOT="$HOME/.claude"
    managed_roots=(
      "$HOME/.claude/agent-guides"
      "$HOME/.claude/scripts"
      "$HOME/.claude/templates"
      "$HOME/.claude/presets"
      "$HOME/.claude/skills"
      "$HOME/.claude/agents"
      "$HOME/.claude/agents.bak"
    )
    protected_roots=(
      "$HOME/.claude/.git"
      "$HOME/.claude/debug"
      "$HOME/.claude/file-history"
      "$HOME/.claude/projects"
      "$HOME/.claude/session-env"
      "$HOME/.claude/tasks"
      "$HOME/.claude/todos"
      "$HOME/.claude/plugins"
      "$HOME/.claude/statsig"
      "$HOME/.claude/logs"
      "$HOME/.claude/shell-snapshots"
      "$HOME/.claude/paste-cache"
      "$HOME/.claude/plans"
      "$HOME/.claude/ide"
      "$HOME/.claude/cache"
    )
    ;;
  *)
    echo "Unsupported runtime: $RUNTIME" >&2
    exit 1
    ;;
esac

[[ -d "$TARGET_ROOT" ]] || { echo "[mosaic-clean] Runtime dir missing: $TARGET_ROOT" >&2; exit 1; }

is_protected() {
  local path="$1"
  for p in "${protected_roots[@]}"; do
    [[ -e "$p" ]] || continue
    case "$path" in
      "$p"|"$p"/*)
        return 0
        ;;
    esac
  done
  return 1
}

collect_empty_dirs() {
  if [[ $ALL_EMPTY -eq 1 ]]; then
    find "$TARGET_ROOT" -depth -type d -empty
  else
    for r in "${managed_roots[@]}"; do
      [[ -d "$r" ]] || continue
      find "$r" -depth -type d -empty
    done
  fi
}

count_candidates=0
count_deletable=0

while IFS= read -r d; do
  [[ -n "$d" ]] || continue

  count_candidates=$((count_candidates + 1))

  # Never remove runtime root.
  [[ "$d" == "$TARGET_ROOT" ]] && continue

  if is_protected "$d"; then
    continue
  fi

  count_deletable=$((count_deletable + 1))

  if [[ $APPLY -eq 1 ]]; then
    rmdir "$d" 2>/dev/null || true
    if [[ ! -d "$d" ]]; then
      echo "[mosaic-clean] deleted: $d"
    fi
  else
    echo "[mosaic-clean] would delete: $d"
  fi
done < <(collect_empty_dirs | sort -u)

mode="managed"
[[ $ALL_EMPTY -eq 1 ]] && mode="all-empty"

if [[ $APPLY -eq 1 ]]; then
  echo "[mosaic-clean] complete: mode=$mode deleted_or_attempted=$count_deletable candidates=$count_candidates runtime=$RUNTIME"
else
  echo "[mosaic-clean] dry-run: mode=$mode deletable=$count_deletable candidates=$count_candidates runtime=$RUNTIME"
  echo "[mosaic-clean] re-run with --apply to delete"
fi