#!/usr/bin/env bash
# A simple control program for running text based presentations within ad
# via an index file.
#
# To run the presentation within ad, execute 'Slide' in a directory with the
# structure shown below. From there the NextSlide and PrevSlide commands can
# be used to move between the slides.
#
# > Example directory structure:
# .
#   body
#   conclusion
#   index
#   intro
#
# > Example index content:
#   intro
#   body
#   conclusion 

. "$HOME/.ad/lib/ad.sh"

requireAd

f="$(basename "$(bufRead "$bufid" filename)")"
d="$(dirname "$fname")"

[ ! -f "$d/index" ] && adError "not in a slideshow directory"
index="$(cat "$d/index")"
toLoad="$(cat "$d/index" | head -n1)"

case "$1" in
  next)
    i="$(grep -n "^$f\$" "$d/index" | cut -d: -f1)"
    j="$(( "$i" + 1 ))"
    toLoad="$(nl "$d/index" | grep "\s$j\s" | cut -f2)"
    [ -z "$toLoad" ] && adError "This is the last slide"
    ;;

  prev)
    i="$(grep -n "^$f\$" "$d/index" | cut -d: -f1)"
    j="$(( "$i" - 1 ))"
    toLoad="$(nl "$d/index" | grep "\s$j\s" | cut -f2)"
    [ -z "$toLoad" ] && adError "This is first slide"
    ;;
esac

# TODO: being able to replace the current buffer with a new one
#       rather than opening new buffers each time would be nice
adCtl "open $toLoad"
adCtl "Get"
adEdit "0 i/[PrevSlide] [NextSlide]\n\n/"
id="$(currentBufferId)"
curToBof "$id"
markClean "$id"