package main

import (
	"bytes"
	"fmt"
	"io"
	"io/ioutil"
	"local/args"
	"local/storage"
	"log"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"sort"
	"time"
)

type Config struct {
	n      int
	conf   string
	rclone string
	ns     string
	root   string
	store  string
	cmd    string
}

type LastN struct {
	store storage.DB
	conf  Config
}

func main() {
	conf := config()
	log.Println(conf)
	storage, err := storage.New(storage.TypeFromString(conf.store), conf.conf, path.Join(conf.rclone+":", conf.ns))
	if err != nil {
		panic(err)
	}
	lastn := &LastN{
		conf:  conf,
		store: storage,
	}
	actions := []func() error{}
	switch conf.cmd {
	case "backup":
		actions = append(actions, lastn.push, lastn.clean)
	case "list":
		actions = append(actions, lastn.list)
	case "clean":
		actions = append(actions, lastn.clean)
	case "restore":
		actions = append(actions, lastn.restore)
	default:
		panic(fmt.Sprintf("not impl: %s"))
	}
	for _, action := range actions {
		if err := action(); err != nil {
			panic(err)
		}
	}
}

func config() Config {
	as := args.NewArgSet()
	as.Append(args.INT, "n", "number of backups to retain", 5)
	as.Append(args.STRING, "conf", "path to rclone conf", path.Join(os.Getenv("HOME"), "/.config/rclone/rclone.conf"))
	as.Append(args.STRING, "root", "path to root", "./public")
	as.Append(args.STRING, "ns", "ns for backups", path.Join("lastn", "dev"))
	as.Append(args.STRING, "rclone", "rclone backend name", "blapointe-drive-enc")
	as.Append(args.STRING, "store", "type of store, like [map rclone]", "map")
	as.Append(args.STRING, "cmd", "[backup, restore, list, clean]", "backup")
	if err := as.Parse(); err != nil {
		panic(err)
	}
	root, err := filepath.Abs(as.Get("root").GetString())
	if err != nil {
		panic(err)
	}
	return Config{
		n:      as.Get("n").GetInt(),
		conf:   as.Get("conf").GetString(),
		rclone: as.Get("rclone").GetString(),
		root:   root,
		ns:     as.Get("ns").GetString(),
		store:  as.Get("store").GetString(),
		cmd:    as.Get("cmd").GetString(),
	}
}

func (lastN *LastN) push() error {
	root := lastN.conf.root
	store := lastN.store
	root, err := filepath.Abs(root)
	if err != nil {
		return err
	}
	archive := path.Join(
		os.TempDir(),
		fmt.Sprintf(
			"%s.tar",
			time.Now().Format("2006.01.02.15.04.05"),
		),
	)
	cmd := exec.Command(
		"tar",
		"-czf",
		archive,
		"-C",
		path.Dir(root),
		path.Base(root),
	)
	out, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("%v: %s", err, out)
	}
	b, err := ioutil.ReadFile(archive)
	if err != nil {
		return err
	}
	log.Println("Created backup", path.Base(archive))
	return store.Set(path.Base(archive), b)
}

func (lastN *LastN) clean() error {
	n := lastN.conf.n
	store := lastN.store
	backups, err := store.List(nil)
	if err != nil {
		return err
	}
	sort.Strings(backups)
	for i := 0; i < len(backups)-n; i++ {
		log.Println("Pruning old backup", backups[i])
		err := store.Set(backups[i], nil)
		if err != nil {
			return err
		}
	}
	return nil
}

func (lastN *LastN) list() error {
	store := lastN.store
	backups, err := store.List(nil)
	if err != nil {
		return err
	}
	sort.Strings(backups)
	for _, backup := range backups {
		log.Println(backup)
	}
	return nil
}

func (lastN *LastN) restore() error {
	root := lastN.conf.root + "-restore"
	os.RemoveAll(root)
	if err := os.MkdirAll(root, os.ModePerm); err != nil {
		return err
	}
	store := lastN.store
	backups, err := store.List(nil)
	if err != nil {
		return fmt.Errorf("cannot list: %v", err)
	}
	sort.Strings(backups)
	backup := backups[len(backups)-1]
	b, err := store.Get(backup)
	if err != nil {
		return fmt.Errorf("cannot get %s: %v", backup, err)
	}
	log.Printf("restoring %s (%v) in %s", backup, len(b), root)
	cmd := exec.Command(
		"tar",
		"-C",
		root,
		"-xzf",
		"-",
	)
	stdin, err := cmd.StdinPipe()
	if err != nil {
		return fmt.Errorf("cannot get stdin: %v", err)
	}
	go func() {
		defer stdin.Close()
		io.Copy(stdin, bytes.NewReader(b))
	}()
	out, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("failed tar -xf: %v: %s", err, out)
	}
	return nil
}