package main

import (
	"bufio"
	"bytes"
	"os/exec"
	"strings"
)

func listInstalledPackages() ([]string, error) {
	// Execute dpkg -l command
	cmd := exec.Command("dpkg", "-l")
	var out bytes.Buffer
	cmd.Stdout = &out

	if err := cmd.Run(); err != nil {
		return nil, err
	}

	// Initialize slice to hold package names
	var packages []string
	scanner := bufio.NewScanner(&out)

	// Skip the first five lines as they are headers in dpkg -l output
	for i := 0; i < 5 && scanner.Scan(); i++ {
		// Ignore header lines
	}

	// Process each remaining line
	for scanner.Scan() {
		line := scanner.Text()
		fields := strings.Fields(line)

		// Ensure the line has enough fields for parsing
		if len(fields) >= 2 {
			status := fields[0]
			packageName := fields[1]

			// Only add packages with "ii" status (installed)
			if status == "ii" {
				packages = append(packages, packageName)
			}
		}
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return packages, nil
}