HackStudio: Add basic Git integration

This adds a "Git" tab to Hackstudio.
Currently has support for staging and unstaging files.

15 files changed, 692 insertions, 42 deletions

diff --git a/Base/res/icons/16x16/minus.png b/Base/res/icons/16x16/minus.png
new file mode 100644
index 0000000000..4288ca17d2
--- /dev/null
+++ b/Base/res/icons/16x16/minus.png
diff --git a/Base/res/icons/16x16/plus.png b/Base/res/icons/16x16/plus.png
new file mode 100644
index 0000000000..c3583756fc
--- /dev/null
+++ b/Base/res/icons/16x16/plus.png
diff --git a/DevTools/HackStudio/CMakeLists.txt b/DevTools/HackStudio/CMakeLists.txt
index 8105917661..2f392cabff 100644
--- a/DevTools/HackStudio/CMakeLists.txt
+++ b/DevTools/HackStudio/CMakeLists.txt
@@ -1,5 +1,9 @@
 set(SOURCES
     CursorTool.cpp
+    Git/GitWidget.cpp
+    Git/GitFilesModel.cpp
+    Git/GitRepo.cpp
+    Git/GitFilesView.cpp
     Debugger/BacktraceModel.cpp
     Debugger/Debugger.cpp
     Debugger/DebugInfoWidget.cpp
diff --git a/DevTools/HackStudio/Git/GitFilesModel.cpp b/DevTools/HackStudio/Git/GitFilesModel.cpp
new file mode 100644
index 0000000000..720198586a
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitFilesModel.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "GitFilesModel.h"
+
+namespace HackStudio {
+
+NonnullRefPtr<GitFilesModel> GitFilesModel::create(Vector<LexicalPath>&& files)
+{
+    return adopt(*new GitFilesModel(move(files)));
+}
+
+GitFilesModel::GitFilesModel(Vector<LexicalPath>&& files)
+    : m_files(move(files))
+{
+}
+
+GUI::Variant GitFilesModel::data(const GUI::ModelIndex& index, GUI::ModelRole role) const
+{
+    if (role == GUI::ModelRole::Display) {
+        return m_files.at(index.row()).string();
+    }
+    return {};
+}
+
+GUI::ModelIndex GitFilesModel::index(int row, int column, const GUI::ModelIndex&) const
+{
+    if (row < 0 || row >= static_cast<int>(m_files.size()))
+        return {};
+    return create_index(row, column, &m_files.at(row));
+}
+
+};
diff --git a/DevTools/HackStudio/Git/GitFilesModel.h b/DevTools/HackStudio/Git/GitFilesModel.h
new file mode 100644
index 0000000000..988be1c472
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitFilesModel.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "GitRepo.h"
+#include <AK/LexicalPath.h>
+#include <AK/NonnullRefPtr.h>
+#include <LibGUI/Model.h>
+
+namespace HackStudio {
+
+class GitFilesModel final : public GUI::Model {
+public:
+    static NonnullRefPtr<GitFilesModel> create(Vector<LexicalPath>&& files);
+
+    virtual int row_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return m_files.size(); }
+    virtual int column_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return 1; }
+
+    virtual String column_name(int) const override
+    {
+        return "";
+    }
+
+    virtual GUI::Variant data(const GUI::ModelIndex&, GUI::ModelRole) const override;
+
+    virtual void update() override {}
+    virtual GUI::ModelIndex index(int row, int column, const GUI::ModelIndex&) const override;
+
+private:
+    explicit GitFilesModel(Vector<LexicalPath>&& files);
+    Vector<LexicalPath> m_files;
+};
+}
diff --git a/DevTools/HackStudio/Git/GitFilesView.cpp b/DevTools/HackStudio/Git/GitFilesView.cpp
new file mode 100644
index 0000000000..76aa3abda8
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitFilesView.cpp
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "GitFilesView.h"
+#include <LibGUI/Model.h>
+#include <LibGUI/Painter.h>
+#include <LibGUI/ScrollBar.h>
+#include <LibGfx/Palette.h>
+
+namespace HackStudio {
+GitFilesView::~GitFilesView()
+{
+}
+
+void GitFilesView::paint_list_item(GUI::Painter& painter, int row_index, int painted_item_index)
+{
+    ListView::paint_list_item(painter, row_index, painted_item_index);
+
+    painter.blit(action_icon_rect((size_t)painted_item_index).top_left(), *m_action_icon, m_action_icon->rect());
+}
+
+Gfx::IntRect GitFilesView::action_icon_rect(size_t painted_item_index)
+{
+    int y = painted_item_index * item_height();
+    return { content_width() - 20, y, m_action_icon->rect().width(), m_action_icon->rect().height() };
+}
+
+GitFilesView::GitFilesView(GitFileActionCallback callback, NonnullRefPtr<Gfx::Bitmap> action_icon)
+    : m_action_callback(move(callback))
+    , m_action_icon(action_icon)
+{
+    set_alternating_row_colors(false);
+}
+
+void GitFilesView::mousedown_event(GUI::MouseEvent& event)
+{
+    if (event.button() != GUI::MouseButton::Left) {
+        ListView::mousedown_event(event);
+        return;
+    }
+
+    if (event.x() < action_icon_rect(0).x() || event.x() > action_icon_rect(0).top_right().x()) {
+        ListView::mousedown_event(event);
+        return;
+    }
+
+    size_t item_index = (event.y() + vertical_scrollbar().value()) / item_height();
+    if (model()->row_count() == 0 || item_index > (size_t)model()->row_count()) {
+        ListView::mousedown_event(event);
+        return;
+    }
+
+    auto data = model()->index(item_index, model_column()).data();
+
+    ASSERT(data.is_string());
+    m_action_callback(LexicalPath(data.to_string()));
+}
+
+};
diff --git a/DevTools/HackStudio/Git/GitFilesView.h b/DevTools/HackStudio/Git/GitFilesView.h
new file mode 100644
index 0000000000..8eb636304c
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitFilesView.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/LexicalPath.h>
+#include <LibGUI/ListView.h>
+#include <LibGfx/Bitmap.h>
+
+namespace HackStudio {
+
+// A "GitFileAction" is either the staging or the unstaging of a file.
+typedef Function<void(const LexicalPath& file)> GitFileActionCallback;
+
+class GitFilesView : public GUI::ListView {
+    C_OBJECT(GitFilesView)
+public:
+    virtual ~GitFilesView() override;
+
+protected:
+    GitFilesView(GitFileActionCallback, NonnullRefPtr<Gfx::Bitmap> action_icon);
+
+private:
+    virtual void paint_list_item(GUI::Painter& painter, int row_index, int painted_item_index);
+
+    virtual void mousedown_event(GUI::MouseEvent&) override;
+    virtual Gfx::IntRect action_icon_rect(size_t painted_item_index);
+
+    GitFileActionCallback m_action_callback;
+    NonnullRefPtr<Gfx::Bitmap> m_action_icon;
+};
+
+}
diff --git a/DevTools/HackStudio/Git/GitRepo.cpp b/DevTools/HackStudio/Git/GitRepo.cpp
new file mode 100644
index 0000000000..1dbd0570ff
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitRepo.cpp
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "GitRepo.h"
+#include <LibCore/Command.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+namespace HackStudio {
+
+GitRepo::CreateResult GitRepo::try_to_create(const LexicalPath& repository_root)
+{
+    if (!git_is_installed()) {
+        return { CreateResult::Type::GitProgramNotFound, nullptr };
+    }
+    if (!git_repo_exists(repository_root)) {
+        return { CreateResult::Type::NoGitRepo, nullptr };
+    }
+
+    return { CreateResult::Type::Success, adopt(*new GitRepo(repository_root)) };
+}
+
+RefPtr<GitRepo> GitRepo::initialize_repository(const LexicalPath& repository_root)
+{
+    auto res = command_wrapper("init", repository_root);
+    if (res.is_null())
+        return {};
+
+    ASSERT(git_repo_exists(repository_root));
+    return adopt(*new GitRepo(repository_root));
+}
+
+Vector<LexicalPath> GitRepo::unstaged_files() const
+{
+    auto modified = modified_files();
+    auto untracked = untracked_files();
+    modified.append(move(untracked));
+    return modified;
+}
+
+Vector<LexicalPath> GitRepo::staged_files() const
+{
+    auto raw_result = command("diff --cached --name-only");
+    if (raw_result.is_null())
+        return {};
+    return parse_files_list(raw_result);
+}
+
+Vector<LexicalPath> GitRepo::modified_files() const
+{
+    auto raw_result = command("ls-files --modified --exclude-standard");
+    if (raw_result.is_null())
+        return {};
+    return parse_files_list(raw_result);
+}
+
+Vector<LexicalPath> GitRepo::untracked_files() const
+{
+    auto raw_result = command("ls-files --others --exclude-standard");
+    if (raw_result.is_null())
+        return {};
+    return parse_files_list(raw_result);
+}
+
+Vector<LexicalPath> GitRepo::parse_files_list(const String& raw_result)
+{
+    auto lines = raw_result.split('\n');
+    Vector<LexicalPath> files;
+    for (const auto& line : lines) {
+        files.empend(line);
+    }
+    return files;
+}
+
+String GitRepo::command(const String& git_command) const
+{
+    return command_wrapper(git_command, m_repository_root);
+}
+
+String GitRepo::command_wrapper(const String& git_command, const LexicalPath& chdir)
+{
+    return Core::command(String::format("git %s", git_command.characters()), chdir);
+}
+
+bool GitRepo::git_is_installed()
+{
+    return !command_wrapper("--help", LexicalPath("/")).is_null();
+}
+
+bool GitRepo::git_repo_exists(const LexicalPath& repo_root)
+{
+    return !command_wrapper("status", repo_root).is_null();
+}
+
+bool GitRepo::stage(const LexicalPath& file)
+{
+    auto cmd = String::format("add %s", file.string().characters());
+    auto res = command(cmd);
+    return !res.is_null();
+}
+
+bool GitRepo::unstage(const LexicalPath& file)
+{
+    auto cmd = String::format("reset HEAD -- %s", file.string().characters());
+    return !command(cmd).is_null();
+}
+
+}
diff --git a/DevTools/HackStudio/Git/GitRepo.h b/DevTools/HackStudio/Git/GitRepo.h
new file mode 100644
index 0000000000..e80edcf39b
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitRepo.h
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/LexicalPath.h>
+#include <AK/Optional.h>
+#include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
+#include <AK/String.h>
+#include <AK/Vector.h>
+
+namespace HackStudio {
+
+class GitRepo final : public RefCounted<GitRepo> {
+public:
+    struct CreateResult {
+        enum class Type {
+            Success,
+            NoGitRepo,
+            GitProgramNotFound,
+        };
+        Type type;
+        RefPtr<GitRepo> repo;
+    };
+
+    static CreateResult try_to_create(const LexicalPath& repository_root);
+    static RefPtr<GitRepo> initialize_repository(const LexicalPath& repository_root);
+
+    Vector<LexicalPath> unstaged_files() const;
+    Vector<LexicalPath> staged_files() const;
+    bool stage(const LexicalPath& file);
+    bool unstage(const LexicalPath& file);
+
+private:
+    static String command_wrapper(const String& git_command, const LexicalPath& chdir);
+    static bool git_is_installed();
+    static bool git_repo_exists(const LexicalPath& repo_root);
+    static Vector<LexicalPath> parse_files_list(const String&);
+
+    explicit GitRepo(const LexicalPath& repository_root)
+        : m_repository_root(repository_root)
+    {
+    }
+
+    Vector<LexicalPath> modified_files() const;
+    Vector<LexicalPath> untracked_files() const;
+
+    String command(const String& git_command) const;
+
+    LexicalPath m_repository_root;
+};
+
+}
diff --git a/DevTools/HackStudio/Git/GitWidget.cpp b/DevTools/HackStudio/Git/GitWidget.cpp
new file mode 100644
index 0000000000..b7dc132b43
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitWidget.cpp
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "GitWidget.h"
+#include "GitFilesModel.h"
+#include <AK/LogStream.h>
+#include <LibGUI/Application.h>
+#include <LibGUI/BoxLayout.h>
+#include <LibGUI/Label.h>
+#include <LibGUI/MessageBox.h>
+#include <LibGUI/Model.h>
+#include <LibGUI/Painter.h>
+#include <LibGfx/Bitmap.h>
+
+namespace HackStudio {
+
+void GitWidget::stage_file(const LexicalPath& file)
+{
+    dbg() << "staging: " << file.string();
+    bool rc = m_git_repo->stage(file);
+    ASSERT(rc);
+    refresh();
+}
+
+void GitWidget::unstage_file(const LexicalPath& file)
+{
+    dbg() << "unstaging: " << file.string();
+    bool rc = m_git_repo->unstage(file);
+    ASSERT(rc);
+    refresh();
+}
+
+GitWidget::GitWidget(const LexicalPath& repo_root)
+    : m_repo_root(repo_root)
+{
+    set_layout<GUI::HorizontalBoxLayout>();
+
+    auto& unstaged = add<GUI::Widget>();
+    unstaged.set_layout<GUI::VerticalBoxLayout>();
+    auto& unstaged_label = unstaged.add<GUI::Label>();
+    unstaged_label.set_text("Unstaged");
+    unstaged_label.set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fixed);
+    unstaged_label.set_preferred_size(0, 20);
+    m_unstaged_files = unstaged.add<GitFilesView>(
+        [this](const auto& file) { stage_file(file); },
+        Gfx::Bitmap::load_from_file("/res/icons/16x16/plus.png").release_nonnull());
+
+    auto& staged = add<GUI::Widget>();
+    staged.set_layout<GUI::VerticalBoxLayout>();
+    auto& staged_label = staged.add<GUI::Label>();
+    staged_label.set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fixed);
+    staged_label.set_preferred_size(0, 20);
+    staged_label.set_text("Staged");
+    m_staged_files = staged.add<GitFilesView>(
+        [this](const auto& file) { unstage_file(file); },
+        Gfx::Bitmap::load_from_file("/res/icons/16x16/minus.png").release_nonnull());
+}
+
+void GitWidget::refresh()
+{
+    auto result = GitRepo::try_to_create(m_repo_root);
+    if (result.type == GitRepo::CreateResult::Type::Success) {
+        m_git_repo = result.repo;
+    } else if (result.type == GitRepo::CreateResult::Type::GitProgramNotFound) {
+        GUI::MessageBox::show(window(), "Please install the Git port", "Error", GUI::MessageBox::Type::Error);
+        return;
+    } else if (result.type == GitRepo::CreateResult::Type::NoGitRepo) {
+        auto decision = GUI::MessageBox::show(window(), "Create git repository?", "Git", GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
+        if (decision != GUI::Dialog::ExecResult::ExecYes)
+            return;
+        m_git_repo = GitRepo::initialize_repository(m_repo_root);
+    }
+
+    ASSERT(!m_git_repo.is_null());
+
+    m_unstaged_files->set_model(GitFilesModel::create(m_git_repo->unstaged_files()));
+    m_staged_files->set_model(GitFilesModel::create(m_git_repo->staged_files()));
+}
+
+};
diff --git a/DevTools/HackStudio/Git/GitWidget.h b/DevTools/HackStudio/Git/GitWidget.h
new file mode 100644
index 0000000000..1bff585c33
--- /dev/null
+++ b/DevTools/HackStudio/Git/GitWidget.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "GitFilesView.h"
+#include "GitRepo.h"
+#include <LibGUI/Forward.h>
+#include <LibGUI/Widget.h>
+
+namespace HackStudio {
+
+class GitWidget final : public GUI::Widget {
+    C_OBJECT(GitWidget)
+public:
+    virtual ~GitWidget() override {}
+
+    void refresh();
+
+private:
+    explicit GitWidget(const LexicalPath& repo_root);
+
+    void stage_file(const LexicalPath&);
+    void unstage_file(const LexicalPath&);
+
+    LexicalPath m_repo_root;
+    RefPtr<GitFilesView> m_unstaged_files;
+    RefPtr<GitFilesView> m_staged_files;
+    RefPtr<GitRepo> m_git_repo;
+};
+
+}
diff --git a/DevTools/HackStudio/Project.h b/DevTools/HackStudio/Project.h
index a7c90fd2b5..d1a3c31ac8 100644
--- a/DevTools/HackStudio/Project.h
+++ b/DevTools/HackStudio/Project.h
@@ -27,6 +27,7 @@
 #pragma once
 
 #include "ProjectFile.h"
+#include <AK/LexicalPath.h>
 #include <AK/Noncopyable.h>
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/OwnPtr.h>
@@ -61,6 +62,7 @@ public:
     String default_file() const;
     String name() const { return m_name; }
     String path() const { return m_path; }
+    String root_directory() const { return LexicalPath(m_path).dirname(); }
 
     template<typename Callback>
     void for_each_text_file(Callback callback) const
diff --git a/DevTools/HackStudio/main.cpp b/DevTools/HackStudio/main.cpp
index c07504e197..78d4764542 100644
--- a/DevTools/HackStudio/main.cpp
+++ b/DevTools/HackStudio/main.cpp
@@ -33,6 +33,7 @@
 #include "FindInFilesWidget.h"
 #include "FormEditorWidget.h"
 #include "FormWidget.h"
+#include "Git/GitWidget.h"
 #include "HackStudio.h"
 #include "Locator.h"
 #include "Project.h"
@@ -192,6 +193,7 @@ static int main_impl(int argc, char** argv)
     }
 
     Function<void()> update_actions;
+    Function<void()> on_action_tab_change;
 
     g_window = GUI::Window::construct();
     g_window->resize(840, 600);
@@ -501,7 +503,14 @@ static int main_impl(int argc, char** argv)
     s_action_tab_widget->set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fixed);
     s_action_tab_widget->set_preferred_size(0, 24);
 
-    s_action_tab_widget->on_change = [&](auto&) { update_actions(); };
+    s_action_tab_widget->on_change = [&](auto&) {
+        on_action_tab_change();
+
+        static bool first_time = true;
+        if (!first_time)
+            s_action_tab_widget->set_preferred_size(0, 200);
+        first_time = false;
+    };
 
     auto reveal_action_tab = [&](auto& widget) {
         if (s_action_tab_widget->preferred_size().height() < 200)
@@ -551,6 +560,8 @@ static int main_impl(int argc, char** argv)
     auto& terminal_wrapper = s_action_tab_widget->add_tab<TerminalWrapper>("Build", false);
     auto& debug_info_widget = s_action_tab_widget->add_tab<DebugInfoWidget>("Debug");
     auto& disassembly_widget = s_action_tab_widget->add_tab<DisassemblyWidget>("Disassembly");
+    auto& git_widget = s_action_tab_widget->add_tab<GitWidget>("Git", LexicalPath(g_project->root_directory()));
+    (void)git_widget;
 
     auto& locator = widget.add<Locator>();
 
@@ -700,7 +711,7 @@ static int main_impl(int argc, char** argv)
             auto widget = s_action_tab_widget->active_widget();
             if (!widget)
                 return false;
-            if (strcmp(widget->class_name(), "TerminalWrapper") != 0)
+            if (StringView { "TerminalWrapper" } != widget->class_name())
                 return false;
             if (!reinterpret_cast<TerminalWrapper*>(widget)->user_spawned())
                 return false;
@@ -711,6 +722,16 @@ static int main_impl(int argc, char** argv)
         remove_current_terminal_action->set_enabled(is_remove_terminal_enabled());
     };
 
+    on_action_tab_change = [&]() {
+        update_actions();
+        auto git_widget = s_action_tab_widget->active_widget();
+        if (!git_widget)
+            return;
+        if (StringView { "GitWidget" } != git_widget->class_name())
+            return;
+        reinterpret_cast<GitWidget*>(git_widget)->refresh();
+    };
+
     g_open_file = open_file;
 
     if (!argument_absolute_path.is_empty() && !argument_absolute_path.ends_with(".hsp"))
diff --git a/Libraries/LibGUI/ListView.cpp b/Libraries/LibGUI/ListView.cpp
index f6a15031a2..255b63d8fd 100644
--- a/Libraries/LibGUI/ListView.cpp
+++ b/Libraries/LibGUI/ListView.cpp
@@ -110,6 +110,48 @@ Gfx::IntPoint ListView::adjusted_position(const Gfx::IntPoint& position) const
     return position.translated(horizontal_scrollbar().value() - frame_thickness(), vertical_scrollbar().value() - frame_thickness());
 }
 
+void ListView::paint_list_item(Painter& painter, int row_index, int painted_item_index)
+{
+    bool is_selected_row = selection().contains_row(row_index);
+
+    int y = painted_item_index * item_height();
+
+    Color background_color;
+    if (is_selected_row) {
+        background_color = is_focused() ? palette().selection() : palette().inactive_selection();
+    } else {
+        Color row_fill_color = palette().color(background_role());
+        if (alternating_row_colors() && (painted_item_index % 2)) {
+            background_color = row_fill_color.darkened(0.8f);
+        } else {
+            background_color = row_fill_color;
+        }
+    }
+
+    Gfx::IntRect row_rect(0, y, content_width(), item_height());
+    painter.fill_rect(row_rect, background_color);
+    auto index = model()->index(row_index, m_model_column);
+    auto data = index.data();
+    auto font = font_for_index(index);
+    if (data.is_bitmap()) {
+        painter.blit(row_rect.location(), data.as_bitmap(), data.as_bitmap().rect());
+    } else if (data.is_icon()) {
+        if (auto bitmap = data.as_icon().bitmap_for_size(16))
+            painter.blit(row_rect.location(), *bitmap, bitmap->rect());
+    } else {
+        Color text_color;
+        if (is_selected_row)
+            text_color = is_focused() ? palette().selection_text() : palette().inactive_selection_text();
+        else
+            text_color = index.data(ModelRole::ForegroundColor).to_color(palette().color(foreground_role()));
+        auto text_rect = row_rect;
+        text_rect.move_by(horizontal_padding(), 0);
+        text_rect.set_width(text_rect.width() - horizontal_padding() * 2);
+        auto text_alignment = index.data(ModelRole::TextAlignment).to_text_alignment(Gfx::TextAlignment::CenterLeft);
+        painter.draw_text(text_rect, data.to_string(), font, text_alignment, text_color);
+    }
+}
+
 void ListView::paint_event(PaintEvent& event)
 {
     Frame::paint_event(event);
@@ -127,45 +169,7 @@ void ListView::paint_event(PaintEvent& event)
     int painted_item_index = 0;
 
     for (int row_index = 0; row_index < model()->row_count(); ++row_index) {
-        bool is_selected_row = selection().contains_row(row_index);
-
-        int y = painted_item_index * item_height();
-
-        Color background_color;
-        if (is_selected_row) {
-            background_color = is_focused() ? palette().selection() : palette().inactive_selection();
-        } else {
-            Color row_fill_color = palette().color(background_role());
-            if (alternating_row_colors() && (painted_item_index % 2)) {
-                background_color = row_fill_color.darkened(0.8f);
-            } else {
-                background_color = row_fill_color;
-            }
-        }
-
-        Gfx::IntRect row_rect(0, y, content_width(), item_height());
-        painter.fill_rect(row_rect, background_color);
-        auto index = model()->index(row_index, m_model_column);
-        auto data = index.data();
-        auto font = font_for_index(index);
-        if (data.is_bitmap()) {
-            painter.blit(row_rect.location(), data.as_bitmap(), data.as_bitmap().rect());
-        } else if (data.is_icon()) {
-            if (auto bitmap = data.as_icon().bitmap_for_size(16))
-                painter.blit(row_rect.location(), *bitmap, bitmap->rect());
-        } else {
-            Color text_color;
-            if (is_selected_row)
-                text_color = is_focused() ? palette().selection_text() : palette().inactive_selection_text();
-            else
-                text_color = index.data(ModelRole::ForegroundColor).to_color(palette().color(foreground_role()));
-            auto text_rect = row_rect;
-            text_rect.move_by(horizontal_padding(), 0);
-            text_rect.set_width(text_rect.width() - horizontal_padding() * 2);
-            auto text_alignment = index.data(ModelRole::TextAlignment).to_text_alignment(Gfx::TextAlignment::CenterLeft);
-            painter.draw_text(text_rect, data.to_string(), font, text_alignment, text_color);
-        }
-
+        paint_list_item(painter, row_index, painted_item_index);
         ++painted_item_index;
     };
 
diff --git a/Libraries/LibGUI/ListView.h b/Libraries/LibGUI/ListView.h
index 4f81364a51..f1accd47ae 100644
--- a/Libraries/LibGUI/ListView.h
+++ b/Libraries/LibGUI/ListView.h
@@ -62,9 +62,11 @@ public:
     virtual void move_cursor(CursorMovement, SelectionUpdate) override;
     void move_cursor_relative(int steps, SelectionUpdate);
 
-private:
+protected:
     ListView();
+    virtual void paint_list_item(Painter&, int row_index, int painted_item_index);
 
+private:
     virtual void did_update_model(unsigned flags) override;
     virtual void paint_event(PaintEvent&) override;
     virtual void keydown_event(KeyEvent&) override;