#!/usr/bin/env bash
#
# Render the UI and screenshot it without touching your session.
#
# A Slint window needs a compositor: under bare Xvfb nothing maps, and on a locked or
# remote machine there is no session to draw into. So this starts a nested headless
# sway, runs the app inside it, drives it with synthetic keys and grabs a frame per
# screen. It is how the shots in README.md were made, and how to check a layout change
# on a machine with no display.
#
#   nix-shell -E '(import ./shell.nix {}).overrideAttrs (o: {
#     nativeBuildInputs = o.nativeBuildInputs ++ (with (import <nixpkgs> {}); [ sway grim wtype ]);
#   })' --run 'tools/headless-shots.sh out/ http://127.0.0.1:8080'
#
set -euo pipefail
OUTDIR="${1:?usage: headless-shots.sh <outdir> [server-url]}"
SERVER="${2:-http://127.0.0.1:8080}"
BIN="${BIN:-./target/release/musicmouse-slint}"
mkdir -p "$OUTDIR"

export XDG_RUNTIME_DIR="$(mktemp -d)"
unset WAYLAND_DISPLAY DISPLAY
export WLR_BACKENDS=headless WLR_LIBINPUT_NO_DEVICES=1 WLR_RENDERER=pixman
trap 'kill %1 2>/dev/null || true; rm -rf "$XDG_RUNTIME_DIR"' EXIT

launcher="$XDG_RUNTIME_DIR/launch.sh"
printf '#!/usr/bin/env bash\nexec %q --server %q >%q/app.log 2>&1\n' \
    "$(realpath "$BIN")" "$SERVER" "$XDG_RUNTIME_DIR" > "$launcher"
chmod +x "$launcher"
printf 'output HEADLESS-1 mode 1920x1080\ndefault_border none\nexec %s\n' "$launcher" \
    > "$XDG_RUNTIME_DIR/sway.cfg"

sway -c "$XDG_RUNTIME_DIR/sway.cfg" >"$XDG_RUNTIME_DIR/sway.log" 2>&1 &
for _ in $(seq 30); do [ -S "$XDG_RUNTIME_DIR/wayland-1" ] && break; sleep 1; done
export WAYLAND_DISPLAY=wayland-1
sleep 16   # library fetch plus the first covers

# Each step is ONE wtype invocation, and starts with a throwaway keypress.
#
# wtype creates a virtual keyboard, sends, and exits. The client needs a moment to
# notice the seat gained a keyboard, so the first key or two of any invocation is
# dropped - which makes a per-key loop lose every key it sends. Batching a step into
# one invocation and opening it with "x" + BackSpace spends that warm-up on a keypress
# that cancels itself out.
WARM=(-s 260 "x" -k BackSpace)
shot() { sleep 2.5; grim "$OUTDIR/$1.png"; echo "  $1"; }

shot 01-root
wtype "${WARM[@]}" -k Down -k Return;             shot 02-categories
wtype "${WARM[@]}" -k Return;                     shot 03-grid
wtype "${WARM[@]}" -k Escape -k Escape "maja";    shot 04-search
wtype "${WARM[@]}" -k Escape -k question "brumm"; shot 05-tracksearch
wtype "${WARM[@]}" -k Return; sleep 4;            shot 06-play
wtype "${WARM[@]}" -k Escape;                     shot 07-bar

echo "wrote 7 frames to $OUTDIR"