#!/usr/bin/env bash
# bar: a second tmux status row assembled from independent modules.
#
#   bar mount              set status 2 and build status-format[1] from the modules file
#   bar on | off | status  fan out to every bar-<name> module on PATH
#   bar set <name> <text>  publish a segment by hand (a hook, a script, an agent)
#   bar format             print the status-format[1] string without touching tmux
#
# Modules file (~/.config/tmux/bar/modules, BAR_MODULES overrides): one
# "<left|centre|right> <name>" per line, # comments, order = display order.
# A segment is #{?@bar_<name>,...,} so an empty option hides it, separator
# included. Daemons follow bin/bar-lib; anything else publishes with `bar set`.

set -uo pipefail
MODULES="${BAR_MODULES:-${XDG_CONFIG_HOME:-$HOME/.config}/tmux/bar/modules}"
SEP='#[fg=#908caa] │ #[default]'

die() { printf 'bar: %s\n' "$*" >&2; exit "${2:-1}"; }

# Prints "align name" pairs; the default is a lone sys module on the right.
modules() {
  [ -f "$MODULES" ] || { echo "right sys"; return; }
  local n=0 align name extra
  while read -r align name extra; do
    n=$((n + 1))
    case "$align" in ''|'#'*) continue ;; esac
    [ -n "$name" ] && [ -z "$extra" ] || die "$MODULES:$n: expected '<align> <name>'" 2
    case "$align" in left|centre|right) ;; *) die "$MODULES:$n: align must be left, centre or right" 2 ;; esac
    [[ "$name" =~ ^[a-z0-9_]+$ ]] || die "$MODULES:$n: name must be lowercase [a-z0-9_]" 2
    echo "$align $name"
  done <"$MODULES"
}

segment() { printf '#{?@bar_%s,%s#{@bar_%s},}' "$1" "$2" "$1"; }

group() {
  local align=$1 first=1 a name
  printf '#[align=%s default]' "$align"
  while read -r a name; do
    [ "$a" = "$align" ] || continue
    segment "$name" "$([ $first = 1 ] || printf '%s' "$SEP")"
    first=0
  done <<<"$2"
}

format() {
  local list; list=$(modules) || exit $?
  group left "$list"; group centre "$list"; group right "$list"; echo
}

each_module() {
  local a name
  while read -r a name; do
    command -v "bar-$name" >/dev/null 2>&1 && "bar-$name" "$1"
  done < <(modules)
}

case "${1:-}" in
  format) format ;;
  mount)
    fmt=$(format) || exit $?
    tmux set -g status 2 && tmux set -g 'status-format[1]' "$fmt" ;;
  on) each_module --on ;;
  off) each_module --off ;;
  status)
    while read -r a name; do
      printf '%-8s %-7s %s\n' "$name" "$a" "$(tmux show -gqv "@bar_$name" 2>/dev/null | sed 's/#\[[^]]*\]//g')"
    done < <(modules) ;;
  set)
    [[ "${2:-}" =~ ^[a-z0-9_]+$ ]] || die "set: name must be lowercase [a-z0-9_]" 2
    BAR_MODULE=$2 . "$(dirname "$(readlink -f "$0")")/bar-lib"
    bar_publish "${3:-}" ;;
  *)
    sed -n '2,12p' "$0" | sed 's/^# \{0,1\}//'; exit 0 ;;
esac