[desktop] Initial data manager prototype

Right now, all this adds is a small dialog to the Widgets frontend
showing the user how much space is taken up by their saves, shaders,
NAND, and mods. It also gives them the choice to clear these directories
(with 2x confirmation), OR open the directory in their system file
manager.

In the future, a lot more can be done with this concept. Notably, a
common import/export (a la android) could be added, the UI can obviously
be polished, etc. We could also add this to Android, but I don't think
common import/export is needed *for* Android, and should probably be
left in qt_common.

Signed-off-by: crueter <crueter@eden-emu.dev>

src/frontend_common/data_manager.cpp

@@ -0,0 +1,72 @@
+#include "data_manager.h"
+#include "common/assert.h"
+#include "common/fs/path_util.h"
+#include <filesystem>
+#include <fmt/format.h>
+
+namespace FrontendCommon::DataManager {
+
+namespace fs = std::filesystem;
+
+const std::string GetDataDir(DataDir dir)
+{
+    const fs::path nand_dir = Common::FS::GetEdenPath(Common::FS::EdenPath::NANDDir);
+
+    switch (dir) {
+    case DataDir::Saves:
+        return (nand_dir / "user" / "save" / "0000000000000000").string();
+    case DataDir::UserNand:
+        return (nand_dir / "user" / "Contents" / "registered").string();
+    case DataDir::SysNand:
+        return (nand_dir / "system").string();
+    case DataDir::Mods:
+        return Common::FS::GetEdenPathString(Common::FS::EdenPath::LoadDir);
+    case DataDir::Shaders:
+        return Common::FS::GetEdenPathString(Common::FS::EdenPath::ShaderDir);
+    default:
+        UNIMPLEMENTED();
+    }
+
+    return "";
+}
+
+u64 ClearDir(DataDir dir)
+{
+    fs::path data_dir = GetDataDir(dir);
+    u64 result = fs::remove_all(data_dir);
+
+    // mkpath at the end just so it actually exists
+    fs::create_directories(data_dir);
+    return result;
+}
+
+const std::string ReadableBytesSize(u64 size)
+{
+    static constexpr std::array units{"B", "KiB", "MiB", "GiB", "TiB", "PiB"};
+    if (size == 0) {
+        return "0 B";
+    }
+
+    const int digit_groups = (std::min) (static_cast<int>(std::log10(size) / std::log10(1024)),
+                                         static_cast<int>(units.size()));
+    return fmt::format("{:.1f} {}", size / std::pow(1024, digit_groups), units[digit_groups]);
+}
+
+u64 DataDirSize(DataDir dir)
+{
+    fs::path data_dir = GetDataDir(dir);
+    u64 size = 0;
+
+    if (!fs::exists(data_dir))
+        return 0;
+
+    for (const auto& entry : fs::recursive_directory_iterator(data_dir)) {
+        if (!entry.is_directory()) {
+            size += entry.file_size();
+        }
+    }
+
+    return size;
+}
+
+}