refactor drive letter

support/include/utils/windows.hpp

@@ -30,6 +30,12 @@ void create_console();
 
 void free_console();
 
+[[nodiscard]] auto get_available_drive_letter(char first = 'a')
+    -> std::optional<std::string_view>;
+
+[[nodiscard]] auto get_available_drive_letters(char first = 'a')
+    -> std::vector<std::string_view>;
+
 [[nodiscard]] auto get_local_app_data_directory() -> const std::string &;
 
 [[nodiscard]] auto get_last_error_code() -> DWORD;

support/src/utils/windows.cpp

@@ -29,6 +29,14 @@
 #include "utils/path.hpp"
 #include "utils/string.hpp"
 
+namespace {
+constexpr std::array<std::string_view, 26U> drive_letters{
+    "a:", "b:", "c:", "d:", "e:", "f:", "g:", "h:", "i:",
+    "j:", "k:", "l:", "m:", "n:", "o:", "p:", "q:", "r:",
+    "s:", "t:", "u:", "v:", "w:", "x:", "y:", "z:",
+};
+}
+
 namespace repertory::utils {
 void create_console() {
   if (::AllocConsole() == 0) {
@@ -61,6 +69,47 @@ void create_console() {
 
 void free_console() { ::FreeConsole(); }
 
+auto get_available_drive_letter(char first) -> std::optional<std::string_view> {
+  const auto *begin = std::ranges::find_if(
+      drive_letters, [first](auto &&val) { return val.at(0U) == first; });
+  if (begin == drive_letters.end()) {
+    begin = drive_letters.begin();
+  }
+
+  auto available =
+      std::ranges::find_if(begin, drive_letters.end(), [](auto &&val) -> bool {
+        return not utils::file::directory{utils::path::combine(val, {"\\"})}
+                       .exists();
+      });
+  if (available == drive_letters.end()) {
+    return std::nullopt;
+  }
+
+  return *available;
+}
+
+auto get_available_drive_letters(char first) -> std::vector<std::string_view> {
+  const auto *begin =
+      std::ranges::find_if(drive_letters, [first](auto &&val) -> bool {
+        return val.at(0U) == first;
+      });
+  if (begin == drive_letters.end()) {
+    begin = drive_letters.begin();
+  }
+
+  return std::accumulate(
+      begin, drive_letters.end(), std::vector<std::string_view>(),
+      [](auto &&vec, auto &&letter) -> auto {
+        if (utils::file::directory{utils::path::combine(letter, {"\\"})}
+                .exists()) {
+          return vec;
+        }
+
+        vec.emplace_back(letter);
+        return vec;
+      });
+}
+
 auto get_last_error_code() -> DWORD { return ::GetLastError(); }
 
 auto get_local_app_data_directory() -> const std::string & {