#!/bin/bash
source ~/.bashrc
# Observability Stack Setup Script (Prometheus + Grafana)
# Run this on the Observability VM after OS installation

set -e

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

log_info() {
    echo -e "${GREEN}[INFO]${NC} $1"
}

log_warn() {
    echo -e "${YELLOW}[WARN]${NC} $1"
}

log_error() {
    echo -e "${RED}[ERROR]${NC} $1"
}

log_step() {
    echo -e "${BLUE}[STEP]${NC} $1"
}

# Check if running as root
if [ "$EUID" -ne 0 ]; then 
    log_error "Please run as root (use sudo)"
    exit 1
fi

PROMETHEUS_VERSION="${PROMETHEUS_VERSION:-2.45.0}"
GRAFANA_VERSION="${GRAFANA_VERSION:-10.0.0}"
PROMETHEUS_USER="${PROMETHEUS_USER:-prometheus}"
GRAFANA_USER="${GRAFANA_USER:-grafana}"

log_step "Step 1: Installing dependencies..."
apt-get update
apt-get install -y wget curl

log_step "Step 2: Installing Prometheus..."

# Create Prometheus user
useradd -r -s /bin/false "$PROMETHEUS_USER" || log_warn "User $PROMETHEUS_USER may already exist"

# Download and install Prometheus
cd /tmp
wget "https://github.com/prometheus/prometheus/releases/download/v${PROMETHEUS_VERSION}/prometheus-${PROMETHEUS_VERSION}.linux-amd64.tar.gz"
tar xzf "prometheus-${PROMETHEUS_VERSION}.linux-amd64.tar.gz"
mv "prometheus-${PROMETHEUS_VERSION}.linux-amd64" /opt/prometheus
mkdir -p /etc/prometheus
mkdir -p /var/lib/prometheus
chown -R "$PROMETHEUS_USER:$PROMETHEUS_USER" /opt/prometheus /etc/prometheus /var/lib/prometheus

# Create Prometheus configuration
cat > /etc/prometheus/prometheus.yml <<EOF
global:
  scrape_interval: 15s
  evaluation_interval: 15s

scrape_configs:
  - job_name: 'prometheus'
    static_configs:
      - targets: ['localhost:9090']
  
  - job_name: 'node-exporter'
    static_configs:
      - targets: ['localhost:9100']
EOF

# Create systemd service
cat > /etc/systemd/system/prometheus.service <<EOF
[Unit]
Description=Prometheus
After=network.target

[Service]
Type=simple
User=$PROMETHEUS_USER
ExecStart=/opt/prometheus/prometheus --config.file=/etc/prometheus/prometheus.yml --storage.tsdb.path=/var/lib/prometheus
Restart=always
RestartSec=5s

[Install]
WantedBy=multi-user.target
EOF

log_step "Step 3: Installing Node Exporter..."
cd /tmp
wget "https://github.com/prometheus/node_exporter/releases/download/v1.6.1/node_exporter-1.6.1.linux-amd64.tar.gz"
tar xzf node_exporter-1.6.1.linux-amd64.tar.gz
mv node_exporter-1.6.1.linux-amd64/node_exporter /usr/local/bin/
chmod +x /usr/local/bin/node_exporter

cat > /etc/systemd/system/node-exporter.service <<EOF
[Unit]
Description=Node Exporter
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/node_exporter
Restart=always
RestartSec=5s

[Install]
WantedBy=multi-user.target
EOF

log_step "Step 4: Installing Grafana..."
apt-get install -y apt-transport-https software-properties-common
wget -q -O - https://packages.grafana.com/gpg.key | apt-key add -
echo "deb https://packages.grafana.com/oss/deb stable main" > /etc/apt/sources.list.d/grafana.list
apt-get update
apt-get install -y grafana

log_step "Step 5: Starting services..."
systemctl daemon-reload
systemctl enable prometheus node-exporter grafana-server
systemctl start prometheus node-exporter grafana-server
sleep 3

log_info "========================================="
log_info "Observability Stack Installation Complete!"
log_info "========================================="
echo ""
log_info "Services:"
echo "  - Prometheus: http://192.168.1.82:9090"
echo "  - Grafana: http://192.168.1.82:3000"
echo "  - Node Exporter: http://192.168.1.82:9100"
echo ""
log_info "Grafana default credentials:"
echo "  Username: admin"
echo "  Password: admin (change on first login)"
echo ""
log_info "Next steps:"
echo "  1. Access Grafana and change default password"
echo "  2. Add Prometheus as data source (http://localhost:9090)"
echo "  3. Import dashboards from grafana.com/dashboards"
echo "  4. Configure alerting rules"