#!/usr/bin/env bash

# =============================================================================
# PulseGrid Metric Agent Installation Script
# =============================================================================
# 
# This script installs the PulseGrid Metric Agent.
# The agent is used for system monitoring and metrics collection.
#
# =============================================================================

set -o errexit
set -o nounset

# =============================================================================
# CONFIGURATION SECTION
# =============================================================================

# Agent download configuration
AGENT_DOWNLOAD_URL="https://download.pulsegrid.uz/pulsegrid-metric-agent/latest/"

# Detect architecture and set binary names
ARCH=$(uname -m)
case $ARCH in
    x86_64)
        AGENT_BINARY_NAME="pulsegrid-metric-agent-linux-amd64.tar.gz"
        AGENT_EXTRACTED_BINARY="pulsegrid-metric-agent-linux-amd64"
        ;;
    aarch64|arm64)
        AGENT_BINARY_NAME="pulsegrid-metric-agent-linux-arm64.tar.gz"
        AGENT_EXTRACTED_BINARY="pulsegrid-metric-agent-linux-arm64"
        ;;
    *)
        print_error "Unsupported architecture: $ARCH"
        print_error "Supported architectures: x86_64, aarch64, arm64"
        exit 1
        ;;
esac

# Installation paths
CONFIG_DIR="/etc/pulsegrid-metric-agent"
DATA_DIR="/var/lib/pulsegrid-metric-agent/data"
BINARY_DIR="/usr/local/bin"

# Service configuration
SERVICE_NAME="pulsegrid-metric-agent"
SERVICE_USER="pulsegrid-metric-agent"
SERVICE_GROUP="pulsegrid-metric-agent"

# =============================================================================
# COLOR OUTPUT FUNCTIONS
# =============================================================================

# Color codes for terminal output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

# Shows general information messages in green
print_status() {
    echo -e "${GREEN}[INFO]${NC} $1"
}

# Shows warning messages in yellow
print_warning() {
    echo -e "${YELLOW}[WARNING]${NC} $1"
}

# Shows error messages in red
print_error() {
    echo -e "${RED}[ERROR]${NC} $1"
}

# Shows section headers in blue
print_header() {
    echo -e "${BLUE}[HEADER]${NC} $1"
}

# Shows step-by-step progress in blue
print_step() {
    echo -e "${BLUE}[STEP]${NC} $1"
}

# Shows success messages in green
print_success() {
    echo -e "${GREEN}[SUCCESS]${NC} $1"
}

# =============================================================================
# SYSTEM CHECKS
# =============================================================================

# Check root privileges
print_status "Checking root privileges..."

if [ "$EUID" -ne 0 ]; then
    print_error "This script must be run as root (use sudo)"
    print_status "Usage: sudo $0"
    exit 1
fi

print_status "Root privileges confirmed"

# Check operating system and architecture
print_status "Checking system requirements..."

# Check if it's Linux
if [ "$(uname)" != "Linux" ]; then
    print_error "This script only supports Linux operating systems"
    print_error "Detected OS: $(uname)"
    exit 1
fi

# Check if it's supported architecture
case $ARCH in
    x86_64|aarch64|arm64)
        print_status "Supported architecture detected: $ARCH"
        ;;
    *)
        print_error "This script only supports x86_64, aarch64, and arm64 architectures"
        print_error "Detected architecture: $ARCH"
        exit 1
        ;;
esac

# Check if it's supported distribution
DISTRO=$(grep PRETTY_NAME /etc/os-release | cut -d'"' -f2 2>/dev/null || echo 'Unknown')
if grep -q "Ubuntu\|Debian" /etc/os-release 2>/dev/null; then
    print_status "Debian/Ubuntu family detected - fully supported"
elif grep -q "Fedora\|Red Hat\|CentOS\|Rocky\|Alma" /etc/os-release 2>/dev/null; then
    print_status "Fedora/RHEL family detected - fully supported"
else
    print_warning "This script is tested on Debian/Ubuntu and Fedora/RHEL families"
    print_warning "Detected distribution: $DISTRO"
    print_warning "Other distributions may work but are not guaranteed"
    
    # Ask for confirmation to continue
    read -p "Do you want to continue anyway? (y/N): " -r
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        print_status "Installation cancelled by user"
        exit 0
    fi
fi

print_status "System requirements check passed"

# Check and install dependencies
print_status "Checking system dependencies..."

missing_deps=()

# List of required dependencies
required_deps=("curl" "tar" "gzip" "systemctl")

# Check each dependency
for dep in "${required_deps[@]}"; do
    if ! command -v "$dep" >/dev/null 2>&1; then
        missing_deps+=("$dep")
    fi
done

# Install missing dependencies if any
if [ ${#missing_deps[@]} -ne 0 ]; then
    print_warning "Missing dependencies: ${missing_deps[*]}"
    print_status "Installing missing dependencies..."
    
    # Detect package manager
    if command -v apt-get >/dev/null 2>&1; then
        print_status "Using apt-get (Debian/Ubuntu family)"
        sudo apt-get update
        sudo apt-get install -y "${missing_deps[@]}"
    elif command -v dnf >/dev/null 2>&1; then
        print_status "Using dnf (Fedora/RHEL family)"
        sudo dnf install -y "${missing_deps[@]}"
    elif command -v yum >/dev/null 2>&1; then
        print_status "Using yum (RHEL/CentOS family)"
        sudo yum install -y "${missing_deps[@]}"
    else
        print_error "No supported package manager found (apt-get, dnf, or yum)"
        print_error "Please install the following packages manually: ${missing_deps[*]}"
        exit 1
    fi
    
    print_status "Dependencies installed successfully"
else
    print_status "All required dependencies are already installed"
fi

# =============================================================================
# ENVIRONMENT VARIABLES VALIDATION
# =============================================================================

print_step "Validating environment variables..."

# Check USER_UUID
if [ -z "${USER_UUID:-}" ]; then
    print_error "USER_UUID environment variable is required"
    print_status "Please set USER_UUID before running this script:"
    print_status "export USER_UUID=\"your-uuid\""
    exit 1
fi

# Check AGENT_TOKEN
if [ -z "${AGENT_TOKEN:-}" ]; then
    print_error "AGENT_TOKEN environment variable is required"
    print_status "Please set AGENT_TOKEN before running this script:"
    print_status "export AGENT_TOKEN=\"your-token\""
    exit 1
fi

print_status "✓ USER_UUID: $USER_UUID"
print_status "✓ AGENT_TOKEN: [HIDDEN]"

# =============================================================================
# CHECK EXISTING INSTALLATION
# =============================================================================

print_step "Checking existing installation..."

# Check if binary exists
if [ -f "$BINARY_DIR/pulsegrid-metric-agent" ]; then
    print_status "✓ Agent binary exists: $BINARY_DIR/pulsegrid-metric-agent"
else
    print_status "Agent binary not found - will install"
fi

# Check if service exists
if [ -f "/etc/systemd/system/$SERVICE_NAME.service" ]; then
    print_status "✓ Systemd service exists: /etc/systemd/system/$SERVICE_NAME.service"
else
    print_status "Systemd service not found - will create"
fi

# Check if service is active
if systemctl is-active --quiet "$SERVICE_NAME" 2>/dev/null; then
    print_status "✓ Service is active and running"
    print_success "PulseGrid Metric Agent is already installed and running"
    print_status "Service status: active"
    print_status "Binary location: $BINARY_DIR/pulsegrid-metric-agent"
    print_status "Config directory: $CONFIG_DIR"
    print_success "No action needed - agent is working properly"
    exit 0
else
    print_status "Service is not active - will start after installation"
fi

# =============================================================================
# CREATE SYSTEM USER AND GROUP
# =============================================================================

print_step "Creating system user and group..."

# Create group if not exists
if ! getent group "$SERVICE_GROUP" >/dev/null 2>&1; then
    print_status "Creating system group: $SERVICE_GROUP"
    if groupadd --system "$SERVICE_GROUP"; then
        print_status "✓ Created system group: $SERVICE_GROUP"
    else
        print_error "Failed to create group: $SERVICE_GROUP"
        exit 1
    fi
else
    print_status "✓ System group already exists: $SERVICE_GROUP"
fi

# Create user if not exists
if ! getent passwd "$SERVICE_USER" >/dev/null 2>&1; then
    print_status "Creating system user: $SERVICE_USER"
    if useradd --system \
        --no-create-home \
        --gid "$SERVICE_GROUP" \
        --shell /bin/false \
        --comment "PulseGrid Metric Agent Service User" \
        "$SERVICE_USER"; then
        print_status "✓ Created system user: $SERVICE_USER"
    else
        print_error "Failed to create user: $SERVICE_USER"
        exit 1
    fi
else
    print_status "✓ System user already exists: $SERVICE_USER"
fi

# =============================================================================
# CREATE DIRECTORIES
# =============================================================================

print_step "Creating directories..."

# Create config directory
if [ ! -d "$CONFIG_DIR" ]; then
    if mkdir -p "$CONFIG_DIR"; then
        print_status "✓ Created config directory: $CONFIG_DIR"
    else
        print_error "Failed to create config directory: $CONFIG_DIR"
        exit 1
    fi
else
    print_status "✓ Config directory already exists: $CONFIG_DIR"
fi

# Create data directory
if [ ! -d "$DATA_DIR" ]; then
    if mkdir -p "$DATA_DIR"; then
        print_status "✓ Created data directory: $DATA_DIR"
    else
        print_error "Failed to create data directory: $DATA_DIR"
        exit 1
    fi
else
    print_status "✓ Data directory already exists: $DATA_DIR"
fi

# Set ownership
if chown "$SERVICE_USER:$SERVICE_GROUP" "$CONFIG_DIR"; then
    print_status "✓ Set config directory ownership"
else
    print_error "Failed to set config directory ownership"
    exit 1
fi

if chown "$SERVICE_USER:$SERVICE_GROUP" "$DATA_DIR"; then
    print_status "✓ Set data directory ownership"
else
    print_error "Failed to set data directory ownership"
    exit 1
fi

# Set permissions
chmod 750 "$CONFIG_DIR"
chmod 750 "$DATA_DIR"

# =============================================================================
# DOWNLOAD AND INSTALL AGENT
# =============================================================================

print_step "Downloading and installing agent..."

# Create temporary directory
temp_dir=$(mktemp -d)
cd "$temp_dir"

# Download agent
download_url="$AGENT_DOWNLOAD_URL/$AGENT_BINARY_NAME"
print_status "Downloading agent from: $download_url"
print_status "This may take a few moments depending on your internet connection..."

if ! curl -fsSL --retry 3 --connect-timeout 30 "$download_url" -o "$AGENT_BINARY_NAME"; then
    print_error "Failed to download the agent"
    print_error "Possible reasons:"
    print_error "  - No internet connection"
    print_error "  - Server is temporarily unavailable"
    print_error "  - Firewall is blocking the connection"
    print_error "Please check your internet connection and try again"
    cd /
    rm -rf "$temp_dir"
    exit 1
fi

print_status "✓ Agent downloaded successfully"

# Extract archive
print_status "Extracting downloaded agent package..."
if ! tar -xzf "$AGENT_BINARY_NAME"; then
    print_error "Failed to extract the agent package"
    print_error "The downloaded file may be corrupted"
    cd /
    rm -rf "$temp_dir"
    exit 1
fi

print_status "✓ Agent package extracted successfully"

# Debug: List extracted files
print_status "Extracted files:"
ls -la

# Check if the binary was extracted
print_status "Looking for binary: $AGENT_EXTRACTED_BINARY"
if [ ! -f "$AGENT_EXTRACTED_BINARY" ]; then
    print_error "Agent binary not found in the downloaded package"
    print_error "Expected file: $AGENT_EXTRACTED_BINARY"
    print_error "Available files:"
    ls -la
    cd /
    rm -rf "$temp_dir"
    exit 1
fi

print_status "✓ Found binary: $AGENT_EXTRACTED_BINARY"

# Install binary (only if not exists)
if [ ! -f "$BINARY_DIR/pulsegrid-metric-agent" ]; then
    if cp "$AGENT_EXTRACTED_BINARY" "$BINARY_DIR/pulsegrid-metric-agent"; then
        chmod +x "$BINARY_DIR/pulsegrid-metric-agent"
        chown root:root "$BINARY_DIR/pulsegrid-metric-agent"
        print_status "✓ Agent binary installed to: $BINARY_DIR/pulsegrid-metric-agent"
    else
        print_error "Failed to install agent binary"
        cd /
        rm -rf "$temp_dir"
        exit 1
    fi
else
    print_status "✓ Agent binary already exists: $BINARY_DIR/pulsegrid-metric-agent"
fi

# Copy config.yaml from archive (only if not exists)
if [ -f "config.yaml" ] && [ ! -f "$CONFIG_DIR/config.yaml" ]; then
    if cp "config.yaml" "$CONFIG_DIR/config.yaml"; then
        chmod 644 "$CONFIG_DIR/config.yaml"
        chown "$SERVICE_USER:$SERVICE_GROUP" "$CONFIG_DIR/config.yaml"
        print_status "✓ Agent config installed to: $CONFIG_DIR/config.yaml"
    else
        print_error "Failed to install config file"
        cd /
        rm -rf "$temp_dir"
        exit 1
    fi
elif [ -f "config/config.yaml" ] && [ ! -f "$CONFIG_DIR/config.yaml" ]; then
    # Fallback for archive with config subdirectory
    if cp "config/config.yaml" "$CONFIG_DIR/config.yaml"; then
        chmod 644 "$CONFIG_DIR/config.yaml"
        chown "$SERVICE_USER:$SERVICE_GROUP" "$CONFIG_DIR/config.yaml"
        print_status "✓ Agent config installed to: $CONFIG_DIR/config.yaml"
    else
        print_error "Failed to install config file"
        cd /
        rm -rf "$temp_dir"
        exit 1
    fi
else
    print_status "✓ Agent config already exists or not found in archive"
fi

# Clean up temporary directory
cd /
rm -rf "$temp_dir"

# =============================================================================
# CREATE CONFIGURATION FILES
# =============================================================================

print_step "Creating configuration files..."

# Create UUID file (only if not exists)
if [ ! -f "$CONFIG_DIR/.uuid" ]; then
    if echo "$USER_UUID" > "$CONFIG_DIR/.uuid"; then
        chmod 600 "$CONFIG_DIR/.uuid"
        chown "$SERVICE_USER:$SERVICE_GROUP" "$CONFIG_DIR/.uuid"
        print_status "✓ Created UUID file"
    else
        print_error "Failed to create UUID file"
        exit 1
    fi
else
    print_status "✓ UUID file already exists"
fi

# Create token file (only if not exists)
if [ ! -f "$CONFIG_DIR/.token" ]; then
    if echo "$AGENT_TOKEN" > "$CONFIG_DIR/.token"; then
        chmod 600 "$CONFIG_DIR/.token"
        chown "$SERVICE_USER:$SERVICE_GROUP" "$CONFIG_DIR/.token"
        print_status "✓ Created token file"
    else
        print_error "Failed to create token file"
        exit 1
    fi
else
    print_status "✓ Token file already exists"
fi

print_status "✓ Configuration files ready"

# =============================================================================
# CREATE SYSTEMD SERVICE
# =============================================================================

print_step "Creating systemd service..."

service_file="/etc/systemd/system/$SERVICE_NAME.service"

# Check if service already exists
if [ -f "$service_file" ]; then
    print_status "✓ Systemd service already exists: $service_file"
else
    # Create service content
    cat > "$service_file" << EOF
[Unit]
Description=PulseGrid Metric Agent
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
User=$SERVICE_USER
Group=$SERVICE_GROUP
ExecStart=$BINARY_DIR/pulsegrid-metric-agent -config $CONFIG_DIR/config.yaml
Restart=always
RestartSec=300
StandardOutput=journal
StandardError=journal
SyslogIdentifier=pulsegrid-metric-agent

# Security settings
NoNewPrivileges=true
PrivateTmp=true
ProtectSystem=strict
ProtectHome=true
ReadWritePaths=$CONFIG_DIR $DATA_DIR
ReadOnlyPaths=/proc /sys /run/udev/data

# Resource limits
LimitNOFILE=65536
LimitNPROC=4096

# Environment variables
Environment=HOME=$CONFIG_DIR

[Install]
WantedBy=multi-user.target
EOF

    if [ $? -eq 0 ]; then
        print_status "✓ Systemd service created: $service_file"
    else
        print_error "Failed to create systemd service file"
        exit 1
    fi
fi

# Reload systemd
if systemctl daemon-reload; then
    print_status "✓ Systemd daemon reloaded"
else
    print_error "Failed to reload systemd daemon"
    exit 1
fi

# =============================================================================
# START AND ENABLE SERVICE
# =============================================================================

print_step "Starting and enabling service..."

# Enable service
if systemctl enable "$SERVICE_NAME"; then
    print_status "✓ Service enabled for auto-start"
else
    print_error "Failed to enable service"
    exit 1
fi

# Start service
if systemctl start "$SERVICE_NAME"; then
    print_status "✓ Service started successfully"
else
    print_error "Failed to start service"
    exit 1
fi

# =============================================================================
# SUCCESS MESSAGE
# =============================================================================

print_success "PulseGrid Metric Agent installation completed successfully!"

# Display ASCII art
echo
echo "  ██████╗ ██╗   ██╗██╗     ███████╗███████╗ ██████╗ ██████╗ ██╗██████╗                           "
echo "  ██╔══██╗██║   ██║██║     ██╔════╝██╔════╝██╔════╝ ██╔══██╗██║██╔══██╗                          "
echo "  ██████╔╝██║   ██║██║     ███████╗█████╗  ██║  ███╗██████╔╝██║██║  ██║                          "
echo "  ██╔═══╝ ██║   ██║██║     ╚════██║██╔══╝  ██║   ██║██╔══██╗██║██║  ██║                          "
echo "  ██║     ╚██████╔╝███████╗███████║███████╗╚██████╔╝██║  ██║██║██████╔╝                          "
echo "  ╚═╝      ╚═════╝ ╚══════╝╚══════╝╚══════╝ ╚═════╝ ╚═╝  ╚═╝╚═╝╚═════╝                           "
echo "                                                                                                 "
echo "  ███╗   ███╗███████╗████████╗██████╗ ██╗ ██████╗     █████╗  ██████╗ ███████╗███╗   ██╗████████╗"
echo "  ████╗ ████║██╔════╝╚══██╔══╝██╔══██╗██║██╔════╝     ██╔══██╗██╔════╝ ██╔════╝████╗  ██║╚══██╔══╝"
echo "  ██╔████╔██║█████╗     ██║   ██████╔╝██║██║          ███████║██║  ███╗█████╗  ██╔██╗ ██║   ██║"
echo "  ██║╚██╔╝██║██╔══╝     ██║   ██╔══██╗██║██║          ██╔══██║██║   ██║██╔══╝  ██║╚██╗██║   ██║"
echo "  ██║ ╚═╝ ██║███████╗   ██║   ██║  ██║██║╚██████╗     ██║  ██║╚██████╔╝███████╗██║ ╚████║   ██║"
echo "  ╚═╝     ╚═╝╚══════╝   ╚═╝   ╚═╝  ╚═╝╚═╝ ╚═════╝     ╚═╝  ╚═╝ ╚═════╝ ╚══════╝╚═╝  ╚═══╝   ╚═╝"
echo
echo "  ════════════════════════════════════════════════════════════════════════════════════════════════"
echo "  🎉 SUCCESSFULLY INSTALLED! 🎉"
echo "  ════════════════════════════════════════════════════════════════════════════════════════════════"
echo
echo "  🛠️  PulseGrid Metric Agent is now installed and running!"
echo
echo "  📁 Installation Details:"
echo "     • Binary: $BINARY_DIR/pulsegrid-metric-agent"
echo "     • Config: $CONFIG_DIR"
echo "     • Data: $DATA_DIR"
echo "     • Service: $SERVICE_NAME"
echo
echo "  🚀 Service Status:"
echo "     • Status: Active and running"
echo "     • Auto-start: Enabled"
echo
echo "  ════════════════════════════════════════════════════════════════════════════════════════════════"
echo "  🎯 Installation completed successfully! 🎯"
echo "  ════════════════════════════════════════════════════════════════════════════════════════════════"
echo