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package mcmap
import (
"bytes"
"encoding/binary"
"github.com/kch42/kagus"
"io"
"time"
)
const sectorSize = 4096
type chunkOffTs struct {
offset, size int64
ts time.Time
}
func (co chunkOffTs) calcLocationEntry() uint32 {
return uint32((co.size>>12)&0xff) | (uint32(co.offset>>12) << 8)
}
func (cOff chunkOffTs) readPreChunk(r io.ReadSeeker) (*preChunk, error) {
pc := preChunk{ts: cOff.ts}
if _, err := r.Seek(cOff.offset, 0); err != nil {
return nil, err
}
lr := io.LimitReader(r, cOff.size)
var length uint32
if err := binary.Read(lr, binary.BigEndian, &length); err != nil {
return nil, err
}
lr = io.LimitReader(lr, int64(length))
compType, err := kagus.ReadByte(lr)
if err != nil {
return nil, err
}
pc.compression = compType
buf := new(bytes.Buffer)
if _, err := io.Copy(buf, lr); err != nil {
return nil, err
}
pc.data = buf.Bytes()
return &pc, err
}
func readRegionFile(r io.ReadSeeker) (map[XZPos]*preChunk, error) {
if _, err := r.Seek(0, 0); err != nil {
return nil, err
}
offs := make(map[XZPos]*chunkOffTs)
for z := 0; z < superchunkSizeXZ; z++ {
for x := 0; x < superchunkSizeXZ; x++ {
var location uint32
if err := binary.Read(r, binary.BigEndian, &location); err != nil {
return nil, err
}
if location == 0 {
continue
}
offs[XZPos{x, z}] = &chunkOffTs{
offset: int64((location >> 8) * sectorSize),
size: int64((location & 0xff) * sectorSize),
}
}
}
for z := 0; z < superchunkSizeXZ; z++ {
for x := 0; x < superchunkSizeXZ; x++ {
pos := XZPos{x, z}
var ts int32
if err := binary.Read(r, binary.BigEndian, &ts); err != nil {
return nil, err
}
if _, ok := offs[pos]; !ok {
continue
}
offs[pos].ts = time.Unix(int64(ts), 0)
}
}
preChunks := make(map[XZPos]*preChunk)
for pos, cOff := range offs {
pc, err := cOff.readPreChunk(r)
if err != nil {
return nil, err
}
preChunks[pos] = pc
}
return preChunks, nil
}
func (pc *preChunk) writePreChunk(w io.Writer) error {
length := uint32(len(pc.data) + 1)
if err := binary.Write(w, binary.BigEndian, length); err != nil {
return err
}
if _, err := w.Write([]byte{pc.compression}); err != nil {
return err
}
_, err := w.Write(pc.data)
return err
}
func writeRegionFile(w io.Writer, pcs map[XZPos]*preChunk) error {
offs := make(map[XZPos]chunkOffTs)
buf := new(bytes.Buffer)
pw := kagus.NewPaddedWriter(buf, sectorSize)
for pos, pc := range pcs {
off := buf.Len()
if err := pc.writePreChunk(pw); err != nil {
return err
}
if err := pw.Pad(); err != nil {
return err
}
offs[pos] = chunkOffTs{
offset: int64(2*sectorSize + off),
size: int64(buf.Len() - off),
ts: pc.ts,
}
}
for z := 0; z < superchunkSizeXZ; z++ {
for x := 0; x < superchunkSizeXZ; x++ {
off := uint32(0)
if cOff, ok := offs[XZPos{x, z}]; ok {
off = cOff.calcLocationEntry()
}
if err := binary.Write(w, binary.BigEndian, off); err != nil {
return err
}
}
}
for z := 0; z < superchunkSizeXZ; z++ {
for x := 0; x < superchunkSizeXZ; x++ {
ts := int32(0)
if cOff, ok := offs[XZPos{x, z}]; ok {
ts = int32(cOff.ts.Unix())
}
if err := binary.Write(w, binary.BigEndian, ts); err != nil {
return err
}
}
}
_, err := io.Copy(w, buf)
return err
}
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