// Copyright 2011 The Go 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 zip

import (
	
	
	
	
	
	
	
	
	
)

var (
	errLongName  = errors.New("zip: FileHeader.Name too long")
	errLongExtra = errors.New("zip: FileHeader.Extra too long")
)

// Writer implements a zip file writer.
type Writer struct {
	cw          *countWriter
	dir         []*header
	last        *fileWriter
	closed      bool
	compressors map[uint16]Compressor
	comment     string

	// testHookCloseSizeOffset if non-nil is called with the size
	// of offset of the central directory at Close.
	testHookCloseSizeOffset func(size, offset uint64)
}

type header struct {
	*FileHeader
	offset uint64
	raw    bool
}

// NewWriter returns a new [Writer] writing a zip file to w.
func ( io.Writer) *Writer {
	return &Writer{cw: &countWriter{w: bufio.NewWriter()}}
}

// SetOffset sets the offset of the beginning of the zip data within the
// underlying writer. It should be used when the zip data is appended to an
// existing file, such as a binary executable.
// It must be called before any data is written.
func ( *Writer) ( int64) {
	if .cw.count != 0 {
		panic("zip: SetOffset called after data was written")
	}
	.cw.count = 
}

// Flush flushes any buffered data to the underlying writer.
// Calling Flush is not normally necessary; calling Close is sufficient.
func ( *Writer) () error {
	return .cw.w.(*bufio.Writer).Flush()
}

// SetComment sets the end-of-central-directory comment field.
// It can only be called before [Writer.Close].
func ( *Writer) ( string) error {
	if len() > uint16max {
		return errors.New("zip: Writer.Comment too long")
	}
	.comment = 
	return nil
}

// Close finishes writing the zip file by writing the central directory.
// It does not close the underlying writer.
func ( *Writer) () error {
	if .last != nil && !.last.closed {
		if  := .last.close();  != nil {
			return 
		}
		.last = nil
	}
	if .closed {
		return errors.New("zip: writer closed twice")
	}
	.closed = true

	// write central directory
	 := .cw.count
	for ,  := range .dir {
		var  [directoryHeaderLen]byte
		 := writeBuf([:])
		.uint32(uint32(directoryHeaderSignature))
		.uint16(.CreatorVersion)
		.uint16(.ReaderVersion)
		.uint16(.Flags)
		.uint16(.Method)
		.uint16(.ModifiedTime)
		.uint16(.ModifiedDate)
		.uint32(.CRC32)
		if .isZip64() || .offset >= uint32max {
			// the file needs a zip64 header. store maxint in both
			// 32 bit size fields (and offset later) to signal that the
			// zip64 extra header should be used.
			.uint32(uint32max) // compressed size
			.uint32(uint32max) // uncompressed size

			// append a zip64 extra block to Extra
			var  [28]byte // 2x uint16 + 3x uint64
			 := writeBuf([:])
			.uint16(zip64ExtraID)
			.uint16(24) // size = 3x uint64
			.uint64(.UncompressedSize64)
			.uint64(.CompressedSize64)
			.uint64(.offset)
			.Extra = append(.Extra, [:]...)
		} else {
			.uint32(.CompressedSize)
			.uint32(.UncompressedSize)
		}

		.uint16(uint16(len(.Name)))
		.uint16(uint16(len(.Extra)))
		.uint16(uint16(len(.Comment)))
		 = [4:] // skip disk number start and internal file attr (2x uint16)
		.uint32(.ExternalAttrs)
		if .offset > uint32max {
			.uint32(uint32max)
		} else {
			.uint32(uint32(.offset))
		}
		if ,  := .cw.Write([:]);  != nil {
			return 
		}
		if ,  := io.WriteString(.cw, .Name);  != nil {
			return 
		}
		if ,  := .cw.Write(.Extra);  != nil {
			return 
		}
		if ,  := io.WriteString(.cw, .Comment);  != nil {
			return 
		}
	}
	 := .cw.count

	 := uint64(len(.dir))
	 := uint64( - )
	 := uint64()

	if  := .testHookCloseSizeOffset;  != nil {
		(, )
	}

	if  >= uint16max ||  >= uint32max ||  >= uint32max {
		var  [directory64EndLen + directory64LocLen]byte
		 := writeBuf([:])

		// zip64 end of central directory record
		.uint32(directory64EndSignature)
		.uint64(directory64EndLen - 12) // length minus signature (uint32) and length fields (uint64)
		.uint16(zipVersion45)           // version made by
		.uint16(zipVersion45)           // version needed to extract
		.uint32(0)                      // number of this disk
		.uint32(0)                      // number of the disk with the start of the central directory
		.uint64()                // total number of entries in the central directory on this disk
		.uint64()                // total number of entries in the central directory
		.uint64()                   // size of the central directory
		.uint64()                 // offset of start of central directory with respect to the starting disk number

		// zip64 end of central directory locator
		.uint32(directory64LocSignature)
		.uint32(0)           // number of the disk with the start of the zip64 end of central directory
		.uint64(uint64()) // relative offset of the zip64 end of central directory record
		.uint32(1)           // total number of disks

		if ,  := .cw.Write([:]);  != nil {
			return 
		}

		// store max values in the regular end record to signal
		// that the zip64 values should be used instead
		 = uint16max
		 = uint32max
		 = uint32max
	}

	// write end record
	var  [directoryEndLen]byte
	 := writeBuf([:])
	.uint32(uint32(directoryEndSignature))
	 = [4:]                        // skip over disk number and first disk number (2x uint16)
	.uint16(uint16())        // number of entries this disk
	.uint16(uint16())        // number of entries total
	.uint32(uint32())           // size of directory
	.uint32(uint32())         // start of directory
	.uint16(uint16(len(.comment))) // byte size of EOCD comment
	if ,  := .cw.Write([:]);  != nil {
		return 
	}
	if ,  := io.WriteString(.cw, .comment);  != nil {
		return 
	}

	return .cw.w.(*bufio.Writer).Flush()
}

// Create adds a file to the zip file using the provided name.
// It returns a [Writer] to which the file contents should be written.
// The file contents will be compressed using the [Deflate] method.
// The name must be a relative path: it must not start with a drive
// letter (e.g. C:) or leading slash, and only forward slashes are
// allowed. To create a directory instead of a file, add a trailing
// slash to the name.
// The file's contents must be written to the [io.Writer] before the next
// call to [Writer.Create], [Writer.CreateHeader], or [Writer.Close].
func ( *Writer) ( string) (io.Writer, error) {
	 := &FileHeader{
		Name:   ,
		Method: Deflate,
	}
	return .CreateHeader()
}

// detectUTF8 reports whether s is a valid UTF-8 string, and whether the string
// must be considered UTF-8 encoding (i.e., not compatible with CP-437, ASCII,
// or any other common encoding).
func detectUTF8( string) (,  bool) {
	for  := 0;  < len(); {
		,  := utf8.DecodeRuneInString([:])
		 += 
		// Officially, ZIP uses CP-437, but many readers use the system's
		// local character encoding. Most encoding are compatible with a large
		// subset of CP-437, which itself is ASCII-like.
		//
		// Forbid 0x7e and 0x5c since EUC-KR and Shift-JIS replace those
		// characters with localized currency and overline characters.
		if  < 0x20 ||  > 0x7d ||  == 0x5c {
			if !utf8.ValidRune() || ( == utf8.RuneError &&  == 1) {
				return false, false
			}
			 = true
		}
	}
	return true, 
}

// prepare performs the bookkeeping operations required at the start of
// CreateHeader and CreateRaw.
func ( *Writer) ( *FileHeader) error {
	if .last != nil && !.last.closed {
		if  := .last.close();  != nil {
			return 
		}
	}
	if len(.dir) > 0 && .dir[len(.dir)-1].FileHeader ==  {
		// See https://golang.org/issue/11144 confusion.
		return errors.New("archive/zip: invalid duplicate FileHeader")
	}
	return nil
}

// CreateHeader adds a file to the zip archive using the provided [FileHeader]
// for the file metadata. [Writer] takes ownership of fh and may mutate
// its fields. The caller must not modify fh after calling [Writer.CreateHeader].
//
// This returns a [Writer] to which the file contents should be written.
// The file's contents must be written to the io.Writer before the next
// call to [Writer.Create], [Writer.CreateHeader], [Writer.CreateRaw], or [Writer.Close].
func ( *Writer) ( *FileHeader) (io.Writer, error) {
	if  := .prepare();  != nil {
		return nil, 
	}

	// The ZIP format has a sad state of affairs regarding character encoding.
	// Officially, the name and comment fields are supposed to be encoded
	// in CP-437 (which is mostly compatible with ASCII), unless the UTF-8
	// flag bit is set. However, there are several problems:
	//
	//	* Many ZIP readers still do not support UTF-8.
	//	* If the UTF-8 flag is cleared, several readers simply interpret the
	//	name and comment fields as whatever the local system encoding is.
	//
	// In order to avoid breaking readers without UTF-8 support,
	// we avoid setting the UTF-8 flag if the strings are CP-437 compatible.
	// However, if the strings require multibyte UTF-8 encoding and is a
	// valid UTF-8 string, then we set the UTF-8 bit.
	//
	// For the case, where the user explicitly wants to specify the encoding
	// as UTF-8, they will need to set the flag bit themselves.
	,  := detectUTF8(.Name)
	,  := detectUTF8(.Comment)
	switch {
	case .NonUTF8:
		.Flags &^= 0x800
	case ( || ) && ( && ):
		.Flags |= 0x800
	}

	.CreatorVersion = .CreatorVersion&0xff00 | zipVersion20 // preserve compatibility byte
	.ReaderVersion = zipVersion20

	// If Modified is set, this takes precedence over MS-DOS timestamp fields.
	if !.Modified.IsZero() {
		// Contrary to the FileHeader.SetModTime method, we intentionally
		// do not convert to UTC, because we assume the user intends to encode
		// the date using the specified timezone. A user may want this control
		// because many legacy ZIP readers interpret the timestamp according
		// to the local timezone.
		//
		// The timezone is only non-UTC if a user directly sets the Modified
		// field directly themselves. All other approaches sets UTC.
		.ModifiedDate, .ModifiedTime = timeToMsDosTime(.Modified)

		// Use "extended timestamp" format since this is what Info-ZIP uses.
		// Nearly every major ZIP implementation uses a different format,
		// but at least most seem to be able to understand the other formats.
		//
		// This format happens to be identical for both local and central header
		// if modification time is the only timestamp being encoded.
		var  [9]byte // 2*SizeOf(uint16) + SizeOf(uint8) + SizeOf(uint32)
		 := uint32(.Modified.Unix())
		 := writeBuf([:])
		.uint16(extTimeExtraID)
		.uint16(5)  // Size: SizeOf(uint8) + SizeOf(uint32)
		.uint8(1)   // Flags: ModTime
		.uint32() // ModTime
		.Extra = append(.Extra, [:]...)
	}

	var (
		 io.Writer
		 *fileWriter
	)
	 := &header{
		FileHeader: ,
		offset:     uint64(.cw.count),
	}

	if strings.HasSuffix(.Name, "/") {
		// Set the compression method to Store to ensure data length is truly zero,
		// which the writeHeader method always encodes for the size fields.
		// This is necessary as most compression formats have non-zero lengths
		// even when compressing an empty string.
		.Method = Store
		.Flags &^= 0x8 // we will not write a data descriptor

		// Explicitly clear sizes as they have no meaning for directories.
		.CompressedSize = 0
		.CompressedSize64 = 0
		.UncompressedSize = 0
		.UncompressedSize64 = 0

		 = dirWriter{}
	} else {
		.Flags |= 0x8 // we will write a data descriptor

		 = &fileWriter{
			zipw:      .cw,
			compCount: &countWriter{w: .cw},
			crc32:     crc32.NewIEEE(),
		}
		 := .compressor(.Method)
		if  == nil {
			return nil, ErrAlgorithm
		}
		var  error
		.comp,  = (.compCount)
		if  != nil {
			return nil, 
		}
		.rawCount = &countWriter{w: .comp}
		.header = 
		 = 
	}
	.dir = append(.dir, )
	if  := writeHeader(.cw, );  != nil {
		return nil, 
	}
	// If we're creating a directory, fw is nil.
	.last = 
	return , nil
}

func writeHeader( io.Writer,  *header) error {
	const  = 1<<16 - 1
	if len(.Name) >  {
		return errLongName
	}
	if len(.Extra) >  {
		return errLongExtra
	}

	var  [fileHeaderLen]byte
	 := writeBuf([:])
	.uint32(uint32(fileHeaderSignature))
	.uint16(.ReaderVersion)
	.uint16(.Flags)
	.uint16(.Method)
	.uint16(.ModifiedTime)
	.uint16(.ModifiedDate)
	// In raw mode (caller does the compression), the values are either
	// written here or in the trailing data descriptor based on the header
	// flags.
	if .raw && !.hasDataDescriptor() {
		.uint32(.CRC32)
		.uint32(uint32(min(.CompressedSize64, uint32max)))
		.uint32(uint32(min(.UncompressedSize64, uint32max)))
	} else {
		// When this package handle the compression, these values are
		// always written to the trailing data descriptor.
		.uint32(0) // crc32
		.uint32(0) // compressed size
		.uint32(0) // uncompressed size
	}
	.uint16(uint16(len(.Name)))
	.uint16(uint16(len(.Extra)))
	if ,  := .Write([:]);  != nil {
		return 
	}
	if ,  := io.WriteString(, .Name);  != nil {
		return 
	}
	,  := .Write(.Extra)
	return 
}

// CreateRaw adds a file to the zip archive using the provided [FileHeader] and
// returns a [Writer] to which the file contents should be written. The file's
// contents must be written to the io.Writer before the next call to [Writer.Create],
// [Writer.CreateHeader], [Writer.CreateRaw], or [Writer.Close].
//
// In contrast to [Writer.CreateHeader], the bytes passed to Writer are not compressed.
func ( *Writer) ( *FileHeader) (io.Writer, error) {
	if  := .prepare();  != nil {
		return nil, 
	}

	.CompressedSize = uint32(min(.CompressedSize64, uint32max))
	.UncompressedSize = uint32(min(.UncompressedSize64, uint32max))

	 := &header{
		FileHeader: ,
		offset:     uint64(.cw.count),
		raw:        true,
	}
	.dir = append(.dir, )
	if  := writeHeader(.cw, );  != nil {
		return nil, 
	}

	if strings.HasSuffix(.Name, "/") {
		.last = nil
		return dirWriter{}, nil
	}

	 := &fileWriter{
		header: ,
		zipw:   .cw,
	}
	.last = 
	return , nil
}

// Copy copies the file f (obtained from a [Reader]) into w. It copies the raw
// form directly bypassing decompression, compression, and validation.
func ( *Writer) ( *File) error {
	,  := .OpenRaw()
	if  != nil {
		return 
	}
	,  := .CreateRaw(&.FileHeader)
	if  != nil {
		return 
	}
	_,  = io.Copy(, )
	return 
}

// RegisterCompressor registers or overrides a custom compressor for a specific
// method ID. If a compressor for a given method is not found, [Writer] will
// default to looking up the compressor at the package level.
func ( *Writer) ( uint16,  Compressor) {
	if .compressors == nil {
		.compressors = make(map[uint16]Compressor)
	}
	.compressors[] = 
}

// AddFS adds the files from fs.FS to the archive.
// It walks the directory tree starting at the root of the filesystem
// adding each file to the zip using deflate while maintaining the directory structure.
func ( *Writer) ( fs.FS) error {
	return fs.WalkDir(, ".", func( string,  fs.DirEntry,  error) error {
		if  != nil {
			return 
		}
		if .IsDir() {
			return nil
		}
		,  := .Info()
		if  != nil {
			return 
		}
		if !.Mode().IsRegular() {
			return errors.New("zip: cannot add non-regular file")
		}
		,  := FileInfoHeader()
		if  != nil {
			return 
		}
		.Name = 
		.Method = Deflate
		,  := .CreateHeader()
		if  != nil {
			return 
		}
		,  := .Open()
		if  != nil {
			return 
		}
		defer .Close()
		_,  = io.Copy(, )
		return 
	})
}

func ( *Writer) ( uint16) Compressor {
	 := .compressors[]
	if  == nil {
		 = compressor()
	}
	return 
}

type dirWriter struct{}

func (dirWriter) ( []byte) (int, error) {
	if len() == 0 {
		return 0, nil
	}
	return 0, errors.New("zip: write to directory")
}

type fileWriter struct {
	*header
	zipw      io.Writer
	rawCount  *countWriter
	comp      io.WriteCloser
	compCount *countWriter
	crc32     hash.Hash32
	closed    bool
}

func ( *fileWriter) ( []byte) (int, error) {
	if .closed {
		return 0, errors.New("zip: write to closed file")
	}
	if .raw {
		return .zipw.Write()
	}
	.crc32.Write()
	return .rawCount.Write()
}

func ( *fileWriter) () error {
	if .closed {
		return errors.New("zip: file closed twice")
	}
	.closed = true
	if .raw {
		return .writeDataDescriptor()
	}
	if  := .comp.Close();  != nil {
		return 
	}

	// update FileHeader
	 := .header.FileHeader
	.CRC32 = .crc32.Sum32()
	.CompressedSize64 = uint64(.compCount.count)
	.UncompressedSize64 = uint64(.rawCount.count)

	if .isZip64() {
		.CompressedSize = uint32max
		.UncompressedSize = uint32max
		.ReaderVersion = zipVersion45 // requires 4.5 - File uses ZIP64 format extensions
	} else {
		.CompressedSize = uint32(.CompressedSize64)
		.UncompressedSize = uint32(.UncompressedSize64)
	}

	return .writeDataDescriptor()
}

func ( *fileWriter) () error {
	if !.hasDataDescriptor() {
		return nil
	}
	// Write data descriptor. This is more complicated than one would
	// think, see e.g. comments in zipfile.c:putextended() and
	// http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7073588.
	// The approach here is to write 8 byte sizes if needed without
	// adding a zip64 extra in the local header (too late anyway).
	var  []byte
	if .isZip64() {
		 = make([]byte, dataDescriptor64Len)
	} else {
		 = make([]byte, dataDescriptorLen)
	}
	 := writeBuf()
	.uint32(dataDescriptorSignature) // de-facto standard, required by OS X
	.uint32(.CRC32)
	if .isZip64() {
		.uint64(.CompressedSize64)
		.uint64(.UncompressedSize64)
	} else {
		.uint32(.CompressedSize)
		.uint32(.UncompressedSize)
	}
	,  := .zipw.Write()
	return 
}

type countWriter struct {
	w     io.Writer
	count int64
}

func ( *countWriter) ( []byte) (int, error) {
	,  := .w.Write()
	.count += int64()
	return , 
}

type nopCloser struct {
	io.Writer
}

func ( nopCloser) () error {
	return nil
}

type writeBuf []byte

func ( *writeBuf) ( uint8) {
	(*)[0] = 
	* = (*)[1:]
}

func ( *writeBuf) ( uint16) {
	binary.LittleEndian.PutUint16(*, )
	* = (*)[2:]
}

func ( *writeBuf) ( uint32) {
	binary.LittleEndian.PutUint32(*, )
	* = (*)[4:]
}

func ( *writeBuf) ( uint64) {
	binary.LittleEndian.PutUint64(*, )
	* = (*)[8:]
}