#!/bin/bash

# Alertmanager Installation and Configuration Script
# This script installs Alertmanager and configures email notifications.

set -e

# 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 Alertmanager
VERSION="0.32.0"
CN_URL="https://s3.cloudyun.top/downloads/alertmanager-${VERSION}.linux-amd64.tar.gz"
GLOBAL_URL="https://github.com/prometheus/alertmanager/releases/download/v${VERSION}/alertmanager-${VERSION}.linux-amd64.tar.gz"
TARGET="/tmp/alertmanager.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
    DOWNLOAD_URL="$CN_URL"
else
    DOWNLOAD_URL="$GLOBAL_URL"
fi

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

# Extract and Install
echo "Extracting Alertmanager..."
tar -zxvf "$TARGET" -C /tmp
sudo mkdir -p /etc/alertmanager
sudo cp "/tmp/alertmanager-${VERSION}.linux-amd64/alertmanager" /usr/bin/
sudo cp "/tmp/alertmanager-${VERSION}.linux-amd64/amtool" /usr/bin/

# Arguments for SMTP
SMTP_HOST="smtp.example.com:465"
SMTP_USER="user@example.com"
SMTP_PASS="password"
SMTP_FROM="alertmanager@example.com"
EMAIL_TO="recipient@example.com"
SMTP_REQUIRE_TLS="false"

# Interactive SMTP Configuration
echo ""
echo "--------------------------------------------------------"
echo "        Alertmanager SMTP Configuration Setup"
echo "--------------------------------------------------------"
read -p "Do you want to enable Email Notifications? [y/N]: " ENABLE_EMAIL
if [[ "$ENABLE_EMAIL" =~ ^[Yy]$ ]]; then
    read -p "Enter SMTP Host (e.g. smtp.qq.com:465): " SMTP_HOST
    read -p "Enter SMTP Auth Username (Email): " SMTP_USER
    read -s -p "Enter SMTP Auth Password: " SMTP_PASS
    echo "" 
    read -p "Enter Sender Email (Default: $SMTP_USER): " SMTP_FROM
    [ -z "$SMTP_FROM" ] && SMTP_FROM="$SMTP_USER"
    read -p "Enter Recipient Email: " EMAIL_TO
    
    # Simple logic to determine TLS requirement
    if [[ "$SMTP_HOST" == *":587" ]] || [[ "$SMTP_HOST" == *":25" ]]; then
        SMTP_REQUIRE_TLS="true"
    else
        SMTP_REQUIRE_TLS="false"
    fi
    echo "Notice: Detected port, setting smtp_require_tls to $SMTP_REQUIRE_TLS"
fi

# Create Configuration
echo "Creating alertmanager.yml..."
sudo tee "/etc/alertmanager/alertmanager.yml" > /dev/null <<EOF
global:
  resolve_timeout: 5m
  smtp_smarthost: '$SMTP_HOST'
  smtp_from: '$SMTP_FROM'
  smtp_auth_username: '$SMTP_USER'
  smtp_auth_password: '$SMTP_PASS'
  smtp_require_tls: $SMTP_REQUIRE_TLS

route:
  group_by: ['alertname']
  group_wait: 10s
  group_interval: 5m
  repeat_interval: 1h
  receiver: 'email-notifications'

receivers:
- name: 'email-notifications'
  email_configs:
  - to: '$EMAIL_TO'
    send_resolved: true
EOF

# Create systemd service
echo "Creating systemd service for Alertmanager..."
sudo tee "/etc/systemd/system/alertmanager.service" > /dev/null <<EOF
[Unit]
Description=Alertmanager
Wants=network-online.target
After=network-online.target

[Service]
User=root
Group=root
Type=simple
ExecStart=/usr/bin/alertmanager \\
  --config.file=/etc/alertmanager/alertmanager.yml \\
  --storage.path=/etc/alertmanager/data
Restart=always

[Install]
WantedBy=multi-user.target
EOF

# Reload and Start
sudo systemctl daemon-reload
sudo systemctl enable --now alertmanager.service

echo "--------------------------------------------------------"
echo "Alertmanager installed and configured with EMAIL support!"
echo "Configuration File: /etc/alertmanager/alertmanager.yml"
echo "Please edit the configuration to set your SMTP details."
echo "--------------------------------------------------------"