//3456789112345676892123456789312345678941234567895123456789612345678971234567898

package main

import "crypto/sha256"
import "fmt"
import "github.com/sirupsen/logrus"
import "github.com/multiformats/go-multihash"
import "github.com/mr-tron/base58"
import "github.com/pkg/xattr"

//import "errors"
import "os"
import "io"
import "flag"
import "time"
import "strconv"

var Version string
var Buildtime string
var Builduser string
var Buildarch string
var log *logrus.Logger

const namespacePrefix = "berlin.sneak.xsum"

//FIXME(sneak) make this parallelize to NUM_CPUS when processing multiple
//args

//FIXME(sneak) add a -r (recursive) flag for directories

//FIXME(sneak) make checking support reading hash algo type from multihash
//instead of assumming sha256

func main() {
	os.Exit(xsum())
}

func xsum() int {
	log = logrus.New()
	log.SetLevel(logrus.ErrorLevel)
	log.SetReportCaller(false)
	debugPtr := flag.Bool("d", false, "debug mode")
	flag.Parse()
	if *debugPtr == true {
		log.SetReportCaller(true)
		log.SetLevel(logrus.DebugLevel)
	}

	log.Debugf(
		"xsum version %s (%s) built %s by %s",
		Version,
		Buildarch,
		Buildtime,
		Builduser,
	)

	paths := flag.Args()
	if len(paths) > 1 {
		paths = paths[1:]
	}
	switch flag.Arg(0) {
	case "cron":
		x := xsfCheckAndUpdate(paths)
		if x != nil {
			return -1
		} else {
			return 0
		}
	case "check-and-update":
		x := xsfCheckAndUpdate(paths)
		if x != nil {
			return -1
		} else {
			return 0
		}
	case "check":
		x := xsfCheck(paths)
		if x != nil {
			return -1
		} else {
			return 0
		}
	case "update":
		x := xsfUpdate(paths)
		if x != nil {
			return -1
		} else {
			return 0
		}
	default:
		usage()
		return -1
	}
}

func usage() {
	fmt.Fprintf(os.Stderr, "usage: %s [-d] <update|check|check-and-update|cron> <path> [path2] [...]\n", os.Args[0])
	flag.PrintDefaults()
}

func xsfCheck(paths []string) error {
	log.Debugf("check")
	log.Fatalf("not implemented")
	for _, path := range paths {
		x := newXsf(path)
		err := x.Check()
		if err != nil {
			return err
		}
	}
	return nil
}

func showError(e error) {
	fmt.Fprintf(os.Stderr, "error: %s\n", e)
}

func xsfUpdate(paths []string) error {
	log.Debugf("update")
	for _, path := range paths {
		x := newXsf(path)
		err := x.Update()
		if err != nil {
			showError(err)
			return err
		}
	}
	return nil
}

func xsfCheckAndUpdate(paths []string) error {
	log.Debugf("check-and-update")
	r := xsfCheck(paths)
	if r != nil {
		return r
	}
	return xsfUpdate(paths)
}

func HashFile(fp *os.File) (string, error) {
	h := sha256.New()

	if _, err := io.Copy(h, fp); err != nil {
		return "", err
	}

	mHashBuf, err := multihash.EncodeName(h.Sum(nil), "sha2-256")

	if err != nil {
		return "", err
	}

	return base58.Encode(mHashBuf), nil
}

/////////////////////////////////////////////////////////////////////////////////
// type xsf
/////////////////////////////////////////////////////////////////////////////////

type xsf struct {
	fi         *os.FileInfo
	fp         *os.File
	multihash  string
	xmultihash string
	mtime      string
	xmtime     string
	path       string
	size       uint64
	xsize      uint64
}

/////////////////////////////////////////////////////////////////////////////////
// constructor
/////////////////////////////////////////////////////////////////////////////////

func newXsf(path string) *xsf {
	x := xsf{}
	x.path = path
	return &x
}

func (x *xsf) readXattrs(fp *os.File) error {
	log.Infof("reading xattrs")
	var xn string
	var err error
	var v []byte

	xn = fmt.Sprintf("%s.%s", namespacePrefix, "mtime")
	v, err = xattr.FGet(x.fp, xn)
	if err != nil {
		return err
	}
	x.xmtime = string(v)

	xn = fmt.Sprintf("%s.%s", namespacePrefix, "size")
	v, err = xattr.FGet(x.fp, xn)
	if err != nil {
		return err
	}

	a, b := strconv.ParseInt(string(v), 10, 64)
	if b != nil {
		return b
	}

	x.xsize = uint64(a)

	xn = fmt.Sprintf("%s.%s", namespacePrefix, "multihash")
	v, err = xattr.FGet(x.fp, xn)

	if err != nil {
		return err
	}
	x.xmultihash = string(v)

	return nil //FIXME
}

func (x *xsf) writeXattrs(fp *os.File) error {
	log.Infof("writing xattrs")

	var xn string
	var err error

	xn = fmt.Sprintf("%s.%s", namespacePrefix, "mtime")
	log.Infof("writing xattr %s=%s", xn, x.mtime)
	err = xattr.FSet(fp, xn, []byte(x.mtime))
	if err != nil {
		return err
	}

	xn = fmt.Sprintf("%s.%s", namespacePrefix, "size")
	log.Infof("writing xattr %s=%s", xn, fmt.Sprintf("%d", x.size))
	err = xattr.FSet(fp, xn, []byte(fmt.Sprintf("%d", x.size)))
	if err != nil {
		return err
	}

	xn = fmt.Sprintf("%s.%s", namespacePrefix, "multihash")
	log.Infof("writing xattr %s=%s", xn, x.multihash)
	err = xattr.FSet(fp, xn, []byte(x.multihash))
	if err != nil {
		return err
	}

	return nil
}

func (x *xsf) stat(fp *os.File) error {
	fi, err := fp.Stat()
	if err != nil {
		return err
	}
	x.size = uint64(fi.Size())
	log.Debugf("size: %d", x.size)
	t := fi.ModTime().UTC().Format(time.RFC3339)
	log.Debugf("modtime: %s", t)
	x.mtime = t
	return nil
}

func (x *xsf) hash(fp *os.File) error {
	log.Debugf("hashing...")
	var err error
	if x.multihash, err = HashFile(fp); err != nil {
		return err
	}
	log.Debugf("hash: %s", x.multihash)
	return nil
}

func (x *xsf) Check() error {
	fp, err := os.Open(x.path)
	defer fp.Close()
	if err != nil {
		return err
	}
	x.stat(x.fp)
	return nil
}

func (x *xsf) Update() error {
	fp, err := os.Open(x.path)
	defer fp.Close()
	log.Debugf("updating file (path: %s)", x.path)
	if err != nil {
		return err
	}

	//FIXME check if size/mtime are defined first
	//and skip update if match (and key 'multihash' exists)

	if err = x.stat(fp); err != nil {
		return err
	}

	if err = x.hash(fp); err != nil {
		return err
	}

	if err = x.writeXattrs(fp); err != nil {
		return err
	}

	return nil
}