#!/bin/bash

# --- CONFIGURATION ---
THRESHOLD=90
LOAD_THRESHOLD=5.0
HOST=$(hostname)

# On envoie à 'root', le système fera la redirection grâce aux aliases
DEST="root"

REPORT=""
ALERT=false

# 1. CHECK DISQUE & INODES
DISK_USAGE=$(df / | awk 'NR==2 {print $5}' | sed 's/%//')
INODE_USAGE=$(df -i / | awk 'NR==2 {print $5}' | sed 's/%//')

if [ "$DISK_USAGE" -gt "$THRESHOLD" ]; then
    REPORT="${REPORT}⚠️ DISQUE : $DISK_USAGE% utilisé\n"
    ALERT=true
fi
if [ "$INODE_USAGE" -gt "$THRESHOLD" ]; then
    REPORT="${REPORT}⚠️ INODES : $INODE_USAGE% utilisé\n"
    ALERT=true
fi

# 2. CHECK RAM & SWAP
RAM_USAGE=$(free | grep Mem | awk '{print int($3/$2 * 100)}')
SWAP_TOTAL=$(free | grep Swap | awk '{print $2}')

if [ "$RAM_USAGE" -gt "$THRESHOLD" ]; then
    REPORT="${REPORT}⚠️ RAM : $RAM_USAGE% utilisé\n"
    ALERT=true
fi
if [ "$SWAP_TOTAL" -gt 0 ]; then
    SWAP_USAGE=$(free | grep Swap | awk '{print int($3/$2 * 100)}')
    if [ "$SWAP_USAGE" -gt 50 ]; then
        REPORT="${REPORT}⚠️ SWAP : $SWAP_USAGE% utilisé\n"
        ALERT=true
    fi
fi

# 3. CHECK CHARGE CPU
CPU_LOAD=$(uptime | awk -F'load average:' '{ print $2 }' | cut -d',' -f1 | tr -d ' ' | tr ',' '.')
if (( $(echo "$CPU_LOAD > $LOAD_THRESHOLD" | bc -l) )); then
    REPORT="${REPORT}🔥 CPU LOAD : $CPU_LOAD (Surcharge)\n"
    ALERT=true
fi

# 4. CHECK SERVICES (SSH et Fail2Ban sont vitaux)
for SVC in "ssh" "fail2ban"; do
    if ! systemctl is-active --quiet "$SVC"; then
        REPORT="${REPORT}❌ SERVICE : $SVC est ARRÊTÉ\n"
        ALERT=true
    fi
done

# --- ENVOI VIA ALIAS ROOT ---
if [ "$ALERT" = true ]; then
    # Le sujet sera automatiquement préfixé par le wrapper [$HOSTNAME]
    echo -e "Détails de l'alerte :\n\n$REPORT\n---\nDate: $(date)" | mail -s "ALERTE RESSOURCES" "$DEST"
fi