From bdb181cb3a3bfef26d65921322420be4a654a48c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mike=20Schw=C3=B6rer?= <pubgit@mikescher.com>
Date: Tue, 20 Dec 2022 09:50:13 +0100
Subject: [PATCH] v0.0.37

---
 dataext/bufferedReadCloser.go | 165 +++++++++++++++++++++++++++-------
 1 file changed, 133 insertions(+), 32 deletions(-)

diff --git a/dataext/bufferedReadCloser.go b/dataext/bufferedReadCloser.go
index ed3b2fa..59bc825 100644
--- a/dataext/bufferedReadCloser.go
+++ b/dataext/bufferedReadCloser.go
@@ -1,56 +1,157 @@
 package dataext
 
-import "io"
+import (
+	"errors"
+	"io"
+)
+
+type brcMode int
+
+const (
+	modeSourceReading  = 0
+	modeSourceFinished = 1
+	modeBufferReading  = 2
+	modeBufferFinished = 3
+)
 
 type BufferedReadCloser interface {
 	io.ReadCloser
 	BufferedAll() ([]byte, error)
+	Reset() error
 }
 
 type bufferedReadCloser struct {
-	buffer   []byte
-	inner    io.ReadCloser
-	finished bool
-}
-
-func (b *bufferedReadCloser) Read(p []byte) (int, error) {
-
-	n, err := b.inner.Read(p)
-	if n > 0 {
-		b.buffer = append(b.buffer, p[0:n]...)
-	}
-
-	if err == io.EOF {
-		b.finished = true
-	}
-
-	return n, err
+	buffer []byte
+	inner  io.ReadCloser
+	mode   brcMode
+	off    int
 }
 
 func NewBufferedReadCloser(sub io.ReadCloser) BufferedReadCloser {
 	return &bufferedReadCloser{
-		buffer:   make([]byte, 0, 1024),
-		inner:    sub,
-		finished: false,
+		buffer: make([]byte, 0, 1024),
+		inner:  sub,
+		mode:   modeSourceReading,
+		off:    0,
+	}
+}
+
+func (b *bufferedReadCloser) Read(p []byte) (int, error) {
+	switch b.mode {
+	case modeSourceReading:
+		n, err := b.inner.Read(p)
+		if n > 0 {
+			b.buffer = append(b.buffer, p[0:n]...)
+		}
+
+		if err == io.EOF {
+			b.mode = modeSourceFinished
+		}
+
+		return n, err
+
+	case modeSourceFinished:
+		return 0, io.EOF
+
+	case modeBufferReading:
+
+		if len(b.buffer) <= b.off {
+			b.mode = modeBufferFinished
+			if len(p) == 0 {
+				return 0, nil
+			}
+			return 0, io.EOF
+		}
+
+		n := copy(p, b.buffer[b.off:])
+		b.off += n
+		return n, nil
+
+	case modeBufferFinished:
+		return 0, io.EOF
+
+	default:
+		return 0, errors.New("object in undefined status")
 	}
 }
 
 func (b *bufferedReadCloser) Close() error {
-	err := b.inner.Close()
-	if err != nil {
-		b.finished = true
+	switch b.mode {
+	case modeSourceReading:
+		_, err := b.BufferedAll()
+		if err != nil {
+			return err
+		}
+		err = b.inner.Close()
+		if err != nil {
+			return err
+		}
+		b.mode = modeSourceFinished
+		return nil
+
+	case modeSourceFinished:
+		return nil
+
+	case modeBufferReading:
+		b.mode = modeBufferFinished
+		return nil
+
+	case modeBufferFinished:
+		return nil
+
+	default:
+		return errors.New("object in undefined status")
 	}
-	return err
+
 }
 
 func (b *bufferedReadCloser) BufferedAll() ([]byte, error) {
-	arr := make([]byte, 1024)
-	for !b.finished {
-		_, err := b.Read(arr)
-		if err != nil && err != io.EOF {
-			return nil, err
+	switch b.mode {
+	case modeSourceReading:
+		arr := make([]byte, 1024)
+		for b.mode == modeSourceReading {
+			_, err := b.Read(arr)
+			if err != nil && err != io.EOF {
+				return nil, err
+			}
 		}
-	}
+		return b.buffer, nil
 
-	return b.buffer, nil
+	case modeSourceFinished:
+		return b.buffer, nil
+
+	case modeBufferReading:
+		return b.buffer, nil
+
+	case modeBufferFinished:
+		return b.buffer, nil
+
+	default:
+		return nil, errors.New("object in undefined status")
+	}
+}
+
+func (b *bufferedReadCloser) Reset() error {
+	switch b.mode {
+	case modeSourceReading:
+		fallthrough
+	case modeSourceFinished:
+		err := b.Close()
+		if err != nil {
+			return err
+		}
+		b.mode = modeBufferReading
+		b.off = 0
+		return nil
+
+	case modeBufferReading:
+		fallthrough
+	case modeBufferFinished:
+		b.mode = modeBufferReading
+		b.off = 0
+		return nil
+
+	default:
+		return errors.New("object in undefined status")
+	}
 }