5 files changed, 144 insertions, 2 deletions
diff --git a/lib/nes/app/application.cc b/lib/nes/app/application.cc
index 521cc40..622fdf7 100644
--- a/lib/nes/app/application.cc
+++ b/lib/nes/app/application.cc
@@ -1,6 +1,5 @@
 #include "nes/app/application.hh"
 #include "nes/app/input/input-device-keyboard.hh"
-#include "nes/app/input/input-device-controller.hh"
 #include "nes/app/ui/screen.hh"
 #include "nes/app/graphics/renderer.hh"
 #include "nes/app/action.hh"
@@ -57,6 +56,7 @@ namespace nes::app
 		, screen_error_{ keyboard }
 		, screen_confirm_quit_{ keyboard }
 		, screen_prompt_key_{ keyboard }
+		, screen_file_viewer_{ keyboard, file_browser }
 	{
 		display_.visible_screen = &screen_title_;
 	}
@@ -193,6 +193,14 @@ namespace nes::app
 			}
 			case action::type::view_file:
 			{
+				if (auto const s = screen_file_viewer_.load(a.get_file_name()); s != status::success)
+				{
+					show_error("Unable to open file", s);
+				}
+				else
+				{
+					display_.visible_popup = &screen_file_viewer_;
+				}
 				break;
 			}
 			case action::type::show_error:
diff --git a/lib/nes/app/application.hh b/lib/nes/app/application.hh
index 5ed7413..cee99ed 100644
--- a/lib/nes/app/application.hh
+++ b/lib/nes/app/application.hh
@@ -8,6 +8,7 @@
 #include "nes/app/ui/screen-error.hh"
 #include "nes/app/ui/screen-confirm-quit.hh"
 #include "nes/app/ui/screen-prompt-key.hh"
+#include "nes/app/ui/screen-file-viewer.hh"
 #include "nes/app/preferences.hh"
 #include "nes/sys/nes.hh"
 #include "nes/common/containers/box.hh"
@@ -66,6 +67,7 @@ namespace nes::app
 		screen_error screen_error_;
 		screen_confirm_quit screen_confirm_quit_;
 		screen_prompt_key screen_prompt_key_;
+		screen_file_viewer screen_file_viewer_;
 
 	public:
 		explicit application(display&, input_device_keyboard&, file_browser&);
diff --git a/lib/nes/app/ui/CMakeLists.txt b/lib/nes/app/ui/CMakeLists.txt
index 1f8d138..5bdad70 100644
--- a/lib/nes/app/ui/CMakeLists.txt
+++ b/lib/nes/app/ui/CMakeLists.txt
@@ -16,4 +16,6 @@ target_sources(
 		screen-confirm-quit.hh
 		screen-confirm-quit.cc
 		screen-prompt-key.hh
-		screen-prompt-key.cc)
-\ No newline at end of file
+		screen-prompt-key.cc
+		screen-file-viewer.hh
+		screen-file-viewer.cc)
diff --git a/lib/nes/app/ui/screen-file-viewer.cc b/lib/nes/app/ui/screen-file-viewer.cc
new file mode 100644
index 0000000..b7551ba
--- /dev/null
+++ b/lib/nes/app/ui/screen-file-viewer.cc
@@ -0,0 +1,96 @@
+#include "nes/app/ui/screen-file-viewer.hh"
+#include "nes/app/file-browser.hh"
+#include "nes/app/graphics/renderer.hh"
+#include "nes/app/graphics/color.hh"
+#include "nes/app/input/input-device-keyboard.hh"
+#include "nes/common/containers/span.hh"
+
+namespace nes::app
+{
+	screen_file_viewer::screen_file_viewer(input_device_keyboard& keyboard, file_browser& file_browser)
+		: keyboard_{ keyboard }
+		, file_browser_{ file_browser }
+	{
+	}
+
+	auto screen_file_viewer::load(string_view const file_name) -> status
+	{
+		auto length = u32{ 0 };
+		if (auto const s = file_browser_.load(file_name, buffer_, &length); s != status::success) { return s; }
+
+		// Do some magical text wrapping
+		auto const data = span{ buffer_ }.subspan(0, length);
+		auto const src = string_view{ data.unsafe_bitcast<char const>() };
+		line_count_ = 0;
+		auto line_pos = u32{ 0 };
+		auto line_start = u32{ 0 };
+		auto const end_line = [&](bool const force)
+		{
+			auto const l = src.substring(line_start, line_pos);
+			if (l.is_empty() && !force) { return; }
+
+			if (line_count_ < max_line_count)
+			{
+				lines_[line_count_] = l;
+				line_count_ += 1;
+			}
+			line_pos = 0;
+		};
+		for (auto i = u32{ 0 }; i < src.get_length(); ++i)
+		{
+			auto const c = src[i];
+			if (c == '\n' || line_pos == line_length)
+			{
+				end_line(c == '\n');
+				line_pos = 0;
+				line_start = i + 1;
+			}
+			else if (c == '\r')
+			{
+				// ignore
+			}
+			else
+			{
+				line_pos += 1;
+			}
+		}
+		end_line(false);
+
+		return status::success;
+	}
+
+	auto screen_file_viewer::render(renderer& renderer) -> void
+	{
+		auto const width = line_length + 4;
+		auto const height = line_count_ + 7;
+		auto const y = (renderer::height - height) / 2 + 2;
+		renderer.render_rect(2, y, width, height, color::background_secondary);
+		renderer.render_border(2, y, width, height, color::foreground_primary);
+
+		auto const attrs = text_attributes{}
+			.set_alignment(text_alignment::left)
+			.set_max_width(line_length);
+		for (auto i = u32{ 0 }; i < line_count_; ++i)
+		{
+			renderer.render_text(4, y + 2 + i, lines_[i], color::foreground_primary, attrs);
+		}
+		auto const button_attrs = text_attributes{}
+			.set_alignment(text_alignment::center)
+			.set_ellipsize_mode(ellipsize_mode::end)
+			.set_max_width(26);
+		renderer.render_text(16, y + height - 3, "> Close <", color::accent_primary, button_attrs);
+	}
+
+	auto screen_file_viewer::process_events() -> action
+	{
+		while (auto const event = keyboard_.poll_event())
+		{
+			if (event == input_event::key_down(key::escape) || event == input_event::key_down(key::enter))
+			{
+				return action::close_popup();
+			}
+		}
+
+		return action{};
+	}
+} // namespace nes::app
diff --git a/lib/nes/app/ui/screen-file-viewer.hh b/lib/nes/app/ui/screen-file-viewer.hh
new file mode 100644
index 0000000..ed01e6f
--- /dev/null
+++ b/lib/nes/app/ui/screen-file-viewer.hh
@@ -0,0 +1,34 @@
+#pragma once
+
+#include "nes/common/types.hh"
+#include "nes/common/containers/string-view.hh"
+#include "nes/app/ui/screen.hh"
+#include "nes/common/containers/string-view.hh"
+
+namespace nes::app
+{
+	class input_device_keyboard;
+	class file_browser;
+
+	/// An popup showing the contents of a file.
+	class screen_file_viewer final : public screen
+	{
+		static constexpr auto line_length = u32{ 24 };
+		static constexpr auto buffer_length = u32{ 1024 };
+		static constexpr auto max_line_count = u32{ 16 };
+
+		input_device_keyboard& keyboard_;
+		file_browser& file_browser_;
+		u8 buffer_[buffer_length];
+		string_view lines_[max_line_count];
+		u32 line_count_{ 0 };
+
+	public:
+		explicit screen_file_viewer(input_device_keyboard&, file_browser&);
+
+		auto load(string_view file_name) -> status;
+
+		auto render(renderer&) -> void override;
+		auto process_events() -> action override;
+	};
+} // namespace nes::app