// service.go
package main

import (
	"fmt"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"text/template"
)

const serviceTemplate = `[Unit]
Description=Blog Server
After=network.target

[Service]
Type=simple
User={{.User}}
WorkingDirectory={{.WorkDir}}
ExecStart={{.BinaryPath}}
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target
`

type ServiceConfig struct {
	User       string
	WorkDir    string
	BinaryPath string
}

func InstallService() {
	// 1. Get Absolute Path to Binary
	binPath, err := os.Executable()
	if err != nil {
		fmt.Printf("Error getting executable path: %v\n", err)
		return
	}
	binPath, _ = filepath.Abs(binPath)

	// 2. Get Working Directory
	workDir, err := os.Getwd()
	if err != nil {
		fmt.Printf("Error getting working directory: %v\n", err)
		return
	}

	// 3. Determine User
	// If running as sudo, try to get the original user, otherwise use current
	username := os.Getenv("SUDO_USER")
	if username == "" {
		u, err := user.Current()
		if err == nil {
			username = u.Username
		} else {
			username = "root"
		}
	}

	config := ServiceConfig{
		User:       username,
		WorkDir:    workDir,
		BinaryPath: binPath,
	}

	// 4. Generate Content
	tmpl, err := template.New("service").Parse(serviceTemplate)
	if err != nil {
		panic(err)
	}

	serviceFile := "/etc/systemd/system/blog.service"

	// Check if we have write permissions to /etc/systemd/system
	f, err := os.OpenFile(serviceFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
	if err != nil {
		// Permission denied or other error: Print instructions instead
		fmt.Println("---------------------------------------------------")
		fmt.Println("Run the following command with sudo to install:")
		fmt.Println("---------------------------------------------------")
		fmt.Printf("sudo bash -c 'cat > %s <<EOF\n", serviceFile)
		tmpl.Execute(os.Stdout, config)
		fmt.Println("EOF'")
		fmt.Println("---------------------------------------------------")
		fmt.Println("Then run:")
		fmt.Println("sudo systemctl daemon-reload")
		fmt.Println("sudo systemctl enable --now blog")
		return
	}
	defer f.Close()

	// Write file
	if err := tmpl.Execute(f, config); err != nil {
		fmt.Printf("Error writing service file: %v\n", err)
		return
	}

	fmt.Printf("Service file created at %s\n", serviceFile)

	// 5. Reload Daemon
	cmd := exec.Command("systemctl", "daemon-reload")
	if err := cmd.Run(); err != nil {
		fmt.Println("Warning: Failed to reload systemd daemon. Run 'sudo systemctl daemon-reload' manually.")
	}

	// 6. Enable and Start
	cmd = exec.Command("systemctl", "enable", "--now", "blog")
	if output, err := cmd.CombinedOutput(); err != nil {
		fmt.Printf("Warning: Failed to enable service: %v\nOutput: %s\n", err, output)
	} else {
		fmt.Println("Service installed, enabled, and started successfully!")
	}
}