#!/bin/sh
# Show the shaders in contrib/shaders on a running session.
#
#   contrib/shader-tour                  spawn a session and cycle every one
#   contrib/shader-tour torch            apply one to the session named below
#   contrib/shader-tour guides           cycle just that group
#   SESSION=work contrib/shader-tour     ...to a different session
#   DWELL=8 contrib/shader-tour          linger longer on each
#
# Like theme-tour, it works by writing the config the session was started with
# and letting the watcher notice. The cursor-following ones (torch, sonar,
# ripples, crosshair) want the mouse moved over the session while they are up:
# `curx`/`cury` is where the cursor is, and standing still tells you nothing.
set -e
here=$(cd "$(dirname "$0")" && pwd)
bin="$here/../build/slosh"
SESSION=${SESSION:-shaders}
CONF=${SLOSH_CONFIG:-/tmp/slosh-shader-tour.kdl}
DWELL=${DWELL:-5}

# A name can be the whole slug (guides-torch), or just the interesting half
# (torch) when that is unambiguous, because nobody wants to remember which
# group a shader is in.
resolve() {
  [ -f "$here/shaders/$1.kdl" ] && { echo "$1"; return 0; }
  set -- $(cd "$here/shaders" && ls -- *-"$1".kdl 2>/dev/null | sed 's|\.kdl$||')
  [ $# -eq 1 ] && { echo "$1"; return 0; }
  return 1
}

apply() {
  name=$(resolve "$1") || { echo "no such shader: $1"; exit 1; }
  f="$here/shaders/$name.kdl"
  # The theme goes with it: shaders resolve default-coloured text through
  # theme's default_fg/default_bg, so a preset judged without one is being
  # judged against a guess.
  {
    cat "$here/themes/sl0p.kdl"
    echo
    cat "$f"
  } > "$CONF"
  printf '  %-26s %s\n' "$name" "$(sed -n '1s|// ||p' "$f")"
}

# A tour needs something to tour. Applying a single shader does not: it may
# well be aimed at a session you already have, or at a config you are editing.
ensure_session() {
  "$bin" ls 2>/dev/null | grep -q "^$SESSION " && return 0
  cp "$here/themes/sl0p.kdl" "$CONF"
  echo "starting a session called $SESSION..."
  SLOSH_CONFIG="$CONF" "$bin" -s "$SESSION" -- "${SHELL:-/bin/sh}" &
  sleep 1
}

if [ -n "$1" ]; then
  # A whole group (guides, crt, motion, built-ins, pane-states) or one shader.
  set +e
  ls "$here/shaders/$1-"*.kdl >/dev/null 2>&1
  isgroup=$?
  set -e
  if [ $isgroup -eq 0 ]; then
    ensure_session
    echo "cycling $1, ${DWELL}s each. ^C to stop wherever you like."
    for f in "$here/shaders/$1-"*.kdl; do
      apply "$(basename "$f" .kdl)"
      sleep "$DWELL"
    done
  else
    apply "$1"
  fi
  exit 0
fi

ensure_session

echo "cycling every shader, ${DWELL}s each. ^C to stop wherever you like."
echo "move the mouse over the session for the ones that follow the cursor."
for f in "$here"/shaders/*.kdl; do
  apply "$(basename "$f" .kdl)"
  sleep "$DWELL"
done