Start work on getting rid of the cobra dependency

Command line parsing is easy and I can do it better.

tools/cli/parse-args.go

@@ -0,0 +1,95 @@
+// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package cli
+
+import (
+	"fmt"
+	"strings"
+)
+
+var _ = fmt.Print
+
+func (self *Command) parse_args(ctx *Context, args []string) error {
+	args_to_parse := make([]string, 0, len(args))
+	copy(args_to_parse, args)
+	ctx.SeenCommands = append(ctx.SeenCommands, self)
+
+	var expecting_arg_for *Option
+	options_allowed := true
+
+	consume_arg := func() string { ans := args_to_parse[0]; args_to_parse = args_to_parse[1:]; return ans }
+
+	handle_option := func(opt_str string, has_val bool, opt_val string) error {
+		opt := self.FindOption(opt_str)
+		if opt == nil {
+			return &ParseError{Message: fmt.Sprintf("Unknown option: :yellow:`%s`", opt_str)}
+		}
+		opt.seen_option = opt_str
+		if has_val {
+			if !opt.needs_argument() {
+				return &ParseError{Message: fmt.Sprintf("The option: :yellow:`%s` does not take values", opt_str)}
+			}
+			return opt.add_value(opt_val)
+		} else if opt.needs_argument() {
+			expecting_arg_for = opt
+		}
+		return nil
+	}
+
+	for len(self.args) > 0 {
+		arg := consume_arg()
+
+		if expecting_arg_for == nil {
+			if options_allowed && strings.HasPrefix(arg, "-") && arg != "-" {
+				// handle option arg
+				if arg == "--" {
+					options_allowed = false
+					continue
+				}
+				opt_str := ""
+				opt_val := ""
+				has_val := false
+				if strings.HasPrefix(opt_str, "--") || len(opt_str) == 2 {
+					parts := strings.SplitN(arg, "=", 2)
+					if len(parts) > 1 {
+						has_val = true
+						opt_val = parts[1]
+					}
+					opt_str = parts[0]
+					handle_option(opt_str, has_val, opt_val)
+				} else {
+					for _, sl := range opt_str[1:] {
+						err := handle_option("-"+string(sl), false, "")
+						if err != nil {
+							return err
+						}
+					}
+				}
+			} else {
+				// handle non option arg
+				if self.AllowOptionsAfterArgs <= len(self.args) {
+					options_allowed = false
+				}
+				if self.HasSubCommands() {
+					sc := self.FindSubCommand(arg)
+					if sc == nil {
+						if !self.SubCommandIsOptional {
+							return &ParseError{Message: fmt.Sprintf(":yellow:`%s` is not a known subcommand for :emph:`%s`. Use --help to get a list of valid subcommands.", arg, self.Name)}
+						}
+					} else {
+						return sc.parse_args(ctx, args_to_parse)
+					}
+				}
+				self.args = append(self.args, arg)
+			}
+		} else {
+			// handle option value
+			err := expecting_arg_for.add_value(arg)
+			if err != nil {
+				return err
+			}
+			expecting_arg_for = nil
+		}
+	}
+	return nil
+}