// Copyright 2016 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package zipfs

import (
	"archive/tar"
	"bytes"
	"compress/bzip2"
	"compress/gzip"
	"context"
	"io"
	"log"
	"os"
	"path/filepath"
	"strings"
	"syscall"

	"github.com/hanwen/go-fuse/v2/fs"
	"github.com/hanwen/go-fuse/v2/fuse"
)

// TODO - handle symlinks.

// HeaderToFileInfo fills a fuse.Attr struct from a tar.Header.
func HeaderToFileInfo(out *fuse.Attr, h *tar.Header) {
	out.Mode = uint32(h.Mode)
	out.Size = uint64(h.Size)
	out.Uid = uint32(h.Uid)
	out.Gid = uint32(h.Gid)
	out.SetTimes(&h.AccessTime, &h.ModTime, &h.ChangeTime)
}

type tarRoot struct {
	fs.Inode
	rc io.ReadCloser
}

// tarRoot implements NodeOnAdder
var _ = (fs.NodeOnAdder)((*tarRoot)(nil))

func (r *tarRoot) OnAdd(ctx context.Context) {
	tr := tar.NewReader(r.rc)
	defer r.rc.Close()

	var longName *string
	for {
		hdr, err := tr.Next()
		if err == io.EOF {
			// end of tar archive
			break
		}
		if err != nil {
			log.Printf("Add: %v", err)
			// XXX handle error
			break
		}
		if hdr.Typeflag == 'L' {
			buf := bytes.NewBuffer(make([]byte, 0, hdr.Size))
			io.Copy(buf, tr)
			s := buf.String()
			longName = &s
			continue
		}

		if longName != nil {
			hdr.Name = *longName
			longName = nil
		}

		buf := bytes.NewBuffer(make([]byte, 0, hdr.Size))
		io.Copy(buf, tr)
		dir, base := filepath.Split(filepath.Clean(hdr.Name))

		p := r.EmbeddedInode()
		for _, comp := range strings.Split(dir, "/") {
			if len(comp) == 0 {
				continue
			}
			ch := p.GetChild(comp)
			if ch == nil {
				ch = p.NewPersistentInode(ctx,
					&fs.Inode{},
					fs.StableAttr{Mode: syscall.S_IFDIR})
				p.AddChild(comp, ch, false)
			}
			p = ch
		}

		var attr fuse.Attr
		HeaderToFileInfo(&attr, hdr)
		switch hdr.Typeflag {
		case tar.TypeSymlink:
			l := &fs.MemSymlink{
				Data: []byte(hdr.Linkname),
			}
			l.Attr = attr
			p.AddChild(base, r.NewPersistentInode(ctx, l, fs.StableAttr{Mode: syscall.S_IFLNK}), false)

		case tar.TypeLink:
			log.Println("don't know how to handle Typelink")

		case tar.TypeChar:
			rf := &fs.MemRegularFile{}
			rf.Attr = attr
			p.AddChild(base, r.NewPersistentInode(ctx, rf, fs.StableAttr{Mode: syscall.S_IFCHR}), false)
		case tar.TypeBlock:
			rf := &fs.MemRegularFile{}
			rf.Attr = attr
			p.AddChild(base, r.NewPersistentInode(ctx, rf, fs.StableAttr{Mode: syscall.S_IFBLK}), false)
		case tar.TypeDir:
			rf := &fs.MemRegularFile{}
			rf.Attr = attr
			p.AddChild(base, r.NewPersistentInode(ctx, rf, fs.StableAttr{Mode: syscall.S_IFDIR}), false)
		case tar.TypeFifo:
			rf := &fs.MemRegularFile{}
			rf.Attr = attr
			p.AddChild(base, r.NewPersistentInode(ctx, rf, fs.StableAttr{Mode: syscall.S_IFIFO}), false)
		case tar.TypeReg, tar.TypeRegA:
			df := &fs.MemRegularFile{
				Data: buf.Bytes(),
			}
			df.Attr = attr
			p.AddChild(base, r.NewPersistentInode(ctx, df, fs.StableAttr{}), false)
		default:
			log.Printf("entry %q: unsupported type '%c'", hdr.Name, hdr.Typeflag)
		}
	}
}

type readCloser struct {
	io.Reader
	close func() error
}

func (rc *readCloser) Close() error {
	return rc.close()
}

// NewTarCompressedTree creates the tree of a tar file as a FUSE
// InodeEmbedder. The inode can either be mounted as the root of a
// FUSE mount, or added as a child to some other FUSE tree.
func NewTarCompressedTree(name string, format string) (fs.InodeEmbedder, error) {
	f, err := os.Open(name)
	if err != nil {
		return nil, err
	}

	var stream io.ReadCloser
	switch format {
	case "gz":
		unzip, err := gzip.NewReader(f)
		if err != nil {
			return nil, err
		}
		stream = &readCloser{
			unzip,
			f.Close,
		}
	case "bz2":
		unzip := bzip2.NewReader(f)
		stream = &readCloser{
			unzip,
			f.Close,
		}
	}

	return &tarRoot{rc: stream}, nil
}