mccl/cmd/mccl/main.go

package main

import (
	"fmt"
	"mccl/cmd/mccl/commands"
	mcclprofile "mccl/internal/mccl_profile"
	"os"
)

var programVersion string

func main() {
	args, err := parseArguments(os.Args[1:])
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		usage()
		os.Exit(1)
	}

	if args.ShowVersion {
		version()
	}

	if args.ShowHelp {
		usage()
	}

	if args.ShowHelp || args.ShowVersion {
		os.Exit(0)
	}

	if len(os.Args) < 2 {
		usage()
		os.Exit(0)
	}

	var cmd commands.Command

	switch args.Command {
	case "install":
		fallthrough
	case "i":
		cmd = commands.NewInstallCommand(args.GameVersion, args.Directory)
	case "run":
		fallthrough
	case "r":
		cmd = commands.NewRunCommand(args.GameVersion, args.Directory,
			args.Username, args.Uuid, args.JavaXmx, args.UseProfile)
	case "list":
		fallthrough
	case "l":
		cmd = commands.NewListCommand(args.Directory)
	default:
		usage()
		os.Exit(0)
	}

	exitCode := 0

	if err := cmd.Run(); err != nil {
		fmt.Println(err)
		exitCode = 1
	}

	if args.DemandPressEnter {
		fmt.Fprint(os.Stderr, "Press the enter key to continue...")
		fmt.Scanln()
	}

	os.Exit(exitCode)
}

func version() {
	fmt.Fprintf(os.Stderr, "mccl ver. %s\nCopyright (c)  2023  Alexander \"Arav\" Andreev <me@arav.su>\n", programVersion)
	fmt.Fprintln(os.Stderr, "License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.")
}

func usage() {
	fmt.Fprintln(os.Stderr, "Usage: mccl [<common options>]... command arguments... [options]...")
	fmt.Fprintln(os.Stderr, "Common options:\n"+
		"  -h,--help     show help\n"+
		"  -v,--version  show version\n"+
		"  --demand-press-enter\n"+
		"                ask to press the enter key before closing\n"+
		"Commands:\n"+
		"  \033[1minstall|i\033[0m version directory\n"+
		"    Install any vanilla version (for mod loaders use theirs installers)\n"+
		"  \033[1mrun|r\033[0m version directory [-u username] [-U UUID] [-java-Xmx memory] [--profile]\n"+
		"    Run vanilla, forge, fabric, quilt, the others aren't tested\n"+
		"  \033[1mlist|l\033[0m directory\n"+
		"    List all installed versions in directory\n"+
		"Explanation of arguments and options for commands:\n"+
		"    version    minecraft's version \n"+
		"    directory  a path to where Minecraft will be installed\n"+
		"    -u,--username username\n"+
		"               player's username (Anonymous by default)\n"+
		"    -U,--uuid UUID\n"+
		"               player's account UUID (all zeroes by default)\n"+
		"    --java-Xmx memory\n"+
		"               java's -Xmx param, e.g. 4G\n"+
		"    --profile\n"+
		"               load/save username, UUID, and -Xmx from/to a file.\n"+
		"               Once saved, you can ommit -u,-U and --java-Xmx,\n"+
		"               since they are stored in", mcclprofile.ProfileFileName)
}

type arguments struct {
	ShowVersion      bool
	ShowHelp         bool
	DemandPressEnter bool

	Command     string
	GameVersion string
	Directory   string
	Username    string
	Uuid        string
	JavaXmx     string

	UseProfile bool
}

type errNoOptArg struct {
	ArgName string
}

func (e errNoOptArg) Error() string {
	return fmt.Sprintf("%s option demands an argument, but it wasn't provided", e.ArgName)
}

func parseArguments(args []string) (parsed arguments, err error) {
	parsed.Username = "Anonymous"
	parsed.Directory = "."
	parsed.Uuid = "00000000-0000-0000-0000-000000000000"
	for i := 0; i < len(args); i++ {
		if len(args[i]) > 2 && args[i][0] == '-' && args[i][1] == '-' {
			switch args[i][2:] {
			case "version":
				parsed.ShowVersion = true
			case "help":
				parsed.ShowHelp = true
			case "demand-press-enter":
				parsed.DemandPressEnter = true
			case "username":
				if len(args) == i+1 || args[i+1][0] == '-' {
					err = errNoOptArg{ArgName: args[i]}
					return
				}
				parsed.Username = args[i+1]
				i++
			case "uuid":
				if len(args) == i+1 || args[i+1][0] == '-' {
					err = errNoOptArg{ArgName: args[i]}
					return
				}
				parsed.Uuid = args[i+1]
				i++
			case "java-Xmx":
				if len(args) == i+1 || args[i+1][0] == '-' {
					err = errNoOptArg{ArgName: args[i]}
					return
				}
				parsed.JavaXmx = args[i+1]
				i++
			case "profile":
				parsed.UseProfile = true
			default:
				err = fmt.Errorf("an unknown option %s was provided", args[i])
				return
			}
		} else if args[i][0] == '-' && len(args[i]) > 1 {
			for _, option := range args[i][1:] {
				switch option {
				case 'v':
					parsed.ShowVersion = true
				case 'h':
					parsed.ShowHelp = true
				case 'u':
					if len(args) == i+1 || args[i+1][0] == '-' {
						err = errNoOptArg{ArgName: args[i]}
						return
					}
					parsed.Username = args[i+1]
					i++
				case 'U':
					if len(args) == i+1 || args[i+1][0] == '-' {
						err = errNoOptArg{ArgName: args[i]}
						return
					}
					parsed.Uuid = args[i+1]
					i++
				default:
					err = fmt.Errorf("an unknown option %c was provided", option)
					return
				}
			}
		} else {
			if parsed.Command != "" {
				err = fmt.Errorf("only one command should present")
				return
			}
			switch parsed.Command = args[i]; parsed.Command {
			case "i":
				fallthrough
			case "install":
				fallthrough
			case "r":
				fallthrough
			case "run":
				if len(args) <= i+3 || args[i+1][0] == '-' || args[i+2][0] == '-' {
					err = fmt.Errorf("not enough arguments was provided")
					return
				}
				parsed.GameVersion = args[i+1]
				parsed.Directory = args[i+2]
				i += 2
			case "l":
				fallthrough
			case "list":
				if len(args) <= i+2 || args[i+1][0] == '-' {
					err = fmt.Errorf("not enough arguments was provided")
					return
				}
				parsed.Directory = args[i+1]
				i++
			default:
				err = fmt.Errorf("an unknown command %s was provided", parsed.Command)
				return
			}
		}
	}
	return
}