#!/bin/bash
# RAM Optimizer Setup Script
# Optimizes Linux memory with ZRAM compression
# Usage: sudo bash setup-zram.sh [PERCENT] [ALGORITHM]

set -e

# Configuration (can be overridden via arguments)
ZRAM_PERCENT=${1:-75}
ZRAM_ALGO=${2:-lz4}

echo "=========================================="
echo "  RAM Compression Optimizer v1.0"
echo "=========================================="

# Detect OS
if [ -f /etc/debian_version ]; then
    OS="debian"
    PKG_MANAGER="apt"
    PKG_INSTALL="apt install -y zram-tools"
elif [ -f /etc/fedora-release ]; then
    OS="fedora"
    PKG_MANAGER="dnf"
    PKG_INSTALL="dnf install -y zram"
elif [ -f /etc/arch-release ]; then
    OS="arch"
    PKG_MANAGER="pacman"
    PKG_INSTALL="pacman -S --noconfirm zram-generator"
else
    echo "Unsupported OS. Trying Debian/Ubuntu method..."
    OS="debian"
    PKG_MANAGER="apt"
    PKG_INSTALL="apt install -y zram-tools"
fi

# Detect total RAM
TOTAL_RAM_MB=$(awk '/MemTotal/ {printf "%.0f", $2/1024}' /proc/meminfo)
echo "[*] Detected RAM: ${TOTAL_RAM_MB} MB"
echo "[*] Target OS: ${OS}"
echo "[*] ZRAM config: ${ZRAM_PERCENT}% RAM, ${ZRAM_ALGO} algorithm"

# Install zram-tools
echo "[1/6] Installing ZRAM tools..."
$PKG_MANAGER update -qq 2>/dev/null || true
$PKG_INSTALL

# Stop existing zram
echo "[2/6] Stopping existing ZRAM services..."
systemctl stop zramswap.service 2>/dev/null || true
systemctl stop dev-zram0.swap 2>/dev/null || true

# Configure zramswap
echo "[3/6] Configuring ZRAM..."
if [ "$OS" = "debian" ]; then
    cat > /etc/default/zramswap << EOF
# RAM Optimizer Configuration
# Generated on $(date)
ALGO=${ZRAM_ALGO}
PERCENT=${ZRAM_PERCENT}
PRIORITY=100
EOF
elif [ "$OS" = "arch" ]; then
    cat > /etc/systemd/zram-generator.conf << EOF
[zram0]
zram-size = min(ram / 2, 4096) * ${ZRAM_PERCENT} / 100
compression-algorithm = ${ZRAM_ALGO}
swap-priority = 100
EOF
fi

# Enable KSM
echo "[4/6] Enabling Kernel Samepage Merging (KSM)..."
if [ -f /sys/kernel/mm/ksm/run ]; then
    echo 1 > /sys/kernel/mm/ksm/run 2>/dev/null || true
    echo 1000 > /sys/kernel/mm/ksm/sleep_millisecs 2>/dev/null || true
    echo "   KSM enabled"
else
    echo "   KSM not available on this kernel"
fi

# Sysctl optimizations
echo "[5/6] Applying sysctl optimizations..."
cat > /etc/sysctl.d/99-lowram.conf << 'EOF'
# RAM Optimizer Sysctl Settings
vm.swappiness=100
vm.vfs_cache_pressure=200
vm.compaction_proactiveness=30
vm.overcommit_memory=1
vm.overcommit_ratio=50
EOF

if [ -f /sys/kernel/mm/ksm/run ]; then
    echo "vm.ksm.run=1" >> /etc/sysctl.d/99-lowram.conf
fi

sysctl --system > /dev/null 2>&1 || true

# Start zram
echo "[6/6] Starting ZRAM service..."
systemctl daemon-reload
systemctl enable zramswap.service 2>/dev/null || systemctl enable systemd-zram-setup@zram0.service 2>/dev/null || true
systemctl start zramswap.service 2>/dev/null || systemctl start systemd-zram-setup@zram0.service 2>/dev/null || true

# Results
echo ""
echo "=========================================="
echo "  Setup Complete!"
echo "=========================================="
echo ""

# Show ZRAM status
if command -v zramctl &> /dev/null; then
    echo "ZRAM Status:"
    zramctl 2>/dev/null || echo "   ZRAM device active"
    echo ""
fi

# Show swap
echo "Swap Status:"
if command -v swapon &> /dev/null; then
    swapon --show 2>/dev/null || cat /proc/swaps
else
    cat /proc/swaps
fi
echo ""

# Show memory
echo "Memory Status:"
free -h
echo ""

# Calculate effective memory
EFFECTIVE_MB=$((TOTAL_RAM_MB + TOTAL_RAM_MB * ZRAM_PERCENT / 100 * 2 / 100))
echo "=========================================="
echo "Physical RAM:  ~${TOTAL_RAM_MB} MB"
echo "ZRAM allocated: ~$((TOTAL_RAM_MB * ZRAM_PERCENT / 100)) MB"
echo "Effective RAM:  ~${EFFECTIVE_MB} MB (with 2:1 compression)"
echo "=========================================="
echo ""
echo "Settings will persist across reboots."