package os

import (
	"fmt"
	"log"
	"os"
	"os/exec"
	"strings"
)

type OS struct {
	ID             string
	Name           string
	Version        string
	PackageManager string
}

func GetLinuxDistribution() (*OS, error) {
	_, err := os.Stat("/etc/os-release")
	if os.IsNotExist(err) {
		return nil, fmt.Errorf("unable to read system information")
	}

	osRelease, _ := os.ReadFile("/etc/os-release")
	return parseOsRelease(string(osRelease)), nil
}

func parseOsRelease(osRelease string) *OS {
	var result OS
	result.ID = "Unknown"
	result.Name = "Unknown"
	result.Version = "Unknown"

	lines := strings.Split(osRelease, "\n")

	for _, line := range lines {
		splitLine := strings.SplitN(line, "=", 2)
		if len(splitLine) != 2 {
			continue
		}
		switch splitLine[0] {
		case "ID":
			result.ID = strings.ToLower(strings.Trim(splitLine[1], "\""))
		case "NAME":
			result.Name = strings.Trim(splitLine[1], "\"")
		case "VERSION_ID":
			result.Version = strings.Trim(splitLine[1], "\"")
		}
	}
	err := result.getPackageManager()
	if err != nil {
		log.Fatal(err)
	}
	return &result
}

func (os *OS) getPackageManager() error {
	switch os.ID {
	case "debian", "ubuntu", "linuxmint":
		os.PackageManager = "apt"
		return nil
	case "arch":
		os.PackageManager = "pacman"
		return nil
	case "fedora":
		os.PackageManager = "dnf"
		return nil
	default:
		pmcommands := []string{
			"apt",
			"dnf",
			"pacman",
		}
		for _, pmname := range pmcommands {
			_, err := exec.LookPath(pmname)
			if err == nil {
				os.PackageManager = pmname
				return nil
			}
		}
		return fmt.Errorf("no packagemanager found for os: %s", os.Name)
	}
}