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(1)
	}

	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, "URL: https://git.arav.su/Arav/mccl")
	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    version of a game (name of a dir inside versions dir)\n"+
		"    directory  a path to where Minecraft will be installed / or will be runned from\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 will be 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 args[i][0] != '-' {
			if parsed.Command != "" {
				return parsed, fmt.Errorf("there is already a command %s, but a second one (%s) was provided",
					parsed.Command, args[i])
			}
			parsed.Command = args[i]
			switch parsed.Command {
			case "i":
				fallthrough
			case "install":
				fallthrough
			case "r":
				fallthrough
			case "run":
				if i+3 > len(args) || args[i+1][0] == '-' {
					return parsed, fmt.Errorf("a command %s is missing its version and directory arguments",
						parsed.Command)
				}
				parsed.GameVersion = args[i+1]
				parsed.Directory = args[i+2]
				i += 2
			case "l":
				fallthrough
			case "list":
				if i+1 >= len(args) || args[i+1][0] == '-' {
					return parsed, fmt.Errorf("a command list is missing its directory argument")
				}
				parsed.Directory = args[i+1]
				i++
			}
			continue
		}

		switch args[i] {
		case "-v":
			fallthrough
		case "--version":
			parsed.ShowVersion = true
		case "-h":
			fallthrough
		case "--help":
			parsed.ShowHelp = true
		case "--demand-press-enter":
			parsed.DemandPressEnter = true
		case "-u":
			fallthrough
		case "--username":
			if len(args) == i+1 || args[i+1][0] == '-' {
				err = errNoOptArg{ArgName: args[i]}
				return
			}
			parsed.Username = args[i+1]
			i++
		case "-U":
			fallthrough
		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
		}
	}
	return
}