Clean Branches

#!/usr/bin/env bash
# find-candidates.sh — Find merged and stale git branches
# Usage: find-candidates.sh [pattern]
# Output: Two labeled sections (MERGED / STALE), one branch per line.
#         Branches checked out in a worktree are annotated: branch [worktree:/path]
#         Empty section = no candidates of that type.
# Exit 0 always; downstream decides what to do with empty output.

set -euo pipefail

PATTERN="${1:-}"

# Detect main branch name (prefer main, fall back to master)
if git rev-parse --verify main >/dev/null 2>&1; then
  BASE="main"
elif git rev-parse --verify master >/dev/null 2>&1; then
  BASE="master"
else
  echo "ERROR: no main or master branch found" >&2
  exit 1
fi

# Build worktree map: branch -> worktree path
# `git worktree list --porcelain` emits blocks like:
#   worktree /path
#   HEAD <sha>
#   branch refs/heads/<name>   (or "detached" for detached HEAD)
# Uses a temp file (tab-separated key/value lines) for bash 3.2 compat
# (no declare -A). Tab is safe as an in-band delimiter because
# git-check-ref-format forbids control characters in refnames.
WORKTREE_MAP_FILE=$(mktemp)
trap 'rm -f "$WORKTREE_MAP_FILE"' EXIT
current_wt=""
while IFS= read -r line; do
  if [[ "$line" == worktree\ * ]]; then
    current_wt="${line#worktree }"
  elif [[ "$line" == branch\ refs/heads/* ]]; then
    branch_name="${line#branch refs/heads/}"
    printf '%s\t%s\n' "$branch_name" "$current_wt" >> "$WORKTREE_MAP_FILE"
  fi
done < <(git worktree list --porcelain)

# Helper: look up branch in worktree map.
# Uses awk with exact-string comparison on field 1 to avoid regex
# metacharacter pitfalls (e.g. a `.` in a branch name matching any char)
# and `=` pitfalls (branch names legally permit `=`).
worktree_for() {
  awk -F'\t' -v b="$1" '$1 == b { print $2; exit }' "$WORKTREE_MAP_FILE"
}

# --- Merged branches ---
echo "=== MERGED ==="
MERGED=$(git branch --merged "$BASE" 2>/dev/null | grep -v "^\*" | sed 's/^[+ ]*//' | grep -vE '^(main|master|develop)$' || true)
if [ -n "$PATTERN" ]; then
  MERGED=$(echo "$MERGED" | grep "$PATTERN" || true)
fi
while IFS= read -r branch; do
  [ -z "$branch" ] && continue
  wt=$(worktree_for "$branch")
  if [[ -n "$wt" ]]; then
    echo "$branch [worktree:$wt]"
  else
    echo "$branch"
  fi
done <<< "$MERGED"

# --- Squash/rebase-merged detection via GitHub PR history ---
# git branch --merged only detects true merge commits; squash and rebase merges
# rewrite commits so the branch ancestry never appears in main. gh pr list is the
# only reliable source for these.
if command -v gh >/dev/null 2>&1 && gh auth status >/dev/null 2>&1; then
  GH_MERGED=$(gh pr list --state merged --limit 300 --json headRefName --jq '.[].headRefName' 2>/dev/null || true)
  if [ -n "$GH_MERGED" ]; then
    while IFS= read -r branch; do
      [ -z "$branch" ] && continue
      # Skip protected branches
      case "$branch" in main|master|develop|release/*) continue ;; esac
      # Skip branches already caught by git branch --merged
      echo "$MERGED" | grep -qFx "$branch" && continue
      # Apply pattern filter
      if [ -n "$PATTERN" ] && ! echo "$branch" | grep -q "$PATTERN"; then
        continue
      fi
      # Confirm branch exists locally
      git rev-parse --verify "$branch" >/dev/null 2>&1 || continue
      # Check if a merged PR targeted this branch
      echo "$GH_MERGED" | grep -qFx "$branch" || continue
      wt=$(worktree_for "$branch")
      if [[ -n "$wt" ]]; then
        echo "$branch [worktree:$wt] [squash-merged]"
      else
        echo "$branch [squash-merged]"
      fi
    done < <(git branch --format='%(refname:short)')
  fi
fi

# --- Stale branches (no commits in 30+ days) ---
# Unix timestamps used for accurate threshold — git relative dates miss edge cases
echo "=== STALE ==="
CUTOFF=$(python3 -c "import time; print(int(time.time()) - 30*86400)")
while read -r branch ts reldate; do
  # Skip protected branches
  case "$branch" in main|master|develop|release/*) continue ;; esac
  # Apply