#!/bin/bash
# =============================================================================
# ram-watchdog.sh - Watchdog memoire pour le photomaton
# =============================================================================
# Usage: Lancer via cron toutes les minutes :
#   * * * * * /home/pi/opencode/scripts/ram-watchdog.sh
#
# Actions par seuil :
#   - Swap > 70% : vider les caches
#   - Swap > 85% : redemarrer photobooth-app
#   - Swap > 95% : reboot du Pi
# =============================================================================

LOG_TAG="ram-watchdog"
log_info()  { logger -t "$LOG_TAG" "[INFO] $1"; }
log_warn()  { logger -t "$LOG_TAG" "[WARN] $1"; }
log_error() { logger -t "$LOG_TAG" "[ERROR] $1"; }

# --- Lire les valeurs memoire ---
SWAP_TOTAL=$(awk '/SwapTotal/ {print $2}' /proc/meminfo)
SWAP_FREE=$(awk '/SwapFree/ {print $2}' /proc/meminfo)
MEM_AVAILABLE=$(awk '/MemAvailable/ {print $2}' /proc/meminfo)

# Eviter division par zero
if [ "$SWAP_TOTAL" -eq 0 ]; then
    exit 0
fi

SWAP_USED=$((SWAP_TOTAL - SWAP_FREE))
SWAP_PERCENT=$((SWAP_USED * 100 / SWAP_TOTAL))
MEM_AVAILABLE_MB=$((MEM_AVAILABLE / 1024))

# --- Seuil 1 : Swap > 70% -> vider les caches ---
if [ "$SWAP_PERCENT" -ge 70 ] && [ "$SWAP_PERCENT" -lt 85 ]; then
    log_warn "Swap a ${SWAP_PERCENT}% (RAM dispo: ${MEM_AVAILABLE_MB}Mo) - Vidage des caches"
    sync
    echo 3 > /proc/sys/vm/drop_caches 2>/dev/null || true
fi

# --- Seuil 2 : Swap > 85% -> redemarrer photobooth-app ---
if [ "$SWAP_PERCENT" -ge 85 ] && [ "$SWAP_PERCENT" -lt 95 ]; then
    log_error "Swap a ${SWAP_PERCENT}% (RAM dispo: ${MEM_AVAILABLE_MB}Mo) - Redemarrage photobooth-app"

    # Redemarrer photobooth-app en tant que l'utilisateur pi
    REAL_USER="pi"
    XDG_RUNTIME_DIR="/run/user/$(id -u "$REAL_USER")"
    DBUS_SESSION_BUS_ADDRESS="unix:path=${XDG_RUNTIME_DIR}/bus"

    runuser -u "$REAL_USER" -- env \
        XDG_RUNTIME_DIR="$XDG_RUNTIME_DIR" \
        DBUS_SESSION_BUS_ADDRESS="$DBUS_SESSION_BUS_ADDRESS" \
        systemctl --user restart photobooth-app 2>/dev/null || true

    log_warn "photobooth-app redemarre"

    # Attendre et vider les caches
    sleep 5
    sync
    echo 3 > /proc/sys/vm/drop_caches 2>/dev/null || true
fi

# --- Seuil 3 : Swap > 95% -> reboot ---
if [ "$SWAP_PERCENT" -ge 95 ]; then
    log_error "CRITIQUE: Swap a ${SWAP_PERCENT}% (RAM dispo: ${MEM_AVAILABLE_MB}Mo) - REBOOT"
    sync
    sleep 2
    reboot
fi