#!/bin/bash

# Xet Setup Script for DTO Framework
# Prometheus - Head of Data Migration & Transfer Operations

set -euo pipefail

# Configuration
XET_VERSION="0.9.0"
INSTALL_DIR="/usr/local/bin"
CONFIG_DIR="/etc/dto/xet"
LOG_DIR="/var/log/dto"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Logging function
log() {
    echo -e "${GREEN}[$(date '+%Y-%m-%d %H:%M:%S')]${NC} $1"
}

error() {
    echo -e "${RED}[ERROR]${NC} $1" >&2
}

warning() {
    echo -e "${YELLOW}[WARNING]${NC} $1"
}

# Check if running as root
check_root() {
    if [[ $EUID -ne 0 ]]; then
        error "This script must be run as root"
        exit 1
    fi
}

# Install Xet CLI
install_xet() {
    log "Installing Xet CLI version ${XET_VERSION}"
    
    # Detect architecture
    ARCH=$(uname -m)
    case $ARCH in
        x86_64) ARCH="amd64" ;;
        aarch64) ARCH="arm64" ;;
        *) error "Unsupported architecture: $ARCH"; exit 1 ;;
    esac
    
    # Download Xet
    DOWNLOAD_URL="https://github.com/xetdata/xet-core/releases/download/v${XET_VERSION}/xet-linux-${ARCH}"
    
    log "Downloading Xet from: $DOWNLOAD_URL"
    curl -L -o "/tmp/xet" "$DOWNLOAD_URL" || {
        error "Failed to download Xet"
        exit 1
    }
    
    # Install to system
    chmod +x "/tmp/xet"
    mv "/tmp/xet" "${INSTALL_DIR}/xet"
    
    # Verify installation
    if command -v xet >/dev/null 2>&1; then
        log "Xet installed successfully: $(xet --version)"
    else
        error "Xet installation failed"
        exit 1
    fi
}

# Configure Xet environment
configure_xet() {
    log "Configuring Xet environment"
    
    # Create directories
    mkdir -p "$CONFIG_DIR" "$LOG_DIR" "/mnt/xet"
    
    # Create configuration
    cat > "${CONFIG_DIR}/environment" << EOF
# Xet Environment Configuration
export XET_CACHE_DIR="/var/cache/xet"
export XET_CONFIG_DIR="${CONFIG_DIR}"
export XET_LOG_DIR="${LOG_DIR}"
export XET_MOUNT_DIR="/mnt/xet"
EOF
    
    # Set permissions
    chmod 755 "/mnt/xet"
    chmod 644 "${CONFIG_DIR}/environment"
    
    log "Xet environment configured"
}

# Setup systemd service (optional)
setup_service() {
    log "Setting up Xet systemd service"
    
    cat > "/etc/systemd/system/dto-xet.service" << EOF
[Unit]
Description=DTO Xet Integration Service
After=network.target

[Service]
Type=simple
User=root
Group=root
EnvironmentFile=${CONFIG_DIR}/environment
ExecStart=/usr/bin/bash -c "source ${CONFIG_DIR}/environment && ${INSTALL_DIR}/xet mount /mnt/xet"
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF
    
    systemctl daemon-reload
    log "Xet systemd service configured"
}

# Install dependencies
install_dependencies() {
    log "Installing dependencies"
    
    # Update package list
    apt-get update || yum update || {
        warning "Package manager update failed - continuing anyway"
    }
    
    # Install required packages
    if command -v apt-get >/dev/null 2>&1; then
        apt-get install -y curl fuse libfuse2
    elif command -v yum >/dev/null 2>&1; then
        yum install -y curl fuse
    elif command -v dnf >/dev/null 2>&1; then
        dnf install -y curl fuse
    else
        warning "Unknown package manager - please install curl and fuse manually"
    fi
}

# Main installation function
main() {
    log "Starting Xet installation for DTO Framework"
    
    check_root
    install_dependencies
    install_xet
    configure_xet
    setup_service
    
    log "Xet installation completed successfully!"
    log "Next steps:"
    log "  1. Configure Xet repositories in ${CONFIG_DIR}/"
    log "  2. Set XET_AUTH_TOKEN environment variable"
    log "  3. Start service: systemctl start dto-xet"
    log "  4. Enable service: systemctl enable dto-xet"
}

# Run main function
main "$@"