e

#!/usr/bin/env bash

# e - Custom EDITOR provider
# Uses nvim, fallback to vim, fallback to vi
#
# Supported environment variables:
# - E_DEBUG=true enable debug logging

# Use a tab-scoped socket inside WezTerm so each tab gets its own nvim
# instance; panes within the same tab share it. Falls back to a single
# global socket for non-WezTerm terminals.
#
# $WEZ_TAB_ID is a cache zsh/wezterm.zsh keeps warm to save a fork. Validate
# rather than trust it -- it is inherited, so it can arrive stale (a tmux
# server started in another tab) or hand-set. wez-tab-id is the authority
# whenever it is missing or junk.
__nvim_state="${XDG_STATE_HOME:-${HOME}/.local/state}/nvim"
_t="${WEZ_TAB_ID:-}"
case "$_t" in
"" | *[!0-9]*) _t=$(wez-tab-id) ;;
esac
case "$_t" in
"" | *[!0-9]*) __server="${__nvim_state}/nvim.sock" ;;
*) __server="${__nvim_state}/nvim-tab-${_t}.sock" ;;
esac
unset _t __nvim_state

log() {
  echo "[e] ${1}"
}

# Set once this invocation is the one that started the server. Only the owner
# may remove the socket: closing a single pane HUPs that pane alone, and the
# nvim sharing this tab's socket may still be running in another one.
__owns_server=""

# Signals that can leave the socket behind, i.e. kill nvim without letting it
# run VimLeavePre. HUP is the tab/terminal going away, which is the common
# one. Note nvim runs the tty in raw mode, so Ctrl-C while it is up is a
# keystroke rather than a signal -- INT mostly lands on the script itself,
# e.g. during the headless --remote-expr calls below.
on_signal() {
  local signal="$1"

  # -S so a signal can never take out something that isn't our socket
  [ -n "$__owns_server" ] && [ -S "$__server" ] && {
    log "Received SIG${signal}, removing ${__server}"
    rm -f "$__server"
  }

  local orphans
  orphans=$(
    # pgrep does NOT return all results
    # shellcheck disable=2009
    ps -U "${USER:-$(id -un)}" -ww -o args= | grep -v grep | grep language-server
  )
  [[ -n $orphans ]] && {
    log "Possible orphan language server processes:"
    log "${orphans}"
  }

  # re-raise so we die from the signal and callers see the usual 128+n status
  trap - "$signal"
  kill -s "$signal" $$
}

main() {
  wez-clean-socks

  ! command -v nvim >/dev/null && {
    local fallback
    fallback="vim"
    ! command -v vim >/dev/null && fallback="vi"

    [[ "$E_DEBUG" != "" ]] && log "Use fallback editor ${fallback}"
    "$fallback" "$@"
    return
  }

  local first="$1"

  local existing
  local running
  # pgrep does NOT return all results. -ww because the socket path sits at the
  # end of a long command line -- macOS ps never truncated it in testing, even
  # on a narrow tty, but Linux procps is not so reliably unlimited
  # shellcheck disable=2009
  running=$(
    ps -U "${USER:-$(id -un)}" -ww -o args= | grep -v grep | grep -F "$__server"
  )
  if [ -z "$running" ]; then
    [[ "$E_DEBUG" != "" ]] && log "Not running"

    # this happens if my neovim crashes/killed without VimLeavePre
    if [ -S "$__server" ]; then
      [[ "$E_DEBUG" != "" ]] && log "Removing dead ${__server}"
      rm -f "$__server"
    elif [ -e "$__server" ]; then
      # not ours to delete -- nvim --listen will fail and say why
      log "Not a socket, leaving alone: ${__server}"
    fi

  else
    # remote-expr outputs to /dev/stderr for some reason
    # 0.9.0 needs headless https://github.com/neovim/neovim/issues/22970
    # @TODO detect multiple instances and pick correct server
    # https://github.com/neovim/neovim/issues/21600
    existing=$(nvim \
      --headless \
      --server "$__server" \
      --remote-expr "execute('echo v:servername')" \
      2>&1 | xargs)
    [[ "$E_DEBUG" != "" ]] && log "Found running $existing"
  fi

  # New server, empty
  [ "$existing" != "$__server" ] && [ -z "$first" ] && {
    [[ "$E_DEBUG" != "" ]] && log "New server ${__server} with empty file"
    __owns_server=1
    nvim --listen "$__server" +enew
    return
  }

  typeset -a files=()
  for file in "$@"; do
    # don't prepend PWD for absolute paths
    case "$file" in
    /*) ;;
    *) file="$(pwd)/${file}" ;;
    esac
    files+=("$file")
  done

  # New server with files
  [ "$existing" != "$__server" ] && {
    [[ "$E_DEBUG" != "" ]] &&
      log "New server ${__server} (did not match ${existing}) with ${files[*]}"
    __owns_server=1
    nvim --listen "$__server" "${files[@]}"
    return
  }

  # ==========================================================================
  # use existing server
  # ==========================================================================

  # 0.9.0 needs headless https://github.com/neovim/neovim/issues/22970
  nvim \
    --headless \
    --server "$__server" \
    --remote-expr "execute('DKOExternal')"

  if [ -z "$first" ]; then
    [[ "$E_DEBUG" != "" ]] && log "No file given, surface existing server"
    nvim --server "$__server" --remote-send '<C-\><C-N><Cmd>e<CR>'
    return
  fi

  [[ "$E_DEBUG" != "" ]] && log "Use server ${__server} with ${files[*]}"
  nvim --server "$__server" --remote-silent "${files[@]}"
}

trap 'on_signal INT' INT
trap 'on_signal HUP' HUP
trap 'on_signal TERM' TERM
main "$@"