// Run with go run ./examples/configuration -format xml, or -config /path/to/app.yaml.
package main

import (
	"embed"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"git.yuntuo.hk/k2safe/go-omni/config"
)

//go:embed config.json config.yaml config.xml
var examples embed.FS

type ClientConfig struct {
	Endpoint string        `json:"endpoint"`
	Timeout  time.Duration `json:"timeout" envDefault:"3s"`
	// This field is deliberately unavailable to configuration files.
	Token string `json:"-" env:"DEMO_CLIENT_TOKEN,secret"`
}
type Config struct {
	Client   ClientConfig `json:"client"`
	MaxItems int          `json:"maxItems" envDefault:"20"`
	Allowed  []string     `json:"allowed"`
}

func (c Config) Validate() error {
	if c.Client.Timeout <= 0 {
		return config.Invalid("client.timeout", "must be positive")
	}
	if c.MaxItems < 0 {
		return config.Invalid("maxItems", "must not be negative")
	}
	return nil
}
func newLoader() (*config.Loader, error) {
	// Example of an instance-local extension. A TOML/etc. adapter can implement
	// Decoder and return Document using that parser instead; no global registry.
	return config.NewLoader(config.WithDecoder("custom", config.DecoderFunc(func(data []byte) (config.Document, error) {
		return (config.JSONDecoder{}).Decode(data)
	})))
}
func load(path string) (Config, error) {
	loader, err := newLoader()
	if err != nil {
		return Config{}, err
	}
	return config.LoadProject(path, Config{}, config.EnvOptions{Prefix: "DEMO_", Empty: "reject"}, loader)
}
func run() error {
	path := flag.String("config", "", "external configuration file")
	format := flag.String("format", "yaml", "embedded example: json, yaml, xml")
	flag.Parse()
	if *path == "" {
		data, err := examples.ReadFile("config." + *format)
		if err != nil {
			return fmt.Errorf("choose json, yaml or xml")
		}
		dir, err := os.MkdirTemp("", "goOmniConfiguration-")
		if err != nil {
			return err
		}
		defer os.RemoveAll(dir)
		*path = filepath.Join(dir, "config."+*format)
		if err = os.WriteFile(*path, data, 0600); err != nil {
			return err
		}
	}
	cfg, err := load(*path)
	if err != nil {
		return err
	}
	// Print selected non-sensitive fields, never the whole configuration.
	fmt.Printf("timeout=%s maxItems=%d allowed=%v\n", cfg.Client.Timeout, cfg.MaxItems, cfg.Allowed)
	return nil
}
func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}