package main

import (
	// External
	"github.com/goccy/go-yaml"

	// Standard
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"os"
	"path"
)

const VERSION = "v1"

type DatagraphNode struct {
	ID       int
	Name     string
	Children []*DatagraphNode
	TypeName string
	Data     struct {
		Exec    string
		Dynamic string
		Inplace bool
	}
}

type Entry struct {
	Name     string
	Exec     string   `yaml:",omitempty"`
	Inplace  bool     `yaml:",omitempty"`
	Dynamic  string   `yaml:",omitempty"`
	Commands []*Entry `yaml:",omitempty"`
}

func (node DatagraphNode) toEntry() (e Entry) {
	e.Name = node.Name
	e.Exec = node.Data.Exec
	e.Dynamic = node.Data.Dynamic
	e.Inplace = node.Data.Inplace

	for _, childNode := range node.Children {
		childEntry := childNode.toEntry()
		e.Commands = append(e.Commands, &childEntry)
	}
	return
}

func init() {
	var flagVersion bool

	flag.BoolVar(&flagVersion, "version", false, "Print version and exit")
	flag.Parse()

	if flagVersion {
		fmt.Println(VERSION)
		os.Exit(0)
	}
}

func main() {
	// Script could be run for different users and have different places where config is supposed to go.
	dir := os.Getenv("DATAGRAPH_DIR")
	if dir == "" {
		fmt.Fprintf(os.Stderr, "Set env variable DATAGRAPH_DIR\n")
		os.Exit(1)
	}

	// Make it easier for admins by creating directories automatically.
	err := os.MkdirAll(dir, 0700)
	if err != nil {
		fmt.Fprintf(os.Stderr, "%s\n", err)
		os.Exit(1)
	}

	// JSON data from datagraph is read into a data structure
	// for further processing into the launcher
	datagraphData, _ := io.ReadAll(os.Stdin)
	var node DatagraphNode
	err = json.Unmarshal(datagraphData, &node)
	if err != nil {
		fmt.Fprintf(os.Stderr, "%s\n", err)
		os.Exit(1)
	}

	// Each top node is a separate file.
	for _, topNode := range node.Children {
		y, err := yaml.Marshal(topNode.toEntry())
		if err != nil {
			fmt.Fprintf(os.Stderr, "%s\n", err)
			os.Exit(1)
		}

		f, err := os.OpenFile(
			path.Join(dir, topNode.Name+".yaml"),
			os.O_CREATE|os.O_WRONLY|os.O_TRUNC,
			0600,
		)
		if err != nil {
			fmt.Fprintf(os.Stderr, "%s\n", err)
			os.Exit(1)
		}
		defer f.Close()

		_, err = f.Write(y)
		if err != nil {
			fmt.Fprintf(os.Stderr, "%s\n", err)
			os.Exit(1)
		}
	}
}