#!/bin/bash
set -e

# Arguments for Basic Auth
USER_NAME=""
PASSWORD_PLAIN=""

while [[ "$#" -gt 0 ]]; do
    case $1 in
        --user) USER_NAME="$2"; shift ;;
        --pass) PASSWORD_PLAIN="$2"; shift ;;
        *) echo "Unknown option: $1"; exit 1 ;;
    esac
    shift
done

# If not provided via arguments, ask interactively
if [ -z "$USER_NAME" ]; then
    read -p "Do you want to enable Basic Authentication for Node Exporter? [y/N]: " ENABLE_AUTH
    if [[ "$ENABLE_AUTH" =~ ^[Yy]$ ]]; then
        read -p "Enter Username: " USER_NAME
        read -s -p "Enter Password: " PASSWORD_PLAIN
        echo "" # New line after password
        if [ -z "$USER_NAME" ] || [ -z "$PASSWORD_PLAIN" ]; then
            echo "Error: Username and Password cannot be empty."
            exit 1
        fi
    fi
fi

# Detect Operation System

if command -v apt >/dev/null 2>&1; then
    echo "Detected apt-based system"
    sudo apt update
    sudo apt install -y wget curl tar 

elif command -v dnf >/dev/null 2>&1; then
    echo "Detected dnf-based system"
    sudo dnf install -y wget curl tar 

else
    echo "Unsupported package manager"
    exit 1
fi


# Download Node Exporter

CN_URL="https://s3.cloudyun.top/downloads/node_exporter-1.10.2.linux-amd64.tar.gz"
GLOBAL_URL="https://github.com/prometheus/node_exporter/releases/download/v1.10.2/node_exporter-1.10.2.linux-amd64.tar.gz"
TARGET="/tmp/node_exporter.tar.gz"

is_cn=false

echo "Detecting geographic location..."
COUNTRY=$(curl -s --max-time 3 https://ipinfo.littlediary.cn/country || true)
if [ "$COUNTRY" = "CN" ]; then
    is_cn=true
fi


if [ "$is_cn" = true ]; then
    echo "Geolocation: China mainland detected"
    DOWNLOAD_URL="$CN_URL"
else
    echo "Geolocation: non-China region detected"
    DOWNLOAD_URL="$GLOBAL_URL"
fi

echo "Downloading from: $DOWNLOAD_URL"
curl -fL -o "$TARGET" "$DOWNLOAD_URL"


# Extract
echo "Extracting Node Exporter..."
tar -zxvf /tmp/node_exporter.tar.gz -C /tmp

# Copy to /node_exporter
echo "Copying Node Exporter to /node_exporter..."
sudo cp -r /tmp/node_exporter-1.10.2.linux-amd64 /node_exporter

# Handle Basic Auth configuration
if [ -n "$USER_NAME" ] && [ -n "$PASSWORD_PLAIN" ]; then
    echo "Configuring Basic Authentication for Node Exporter..."
    
    # Generate bcrypt hash using python3 (common on Linux)
    # If python3 is not available, you'll need to provide the hash manually
    if command -v python3 >/dev/null 2>&1; then
        HASHED_PASSWORD=$(python3 -c "import bcrypt; print(bcrypt.hashpw('$PASSWORD_PLAIN'.encode(), bcrypt.gensalt()).decode())" 2>/dev/null || true)
        
        # Fallback if bcrypt module is not installed
        if [ -z "$HASHED_PASSWORD" ]; then
             echo "Python bcrypt module not found, using simple crypt fallback (not bcrypt!)..."
             HASHED_PASSWORD=$(python3 -c "import crypt; print(crypt.crypt('$PASSWORD_PLAIN', crypt.mksalt(crypt.METHOD_SHA512)))" 2>/dev/null || true)
        fi
    fi

    if [ -n "$HASHED_PASSWORD" ]; then
        sudo tee "/node_exporter/web-config.yml" > /dev/null <<EOF
basic_auth_users:
    $USER_NAME: $HASHED_PASSWORD
EOF
        EXTRA_OPTS="--web.config.file=/node_exporter/web-config.yml"
        echo "Basic Auth configured for user: $USER_NAME"
    else
        echo "Warning: Could not generate password hash. Standard Node Exporter will be installed without auth."
        EXTRA_OPTS=""
    fi
else
    EXTRA_OPTS=""
fi

# Create systemd service file
SERVICE_FILE="/etc/systemd/system/node_exporter.service"

echo "Creating systemd service file..."
sudo tee "$SERVICE_FILE" > /dev/null <<EOF
[Unit]
Description=Node Exporter
Wants=network-online.target
After=network-online.target

[Service]
User=root
ExecStart=/node_exporter/node_exporter --web.listen-address=":9100" $EXTRA_OPTS
Restart=always

[Install]
WantedBy=multi-user.target
EOF

# Reload systemd, enable and start service
echo "Enabling and starting node_exporter service..."
sudo systemctl daemon-reload
sudo systemctl enable --now node_exporter.service

echo "Node Exporter installation completed, listening on port 9100"
if [ -n "$EXTRA_OPTS" ]; then
    echo "Basic authentication is ENABLED."
fi