#!/bin/sh
#
# mtmux — initialise tmux session with multiple windows
#
# Usage:
#   1. mtmux [-n name] [-c cwd] -- cmd1 . windowname: cmd2 . shellname:
#
#      Spawns a tmux session, optionally named "name", and optionally with the
#      working directory set to "cwd", with three windows, one running cmd1,
#      one running cmd2 and named "windowname", and one named "shellname"
#      running the default command.
#
#   2. mtmux -n name -w 2
#
#      Attach to session "name" and switch to window 2
#
# Copyright © 2020 martin f. krafft <madduck@madduck.net>
# Released under the WTFPL.
#
set -eu

warn() {
  echo >&2 "$@"
}

err() {
  local exitcode; exitcode="$1"; shift
  warn "$@"
  exit $exitcode
}

cmds=
for i in "$@"; do
  case "${state:-}:$i" in
    (:-c) state=cwd;;
    (cwd:*)
      [ -z "${cwd:-}" ] && cwd="$i" || err 1 "Option -c already specified"
      state=
      ;;

    (:-n) state=name;;
    (name:*)
      [ -z "${name:-}" ] && name="$i" || err 1 "Option -n already specified"
      state=
      ;;

    (:-w) state=win;;
    win:*)
      [ -z "${window:-}" ] && window="$i" || err 1 "Option -w already specified"
      state=
      ;;

    (:--) shift; set -- "$@"; break;;

    (:\;) cmds="$cmds \;";;
    (:*) cmds="${cmds:+$cmds }$i";;
  esac
  shift 2>/dev/null || break
done

args=
if [ -n "${window:-}" ]; then

  if [ -n "${cwd:-}" ]; then
    warn "Both -w and -c don't make sense, ignoring -c"
    cwd=
  fi
  if [ -n "$*" ]; then
    warn "Ignoring commands specified with -w"
    set --
  fi
  if [ -z "$name" ]; then
    err 1 "Missing option -n, required with -w"
  fi

  args="new -t $name \;${cmds:+ $cmds \;} select-window -t $window"

else

  subcmd="new${name:+ -s $name}"
  for i in "$@" +; do
    case "$i" in
      (*:) wname="${i%:}";;
      (+|.|\;)
        args="${args}${subcmd}${cwd:+ -c $cwd}${wname:+ -n $wname}${cmd:-} \; "
        args="$args${cmds:+$cmds \; }"
        subcmd="neww -d"
        cmd= cmds=
        ;;
      (*) cmd="${cmd:-} $i";;
    esac
  done

fi

eval exec tmux $args