1 files changed, 101 insertions, 0 deletions
diff --git a/mcmap/regionfile.go b/mcmap/regionfile.go
new file mode 100644
index 0000000..1be08ea
--- /dev/null
+++ b/mcmap/regionfile.go
@@ -0,0 +1,101 @@
+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 (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 < 32; z++ {
+		for x := 0; x < 32; 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 < 32; z++ {
+		for x := 0; x < 32; 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
+}