package main

import (
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"os"
	"strings"

	"github.com/pelletier/go-toml/v2"
	"go.jolheiser.com/nixfig"
	"gopkg.in/yaml.v3"
)

func maine() error {
	fs := flag.NewFlagSet("nixgen", flag.ExitOnError)

	format := func(v any) ([]byte, error) {
		return json.MarshalIndent(v, "", "\t")
	}
	formatFunc := func(s string) error {
		switch strings.ToLower(s) {
		case "json":
			// Default
		case "yaml":
			format = yaml.Marshal
		case "toml":
			format = toml.Marshal
		default:
			return fmt.Errorf("unknown format %q, should be one of [json yaml toml]", s)
		}
		return nil
	}
	fs.Func("format", "Output format [json, yaml, toml]: default 'json'", formatFunc)
	fs.Func("f", "--format", formatFunc)
	if err := fs.Parse(os.Args[1:]); err != nil {
		return err
	}

	if len(fs.Args()) < 1 {
		return errors.New("nixgen requires a file")
	}

	fp := fs.Arg(0)
	data, err := os.ReadFile(fp)
	if err != nil {
		return err
	}

	var nix map[string]any
	if err := nixfig.Unmarshal(data, &nix); err != nil {
		return err
	}

	out, err := format(nix)
	if err != nil {
		return err
	}
	fmt.Println(string(out))

	return nil
}

func main() {
	if err := maine(); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}