package rbar_util

import (
	"os"
	"io"
	"fmt"
)


type Impl struct {
	LeftClick func() error
	MiddleClick func() error
	RightClick func() error
	ScrollUp func() error
	ScrollDown func() error
	Update func(tag string) error
}

func gerror(status int, err error, format string, a ...interface{}) {
	msg := fmt.Sprintf(format, a...)
	if err == nil {
		fmt.Fprintf(os.Stderr, "%s: %s", os.Args[0], msg)
	} else {
		fmt.Fprintf(os.Stderr, "%s: %s: %v", os.Args[0], msg, err)
	}
	if status != 0 {
		os.Exit(status)
	}
}

func errusage(fmt string, a ...interface{}) {
	gerror(0, nil, fmt, a...)
	usage(os.Stderr)
	os.Exit(2)
}

func usage(w io.Writer) {
	fmt.Fprintf(w, "Usage: %[1]v NN_LABEL\n    or: %[1]v BTN_ID\n    or: %[1]v -h\n", os.Args[0])
}

func Main(impl Impl) {
	if len(os.Args) != 2 {
		errusage("exactly 1 argument expected, got %d", len(os.Args)-1)
	}
	var fn func() error
	switch os.Args[1] {
	case "-h":
		usage(os.Stdout)
		os.Exit(0)
	case "1": fn = impl.LeftClick;
	case "2": fn = impl.MiddleClick;
	case "3": fn = impl.RightClick;
	case "4": fn = impl.ScrollUp;
	case "5": fn = impl.ScrollDown;
	default:
		arg := os.Args[1]
		if len(arg) > 3 && '0' <= arg[0] && arg[0] <= '9' && '0' <= arg[1] && arg[1] <= '9' && arg[2] == '_' {
			if impl.Update != nil {
				fn = func() error { return impl.Update(arg)  }
			}
		} else {
			errusage("invalid argument: %s\n", os.Args[1])
		}			
	}
	if fn == nil {
		fn = func() error { return nil }
	}
	if os.Getenv("XDG_RUNTIME_DIR") == "" {
		gerror(6, nil, "XDG_RUNTIME_DIR isn't set")
	}
	err := fn()
	if err != nil && err != NoRbar{
		gerror(1, err, "")
	}
	os.Exit(0)
}