git worktree helpers

worktrees.zsh

# wtswitch [query]
#   Switch to an existing worktree using fzf. Works from any worktree.
#   With no argument: opens fzf picker.
#   With argument: if exactly one worktree matches, cd there directly.
#                  if multiple match, open fzf pre-filled with the query.
#                  if no match, exit with error.
#
#   Requires: fzf
#
#   Example:
#     wtswitch          # interactive picker
#     wtswitch foo      # direct cd if unambiguous, fzf otherwise
#
wtswitch() {
  if ! git rev-parse --show-toplevel &>/dev/null; then
    echo "Not in a git repository" >&2
    return 1
  fi

  local worktrees
  worktrees=$(git worktree list --porcelain | awk '/^worktree /{print $2}')

  if [[ -z "$worktrees" ]]; then
    echo "No worktrees found" >&2
    return 1
  fi

  local selection

  if [[ -n "$1" ]]; then
    local matches
    matches=$(echo "$worktrees" | fzf --filter="$1")
    local match_count
    match_count=$(echo "$matches" | grep -c .)

    if [[ $match_count -eq 0 ]]; then
      echo "No worktree matching '$1' found" >&2
      return 1
    elif [[ $match_count -eq 1 ]]; then
      selection="$matches"
    fi
  fi

  if [[ -z "$selection" ]]; then
    selection=$(echo "$worktrees" | fzf --prompt="worktree > " ${1:+--query="$1"})
    [[ -z "$selection" ]] && return 0
  fi

  echo "✓ Switched to ${selection/#$HOME/~}"
  cd "$selection"
}


# wtcreate <branch>
#   Create a new branch and worktree from the base branch.
#   Must be called from a base repo (~/src/REPO), not from within a worktree.
#   Worktree is created at ~/src/REPO.branch and cd'd into automatically.
#
#   Base branch resolution order:
#     1. .worktreebase file in repo root (single line, branch name)
#     2. origin/HEAD (set via: git remote set-head origin --auto)
#     3. main or master, whichever exists
#
#   Branch names are sanitized: lowercased, non-alphanumeric runs replaced
#   with dashes, leading/trailing dashes stripped, truncated to 200 chars.
#
#   Example:
#     ~/src/myrepo $ wtcreate feature/my-thing
#     ✓ Created branch feature-my-thing from main and worktree @ ~/src/myrepo.feature-my-thing
#
wtcreate() {
  local branch_name="$1"

  if [[ -z "$branch_name" ]]; then
    echo "Usage: wtc <branch-name>" >&2
    return 1
  fi

  local git_root
  git_root=$(git rev-parse --show-toplevel 2>/dev/null)
  if [[ -z "$git_root" ]]; then
    echo "Not in a git repository" >&2
    return 1
  fi

  local src_dir="${HOME}/src"
  local repo_name
  repo_name=$(basename "$git_root")

  if [[ "$git_root" != "${src_dir}/${repo_name}" ]]; then
    echo "Not in a base repo under ${src_dir}" >&2
    return 1
  fi

  branch_name="${branch_name:l}"
  branch_name="${branch_name//[^a-z0-9]/-}"
  branch_name="${branch_name##-}"
  branch_name="${branch_name%%-}"
  branch_name="${branch_name[1,200]}"
  branch_name="${branch_name%%-}"

  if [[ -z "$branch_name" ]]; then
    echo "Branch name is empty after sanitization" >&2
    return 1
  fi

  local base_branch
  local worktreebase_file="${git_root}/.worktreebase"
  if [[ -f "$worktreebase_file" ]]; then
    base_branch=$(cat "$worktreebase_file" | tr -d '[:space:]')
  fi

  if [[ -z "$base_branch" ]]; then
    base_branch=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's|refs/remotes/origin/||')
  fi

  if [[ -z "$base_branch" ]]; then
    if git show-ref --verify --quiet refs/heads/main; then
      base_branch="main"
    elif git show-ref --verify --quiet refs/heads/master; then
      base_branch="master"
    else
      echo "Could not determine base branch" >&2
      return 1
    fi
  fi

  if ! git show-ref --verify --quiet "refs/heads/${base_branch}" && \
     ! git show-ref --verify --quiet "refs/remotes/origin/${base_branch}"; then
    echo "Base branch '${base_branch}' not found locally or in origin" >&2
    return 1
  fi

  local worktree_path="${src_dir}/${repo_name}.${branch_name}"

  if [[ -d "$worktree_path" ]]; then
    echo "Worktree already exists: ${worktree_path}" >&2
    return 1
  fi

  if git show-ref --verify --quiet "refs/heads/${branch_name}"; then
    echo "Branch '${branch_name}' already exists" >&2
    return 1
  fi

  git worktree add -b "$branch_name" "$worktree_path" "$base_branch" || return 1

  echo "✓ Created branch ${branch_name} from ${base_branch} and worktree @ ${worktree_path/#$HOME/~}"

  cd "$worktree_path"
}