package config

import (
	"fmt"
	"github.com/urfave/cli/v2"
	"gopkg.in/yaml.v3"
	"os"
	"reflect"
)

const cliMetaKey = "cli.config"

type IConfig interface {
	Invalidate() error
}

func Invalidate(config IConfig) error {
	if config == nil {
		return fmt.Errorf("config must not be a nil")
	}

	val := reflect.ValueOf(config)
	if val.Kind() != reflect.Struct {
		if val.IsZero() {
			return fmt.Errorf("config is empty")
		}

		val = reflect.ValueOf(config).Elem()
	}

	for i := 0; i < val.NumField(); i++ {
		if !val.Field(i).CanInterface() || val.Field(i).IsZero() {
			continue
		}

		if elm, ok := val.Field(i).Interface().(IConfig); ok {
			if er := elm.Invalidate(); er != nil {
				return er
			}
		}
	}

	return nil
}

func ReadConfig[T IConfig](path string) (*T, error) {
	var (
		cfg = new(T)
		fd  []byte
		err error
	)

	if fd, err = os.ReadFile(path); err != nil {
		return nil, err
	}

	if err = yaml.Unmarshal(fd, cfg); err != nil {
		return nil, err
	}

	if err = Invalidate(*cfg); err != nil {
		return nil, err
	}

	return cfg, nil
}

func LoadConfig[T IConfig](ctx *cli.Context, path cli.Path) error {
	cfg, err := ReadConfig[T](path)
	if err != nil {
		return fmt.Errorf("could not load config from: %s; %v", path, err)
	}

	if cfg == nil {
		return fmt.Errorf("could not load config from: %s", path)
	}

	ctx.App.Metadata[cliMetaKey] = cfg
	return nil
}