/*
Writes this vector to the file name in Directory d, in a format that
can be read by the constructor BitVector(Directory, String, IOContext)
*/
func (bv *BitVector) Write(d store.Directory, name string, ctx store.IOContext) (err error) {
	assert(reflect.TypeOf(d).Name() != "CompoundFileDirectory")
	var output store.IndexOutput
	if output, err = d.CreateOutput(name, ctx); err != nil {
		return err
	}
	defer func() {
		err = mergeError(err, output.Close())
	}()

	if err = output.WriteInt(-2); err != nil {
		return err
	}
	if err = codec.WriteHeader(output, CODEC, BV_VERSION_CURRENT); err != nil {
		return err
	}
	if bv.isSparse() {
		// sparse bit-set more efficiently saved as d-gaps.
		err = bv.writeClearedDgaps(output)
	} else {
		err = bv.writeBits(output)
	}
	if err != nil {
		return err
	}
	if err = codec.WriteFooter(output); err != nil {
		return err
	}
	bv.assertCount()
	return nil
}

/* Write as a d-gaps list */
func (bv *BitVector) writeClearedDgaps(output store.IndexOutput) error {
	err := store.Stream(output).
		WriteInt(-1). // mark using d-gaps
		WriteInt(int32(bv.size)).
		WriteInt(int32(bv.Count())).
		Close()
	if err != nil {
		return err
	}
	last, numCleared := 0, bv.size-bv.Count()
	for i, v := range bv.bits {
		if v == byte(0xff) {
			continue
		}
		err = output.WriteVInt(int32(i - last))
		if err == nil {
			err = output.WriteByte(v)
		}
		if err != nil {
			return err
		}
		last = i
		numCleared -= (8 - util.BitCount(v))
		assert(numCleared >= 0 ||
			i == len(bv.bits)-1 && numCleared == -(8-(bv.size&7)))
		if numCleared <= 0 {
			break
		}
	}
	return nil
}

func (w *Lucene41PostingsWriter) Init(termsOut store.IndexOutput) error {
	err := codec.WriteHeader(termsOut, LUCENE41_TERMS_CODEC, LUCENE41_VERSION_CURRENT)
	if err == nil {
		err = termsOut.WriteVInt(LUCENE41_BLOCK_SIZE)
	}
	return err
}

/*
A utility for writing the SEGMENTS_GEN file to a Directory.

NOTE: this is an internal utility which is kept public so that it's
accessible by code from other packages. You should avoid calling this
method unless you're absolutely sure what you're doing!
*/
func writeSegmentsGen(dir store.Directory, generation int64) {
	if err := func() (err error) {
		var genOutput store.IndexOutput
		genOutput, err = dir.CreateOutput(INDEX_FILENAME_SEGMENTS_GEN, store.IO_CONTEXT_READONCE)
		if err != nil {
			return err
		}

		defer func() {
			err = mergeError(err, genOutput.Close())
			err = mergeError(err, dir.Sync([]string{INDEX_FILENAME_SEGMENTS_GEN}))
		}()

		if err = genOutput.WriteInt(FORMAT_SEGMENTS_GEN_CURRENT); err == nil {
			if err = genOutput.WriteLong(generation); err == nil {
				if err = genOutput.WriteLong(generation); err == nil {
					err = codec.WriteFooter(genOutput)
				}
			}
		}
		return err
	}(); err != nil {
		// It's OK if we fail to write this file since it's used only as
		// one of the retry fallbacks.
		dir.DeleteFile(INDEX_FILENAME_SEGMENTS_GEN)
		// Ignore error; this file is only used in a retry fallback on init
	}
}

func NewStoredFieldsIndexWriter(indexOutput store.IndexOutput) (*StoredFieldsIndexWriter, error) {
	err := indexOutput.WriteVInt(packed.VERSION_CURRENT)
	if err != nil {
		return nil, err
	}
	return &StoredFieldsIndexWriter{
		fieldsIndexOut:     indexOutput,
		blockChunks:        0,
		blockDocs:          0,
		firstStartPointer:  -1,
		totalDocs:          0,
		docBaseDeltas:      make([]int, BLOCK_SIZE),
		startPointerDeltas: make([]int64, BLOCK_SIZE),
	}, nil
}

func (w *Lucene40SegmentInfoWriter) Write(dir store.Directory,
	si *SegmentInfo, fis FieldInfos, ctx store.IOContext) (err error) {

	filename := util.SegmentFileName(si.Name, "", LUCENE40_SI_EXTENSION)
	si.AddFile(filename)

	var output store.IndexOutput
	output, err = dir.CreateOutput(filename, ctx)
	if err != nil {
		return err
	}

	var success = false
	defer func() {
		if !success {
			util.CloseWhileSuppressingError(output)
			si.Dir.DeleteFile(filename) // ignore error
		} else {
			err = mergeError(err, output.Close())
		}
	}()

	err = codec.WriteHeader(output, LUCENE40_CODEC_NAME, LUCENE40_VERSION_CURRENT)
	if err != nil {
		return err
	}
	// Write the Lucene version that created this segment, since 3.1
	err = store.Stream(output).WriteString(si.Version().String()).
		WriteInt(int32(si.DocCount())).
		WriteByte(func() byte {
			if si.IsCompoundFile() {
				return SEGMENT_INFO_YES
			}
			return byte((SEGMENT_INFO_NO + 256) % 256) // Go byte is non-negative, unlike Java
		}()).WriteStringStringMap(si.Diagnostics()).
		WriteStringStringMap(map[string]string{}).
		WriteStringSet(si.Files()).Close()
	if err != nil {
		return err
	}

	success = true
	return nil
}

func (sis *SegmentInfos) write(directory store.Directory) (err error) {
	segmentsFilename := sis.nextSegmentFilename()

	// Always advance the generation on write:
	if sis.generation == -1 {
		sis.generation = 1
	} else {
		sis.generation++
	}

	var segnOutput store.IndexOutput
	var success = false
	// var upgradedSIFiles = make(map[string]bool)

	defer func() {
		if !success {
			// We hit an error above; try to close the file but suppress
			// any errors
			util.CloseWhileSuppressingError(segnOutput)

			// for filename, _ := range upgradedSIFiles {
			// 	directory.DeleteFile(filename) // ignore error
			// }

			// Try not to leave a truncated segments_N fle in the index:
			directory.DeleteFile(segmentsFilename) // ignore error
		}
	}()

	if segnOutput, err = directory.CreateOutput(segmentsFilename, store.IO_CONTEXT_DEFAULT); err != nil {
		return
	}
	if err = codec.WriteHeader(segnOutput, "segments", VERSION_49); err != nil {
		return
	}
	if err = segnOutput.WriteLong(sis.version); err == nil {
		if err = segnOutput.WriteInt(int32(sis.counter)); err == nil {
			err = segnOutput.WriteInt(int32(len(sis.Segments)))
		}
	}
	if err != nil {
		return
	}
	for _, siPerCommit := range sis.Segments {
		si := siPerCommit.Info
		if err = segnOutput.WriteString(si.Name); err == nil {
			if err = segnOutput.WriteString(si.Codec().(Codec).Name()); err == nil {
				if err = segnOutput.WriteLong(siPerCommit.DelGen()); err == nil {
					assert2(siPerCommit.DelCount() >= 0 && siPerCommit.DelCount() <= si.DocCount(),
						"cannot write segment: invalid docCount segment=%v docCount=%v delCount=%v",
						si.Name, si.DocCount(), siPerCommit.DelCount())
					if err = segnOutput.WriteInt(int32(siPerCommit.DelCount())); err == nil {
						if err = segnOutput.WriteLong(siPerCommit.FieldInfosGen()); err == nil {
							if err = segnOutput.WriteLong(siPerCommit.DocValuesGen()); err == nil {
								if err = segnOutput.WriteStringSet(siPerCommit.FieldInfosFiles()); err == nil {
									dvUpdatesFiles := siPerCommit.DocValuesUpdatesFiles()
									if err = segnOutput.WriteInt(int32(len(dvUpdatesFiles))); err == nil {
										for k, v := range dvUpdatesFiles {
											if err = segnOutput.WriteInt(int32(k)); err != nil {
												break
											}
											if err = segnOutput.WriteStringSet(v); err != nil {
												break
											}
										}
									}
								}
							}
						}
					}
				}
			}
		}
		if err != nil {
			return
		}
		assert(si.Dir == directory)

		// If this segment is pre-4.x, perform a one-time "upgrade" to
		// write the .si file for it:
		if version := si.Version(); len(version) == 0 || !version.OnOrAfter(util.VERSION_4_0) {
			panic("not implemented yet")
		}
	}
	if err = segnOutput.WriteStringStringMap(sis.userData); err != nil {
		return
	}
	sis.pendingSegnOutput = segnOutput
	success = true
	return nil
}

func writeBytesRef(out store.IndexOutput, bytes []byte) (err error) {
	if err = out.WriteVInt(int32(len(bytes))); err == nil {
		err = out.WriteBytes(bytes)
	}
	return
}

/* Writes the index file trailer. */
func (w *BlockTreeTermsWriter) writeIndexTrailer(indexOut store.IndexOutput, dirStart int64) error {
	return indexOut.WriteLong(dirStart)
}

func (w *SkipWriter) WriteSkipData(level int, skipBuffer store.IndexOutput) error {
	delta := w.curDoc - w.lastSkipDoc[level]
	var err error
	if err = skipBuffer.WriteVInt(int32(delta)); err != nil {
		return err
	}
	w.lastSkipDoc[level] = w.curDoc

	if err = skipBuffer.WriteVInt(int32(w.curDocPointer - w.lastSkipDocPointer[level])); err != nil {
		return err
	}
	w.lastSkipDocPointer[level] = w.curDocPointer

	if w.fieldHasPositions {
		if err = skipBuffer.WriteVInt(int32(w.curPosPointer - w.lastSkipPosPointer[level])); err != nil {
			return err
		}
		w.lastSkipPosPointer[level] = w.curPosPointer
		if err = skipBuffer.WriteVInt(int32(w.curPosBufferUpto)); err != nil {
			return err
		}

		if w.fieldHasPayloads {
			if err = skipBuffer.WriteVInt(int32(w.curPayloadByteUpto)); err != nil {
				return err
			}
		}

		if w.fieldHasOffsets || w.fieldHasPayloads {
			if err = skipBuffer.WriteVInt(int32(w.curPayPointer - w.lastSkipPayPointer[level])); err != nil {
				return err
			}
			w.lastSkipPayPointer[level] = w.curPayPointer
		}
	}
	return nil
}

func (w *MockDirectoryWrapper) _crash() error {
	w.crashed = true
	w.openFiles = make(map[string]int)
	w.openFilesForWrite = make(map[string]bool)
	w.openFilesDeleted = make(map[string]bool)
	files := w.unSyncedFiles
	w.unSyncedFiles = make(map[string]bool)
	// first force-close all files, so we can corrupt on windows etc.
	// clone the file map, as these guys want to remove themselves on close.
	m := make(map[io.Closer]error)
	for k, v := range w.openFileHandles {
		m[k] = v
	}
	for f, _ := range m {
		f.Close() // ignore error
	}

	for name, _ := range files {
		var action string
		var err error
		switch w.randomState.Intn(5) {
		case 0:
			action = "deleted"
			err = w.deleteFile(name, true)
		case 1:
			action = "zeroes"
			// Zero out file entirely
			var length int64
			length, err = w.FileLength(name)
			if err == nil {
				zeroes := make([]byte, 256)
				var upto int64 = 0
				var out store.IndexOutput
				out, err = w.BaseDirectoryWrapperImpl.CreateOutput(name, NewDefaultIOContext(w.randomState))
				if err == nil {
					for upto < length && err == nil {
						limit := length - upto
						if int64(len(zeroes)) < limit {
							limit = int64(len(zeroes))
						}
						err = out.WriteBytes(zeroes[:limit])
						upto += limit
					}
					if err == nil {
						err = out.Close()
					}
				}
			}
		case 2:
			action = "partially truncated"
			// Partially Truncate the file:

			// First, make temp file and copy only half this file over:
			var tempFilename string
			for {
				tempFilename = fmt.Sprintf("%v", w.randomState.Int())
				if !w.BaseDirectoryWrapperImpl.FileExists(tempFilename) {
					break
				}
			}
			var tempOut store.IndexOutput
			if tempOut, err = w.BaseDirectoryWrapperImpl.CreateOutput(tempFilename, NewDefaultIOContext(w.randomState)); err == nil {
				var ii store.IndexInput
				if ii, err = w.BaseDirectoryWrapperImpl.OpenInput(name, NewDefaultIOContext(w.randomState)); err == nil {
					if err = tempOut.CopyBytes(ii, ii.Length()/2); err == nil {
						if err = tempOut.Close(); err == nil {
							if err = ii.Close(); err == nil {
								// Delete original and copy bytes back:
								if err = w.deleteFile(name, true); err == nil {
									var out store.IndexOutput
									if out, err = w.BaseDirectoryWrapperImpl.CreateOutput(name, NewDefaultIOContext(w.randomState)); err == nil {
										if ii, err = w.BaseDirectoryWrapperImpl.OpenInput(tempFilename, NewDefaultIOContext(w.randomState)); err == nil {
											if err = out.CopyBytes(ii, ii.Length()); err == nil {
												if err = out.Close(); err == nil {
													if err = ii.Close(); err == nil {
														err = w.deleteFile(tempFilename, true)
													}
												}
											}
										}
									}
								}
							}
						}
					}
				}
			}
		case 3:
			// the file survived intact:
			action = "didn't change"
		default:
			action = "fully truncated"
			// totally truncate the file to zero bytes
			if err = w.deleteFile(name, true); err == nil {
				var out store.IndexOutput
				if out, err = w.BaseDirectoryWrapperImpl.CreateOutput(name, NewDefaultIOContext(w.randomState)); err == nil {
					if err = out.SetLength(0); err == nil {
						err = out.Close()
					}
				}
//.........这里部分代码省略.........

		return DOC_VALUES_TYPE_BINARY, nil
	case 3:
		return DOC_VALUES_TYPE_SORTED, nil
	case 4:
		return DOC_VALUES_TYPE_SORTED_SET, nil
	default:
		return DocValuesType(0), errors.New(
			fmt.Sprintf("invalid docvalues byte: %v (resource=%v)", b, input))
	}
}

var Lucene46FieldInfosWriter = func(dir store.Directory,
	segName, suffix string, infos FieldInfos, ctx store.IOContext) (err error) {

	filename := util.SegmentFileName(segName, suffix, FI_EXTENSION)
	var output store.IndexOutput
	if output, err = dir.CreateOutput(filename, ctx); err != nil {
		return
	}

	var success = false
	defer func() {
		if success {
			err = output.Close()
		} else {
			util.CloseWhileSuppressingError(output)
		}
	}()

	if err = codec.WriteHeader(output, FI_CODEC_NAME, FI_FORMAT_CURRENT); err != nil {
		return