Add abstraction and tests for #387

diff --git a/file.go b/file.go
index b9548ebae87a2d0b51fe487315a63e1d8c0ddcb3..167948be15dd142cada7c5315adf5880776a5226 100644 (file)
--- a/file.go
+++ b/file.go
@@ -54,11 +54,9 @@ func (f *File) bytesCompleted() int64 {
        return f.length - f.bytesLeft()
 }
 
-func (f *File) bytesLeft() (left int64) {
-       pieceSize := int64(f.t.usualPieceSize())
-       firstPieceIndex := f.firstPieceIndex()
-       endPieceIndex := f.endPieceIndex() - 1
-       bitmap.Flip(f.t._completedPieces, firstPieceIndex+1, endPieceIndex).IterTyped(func(piece int) bool {
+func fileBytesLeft(pieceSize int64, firstPieceIndex int, endPieceIndex int, fileOffset int64, fileLength int64, completedPieces bitmap.Bitmap) (left int64) {
+       endPieceIndex--
+       bitmap.Flip(completedPieces, firstPieceIndex+1, endPieceIndex).IterTyped(func(piece int) bool {
                if piece >= endPieceIndex {
                        return false
                }
@@ -67,15 +65,19 @@ func (f *File) bytesLeft() (left int64) {
                }
                return true
        })
-       if !f.t.pieceComplete(firstPieceIndex) {
-               left += pieceSize - (f.offset % pieceSize)
+       if !completedPieces.Get(firstPieceIndex) {
+               left += pieceSize - (fileOffset % pieceSize)
        }
-       if !f.t.pieceComplete(endPieceIndex) {
-               left += (f.offset + f.length) % pieceSize
+       if !completedPieces.Get(endPieceIndex) {
+               left += (fileOffset + fileLength) % pieceSize
        }
        return
 }
 
+func (f *File) bytesLeft() (left int64) {
+       return fileBytesLeft(int64(f.t.usualPieceSize()), f.firstPieceIndex(), f.endPieceIndex(), f.offset, f.length, f.t._completedPieces)
+}
+
 // The relative file path for a multi-file torrent, and the torrent name for a
 // single-file torrent.
 func (f *File) DisplayPath() string {

diff --git a/file_test.go b/file_test.go
index b66d198529fe46390a83b557c7251a58bf62362c..b411126808ba922e8f48a4dcfa65cc59727e613a 100644 (file)
--- a/file_test.go
+++ b/file_test.go
@@ -3,6 +3,7 @@ package torrent
 import (
        "testing"
 
+       "github.com/anacrolix/missinggo/v2/bitmap"
        "github.com/stretchr/testify/assert"
 )
 
@@ -20,3 +21,51 @@ func TestFileExclusivePieces(t *testing.T) {
                assert.EqualValues(t, _case.end, end)
        }
 }
+
+type testFileBytesLeft struct {
+       usualPieceSize  int64
+       firstPieceIndex int
+       endPieceIndex   int
+       fileOffset      int64
+       fileLength      int64
+       completedPieces bitmap.Bitmap
+       expected        int64
+       name            string
+}
+
+func (me testFileBytesLeft) Run(t *testing.T) {
+       t.Run(me.name, func(t *testing.T) {
+               assert.EqualValues(t, me.expected, fileBytesLeft(me.usualPieceSize, me.firstPieceIndex, me.endPieceIndex, me.fileOffset, me.fileLength, me.completedPieces))
+       })
+}
+
+func TestFileBytesLeft(t *testing.T) {
+       testFileBytesLeft{
+               usualPieceSize:  2,
+               firstPieceIndex: 1,
+               endPieceIndex:   1,
+               fileOffset:      1,
+               fileLength:      1,
+               expected:        1,
+       }.Run(t)
+
+       testFileBytesLeft{
+               usualPieceSize:  3,
+               firstPieceIndex: 0,
+               endPieceIndex:   0,
+               fileOffset:      1,
+               fileLength:      1,
+               expected:        1,
+               name:            "FileInFirstPiece",
+       }.Run(t)
+
+       testFileBytesLeft{
+               usualPieceSize:  3,
+               firstPieceIndex: 0,
+               endPieceIndex:   0,
+               fileOffset:      1,
+               fileLength:      1,
+               expected:        1,
+               name:            "LandLocked",
+       }.Run(t)
+}