#!/bin/bash
# steamos-session-select — switch between Gamescope and KDE Plasma (no SDDM).
#
# Called by Steam's "Power > Switch to Desktop" (passes "desktop") and by the
# "Return to Gaming Mode" desktop shortcut (passes "gamescope").
#
# Mechanism
#   Root    : write ~/.config/ps5-next-session to "plasma" or "gamescope"
#   Non-root: sudo to write the token, then end / restart the session.
#
# Direction notes
#   Plasma -> Gamescope: terminate the Plasma session; agetty autologin re-runs the
#     profile.d script, reads the token and execs gamescope-session-ps5.
#   Gamescope -> Plasma: a soft tty handoff leaves the AMD GPU's DP->HDMI bridge in
#     a state that produces a black HDMI image even with KWin running and a valid
#     2560x1440 mode set. PCI function-level reset hangs the GPU; amdgpu module
#     reload fails with EBUSY because fbcon / snd-hda hold refcounts. Only a real
#     reboot — which power-cycles PCI and re-runs atombios — clears the bridge,
#     so this direction calls `systemctl reboot`. The next-session token has
#     already been written, so tty1 boots straight into Plasma after the reboot.
#     On PS5 the boot chain requires re-running the jailbreak after a reboot;
#     this is an accepted limitation.
#
# Optional: write `plasmax11` to ~/.config/ps5-next-session for an X11 escape
# hatch via startx + startplasma-x11 (ps5-tty-session.sh).

set -euo pipefail

MARKER="/etc/ps5-use-tty-sessions"
SESSION_FILE="/home/steam/.config/ps5-next-session"

session="${1:-gamescope}"

# ---------- Root path: write next tty session token ----------
if [[ $EUID -eq 0 ]]; then
    case "$session" in
        gamescope)
            next="gamescope"
            ;;
        desktop|plasma|plasma-wayland|plasmax11)
            next="plasma"
            ;;
        *)
            echo >&2 "steamos-session-select: unrecognised session '$session'"
            exit 1
            ;;
    esac

    if [[ ! -f "$MARKER" ]]; then
        echo >&2 "steamos-session-select: $MARKER missing — image not using tty sessions"
        exit 1
    fi

    mkdir -p "$(dirname "$SESSION_FILE")"
    printf '%s\n' "$next" >"$SESSION_FILE"
    sync
    chown steam:steam "$SESSION_FILE"
    chmod 644 "$SESSION_FILE"
    echo "steamos-session-select: next tty1 session set to $next"
    exit 0
fi

# ---------- Non-root path: escalate, then end / restart the session ----------
sudo "$(realpath "$0")" "$session"

case "$session" in
    gamescope)
        if [[ -n "${XDG_SESSION_ID:-}" ]]; then
            loginctl terminate-session "$XDG_SESSION_ID"
        else
            pkill -u steam kwin_wayland || true
            pkill -u steam kwin_x11 || true
        fi
        ;;
    desktop|plasma|plasma-wayland|plasmax11)
        exec sudo systemctl reboot
        ;;
esac