package app

import (
	"context"
	"errors"
	"os"
	"slices"
	"strconv"
	"strings"
)

func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}

func check(e error) {
	if e != nil {
		panic(e)
	}
}

func exitOnError(err error) {
	if err != nil {
		os.Stderr.WriteString(err.Error())
		os.Exit(1)
	}
}

func async(cb func(ctx context.Context)) {
	wg.Add(1)
	go func() {
		defer wg.Done()
		select {
		case <-ctx.Done():
			return
		default:
			cb(ctx)
		}
	}()
}

func getArg[T any](args []string, name string, f func(string, bool) T) T {
	i := slices.Index(args, name)
	if i == -1 {
		return f("", false)
	}
	if i == len(args)-1 {
		panic(errors.New("invalid " + name + " option"))
	}
	s := args[i+1]
	if strings.HasPrefix(s, "--") {
		return f("", true)
	}
	return f(s, true)
}

func strArg(args []string, name string, def ...string) string {
	return getArg(args, name, func(s string, b bool) string {
		if b {
			return s
		}
		for _, v := range def {
			return v
		}
		return ""
	})
}

func intArg(args []string, name string, def ...int) int {
	return getArg(args, name, func(s string, b bool) int {
		if b {
			size, err := strconv.Atoi(s)
			check(err)
			assert(size > 0, "invalid "+name+" option")
			return size
		}
		for _, v := range def {
			return v
		}
		return 0
	})
}

func boolArg(args []string, name string, def ...bool) bool {
	return getArg(args, name, func(s string, b bool) bool {
		if b {
			if s == "" {
				return true
			}
			v, err := strconv.ParseBool(s)
			check(err)
			return v
		}
		for _, v := range def {
			return v
		}
		return false
	})
}