properly resolve cyclic dependency

12 files changed, 350 insertions, 579 deletions

diff --git a/pkg/gui/filetree/README.md b/pkg/gui/filetree/README.md
new file mode 100644
index 000000000..d2d16ace6
--- /dev/null
+++ b/pkg/gui/filetree/README.md
@@ -0,0 +1,22 @@
+## FileTree Package
+
+This package handles the representation of file trees. There are two ways to render files: one is to render them flat, so something like this:
+
+```
+dir1/file1
+dir1/file2
+file3
+```
+
+And the other is to render them as a tree
+
+```
+dir1/
+  file1
+  file2
+file3
+```
+
+Internally we represent each of the above as a tree, but with the flat approach there's just a single root node and every path is a direct child of that root. Viewing in 'tree' mode (as opposed to 'flat' mode) allows for collapsing and expanding directories, and lets you perform actions on directories e.g. staging a whole directory. But it takes up more vertical space and sometimes you just want to have a flat view where you can go flick through your files one by one to see the diff.
+
+This package is not concerned about rendering the tree: only representing its internal state.
diff --git a/pkg/gui/filetree/commit_file_manager.go b/pkg/gui/filetree/commit_file_manager.go
deleted file mode 100644
index 852a67b09..000000000
--- a/pkg/gui/filetree/commit_file_manager.go
+++ /dev/null
@@ -1,118 +0,0 @@
-package filetree
-
-import (
-	"github.com/jesseduffield/lazygit/pkg/commands/models"
-	"github.com/jesseduffield/lazygit/pkg/commands/patch"
-	"github.com/sirupsen/logrus"
-)
-
-type CommitFileManager struct {
-	files          []*models.CommitFile
-	tree           *CommitFileNode
-	showTree       bool
-	log            *logrus.Entry
-	collapsedPaths CollapsedPaths
-	// parent is the identifier of the parent object e.g. a commit SHA if this commit file is for a commit, or a stash entry ref like 'stash@{1}'
-	parent string
-}
-
-func (m *CommitFileManager) GetParent() string {
-	return m.parent
-}
-
-func NewCommitFileManager(files []*models.CommitFile, log *logrus.Entry, showTree bool) *CommitFileManager {
-	return &CommitFileManager{
-		files:          files,
-		log:            log,
-		showTree:       showTree,
-		collapsedPaths: CollapsedPaths{},
-	}
-}
-
-func (m *CommitFileManager) ExpandToPath(path string) {
-	m.collapsedPaths.ExpandToPath(path)
-}
-
-func (m *CommitFileManager) ToggleShowTree() {
-	m.showTree = !m.showTree
-	m.SetTree()
-}
-
-func (m *CommitFileManager) GetItemAtIndex(index int) *CommitFileNode {
-	// need to traverse the three depth first until we get to the index.
-	return m.tree.GetNodeAtIndex(index+1, m.collapsedPaths) // ignoring root
-}
-
-func (m *CommitFileManager) GetIndexForPath(path string) (int, bool) {
-	index, found := m.tree.GetIndexForPath(path, m.collapsedPaths)
-	return index - 1, found
-}
-
-func (m *CommitFileManager) GetAllItems() []*CommitFileNode {
-	if m.tree == nil {
-		return nil
-	}
-
-	return m.tree.Flatten(m.collapsedPaths)[1:] // ignoring root
-}
-
-func (m *CommitFileManager) GetItemsLength() int {
-	return m.tree.Size(m.collapsedPaths) - 1 // ignoring root
-}
-
-func (m *CommitFileManager) GetAllFiles() []*models.CommitFile {
-	return m.files
-}
-
-func (m *CommitFileManager) SetFiles(files []*models.CommitFile, parent string) {
-	m.files = files
-	m.parent = parent
-
-	m.SetTree()
-}
-
-func (m *CommitFileManager) SetTree() {
-	if m.showTree {
-		m.tree = BuildTreeFromCommitFiles(m.files)
-	} else {
-		m.tree = BuildFlatTreeFromCommitFiles(m.files)
-	}
-}
-
-func (m *CommitFileManager) IsCollapsed(path string) bool {
-	return m.collapsedPaths.IsCollapsed(path)
-}
-
-func (m *CommitFileManager) ToggleCollapsed(path string) {
-	m.collapsedPaths.ToggleCollapsed(path)
-}
-
-func (m *CommitFileManager) Render(diffName string, patchManager *patch.PatchManager) []string {
-	// can't rely on renderAux to check for nil because an interface won't be nil if its concrete value is nil
-	if m.tree == nil {
-		return []string{}
-	}
-
-	return renderAux(m.tree, m.collapsedPaths, "", -1, func(n INode, depth int) string {
-		castN := n.(*CommitFileNode)
-
-		// This is a little convoluted because we're dealing with either a leaf or a non-leaf.
-		// But this code actually applies to both. If it's a leaf, the status will just
-		// be whatever status it is, but if it's a non-leaf it will determine its status
-		// based on the leaves of that subtree
-		var status patch.PatchStatus
-		if castN.EveryFile(func(file *models.CommitFile) bool {
-			return patchManager.GetFileStatus(file.Name, m.parent) == patch.WHOLE
-		}) {
-			status = patch.WHOLE
-		} else if castN.EveryFile(func(file *models.CommitFile) bool {
-			return patchManager.GetFileStatus(file.Name, m.parent) == patch.UNSELECTED
-		}) {
-			status = patch.UNSELECTED
-		} else {
-			status = patch.PART
-		}
-
-		return getCommitFileLine(castN.NameAtDepth(depth), diffName, castN.File, status)
-	})
-}
diff --git a/pkg/gui/filetree/commit_file_node.go b/pkg/gui/filetree/commit_file_node.go
index 173281035..14960ee30 100644
--- a/pkg/gui/filetree/commit_file_node.go
+++ b/pkg/gui/filetree/commit_file_node.go
@@ -11,6 +11,8 @@ type CommitFileNode struct {
 	CompressionLevel int    // equal to the number of forward slashes you'll see in the path when it's rendered in tree mode
 }
 
+var _ INode = &CommitFileNode{}
+
 // methods satisfying ListItem interface
 
 func (s *CommitFileNode) ID() string {
@@ -23,6 +25,10 @@ func (s *CommitFileNode) Description() string {
 
 // methods satisfying INode interface
 
+func (s *CommitFileNode) IsNil() bool {
+	return s == nil
+}
+
 func (s *CommitFileNode) IsLeaf() bool {
 	return s.File != nil
 }
@@ -139,13 +145,6 @@ func (s *CommitFileNode) Compress() {
 	compressAux(s)
 }
 
-// This ignores the root
-func (node *CommitFileNode) GetPathsMatching(test func(*CommitFileNode) bool) []string {
-	return getPathsMatching(node, func(n INode) bool {
-		return test(n.(*CommitFileNode))
-	})
-}
-
 func (s *CommitFileNode) GetLeaves() []*CommitFileNode {
 	leaves := getLeaves(s)
 	castLeaves := make([]*CommitFileNode, len(leaves))
diff --git a/pkg/gui/filetree/commit_file_tree_view_model.go b/pkg/gui/filetree/commit_file_tree_view_model.go
new file mode 100644
index 000000000..301396462
--- /dev/null
+++ b/pkg/gui/filetree/commit_file_tree_view_model.go
@@ -0,0 +1,101 @@
+package filetree
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/commands/models"
+	"github.com/sirupsen/logrus"
+)
+
+type CommitFileTreeViewModel struct {
+	files          []*models.CommitFile
+	tree           *CommitFileNode
+	showTree       bool
+	log            *logrus.Entry
+	collapsedPaths CollapsedPaths
+	// parent is the identifier of the parent object e.g. a commit SHA if this commit file is for a commit, or a stash entry ref like 'stash@{1}'
+	parent string
+}
+
+func (self *CommitFileTreeViewModel) GetParent() string {
+	return self.parent
+}
+
+func (self *CommitFileTreeViewModel) SetParent(parent string) {
+	self.parent = parent
+}
+
+func NewCommitFileTreeViewModel(files []*models.CommitFile, log *logrus.Entry, showTree bool) *CommitFileTreeViewModel {
+	viewModel := &CommitFileTreeViewModel{
+		log:            log,
+		showTree:       showTree,
+		collapsedPaths: CollapsedPaths{},
+	}
+
+	viewModel.SetFiles(files)
+
+	return viewModel
+}
+
+func (self *CommitFileTreeViewModel) ExpandToPath(path string) {
+	self.collapsedPaths.ExpandToPath(path)
+}
+
+func (self *CommitFileTreeViewModel) ToggleShowTree() {
+	self.showTree = !self.showTree
+	self.SetTree()
+}
+
+func (self *CommitFileTreeViewModel) GetItemAtIndex(index int) *CommitFileNode {
+	// need to traverse the three depth first until we get to the index.
+	return self.tree.GetNodeAtIndex(index+1, self.collapsedPaths) // ignoring root
+}
+
+func (self *CommitFileTreeViewModel) GetIndexForPath(path string) (int, bool) {
+	index, found := self.tree.GetIndexForPath(path, self.collapsedPaths)
+	return index - 1, found
+}
+
+func (self *CommitFileTreeViewModel) GetAllItems() []*CommitFileNode {
+	if self.tree == nil {
+		return nil
+	}
+
+	return self.tree.Flatten(self.collapsedPaths)[1:] // ignoring root
+}
+
+func (self *CommitFileTreeViewModel) GetItemsLength() int {
+	return self.tree.Size(self.collapsedPaths) - 1 // ignoring root
+}
+
+func (self *CommitFileTreeViewModel) GetAllFiles() []*models.CommitFile {
+	return self.files
+}
+
+func (self *CommitFileTreeViewModel) SetFiles(files []*models.CommitFile) {
+	self.files = files
+
+	self.SetTree()
+}
+
+func (self *CommitFileTreeViewModel) SetTree() {
+	if self.showTree {
+		self.tree = BuildTreeFromCommitFiles(self.files)
+	} else {
+		self.tree = BuildFlatTreeFromCommitFiles(self.files)
+	}
+}
+
+func (self *CommitFileTreeViewModel) IsCollapsed(path string) bool {
+	return self.collapsedPaths.IsCollapsed(path)
+}
+
+func (self *CommitFileTreeViewModel) ToggleCollapsed(path string) {
+	self.collapsedPaths.ToggleCollapsed(path)
+}
+
+func (self *CommitFileTreeViewModel) Tree() INode {
+	return self.tree
+}
+
+func (self *CommitFileTreeViewModel) CollapsedPaths() CollapsedPaths {
+	return self.collapsedPaths
+}
diff --git a/pkg/gui/filetree/constants.go b/pkg/gui/filetree/constants.go
deleted file mode 100644
index d510650e2..000000000
--- a/pkg/gui/filetree/constants.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package filetree
-
-const EXPANDED_ARROW = "▼"
-const COLLAPSED_ARROW = "►"
-
-const INNER_ITEM = "├─ "
-const LAST_ITEM = "└─ "
-const NESTED = "│  "
-const NOTHING = "   "
diff --git a/pkg/gui/filetree/file_manager.go b/pkg/gui/filetree/file_manager.go
deleted file mode 100644
index b028ef961..000000000
--- a/pkg/gui/filetree/file_manager.go
+++ /dev/null
@@ -1,140 +0,0 @@
-package filetree
-
-import (
-	"sync"
-
-	"github.com/jesseduffield/lazygit/pkg/commands/models"
-	"github.com/sirupsen/logrus"
-)
-
-type FileManagerDisplayFilter int
-
-const (
-	DisplayAll FileManagerDisplayFilter = iota
-	DisplayStaged
-	DisplayUnstaged
-)
-
-type FileManager struct {
-	files          []*models.File
-	tree           *FileNode
-	showTree       bool
-	log            *logrus.Entry
-	filter         FileManagerDisplayFilter
-	collapsedPaths CollapsedPaths
-	sync.RWMutex
-}
-
-func NewFileManager(files []*models.File, log *logrus.Entry, showTree bool) *FileManager {
-	return &FileManager{
-		files:          files,
-		log:            log,
-		showTree:       showTree,
-		filter:         DisplayAll,
-		collapsedPaths: CollapsedPaths{},
-		RWMutex:        sync.RWMutex{},
-	}
-}
-
-func (m *FileManager) InTreeMode() bool {
-	return m.showTree
-}
-
-func (m *FileManager) ExpandToPath(path string) {
-	m.collapsedPaths.ExpandToPath(path)
-}
-
-func (m *FileManager) GetFilesForDisplay() []*models.File {
-	files := m.files
-	if m.filter == DisplayAll {
-		return files
-	}
-
-	result := make([]*models.File, 0)
-	if m.filter == DisplayStaged {
-		for _, file := range files {
-			if file.HasStagedChanges {
-				result = append(result, file)
-			}
-		}
-	} else {
-		for _, file := range files {
-			if !file.HasStagedChanges {
-				result = append(result, file)
-			}
-		}
-	}
-
-	return result
-}
-
-func (m *FileManager) SetDisplayFilter(filter FileManagerDisplayFilter) {
-	m.filter = filter
-	m.SetTree()
-}
-
-func (m *FileManager) ToggleShowTree() {
-	m.showTree = !m.showTree
-	m.SetTree()
-}
-
-func (m *FileManager) GetItemAtIndex(index int) *FileNode {
-	// need to traverse the three depth first until we get to the index.
-	return m.tree.GetNodeAtIndex(index+1, m.collapsedPaths) // ignoring root
-}
-
-func (m *FileManager) GetIndexForPath(path string) (int, bool) {
-	index, found := m.tree.GetIndexForPath(path, m.collapsedPaths)
-	return index - 1, found
-}
-
-func (m *FileManager) GetAllItems() []*FileNode {
-	if m.tree == nil {
-		return nil
-	}
-
-	return m.tree.Flatten(m.collapsedPaths)[1:] // ignoring root
-}
-
-func (m *FileManager) GetItemsLength() int {
-	return m.tree.Size(m.collapsedPaths) - 1 // ignoring root
-}
-
-func (m *FileManager) GetAllFiles() []*models.File {
-	return m.files
-}
-
-func (m *FileManager) SetFiles(files []*models.File) {
-	m.files = files
-
-	m.SetTree()
-}
-
-func (m *FileManager) SetTree() {
-	filesForDisplay := m.GetFilesForDisplay()
-	if m.showTree {
-		m.tree = BuildTreeFromFiles(filesForDisplay)
-	} else {
-		m.tree = BuildFlatTreeFromFiles(filesForDisplay)
-	}
-}
-
-func (m *FileManager) IsCollapsed(path string) bool {
-	return m.collapsedPaths.IsCollapsed(path)
-}
-
-func (m *FileManager) ToggleCollapsed(path string) {
-	m.collapsedPaths.ToggleCollapsed(path)
-}
-
-func (m *FileManager) Render(diffName string, submoduleConfigs []*models.SubmoduleConfig) []string {
-	// can't rely on renderAux to check for nil because an interface won't be nil if its concrete value is nil
-	if m.tree == nil {
-		return []string{}
-	}
-
-	return renderAux(m.tree, m.collapsedPaths, "", -1, func(n INode, depth int) string {
-		castN := n.(*FileNode)
-		return getFileLine(castN.GetHasUnstagedChanges(), castN.GetHasStagedChanges(), castN.NameAtDepth(depth), diffName, submoduleConfigs, castN.File)
-	})
-}
diff --git a/pkg/gui/filetree/file_manager_test.go b/pkg/gui/filetree/file_manager_test.go
deleted file mode 100644
index 83ba5b086..000000000
--- a/pkg/gui/filetree/file_manager_test.go
+++ /dev/null
@@ -1,156 +0,0 @@
-package filetree
-
-import (
-	"testing"
-
-	"github.com/gookit/color"
-	"github.com/jesseduffield/lazygit/pkg/commands/models"
-	"github.com/stretchr/testify/assert"
-	"github.com/xo/terminfo"
-)
-
-func init() {
-	color.ForceSetColorLevel(terminfo.ColorLevelNone)
-}
-
-func TestRender(t *testing.T) {
-	scenarios := []struct {
-		name           string
-		root           *FileNode
-		collapsedPaths map[string]bool
-		expected       []string
-	}{
-		{
-			name:     "nil node",
-			root:     nil,
-			expected: []string{},
-		},
-		{
-			name: "leaf node",
-			root: &FileNode{
-				Path: "",
-				Children: []*FileNode{
-					{File: &models.File{Name: "test", ShortStatus: " M", HasStagedChanges: true}, Path: "test"},
-				},
-			},
-			expected: []string{" M test"},
-		},
-		{
-			name: "big example",
-			root: &FileNode{
-				Path: "",
-				Children: []*FileNode{
-					{
-						Path: "dir1",
-						Children: []*FileNode{
-							{
-								File: &models.File{Name: "dir1/file2", ShortStatus: "M ", HasUnstagedChanges: true},
-								Path: "dir1/file2",
-							},
-							{
-								File: &models.File{Name: "dir1/file3", ShortStatus: "M ", HasUnstagedChanges: true},
-								Path: "dir1/file3",
-							},
-						},
-					},
-					{
-						Path: "dir2",
-						Children: []*FileNode{
-							{
-								Path: "dir2/dir2",
-								Children: []*FileNode{
-									{
-										File: &models.File{Name: "dir2/dir2/file3", ShortStatus: " M", HasStagedChanges: true},
-										Path: "dir2/dir2/file3",
-									},
-									{
-										File: &models.File{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
-										Path: "dir2/dir2/file4",
-									},
-								},
-							},
-							{
-								File: &models.File{Name: "dir2/file5", ShortStatus: "M ", HasUnstagedChanges: true},
-								Path: "dir2/file5",
-							},
-						},
-					},
-					{
-						File: &models.File{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
-						Path: "file1",
-					},
-				},
-			},
-			expected:       []string{"dir1 ►", "dir2 ▼", "├─ dir2 ▼", "│  ├─  M file3", "│  └─ M  file4", "└─ M  file5", "M  file1"},
-			collapsedPaths: map[string]bool{"dir1": true},
-		},
-	}
-
-	for _, s := range scenarios {
-		s := s
-		t.Run(s.name, func(t *testing.T) {
-			mngr := &FileManager{tree: s.root, collapsedPaths: s.collapsedPaths}
-			result := mngr.Render("", nil)
-			assert.EqualValues(t, s.expected, result)
-		})
-	}
-}
-
-func TestFilterAction(t *testing.T) {
-	scenarios := []struct {
-		name     string
-		filter   FileManagerDisplayFilter
-		files    []*models.File
-		expected []*models.File
-	}{
-		{
-			name:   "filter files with unstaged changes",
-			filter: DisplayUnstaged,
-			files: []*models.File{
-				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
-				{Name: "dir2/file5", ShortStatus: "M ", HasStagedChanges: true},
-				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
-			},
-			expected: []*models.File{
-				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
-				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
-			},
-		},
-		{
-			name:   "filter files with staged changes",
-			filter: DisplayStaged,
-			files: []*models.File{
-				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasStagedChanges: true},
-				{Name: "dir2/file5", ShortStatus: "M ", HasStagedChanges: false},
-				{Name: "file1", ShortStatus: "M ", HasStagedChanges: true},
-			},
-			expected: []*models.File{
-				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasStagedChanges: true},
-				{Name: "file1", ShortStatus: "M ", HasStagedChanges: true},
-			},
-		},
-		{
-			name:   "filter all files",
-			filter: DisplayAll,
-			files: []*models.File{
-				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
-				{Name: "dir2/file5", ShortStatus: "M ", HasUnstagedChanges: true},
-				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
-			},
-			expected: []*models.File{
-				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
-				{Name: "dir2/file5", ShortStatus: "M ", HasUnstagedChanges: true},
-				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
-			},
-		},
-	}
-
-	for _, s := range scenarios {
-		s := s
-		t.Run(s.name, func(t *testing.T) {
-			mngr := &FileManager{files: s.files, filter: s.filter}
-			result := mngr.GetFilesForDisplay()
-			assert.EqualValues(t, s.expected, result)
-		})
-	}
-}
diff --git a/pkg/gui/filetree/file_node.go b/pkg/gui/filetree/file_node.go
index cb545d391..f332f0a76 100644
--- a/pkg/gui/filetree/file_node.go
+++ b/pkg/gui/filetree/file_node.go
@@ -11,6 +11,8 @@ type FileNode struct {
 	CompressionLevel int    // equal to the number of forward slashes you'll see in the path when it's rendered in tree mode
 }
 
+var _ INode = &FileNode{}
+
 // methods satisfying ListItem interface
 
 func (s *FileNode) ID() string {
@@ -23,6 +25,12 @@ func (s *FileNode) Description() string {
 
 // methods satisfying INode interface
 
+// interfaces values whose concrete value is nil are not themselves nil
+// hence the existence of this method
+func (s *FileNode) IsNil() bool {
+	return s == nil
+}
+
 func (s *FileNode) IsLeaf() bool {
 	return s.File != nil
 }
@@ -124,10 +132,13 @@ func (s *FileNode) Compress() {
 	compressAux(s)
 }
 
-// This ignores the root
-func (node *FileNode) GetPathsMatching(test func(*FileNode) bool) []string {
+func (node *FileNode) GetFilePathsMatching(test func(*models.File) bool) []string {
 	return getPathsMatching(node, func(n INode) bool {
-		return test(n.(*FileNode))
+		castNode := n.(*FileNode)
+		if castNode.File == nil {
+			return false
+		}
+		return test(castNode.File)
 	})
 }
 
diff --git a/pkg/gui/filetree/file_tree_view_model.go b/pkg/gui/filetree/file_tree_view_model.go
new file mode 100644
index 000000000..d12814976
--- /dev/null
+++ b/pkg/gui/filetree/file_tree_view_model.go
@@ -0,0 +1,139 @@
+package filetree
+
+import (
+	"sync"
+
+	"github.com/jesseduffield/lazygit/pkg/commands/models"
+	"github.com/sirupsen/logrus"
+)
+
+type FileTreeDisplayFilter int
+
+const (
+	DisplayAll FileTreeDisplayFilter = iota
+	DisplayStaged
+	DisplayUnstaged
+)
+
+type FileTreeViewModel struct {
+	files          []*models.File
+	tree           *FileNode
+	showTree       bool
+	log            *logrus.Entry
+	filter         FileTreeDisplayFilter
+	collapsedPaths CollapsedPaths
+	sync.RWMutex
+}
+
+func NewFileTreeViewModel(files []*models.File, log *logrus.Entry, showTree bool) *FileTreeViewModel {
+	viewModel := &FileTreeViewModel{
+		log:            log,
+		showTree:       showTree,
+		filter:         DisplayAll,
+		collapsedPaths: CollapsedPaths{},
+		RWMutex:        sync.RWMutex{},
+	}
+
+	viewModel.SetFiles(files)
+
+	return viewModel
+}
+
+func (self *FileTreeViewModel) InTreeMode() bool {
+	return self.showTree
+}
+
+func (self *FileTreeViewModel) ExpandToPath(path string) {
+	self.collapsedPaths.ExpandToPath(path)
+}
+
+func (self *FileTreeViewModel) GetFilesForDisplay() []*models.File {
+	files := self.files
+	if self.filter == DisplayAll {
+		return files
+	}
+
+	result := make([]*models.File, 0)
+	if self.filter == DisplayStaged {
+		for _, file := range files {
+			if file.HasStagedChanges {
+				result = append(result, file)
+			}
+		}
+	} else {
+		for _, file := range files {
+			if !file.HasStagedChanges {
+				result = append(result, file)
+			}
+		}
+	}
+
+	return result
+}
+
+func (self *FileTreeViewModel) SetDisplayFilter(filter FileTreeDisplayFilter) {
+	self.filter = filter
+	self.SetTree()
+}
+
+func (self *FileTreeViewModel) ToggleShowTree() {
+	self.showTree = !self.showTree
+	self.SetTree()
+}
+
+func (self *FileTreeViewModel) GetItemAtIndex(index int) *FileNode {
+	// need to traverse the three depth first until we get to the index.
+	return self.tree.GetNodeAtIndex(index+1, self.collapsedPaths) // ignoring root
+}
+
+func (self *FileTreeViewModel) GetIndexForPath(path string) (int, bool) {
+	index, found := self.tree.GetIndexForPath(path, self.collapsedPaths)
+	return index - 1, found
+}
+
+func (self *FileTreeViewModel) GetAllItems() []*FileNode {
+	if self.tree == nil {
+		return nil
+	}
+
+	return self.tree.Flatten(self.collapsedPaths)[1:] // ignoring root
+}
+
+func (self *FileTreeViewModel) GetItemsLength() int {
+	return self.tree.Size(self.collapsedPaths) - 1 // ignoring root
+}
+
+func (self *FileTreeViewModel) GetAllFiles() []*models.File {
+	return self.files
+}
+
+func (self *FileTreeViewModel) SetFiles(files []*models.File) {
+	self.files = files
+
+	self.SetTree()
+}
+
+func (self *FileTreeViewModel) SetTree() {
+	filesForDisplay := self.GetFilesForDisplay()
+	if self.showTree {
+		self.tree = BuildTreeFromFiles(filesForDisplay)
+	} else {
+		self.tree = BuildFlatTreeFromFiles(filesForDisplay)
+	}
+}
+
+func (self *FileTreeViewModel) IsCollapsed(path string) bool {
+	return self.collapsedPaths.IsCollapsed(path)
+}
+
+func (self *FileTreeViewModel) ToggleCollapsed(path string) {
+	self.collapsedPaths.ToggleCollapsed(path)
+}
+
+func (self *FileTreeViewModel) Tree() INode {
+	return self.tree
+}
+
+func (self *FileTreeViewModel) CollapsedPaths() CollapsedPaths {
+	return self.collapsedPaths
+}
diff --git a/pkg/gui/filetree/file_tree_view_model_test.go b/pkg/gui/filetree/file_tree_view_model_test.go
new file mode 100644
index 000000000..10c32d31d
--- /dev/null
+++ b/pkg/gui/filetree/file_tree_view_model_test.go
@@ -0,0 +1,67 @@
+package filetree
+
+import (
+	"testing"
+
+	"github.com/jesseduffield/lazygit/pkg/commands/models"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFilterAction(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		filter   FileTreeDisplayFilter
+		files    []*models.File
+		expected []*models.File
+	}{
+		{
+			name:   "filter files with unstaged changes",
+			filter: DisplayUnstaged,
+			files: []*models.File{
+				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
+				{Name: "dir2/file5", ShortStatus: "M ", HasStagedChanges: true},
+				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
+			},
+			expected: []*models.File{
+				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
+				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
+			},
+		},
+		{
+			name:   "filter files with staged changes",
+			filter: DisplayStaged,
+			files: []*models.File{
+				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasStagedChanges: true},
+				{Name: "dir2/file5", ShortStatus: "M ", HasStagedChanges: false},
+				{Name: "file1", ShortStatus: "M ", HasStagedChanges: true},
+			},
+			expected: []*models.File{
+				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasStagedChanges: true},
+				{Name: "file1", ShortStatus: "M ", HasStagedChanges: true},
+			},
+		},
+		{
+			name:   "filter all files",
+			filter: DisplayAll,
+			files: []*models.File{
+				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
+				{Name: "dir2/file5", ShortStatus: "M ", HasUnstagedChanges: true},
+				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
+			},
+			expected: []*models.File{
+				{Name: "dir2/dir2/file4", ShortStatus: "M ", HasUnstagedChanges: true},
+				{Name: "dir2/file5", ShortStatus: "M ", HasUnstagedChanges: true},
+				{Name: "file1", ShortStatus: "M ", HasUnstagedChanges: true},
+			},
+		},
+	}
+
+	for _, s := range scenarios {
+		s := s
+		t.Run(s.name, func(t *testing.T) {
+			mngr := &FileTreeViewModel{files: s.files, filter: s.filter}
+			result := mngr.GetFilesForDisplay()
+			assert.EqualValues(t, s.expected, result)
+		})
+	}
+}
diff --git a/pkg/gui/filetree/inode.go b/pkg/gui/filetree/inode.go
index f7bfc0518..7d9035fe3 100644
--- a/pkg/gui/filetree/inode.go
+++ b/pkg/gui/filetree/inode.go
@@ -1,12 +1,11 @@
 package filetree
 
 import (
-	"fmt"
 	"sort"
-	"strings"
 )
 
 type INode interface {
+	IsNil() bool
 	IsLeaf() bool
 	GetPath() string
 	GetChildren() []INode
@@ -212,51 +211,3 @@ func getLeaves(node INode) []INode {
 
 	return output
 }
-
-func renderAux(s INode, collapsedPaths CollapsedPaths, prefix string, depth int, renderLine func(INode, int) string) []string {
-	isRoot := depth == -1
-
-	renderLineWithPrefix := func() string {
-		return prefix + renderLine(s, depth)
-	}
-
-	if s.IsLeaf() {
-		if isRoot {
-			return []string{}
-		}
-		return []string{renderLineWithPrefix()}
-	}
-
-	if collapsedPaths.IsCollapsed(s.GetPath()) {
-		return []string{fmt.Sprintf("%s %s", renderLineWithPrefix(), COLLAPSED_ARROW)}
-	}
-
-	arr := []string{}
-	if !isRoot {
-		arr = append(arr, fmt.Sprintf("%s %s", renderLineWithPrefix(), EXPANDED_ARROW))
-	}
-
-	newPrefix := prefix
-	if strings.HasSuffix(prefix, LAST_ITEM) {
-		newPrefix = strings.TrimSuffix(prefix, LAST_ITEM) + NOTHING
-	} else if strings.HasSuffix(prefix, INNER_ITEM) {
-		newPrefix = strings.TrimSuffix(prefix, INNER_ITEM) + NESTED
-	}
-
-	for i, child := range s.GetChildren() {
-		isLast := i == len(s.GetChildren())-1
-
-		var childPrefix string
-		if isRoot {
-			childPrefix = newPrefix
-		} else if isLast {
-			childPrefix = newPrefix + LAST_ITEM
-		} else {
-			childPrefix = newPrefix + INNER_ITEM
-		}
-
-		arr = append(arr, renderAux(child, collapsedPaths, childPrefix, depth+1+s.GetCompressionLevel(), renderLine)...)
-	}
-
-	return arr
-}
diff --git a/pkg/gui