package main

import (
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/restic/restic"
	"github.com/restic/restic/backend"
	"golang.org/x/crypto/ssh/terminal"
)

type CmdBackup struct{}

func init() {
	_, err := parser.AddCommand("backup",
		"save file/directory",
		"The backup command creates a snapshot of a file or directory",
		&CmdBackup{})
	if err != nil {
		panic(err)
	}
}

func format_bytes(c uint64) string {
	b := float64(c)

	switch {
	case c > 1<<40:
		return fmt.Sprintf("%.3f TiB", b/(1<<40))
	case c > 1<<30:
		return fmt.Sprintf("%.3f GiB", b/(1<<30))
	case c > 1<<20:
		return fmt.Sprintf("%.3f MiB", b/(1<<20))
	case c > 1<<10:
		return fmt.Sprintf("%.3f KiB", b/(1<<10))
	default:
		return fmt.Sprintf("%dB", c)
	}
}

func format_seconds(sec uint64) string {
	hours := sec / 3600
	sec -= hours * 3600
	min := sec / 60
	sec -= min * 60
	if hours > 0 {
		return fmt.Sprintf("%d:%02d:%02d", hours, min, sec)
	}

	return fmt.Sprintf("%d:%02d", min, sec)
}

func format_duration(d time.Duration) string {
	sec := uint64(d / time.Second)
	return format_seconds(sec)
}

func print_tree2(indent int, t *restic.Tree) {
	for _, node := range t.Nodes {
		if node.Tree() != nil {
			fmt.Printf("%s%s/\n", strings.Repeat("  ", indent), node.Name)
			print_tree2(indent+1, node.Tree())
		} else {
			fmt.Printf("%s%s\n", strings.Repeat("  ", indent), node.Name)
		}
	}
}

func (cmd CmdBackup) Usage() string {
	return "DIR/FILE [snapshot-ID]"
}

func newScanProgress() *restic.Progress {
	if !terminal.IsTerminal(int(os.Stdout.Fd())) {
		return nil
	}

	p := restic.NewProgress(time.Second)
	p.OnUpdate = func(s restic.Stat, d time.Duration, ticker bool) {
		fmt.Printf("\x1b[2K\r[%s] %d directories, %d files, %s", format_duration(d), s.Dirs, s.Files, format_bytes(s.Bytes))
	}
	p.OnDone = func(s restic.Stat, d time.Duration, ticker bool) {
		fmt.Printf("\nDone in %s\n", format_duration(d))
	}

	return p
}

func newLoadBlobsProgress(s restic.Server) (*restic.Progress, error) {
	if !terminal.IsTerminal(int(os.Stdout.Fd())) {
		return nil, nil
	}

	trees, err := s.Count(backend.Tree)
	if err != nil {
		return nil, err
	}

	eta := uint64(0)
	tps := uint64(0) // trees per second

	p := restic.NewProgress(time.Second)
	p.OnUpdate = func(s restic.Stat, d time.Duration, ticker bool) {
		sec := uint64(d / time.Second)
		if trees > 0 && sec > 0 && ticker {
			tps = uint64(s.Trees) / sec
			if tps > 0 {
				eta = (uint64(trees) - s.Trees) / tps
			}
		}

		fmt.Printf("\x1b[2K\r[%s] %3.2f%%  %d trees/s  %d / %d trees, %d blobs  ETA %s",
			format_duration(d),
			float64(s.Trees)/float64(trees)*100,
			tps,
			s.Trees, trees,
			s.Blobs,
			format_seconds(eta))
	}
	p.OnDone = func(s restic.Stat, d time.Duration, ticker bool) {
		fmt.Printf("\nDone in %s\n", format_duration(d))
	}

	return p, nil
}

func newArchiveProgress(todo restic.Stat) *restic.Progress {
	if !terminal.IsTerminal(int(os.Stdout.Fd())) {
		return nil
	}

	archiveProgress := restic.NewProgress(time.Second)

	var bps, eta uint64
	itemsTodo := todo.Files + todo.Dirs

	archiveProgress.OnUpdate = func(s restic.Stat, d time.Duration, ticker bool) {
		sec := uint64(d / time.Second)
		if todo.Bytes > 0 && sec > 0 && ticker {
			bps = s.Bytes / sec
			if bps > 0 {
				eta = (todo.Bytes - s.Bytes) / bps
			}
		}

		itemsDone := s.Files + s.Dirs
		fmt.Printf("\x1b[2K\r[%s] %3.2f%%  %s/s  %s / %s  %d / %d items  ETA %s",
			format_duration(d),
			float64(s.Bytes)/float64(todo.Bytes)*100,
			format_bytes(bps),
			format_bytes(s.Bytes), format_bytes(todo.Bytes),
			itemsDone, itemsTodo,
			format_seconds(eta))
	}

	archiveProgress.OnDone = func(s restic.Stat, d time.Duration, ticker bool) {
		sec := uint64(d / time.Second)
		fmt.Printf("\nduration: %s, %.2fMiB/s\n",
			format_duration(d),
			float64(todo.Bytes)/float64(sec)/(1<<20))
	}

	return archiveProgress
}

func (cmd CmdBackup) Execute(args []string) error {
	if len(args) == 0 || len(args) > 2 {
		return fmt.Errorf("wrong number of parameters, Usage: %s", cmd.Usage())
	}

	s, err := OpenRepo()
	if err != nil {
		return err
	}

	var parentSnapshotID backend.ID

	target := args[0]
	if len(args) > 1 {
		parentSnapshotID, err = s.FindSnapshot(args[1])
		if err != nil {
			return fmt.Errorf("invalid id %q: %v", args[1], err)
		}

		fmt.Printf("found parent snapshot %v\n", parentSnapshotID)
	}

	fmt.Printf("scan %s\n", target)

	stat, err := restic.Scan(target, newScanProgress())

	// TODO: add filter
	// arch.Filter = func(dir string, fi os.FileInfo) bool {
	// 	return true
	// }

	if parentSnapshotID != nil {
		return errors.New("not implemented")
	}

	arch, err := restic.NewArchiver(s)
	if err != nil {
		fmt.Fprintf(os.Stderr, "err: %v\n", err)
	}

	arch.Error = func(dir string, fi os.FileInfo, err error) error {
		// TODO: make ignoring errors configurable
		fmt.Fprintf(os.Stderr, "\x1b[2K\rerror for %s: %v\n", dir, err)
		return nil
	}

	fmt.Printf("loading blobs\n")
	pb, err := newLoadBlobsProgress(s)
	if err != nil {
		return err
	}

	err = arch.Preload(pb)
	if err != nil {
		return err
	}

	_, id, err := arch.Snapshot(newArchiveProgress(stat), target, parentSnapshotID)
	if err != nil {
		return err
	}

	plen, err := s.PrefixLength(backend.Snapshot)
	if err != nil {
		return err
	}

	fmt.Printf("snapshot %s saved\n", id[:plen])

	return nil
}