staging lines and hunks

21 files changed, 699 insertions, 95 deletions

diff --git a/pkg/commands/git.go b/pkg/commands/git.go
index 262a57c2f..1d8e5a10d 100644
--- a/pkg/commands/git.go
+++ b/pkg/commands/git.go
@@ -3,7 +3,6 @@ package commands
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"strings"
@@ -486,7 +485,6 @@ func (c *GitCommand) getMergeBase() (string, error) {
 	output, err := c.OSCommand.RunCommandWithOutput(fmt.Sprintf("git merge-base HEAD %s", baseBranch))
 	if err != nil {
 		// swallowing error because it's not a big deal; probably because there are no commits yet
-		c.Log.Error(err)
 	}
 	return output, nil
 }
@@ -595,24 +593,13 @@ func (c *GitCommand) Diff(file *File, plain bool) string {
 }
 
 func (c *GitCommand) ApplyPatch(patch string) (string, error) {
-
-	content := []byte(patch)
-	tmpfile, err := ioutil.TempFile("", "patch")
+	filename, err := c.OSCommand.CreateTempFile("patch", patch)
 	if err != nil {
 		c.Log.Error(err)
-		return "", errors.New("Could not create patch file") // TODO: i18n
-	}
-
-	defer os.Remove(tmpfile.Name()) // clean up
-
-	if _, err := tmpfile.Write(content); err != nil {
-		c.Log.Error(err)
-		return "", err
-	}
-	if err := tmpfile.Close(); err != nil {
-		c.Log.Error(err)
 		return "", err
 	}
 
-	return c.OSCommand.RunCommandWithOutput(fmt.Sprintf("git apply --cached %s", tmpfile.Name()))
+	defer func() { _ = c.OSCommand.RemoveFile(filename) }()
+
+	return c.OSCommand.RunCommandWithOutput(fmt.Sprintf("git apply --cached %s", filename))
 }
diff --git a/pkg/commands/git_test.go b/pkg/commands/git_test.go
index 0e1390535..206696b22 100644
--- a/pkg/commands/git_test.go
+++ b/pkg/commands/git_test.go
@@ -1770,6 +1770,7 @@ func TestGitCommandDiff(t *testing.T) {
 		testName string
 		command  func(string, ...string) *exec.Cmd
 		file     *File
+		plain    bool
 	}
 
 	scenarios := []scenario{
@@ -1786,6 +1787,22 @@ func TestGitCommandDiff(t *testing.T) {
 				HasStagedChanges: false,
 				Tracked:          true,
 			},
+			false,
+		},
+		{
+			"Default case",
+			func(cmd string, args ...string) *exec.Cmd {
+				assert.EqualValues(t, "git", cmd)
+				assert.EqualValues(t, []string{"diff", "--", "test.txt"}, args)
+
+				return exec.Command("echo")
+			},
+			&File{
+				Name:             "test.txt",
+				HasStagedChanges: false,
+				Tracked:          true,
+			},
+			true,
 		},
 		{
 			"All changes staged",
@@ -1801,6 +1818,7 @@ func TestGitCommandDiff(t *testing.T) {
 				HasUnstagedChanges: false,
 				Tracked:            true,
 			},
+			false,
 		},
 		{
 			"File not tracked and file has no staged changes",
@@ -1815,6 +1833,7 @@ func TestGitCommandDiff(t *testing.T) {
 				HasStagedChanges: false,
 				Tracked:          false,
 			},
+			false,
 		},
 	}
 
@@ -1822,7 +1841,7 @@ func TestGitCommandDiff(t *testing.T) {
 		t.Run(s.testName, func(t *testing.T) {
 			gitCmd := newDummyGitCommand()
 			gitCmd.OSCommand.command = s.command
-			gitCmd.Diff(s.file, false)
+			gitCmd.Diff(s.file, s.plain)
 		})
 	}
 }
@@ -1979,3 +1998,61 @@ func TestGitCommandCurrentBranchName(t *testing.T) {
 		})
 	}
 }
+
+func TestGitCommandApplyPatch(t *testing.T) {
+	type scenario struct {
+		testName string
+		command  func(string, ...string) *exec.Cmd
+		test     func(string, error)
+	}
+
+	scenarios := []scenario{
+		{
+			"valid case",
+			func(cmd string, args ...string) *exec.Cmd {
+				assert.Equal(t, "git", cmd)
+				assert.EqualValues(t, []string{"apply", "--cached"}, args[0:2])
+				filename := args[2]
+				content, err := ioutil.ReadFile(filename)
+				assert.NoError(t, err)
+
+				assert.Equal(t, "test", string(content))
+
+				return exec.Command("echo", "done")
+			},
+			func(output string, err error) {
+				assert.NoError(t, err)
+				assert.EqualValues(t, "done\n", output)
+			},
+		},
+		{
+			"command returns error",
+			func(cmd string, args ...string) *exec.Cmd {
+				assert.Equal(t, "git", cmd)
+				assert.EqualValues(t, []string{"apply", "--cached"}, args[0:2])
+				filename := args[2]
+				// TODO: Ideally we want to mock out OSCommand here so that we're not
+				// double handling testing it's CreateTempFile functionality,
+				// but it is going to take a bit of work to make a proper mock for it
+				// so I'm leaving it for another PR
+				content, err := ioutil.ReadFile(filename)
+				assert.NoError(t, err)
+
+				assert.Equal(t, "test", string(content))
+
+				return exec.Command("test")
+			},
+			func(output string, err error) {
+				assert.Error(t, err)
+			},
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			gitCmd := newDummyGitCommand()
+			gitCmd.OSCommand.command = s.command
+			s.test(gitCmd.ApplyPatch("test"))
+		})
+	}
+}
diff --git a/pkg/commands/os.go b/pkg/commands/os.go
index 8b4b7879e..6b28a69bb 100644
--- a/pkg/commands/os.go
+++ b/pkg/commands/os.go
@@ -2,6 +2,7 @@ package commands
 
 import (
 	"errors"
+	"io/ioutil"
 	"os"
 	"os/exec"
 	"strings"
@@ -176,3 +177,28 @@ func (c *OSCommand) AppendLineToFile(filename, line string) error {
 	_, err = f.WriteString("\n" + line)
 	return err
 }
+
+// CreateTempFile writes a string to a new temp file and returns the file's name
+func (c *OSCommand) CreateTempFile(filename, content string) (string, error) {
+	tmpfile, err := ioutil.TempFile("", filename)
+	if err != nil {
+		c.Log.Error(err)
+		return "", err
+	}
+
+	if _, err := tmpfile.Write([]byte(content)); err != nil {
+		c.Log.Error(err)
+		return "", err
+	}
+	if err := tmpfile.Close(); err != nil {
+		c.Log.Error(err)
+		return "", err
+	}
+
+	return tmpfile.Name(), nil
+}
+
+// RemoveFile removes a file at the specified path
+func (c *OSCommand) RemoveFile(filename string) error {
+	return os.Remove(filename)
+}
diff --git a/pkg/commands/os_test.go b/pkg/commands/os_test.go
index ebb855cbe..a08c4b57d 100644
--- a/pkg/commands/os_test.go
+++ b/pkg/commands/os_test.go
@@ -1,6 +1,7 @@
 package commands
 
 import (
+	"io/ioutil"
 	"os"
 	"os/exec"
 	"testing"
@@ -364,3 +365,34 @@ func TestOSCommandFileType(t *testing.T) {
 		_ = os.RemoveAll(s.path)
 	}
 }
+
+func TestOSCommandCreateTempFile(t *testing.T) {
+	type scenario struct {
+		testName string
+		filename string
+		content  string
+		test     func(string, error)
+	}
+
+	scenarios := []scenario{
+		{
+			"valid case",
+			"filename",
+			"content",
+			func(path string, err error) {
+				assert.NoError(t, err)
+
+				content, err := ioutil.ReadFile(path)
+				assert.NoError(t, err)
+
+				assert.Equal(t, "content", string(content))
+			},
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			s.test(newDummyOSCommand().CreateTempFile(s.filename, s.content))
+		})
+	}
+}
diff --git a/pkg/git/patch_modifier.go b/pkg/git/patch_modifier.go
index 05afcf5ba..3c523232e 100644
--- a/pkg/git/patch_modifier.go
+++ b/pkg/git/patch_modifier.go
@@ -6,11 +6,14 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/jesseduffield/lazygit/pkg/i18n"
+	"github.com/jesseduffield/lazygit/pkg/utils"
 	"github.com/sirupsen/logrus"
 )
 
 type PatchModifier struct {
 	Log *logrus.Entry
+	Tr  *i18n.Localizer
 }
 
 // NewPatchModifier builds a new branch list builder
@@ -20,11 +23,49 @@ func NewPatchModifier(log *logrus.Entry) (*PatchModifier, error) {
 	}, nil
 }
 
-// ModifyPatch takes the original patch, which may contain several hunks,
+// ModifyPatchForHunk takes the original patch, which may contain several hunks,
+// and removes any hunks that aren't the selected hunk
+func (p *PatchModifier) ModifyPatchForHunk(patch string, hunkStarts []int, currentLine int) (string, error) {
+	// get hunk start and end
+	lines := strings.Split(patch, "\n")
+	hunkStartIndex := utils.PrevIndex(hunkStarts, currentLine)
+	hunkStart := hunkStarts[hunkStartIndex]
+	nextHunkStartIndex := utils.NextIndex(hunkStarts, currentLine)
+	var hunkEnd int
+	if nextHunkStartIndex == 0 {
+		hunkEnd = len(lines) - 1
+	} else {
+		hunkEnd = hunkStarts[nextHunkStartIndex]
+	}
+
+	headerLength, err := p.getHeaderLength(lines)
+	if err != nil {
+		return "", err
+	}
+
+	output := strings.Join(lines[0:headerLength], "\n") + "\n"
+	output += strings.Join(lines[hunkStart:hunkEnd], "\n") + "\n"
+
+	return output, nil
+}
+
+func (p *PatchModifier) getHeaderLength(patchLines []string) (int, error) {
+	for index, line := range patchLines {
+		if strings.HasPrefix(line, "@@") {
+			return index, nil
+		}
+	}
+	return 0, errors.New(p.Tr.SLocalize("CantFindHunks"))
+}
+
+// ModifyPatchForLine takes the original patch, which may contain several hunks,
 // and the line number of the line we want to stage
-func (p *PatchModifier) ModifyPatch(patch string, lineNumber int) (string, error) {
+func (p *PatchModifier) ModifyPatchForLine(patch string, lineNumber int) (string, error) {
 	lines := strings.Split(patch, "\n")
-	headerLength := 4
+	headerLength, err := p.getHeaderLength(lines)
+	if err != nil {
+		return "", err
+	}
 	output := strings.Join(lines[0:headerLength], "\n") + "\n"
 
 	hunkStart, err := p.getHunkStart(lines, lineNumber)
@@ -55,7 +96,8 @@ func (p *PatchModifier) getHunkStart(patchLines []string, lineNumber int) (int,
 			return hunkStart, nil
 		}
 	}
-	return 0, errors.New("Could not find hunk")
+
+	return 0, errors.New(p.Tr.SLocalize("CantFindHunk"))
 }
 
 func (p *PatchModifier) getModifiedHunk(patchLines []string, hunkStart int, lineNumber int) ([]string, error) {
@@ -101,13 +143,8 @@ func (p *PatchModifier) getModifiedHunk(patchLines []string, hunkStart int, line
 // @@ -14,8 +14,9 @@ import (
 func (p *PatchModifier) updatedHeader(currentHeader string, lineChanges int) (string, error) {
 	// current counter is the number after the second comma
-	re := regexp.MustCompile(`^[^,]+,[^,]+,(\d+)`)
-	matches := re.FindStringSubmatch(currentHeader)
-	if len(matches) < 2 {
-		re = regexp.MustCompile(`^[^,]+,[^+]+\+(\d+)`)
-		matches = re.FindStringSubmatch(currentHeader)
-	}
-	prevLengthString := matches[1]
+	re := regexp.MustCompile(`(\d+) @@`)
+	prevLengthString := re.FindStringSubmatch(currentHeader)[1]
 
 	prevLength, err := strconv.Atoi(prevLengthString)
 	if err != nil {
diff --git a/pkg/git/patch_modifier_test.go b/pkg/git/patch_modifier_test.go
index af7be3751..bc2073d55 100644
--- a/pkg/git/patch_modifier_test.go
+++ b/pkg/git/patch_modifier_test.go
@@ -19,7 +19,7 @@ func newDummyPatchModifier() *PatchModifier {
 		Log: newDummyLog(),
 	}
 }
-func TestModifyPatch(t *testing.T) {
+func TestModifyPatchForLine(t *testing.T) {
 	type scenario struct {
 		testName              string
 		patchFilename         string
@@ -43,6 +43,27 @@ func TestModifyPatch(t *testing.T) {
 			false,
 			"testdata/testPatchAfter2.diff",
 		},
+		{
+			"Adding one line in top hunk in diff with multiple hunks",
+			"testdata/testPatchBefore2.diff",
+			20,
+			false,
+			"testdata/testPatchAfter3.diff",
+		},
+		{
+			"Adding one line in top hunk in diff with multiple hunks",
+			"testdata/testPatchBefore2.diff",
+			53,
+			false,
+			"testdata/testPatchAfter4.diff",
+		},
+		{
+			"adding unstaged file with a single line",
+			"testdata/addedFile.diff",
+			6,
+			false,
+			"testdata/addedFile.diff",
+		},
 	}
 
 	for _, s := range scenarios {
@@ -52,7 +73,7 @@ func TestModifyPatch(t *testing.T) {
 			if err != nil {
 				panic("Cannot open file at " + s.patchFilename)
 			}
-			afterPatch, err := p.ModifyPatch(string(beforePatch), s.lineNumber)
+			afterPatch, err := p.ModifyPatchForLine(string(beforePatch), s.lineNumber)
 			if s.shouldError {
 				assert.Error(t, err)
 			} else {
diff --git a/pkg/git/patch_parser.go b/pkg/git/patch_parser.go
index 8fa4d355b..1dbacd01c 100644
--- a/pkg/git/patch_parser.go
+++ b/pkg/git/patch_parser.go
@@ -21,15 +21,16 @@ func (p *PatchParser) ParsePatch(patch string) ([]int, []int, error) {
 	lines := strings.Split(patch, "\n")
 	hunkStarts := []int{}
 	stageableLines := []int{}
-	headerLength := 4
-	for offsetIndex, line := range lines[headerLength:] {
-		index := offsetIndex + headerLength
+	pastHeader := false
+	for index, line := range lines {
 		if strings.HasPrefix(line, "@@") {
+			pastHeader = true
 			hunkStarts = append(hunkStarts, index)
 		}
-		if strings.HasPrefix(line, "-") || strings.HasPrefix(line, "+") {
+		if pastHeader && (strings.HasPrefix(line, "-") || strings.HasPrefix(line, "+")) {
 			stageableLines = append(stageableLines, index)
 		}
 	}
+	p.Log.WithField("staging", "staging").Info(stageableLines)
 	return hunkStarts, stageableLines, nil
 }
diff --git a/pkg/git/patch_parser_test.go b/pkg/git/patch_parser_test.go
new file mode 100644
index 000000000..6670aaea2
--- /dev/null
+++ b/pkg/git/patch_parser_test.go
@@ -0,0 +1,65 @@
+package git
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func newDummyPatchParser() *PatchParser {
+	return &PatchParser{
+		Log: newDummyLog(),
+	}
+}
+func TestParsePatch(t *testing.T) {
+	type scenario struct {
+		testName               string
+		patchFilename          string
+		shouldError            bool
+		expectedStageableLines []int
+		expectedHunkStarts     []int
+	}
+
+	scenarios := []scenario{
+		{
+			"Diff with one hunk",
+			"testdata/testPatchBefore.diff",
+			false,
+			[]int{8, 9, 10, 11},
+			[]int{4},
+		},
+		{
+			"Diff with two hunks",
+			"testdata/testPatchBefore2.diff",
+			false,
+			[]int{8, 9, 10, 11, 12, 13, 20, 21, 22, 23, 24, 25, 26, 27, 28, 33, 34, 35, 36, 37, 45, 46, 47, 48, 49, 50, 51, 52, 53},
+			[]int{4, 41},
+		},
+		{
+			"Unstaged file",
+			"testdata/addedFile.diff",
+			false,
+			[]int{6},
+			[]int{5},
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			p := newDummyPatchParser()
+			beforePatch, err := ioutil.ReadFile(s.patchFilename)
+			if err != nil {
+				panic("Cannot open file at " + s.patchFilename)
+			}
+			hunkStarts, stageableLines, err := p.ParsePatch(string(beforePatch))
+			if s.shouldError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, s.expectedStageableLines, stageableLines)
+				assert.Equal(t, s.expectedHunkStarts, hunkStarts)
+			}
+		})
+	}
+}
diff --git a/pkg/git/testdata/addedFile.diff b/pkg/git/testdata/addedFile.diff
new file mode 100644
index 000000000..53966c4a1
--- /dev/null
+++ b/pkg/git/testdata/addedFile.diff
@@ -0,0 +1,7 @@
+diff --git a/blah b/blah
+new file mode 100644
+index 0000000..907b308
+--- /dev/null
++++ b/blah
+@@ -0,0 +1 @@
++blah
diff --git a/pkg/git/testdata/testPatchAfter3.diff b/pkg/git/testdata/testPatchAfter3.diff
new file mode 100644
index 000000000..03492450d
--- /dev/null
+++ b/pkg/git/testdata/testPatchAfter3.diff
@@ -0,0 +1,25 @@
+diff --git a/pkg/git/patch_modifier.go b/pkg/git/patch_modifier.go
+index a8fc600..6d8f7d7 100644
+--- a/pkg/git/patch_modifier.go
++++ b/pkg/git/patch_modifier.go
+@@ -36,18 +36,19 @@ func (p *PatchModifier) ModifyPatchForHunk(patch string, hunkStarts []int, curre
+ 		hunkEnd = hunkStarts[nextHunkStartIndex]
+ 	}
+ 
+ 	headerLength := 4
+ 	output := strings.Join(lines[0:headerLength], "\n") + "\n"
+ 	output += strings.Join(lines[hunkStart:hunkEnd], "\n") + "\n"
+ 
+ 	return output, nil
+ }
+ 
++func getHeaderLength(patchLines []string) (int, error) {
+ // ModifyPatchForLine takes the original patch, which may contain several hunks,
+ // and the line number of the line we want to stage
+ func (p *PatchModifier) ModifyPatchForLine(patch string, lineNumber int) (string, error) {
+ 	lines := strings.Split(patch, "\n")
+ 	headerLength := 4
+ 	output := strings.Join(lines[0:headerLength], "\n") + "\n"
+ 
+ 	hunkStart, err := p.getHunkStart(lines, lineNumber)
+
diff --git a/pkg/git/testdata/testPatchAfter4.diff b/pkg/git/testdata/testPatchAfter4.diff
new file mode 100644
index 000000000..99f894d9d
--- /dev/null
+++ b/pkg/git/testdata/testPatchAfter4.diff
@@ -0,0 +1,19 @@
+diff --git a/pkg/git/patch_modifier.go b/pkg/git/patch_modifier.go
+index a8fc600..6d8f7d7 100644
+--- a/pkg/git/patch_modifier.go
++++ b/pkg/git/patch_modifier.go
+@@ -124,13 +140,14 @@ func (p *PatchModifier) getModifiedHunk(patchLines []string, hunkStart int, line
+ // @@ -14,8 +14,9 @@ import (
+ func (p *PatchModifier) updatedHeader(currentHeader string, lineChanges int) (string, error) {
+ 	// current counter is the number after the second comma
+ 	re := regexp.MustCompile(`^[^,]+,[^,]+,(\d+)`)
+ 	matches := re.FindStringSubmatch(currentHeader)
+ 	if len(matches) < 2 {
+ 		re = regexp.MustCompile(`^[^,]+,[^+]+\+(\d+)`)
+ 		matches = re.FindStringSubmatch(currentHeader)
+ 	}
+ 	prevLengthString := matches[1]
++	prevLengthString := re.FindStringSubmatch(currentHeader)[1]
+ 
+ 	prevLength, err := strconv.Atoi(prevLengthString)
+ 	if err != nil {
diff --git a/pkg/git/testdata/testPatchBefore2.diff b/pkg/git/testdata/testPatchBefore2.diff
new file mode 100644
index 000000000..552c04f5e
--- /dev/null
+++ b/pkg/git/testdata/testPatchBefore2.diff
@@ -0,0 +1,57 @@
+diff --git a/pkg/git/patch_modifier.go b/pkg/git/patch_modifier.go
+index a8fc600..6d8f7d7 100644
+--- a/pkg/git/patch_modifier.go
++++ b/pkg/git/patch_modifier.go
+@@ -36,18 +36,34 @@ func (p *PatchModifier) ModifyPatchForHunk(patch string, hunkStarts []int, curre
+ 		hunkEnd = hunkStarts[nextHunkStartIndex]
+ 	}
+ 
+-	headerLength := 4
++	headerLength, err := getHeaderLength(lines)
++	if err != nil {
++		return "", err
++	}
++
+ 	output := strings.Join(lines[0:headerLength], "\n") + "\n"
+ 	output += strings.Join(lines[hunkStart:hunkEnd], "\n") + "\n"
+ 
+ 	return output, nil
+ }
+ 
++func getHeaderLength(patchLines []string) (int, error) {
++	for index, line := range patchLines {
++		if strings.HasPrefix(line, "@@") {
++			return index, nil
++		}
++	}
++	return 0, errors.New("Could not find any hunks in this patch")
++}
++
+ // ModifyPatchForLine takes the original patch, which may contain several hunks,
+ // and the line number of the line we want to stage
+ func (p *PatchModifier) ModifyPatchForLine(patch string, lineNumber int) (string, error) {
+ 	lines := strings.Split(patch, "\n")
+-	headerLength := 4
++	headerLength, err := getHeaderLength(lines)
++	if err != nil {
++		return "", err
++	}
+ 	output := strings.Join(lines[0:headerLength], "\n") + "\n"
+ 
+ 	hunkStart, err := p.getHunkStart(lines, lineNumber)
+@@ -124,13 +140,8 @@ func (p *PatchModifier) getModifiedHunk(patchLines []string, hunkStart int, line
+ // @@ -14,8 +14,9 @@ import (
+ func (p *PatchModifier) updatedHeader(currentHeader string, lineChanges int) (string, error) {
+ 	// current counter is the number after the second comma
+-	re := regexp.MustCompile(`^[^,]+,[^,]+,(\d+)`)
+-	matches := re.FindStringSubmatch(currentHeader)
+-	if len(matches) < 2 {
+-		re = regexp.MustCompile(`^[^,]+,[^+]+\+(\d+)`)
+-		matches = re.FindStringSubmatch(currentHeader)
+-	}
+-	prevLengthString := matches[1]
++	re := regexp.MustCompile(`(\d+) @@`)
++	prevLengthString := re.FindStringSubmatch(currentHeader)[1]
+ 
+ 	prevLength, err := strconv.Atoi(prevLengthString)
+ 	if err != nil {
diff --git a/pkg/gui/confirmation_panel.go b/pkg/gui/confirmation_panel.go
index 58577e430..afe53ca2c 100644
--- a/pkg/gui/confirmation_panel.go
+++ b/pkg/gui/confirmation_panel.go
@@ -8,6 +8,7 @@ package gui
 
 import (
 	"strings"
+	"time"
 
 	"github.com/fatih/color"
 	"github.com/jesseduffield/gocui"
@@ -73,6 +74,7 @@ func (gui *Gui) prepareConfirmationPanel(currentView *gocui.View, title, prompt
 			return nil, err
 		}
 		confirmationView.Title = title
+		confirmationView.Wrap = true
 		confirmationView.FgColor = gocui.ColorWhite
 	}
 	confirmationView.Clear()
@@ -137,7 +139,15 @@ func (gui *Gui) createMessagePanel(g *gocui.Gui, currentView *gocui.View, title,
 }
 
 func (gui *Gui) createErrorPanel(g *gocui.Gui, message string) error {
-	gui.Log.Error(message)
+	go func() {
+		// when reporting is switched on this log call sometimes introduces
+		// a delay on the error panel popping up. Here I'm adding a second wait
+		// so that the error is logged while the user is reading the error message
+		time.Sleep(time.Second)
+		gui.Log.Error(message)
+	}()
+
+	// gui.Log.WithField("staging", "staging").Info("creating confirmation panel")
 	currentView := g.CurrentView()
 	colorFunction := color.New(color.FgRed).SprintFunc()
 	coloredMessage := colorFunction(strings.TrimSpace(message))
diff --git a/pkg/gui/files_panel.go b/pkg/gui/files_panel.go
index 3404903ef..a16ef4909 100644
--- a/pkg/gui/files_panel.go
+++ b/pkg/gui/files_panel.go
@@ -57,10 +57,13 @@ func (gui *Gui) handleSwitchToStagingPanel(g *gocui.Gui, v *gocui.View) error {
 		}
 		return nil
 	}
-	if !file.Tracked || !file.HasUnstagedChanges {
+	if !file.HasUnstagedChanges {
+		gui.Log.WithField("staging", "staging").Info("making error panel")
 		return gui.createErrorPanel(g, gui.Tr.SLocalize("FileStagingRequirements"))
 	}
-	gui.switchFocus(g, v, stagingView)
+	if err := gui.switchFocus(g, v, stagingView); err != nil {
+		return err
+	}
 	return gui.refreshStagingPanel()
 }
 
diff --git a/pkg/gui/gui.go b/pkg/gui/gui.go
index 67415c5ce..9f25121d5 100644
--- a/pkg/gui/gui.go
+++ b/pkg/gui/gui.go
@@ -222,7 +222,6 @@ func (gui *Gui) layout(g *gocui.Gui) error {
 			return err
 		}
 		v.Title = gui.Tr.SLocalize("StagingTitle")
-		v.Wrap = true
 		v.Highlight = true
 		v.FgColor = gocui.ColorWhite
 		if _, err := g.SetViewOnBottom("staging"); err != nil {
diff --git a/pkg/gui/keybindings.go b/pkg/gui/keybindings.go
index 2c47ab4f3..4158bedb7 100644
--- a/pkg/gui/keybindings.go
+++ b/pkg/gui/keybindings.go
@@ -392,25 +392,64 @@ func (gui *Gui) GetKeybindings() []*Binding {
 			Modifier: gocui.ModNone,
 			Handler:  gui.handleMenuClose,
 		}, {
-			ViewName: "staging",
-			Key:      gocui.KeyEsc,
-			Modifier: gocui.ModNone,
-			Handler:  gui.handleStagingEscape,
+			ViewName:    "staging",
+			Key:         gocui.KeyEsc,
+			Modifier:    gocui.ModNone,
+			Handler:     gui.handleStagingEscape,
+			KeyReadable: "esc",
+			Description: gui.Tr.SLocalize("EscapeStaging"),
 		}, {
 			ViewName: "staging",
 			Key:      gocui.KeyArrowUp,
 			Modifier: gocui.ModNone,
-			Handler:  gui.handleStagingKeyUp,
+			Handler:  gui.handleStagingPrevLine,
 		}, {
 			ViewName: "staging",
 			Key:      gocui.KeyArrowDown,
 			Modifier: gocui.ModNone,
-			Handler:  gui.handleStagingKeyDown,
+			Handler:  gui.handleStagingNextLine,
 		}, {
 			ViewName: "staging",
-			Key:      gocui.KeySpace,
+			Key:      'k',
+			Modifier: gocui.ModNone,
+			Handler:  gui.handleStagingPrevLine,
+		}, {
+			ViewName: "staging",
+			Key:      'j',
+			Modifier: gocui.ModNone,
+			Handler:  gui.handleStagingNextLine,
+		}, {
+			ViewName: "staging",
+			Key:      gocui.KeyArrowLeft,
+			Modifier: gocui.ModNone,
+			Handler:  gui.handleStagingPrevHunk,
+		}, {
+			ViewName: "staging",
+			Key:      gocui.KeyArrowRight,
+			Modifier: gocui.ModNone,
+			Handler:  gui.handleStagingNextHunk,
+		}, {
+			ViewName: "staging",
+			Key:      'h',
+			Modifier: gocui.ModNone,
+			Handler:  gui.handleStagingPrevHunk,
+		}, {
+			ViewName: "staging",
+			Key:      'l',
 			Modifier: gocui.ModNone,
-			Handler:  gui.handleStageLine,
+			Handler:  gui.handleStagingNextHunk,
+		}, {
+			ViewName:    "staging",
+			Key:         gocui.KeySpace,
+			Modifier:    gocui.ModNone,
+			Handler:     gui.handleStageLine,
+			Description: gui.Tr.SLocalize("StageLine"),
+		}, {
+			ViewName:    "staging",
+			Key:         'a',
+			Modifier:    gocui.ModNone,
+			Handler:     gui.handleStageHunk,
+			Description: gui.Tr.SLocalize("StageHunk"),
 		},
 	}
 
diff --git a/pkg/gui/staging_panel.go b/pkg/gui/staging_panel.go
index be207c2fb..cba7d7638 100644
--- a/pkg/gui/staging_panel.go
+++ b/pkg/gui/staging_panel.go
@@ -2,19 +2,13 @@ package gui
 
 import (
 	"errors"
-	"io/ioutil"
-
-	"github.com/davecgh/go-spew/spew"
 
 	"github.com/jesseduffield/gocui"
 	"github.com/jesseduffield/lazygit/pkg/git"
+	"github.com/jesseduffield/lazygit/pkg/utils"
 )
 
 func (gui *Gui) refreshStagingPanel() error {
-	// get the currently selected file. Get the diff of that file directly, not
-	// using any custom diff tools.
-	// parse the file to find out where the chunks and unstaged changes are
-
 	file, err := gui.getSelectedFile(gui.g)
 	if err != nil {
 		if err != gui.Errors.ErrNoFiles {
@@ -31,10 +25,6 @@ func (gui *Gui) refreshStagingPanel() error {
 	diff := gui.GitCommand.Diff(file, true)
 	colorDiff := gui.GitCommand.Diff(file, false)
 
-	gui.Log.WithField("staging", "staging").Info("DIFF IS:")
-	gui.Log.WithField("staging", "staging").Info(spew.Sdump(diff))
-	gui.Log.WithField("staging", "staging").Info("hello")
-
 	if len(diff) < 2 {
 		return gui.handleStagingEscape(gui.g, nil)
 	}
@@ -73,9 +63,9 @@ func (gui *Gui) refreshStagingPanel() error {
 		return errors.New("No lines to stage")
 	}
 
-	stagingView := gui.getStagingView(gui.g)
-	stagingView.SetCursor(0, stageableLines[currentLineIndex])
-	stagingView.SetOrigin(0, 0)
+	if err := gui.focusLineAndHunk(); err != nil {
+		return err
+	}
 	return gui.renderString(gui.g, "staging", colorDiff)
 }
 
@@ -84,57 +74,130 @@ func (gui *Gui) handleStagingEscape(g *gocui.Gui, v *gocui.View) error {
 		return err
 	}
 
+	gui.State.StagingState = nil
+
 	return gui.switchFocus(gui.g, nil, gui.getFilesView(gui.g))
 }
 
-// nextNumber returns the next index, cycling if we reach the end
-func nextIndex(numbers []int, currentNumber int) int {
-	for index, number := range numbers {
-		if number > currentNumber {
-			return index
-		}
-	}
-	return 0
+func (gui *Gui) handleStagingPrevLine(g *gocui.Gui, v *gocui.View) error {
+	return gui.handleCycleLine(true)
 }
 
-// prevNumber returns the next number, cycling if we reach the end
-func prevIndex(numbers []int, currentNumber int) int {
-	end := len(numbers) - 1
-	for i := end; i >= 0; i -= 1 {
-		if numbers[i] < currentNumber {
-			return i
-		}
-	}
-	return end
+func (gui *Gui) handleStagingNextLine(g *gocui.Gui, v *gocui.View) error {
+	return gui.handleCycleLine(false)
 }
 
-func (gui *Gui) handleStagingKeyUp(g *gocui.Gui, v *gocui.View) error {
-	return gui.handleCycleLine(true)
+func (gui *Gui) handleStagingPrevHunk(g *gocui.Gui, v *gocui.View) error {
+	return gui.handleCycleHunk(true)
 }
 
-func (gui *Gui) handleStagingKeyDown(g *gocui.Gui, v *gocui.View) error {
-	return gui.handleCycleLine(false)
+func (gui *Gui) handleStagingNextHunk(g *gocui.Gui, v *gocui.View) error {
+	return gui.handleCycleHunk(false)
 }
 
-func (gui *Gui) handleCycleLine(up bool) error {
+func (gui *Gui) handleCycleHunk(prev bool) error {
 	state := gui.State.StagingState
 	lineNumbers := state.StageableLines
 	currentLine := lineNumbers[state.CurrentLineIndex]
-	var newIndex int
-	if up {
-		newIndex = prevIndex(lineNumbers, currentLine)
+	currentHunkIndex := utils.PrevIndex(state.HunkStarts, currentLine)
+	var newHunkIndex int
+	if prev {
+		if currentHunkIndex == 0 {
+			newHunkIndex = len(state.HunkStarts) - 1
+		} else {
+			newHunkIndex = currentHunkIndex - 1
+		}
 	} else {
-		newIndex = nextIndex(lineNumbers, currentLine)
+		if currentHunkIndex == len(state.HunkStarts)-1 {
+			newHunkIndex = 0
+		} else {
+			newHunkIndex = currentHunkIndex + 1
+		}
 	}
 
+	state.CurrentLineIndex = utils.NextIndex(lineNumbers, state.HunkStarts[newHunkIndex])
+
+	return gui.focusLineAndHunk()
+}
+
+func (gui *Gui) handleCycleLine(prev bool) error {
+	state := gui.State.StagingState
+	lineNumbers := state.StageableLines
+	currentLine := lineNumbers[state.CurrentLineIndex]
+	var newIndex int
+	if prev {
+		newIndex = utils.PrevIndex(lineNumbers, currentLine)
+	} else {
+		newIndex = utils.NextIndex(lineNumbers, currentLine)
+	}
 	state.CurrentLineIndex = newIndex
+
+	return gui.focusLineAndHunk()
+}
+
+// focusLineAndHunk works out the best focus for the staging panel given the
+// selected line and size of the hunk
+func (gui *Gui) focusLineAndHunk() error {
 	stagingView := gui.getStagingView(gui.g)
-	stagingView.SetCursor(0, lineNumbers[newIndex])
-	stagingView.SetOrigin(0, 0)
+	state := gui.State.StagingState
+
+	lineNumber := state.StageableLines[state.CurrentLineIndex]
+
+	// we want the bottom line of the view buffer to ideally be the bottom line
+	// of the hunk, but if the hunk is too big we'll just go three lines beyond
+	// the currently selected line so that the user can see the context
+	var bottomLine int
+	nextHunkStartIndex := utils.NextIndex(state.HunkStarts, lineNumber)
+	if nextHunkStartIndex == 0 {
+		// for now linesHeight is an efficient means of getting the number of lines
+		// in the patch. However if we introduce word wrap we'll need to update this
+		bottomLine = stagingView.LinesHeight() - 1
+	} else {
+		bottomLine = state.HunkStarts[nextHunkStartIndex] - 1
+	}
+
+	hunkStartIndex := utils.PrevIndex(state.HunkStarts, lineNumber)
+	hunkStart := state.HunkStarts[hunkStartIndex]
+	// if it's the first hunk we'll also show the diff header
+	if hunkStartIndex == 0 {
+		hunkStart = 0
+	}
+
+	_, height := stagingView.Size()
+	// if this hunk is too big, we will just ensure that the user can at least
+	// see three lines of context below the cursor
+	if bottomLine-hunkStart > height {
+		bottomLine = lineNumber + 3
+	}
+
+	return gui.focusLine(lineNumber, bottomLine, stagingView)
+}
+
+// focusLine takes a lineNumber to focus, and a bottomLine to ensure we can see
+func (gui *Gui) focusLine(lineNumber int, bottomLine int, v *gocui.View) error {
+	_, height := v.Size()
+	overScroll := bottomLine - height + 1
+	if overScroll < 0 {
+		overScroll = 0
+	}
+	if err := v.SetOrigin(0, overScroll); err != nil {
+		return err
+	}
+	if err := v.SetCursor(0, lineNumber-overScroll); err != nil {
+		return err
+	}
 	return nil
 }
 
+func (gui *Gui) handleStageHunk(g *gocui.Gui, v *gocui.View) error {
+	return gui.handleStageLineOrHunk(true)
+}
+
 func (gui *Gui) handleStageLine(g *gocui.Gui, v *gocui.View) error {
+	return gui.handleStageLineOrHunk(false)
+}
+
+func (gui *Gui) handleStageLineOrHunk(hunk bool) error {
 	state := gui.State.StagingState
 	p, err := git.NewPatchModifier(gui.Log)
 	if err != nil {
@@ -142,22 +205,31 @@ func (gui *Gui) handleStageLine(g *gocui.Gui, v *gocui.View) error {
 	}
 
 	currentLine := state.StageableLines[state.CurrentLineIndex]
-	patch, err := p.ModifyPatch(state.Diff, currentLine)
+	var patch string
+	if hunk {
+		patch, err = p.ModifyPatchForHunk(state.Diff, state.HunkStarts, currentLine)
+	} else {
+		patch, err = p.ModifyPatchForLine(state.Diff, currentLine)
+	}
 	if err != nil {
 		return err
 	}
 
 	// for logging purposes
-	ioutil.WriteFile("patch.diff", []byte(patch), 0600)
+	// ioutil.WriteFile("patch.diff", []byte(patch), 0600)
 
 	// apply the patch then refresh this panel
 	// create a new temp file with the patch, then call git apply with that patch
 	_, err = gui.GitCommand.ApplyPatch(patch)
 	if err != nil {
-		panic(err)
+		return err
 	}
 
-	gui.refreshStagingPanel()
-	gui.refreshFiles(gui.g)
+	if err := gui.refreshFiles(gui.g); err != nil {
+		return err
+	}
+	if err := gui.refreshStagingPanel(); err != nil {
+		return err
+	}
 	return nil
 }
diff --git a/pkg/gui/view_helpers.go b/pkg/gui/view_helpers.go
index e6970d92f..525b05f97 100644
--- a/pkg/gui/view_helpers.go
+++ b/pkg/gui/view_helpers.go
@@ -259,7 +259,6 @@ func (gui *Gui) renderString(g *gocui.Gui, viewName, s string) error {
 		output := string(bom.Clean([]byte(s)))
 		output = utils.NormalizeLinefeeds(output)
 		fmt.Fprint(v, output)
-		v.Wrap = true
 		return nil
 	})
 	return nil
diff --git a/pkg/i18n/english.go b/pkg/i18n/english.go
index 7a032e105..a3ce14d2e 100644
--- a/pkg/i18n/english.go
+++ b/pkg/i18n/english.go
@@ -420,6 +420,21 @@ func addEnglish(i18nObject *i18n.Bundle) error {
 		}, &i18n.Message{
 			ID:    "StagingTitle",
 			Other: `Staging`,
+		}, &i18n.Message{
+			ID:    "StageHunk",
+			Other: `stage hunk`,
+		}, &i18n.Message{
+			ID:    "StageLine",
+			Other: `stage line`,
+		}, &i18n.Message{
+			ID:    "EscapeStaging",
+			Other: `return to files panel`,
+		}, &i18n.Message{
+			ID:    "CantFindHunks",
+			Other: `Could not find any hunks in this patch`,
+		}, &i18n.Message{
+			ID:    "CantFindHunk",
+			Other: `Could not find hunk`,
 		},
 	)
 }
diff --git a/pkg/utils/utils.go b/pkg/utils/utils.go
index 8e481b3a4..e2a5337e3 100644
--- a/pkg/utils/utils.go
+++ b/pkg/utils/utils.go
@@ -214,3 +214,24 @@ func IncludesString(list []string, a string) bool {
 	}
 	return false
 }
+
+// NextIndex returns the index of the element that comes after the given number
+func NextIndex(numbers []int, currentNumber int) int {
+	for index, number := range numbers {
+		if number > currentNumber {
+			return index
+		}
+	}
+	return 0
+}
+
+// PrevIndex returns the index that comes before the given number, cycling if we reach the end
+func PrevIndex(numbers []int, currentNumber int) int {
+	end := len(numbers) - 1
+	for i := end; i >= 0; i -= 1 {
+		if numbers[i] < currentNumber {
+			return i
+		}
+	}
+	return end
+}
diff --git a/pkg/utils/utils_test.go b/pkg/utils/utils_test.go
index 41774051b..f03bc087a 100644
--- a/pkg/utils/utils_test.go
+++ b/pkg/utils/utils_test.go
@@ -425,3 +425,95 @@ func TestIncludesString(t *testing.T) {
 		assert.EqualValues(t, s.expected, IncludesString(s.list, s.element))
 	}
 }
+
+func TestNextIndex(t *testing.T) {
+	type scenario struct {
+		testName string
+		list     []int
+		element  int
+		expected int
+	}
+
+	scenarios := []scenario{
+		{
+			// I'm not really fussed about how it behaves here
+			"no elements",
+			[]int{},
+			1,
+			0,
+		},
+		{
+			"one element",
+			[]int{1},
+			1,
+			0,
+		},
+		{
+			"two elements",
+			[]int{1, 2},
+			1,
+			1,
+		},
+		{
+			"two elements, giving second one",
+			[]int{1, 2},
+			2,
+			0,
+		},
+		{
+			"three elements, giving second one",
+			[]int{1, 2, 3},
+			2,
+			2,
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			assert.EqualValues(t, s.expected, NextIndex(s.list, s.element))
+		})
+	}
+}
+
+func TestPrevIndex(t *testing.T) {
+	type scenario struct {
+		testName string
+		list     []int
+		element  int
+		expected int
+	}
+
+	scenarios := []scenario{
+		{
+			// I'm not really fussed about how it behaves here
+			"no elements",
+			[]int{},
+			1,
+			-1,
+		},
+		{
+			"one element",
+			[]int{1},
+			1,
+			0,
+		},
+		{
+			"two elements",
+			[]int{1, 2},
+			1,
+			1,
+		},
+		{
+			"three elements, giving second one",
+			[]int{1, 2, 3},
+			2,
+			0,
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.testName, func(t *testing.T) {
+			assert.EqualValues(t, s.expected, PrevIndex(s.list, s.element))
+		})
+	}
+}