/*

-----------------------------------------------------------------------
# Taken from https://github.com/AirGuanZ/imgui-filebrowser
-----------------------------------------------------------------------

MIT License

Copyright (c) 2019-2025 Zhuang Guan

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

#pragma once

#include <algorithm>
#include <array>
#include <cctype>
#include <cstring>
#include <filesystem>
#include <set>
#include <string>
#include <string_view>
#include <vector>

#ifndef IMGUI_VERSION
#   error "include imgui.h before this header"
#endif

using ImGuiFileBrowserFlags = std::uint32_t;

enum ImGuiFileBrowserFlags_ : std::uint32_t
{
    ImGuiFileBrowserFlags_SelectDirectory       = 1 << 0,  // select directory instead of regular file
    ImGuiFileBrowserFlags_EnterNewFilename      = 1 << 1,  // allow user to enter new filename when selecting regular file
    ImGuiFileBrowserFlags_NoModal               = 1 << 2,  // file browsing window is modal by default. specify this to use a popup window
    ImGuiFileBrowserFlags_NoTitleBar            = 1 << 3,  // hide window title bar
    ImGuiFileBrowserFlags_NoStatusBar           = 1 << 4,  // hide status bar at the bottom of browsing window
    ImGuiFileBrowserFlags_CloseOnEsc            = 1 << 5,  // close file browser when pressing 'ESC'
    ImGuiFileBrowserFlags_CreateNewDir          = 1 << 6,  // allow user to create new directory
    ImGuiFileBrowserFlags_MultipleSelection     = 1 << 7,  // allow user to select multiple files. this will hide ImGuiFileBrowserFlags_EnterNewFilename
    ImGuiFileBrowserFlags_HideRegularFiles      = 1 << 8,  // hide regular files when ImGuiFileBrowserFlags_SelectDirectory is enabled
    ImGuiFileBrowserFlags_ConfirmOnEnter        = 1 << 9,  // confirm selection when pressing 'ENTER'
    ImGuiFileBrowserFlags_SkipItemsCausingError = 1 << 10, // when entering a new directory, any error will interrupt the process, causing the file browser to fall back to the working directory.
                                                           // with this flag, if an error is caused by a specific item in the directory, that item will be skipped, allowing the process to continue.
    ImGuiFileBrowserFlags_EditPathString        = 1 << 11, // allow user to directly edit the whole path string
};

namespace ImGui
{
    class FileBrowser
    {
    public:

        explicit FileBrowser(
            ImGuiFileBrowserFlags flags = 0,
            std::filesystem::path defaultDirectory = std::filesystem::current_path());

        FileBrowser(const FileBrowser &copyFrom);

        FileBrowser &operator=(const FileBrowser &copyFrom);

        // set the window position (in pixels)
        // default is centered
        void SetWindowPos(int posX, int posY) noexcept;

        // set the window size (in pixels)
        // default is (700, 450)
        void SetWindowSize(int width, int height) noexcept;

        // set the window title text
        void SetTitle(std::string title);

        // open the browsing window
        void Open();

        // close the browsing window
        void Close();

        // the browsing window is opened or not
        bool IsOpened() const noexcept;

        // display the browsing window if opened
        void Display();

        // returns true when there is a selected filename
        bool HasSelected() const noexcept;

        // set current browsing directory
        bool SetDirectory(const std::filesystem::path &dir = std::filesystem::current_path());

        // legacy interface. use SetDirectory instead.
        bool SetPwd(const std::filesystem::path &dir = std::filesystem::current_path())
        {
            return SetDirectory(dir);
        }

        // get current browsing directory
        const std::filesystem::path &GetDirectory() const noexcept;

        // legacy interface. use GetDirectory instead.
        const std::filesystem::path &GetPwd() const noexcept
        {
            return GetDirectory();
        }

        // returns selected filename. make sense only when HasSelected returns true
        // when ImGuiFileBrowserFlags_MultipleSelection is enabled, only one of
        // selected filename will be returned
        std::filesystem::path GetSelected() const;

        // returns all selected filenames.
        // when ImGuiFileBrowserFlags_MultipleSelection is enabled, use this
        // instead of GetSelected
        std::vector<std::filesystem::path> GetMultiSelected() const;

        // set selected filename to empty
        void ClearSelected();

        // (optional) set file type filters. eg. { ".h", ".cpp", ".hpp" }
        // ".*" matches any file types
        void SetTypeFilters(const std::vector<std::string> &typeFilters);

        // set currently applied type filter
        // default value is 0 (the first type filter)
        void SetCurrentTypeFilterIndex(int index);

        // when ImGuiFileBrowserFlags_EnterNewFilename is set
        // this function will pre-fill the input dialog with a filename.
        void SetInputName(std::string_view input);

    private:

        template <class Functor>
        struct ScopeGuard
        {
            ScopeGuard(Functor&& t) : func(std::move(t)) { }

            ~ScopeGuard() { func(); }

        private:

            Functor func;
        };

        struct FileRecord
        {
            bool                  isDir = false;
            std::filesystem::path name;
            std::string           showName;
            std::filesystem::path extension;
        };

        static std::string ToLower(const std::string &s);

        void ToolTip(const std::string_view &s);

        void UpdateFileRecords();

        void SetCurrentDirectoryUncatched(const std::filesystem::path &pwd);

        bool SetCurrentDirectoryInternal(
            const std::filesystem::path &dir,
            const std::filesystem::path &preferredFallback);

        bool IsExtensionMatched(const std::filesystem::path &extension) const;

        void ClearRangeSelectionState();

        static void AssignToArrayStyleString(std::vector<char> &arr, std::string_view content);

        static int ExpandInputBuffer(ImGuiInputTextCallbackData *callbackData);

#ifdef _WIN32
        static std::uint32_t GetDrivesBitMask();
#endif

        // for c++17 compatibility

#if defined(__cpp_lib_char8_t)
        static std::string u8StrToStr(std::u8string s);
#endif
        static std::string u8StrToStr(std::string s);

        static std::filesystem::path u8StrToPath(const char *str);

        int width_;
        int height_;
        int posX_;
        int posY_;
        ImGuiFileBrowserFlags flags_;
        std::filesystem::path defaultDirectory_;

        std::string title_;
        std::string openLabel_;

        bool shouldOpen_;
        bool shouldClose_;
        bool isOpened_;
        bool isOk_;
        bool isPosSet_;

        std::string statusStr_;

        std::vector<std::string> typeFilters_;
        unsigned int             typeFilterIndex_;
        bool                     hasAllFilter_;

        std::filesystem::path   currentDirectory_;
        std::vector<FileRecord> fileRecords_;

        unsigned int                    rangeSelectionStart_; // enable range selection when shift is pressed
        std::set<std::filesystem::path> selectedFilenames_;

        std::string       openNewDirLabel_;
        std::vector<char> newDirNameBuffer_;
        std::vector<char> inputNameBuffer_;
        std::string       customizedInputName_;

        bool              editDir_;
        bool              setFocusToEditDir_;
        std::vector<char> currDirBuffer_;

#ifdef _WIN32
        std::uint32_t drives_;
#endif
    };
} // namespace ImGui

inline ImGui::FileBrowser::FileBrowser(ImGuiFileBrowserFlags flags, std::filesystem::path defaultDirectory)
    : width_(700)
    , height_(450)
    , posX_(0)
    , posY_(0)
    , flags_(flags)
    , defaultDirectory_(std::move(defaultDirectory))
    , shouldOpen_(false)
    , shouldClose_(false)
    , isOpened_(false)
    , isOk_(false)
    , isPosSet_(false)
    , rangeSelectionStart_(0)
    , editDir_(false)
    , setFocusToEditDir_(false)
{
    assert(!((flags_ & ImGuiFileBrowserFlags_SelectDirectory) && (flags_ & ImGuiFileBrowserFlags_EnterNewFilename)) &&
           "'EnterNewFilename' doesn't work when 'SelectDirectory' is enabled");
    if(flags_ & ImGuiFileBrowserFlags_CreateNewDir)
    {
        newDirNameBuffer_.resize(32, '\0');
    }

    SetTitle("file browser");
    SetDirectory(defaultDirectory_);

    typeFilters_.clear();
    typeFilterIndex_ = 0;
    hasAllFilter_ = false;

#ifdef _WIN32
    drives_ = GetDrivesBitMask();
#endif
}

inline ImGui::FileBrowser::FileBrowser(const FileBrowser &copyFrom)
    : FileBrowser()
{
    *this = copyFrom;
}

inline ImGui::FileBrowser &ImGui::FileBrowser::operator=(
    const FileBrowser &copyFrom)
{
    width_  = copyFrom.width_;
    height_ = copyFrom.height_;

    posX_ = copyFrom.posX_;
    posY_ = copyFrom.posY_;

    flags_ = copyFrom.flags_;
    SetTitle(copyFrom.title_);

    shouldOpen_  = copyFrom.shouldOpen_;
    shouldClose_ = copyFrom.shouldClose_;
    isOpened_    = copyFrom.isOpened_;
    isOk_        = copyFrom.isOk_;
    isPosSet_    = copyFrom.isPosSet_;

    statusStr_ = "";

    typeFilters_     = copyFrom.typeFilters_;
    typeFilterIndex_ = copyFrom.typeFilterIndex_;
    hasAllFilter_    = copyFrom.hasAllFilter_;

    selectedFilenames_   = copyFrom.selectedFilenames_;
    rangeSelectionStart_ = copyFrom.rangeSelectionStart_;

    currentDirectory_ = copyFrom.currentDirectory_;
    fileRecords_      = copyFrom.fileRecords_;

    openNewDirLabel_     = copyFrom.openNewDirLabel_;
    newDirNameBuffer_    = copyFrom.newDirNameBuffer_;
    inputNameBuffer_     = copyFrom.inputNameBuffer_;
    customizedInputName_ = copyFrom.customizedInputName_;

    editDir_ = copyFrom.editDir_;
    currDirBuffer_ = copyFrom.currDirBuffer_;

#ifdef _WIN32
    drives_ = copyFrom.drives_;
#endif

    return *this;
}

inline void ImGui::FileBrowser::SetWindowPos(int posX, int posY) noexcept
{
    posX_ = posX;
    posY_ = posY;
    isPosSet_ = true;
}

inline void ImGui::FileBrowser::SetWindowSize(int width, int height) noexcept
{
    assert(width > 0 && height > 0);
    width_  = width;
    height_ = height;
}

inline void ImGui::FileBrowser::SetTitle(std::string title)
{
    title_ = std::move(title);

    const std::string thisPtrStr = std::to_string(reinterpret_cast<size_t>(this));
    openLabel_ = title_ + "##filebrowser_" + thisPtrStr;
    openNewDirLabel_ = "new dir##new_dir_" + thisPtrStr;
}

inline void ImGui::FileBrowser::Open()
{
    UpdateFileRecords();
    ClearSelected();
    statusStr_ = std::string();
    shouldOpen_ = true;
    shouldClose_ = false;
    if((flags_ & ImGuiFileBrowserFlags_EnterNewFilename) && !customizedInputName_.empty())
    {
        AssignToArrayStyleString(inputNameBuffer_, customizedInputName_);
        selectedFilenames_ = { u8StrToPath(inputNameBuffer_.data()) };
    }
}

inline void ImGui::FileBrowser::Close()
{
    ClearSelected();
    statusStr_ = std::string();
    shouldClose_ = true;
    shouldOpen_ = false;
}

inline bool ImGui::FileBrowser::IsOpened() const noexcept
{
    return isOpened_;
}

inline void ImGui::FileBrowser::Display()
{
    PushID(this);
    ScopeGuard exitThis([this]
    {
        shouldOpen_ = false;
        shouldClose_ = false;
        PopID();
    });

    if(shouldOpen_)
    {
        OpenPopup(openLabel_.c_str());
    }
    isOpened_ = false;

    // open the popup window

    if(shouldOpen_ && (flags_ & ImGuiFileBrowserFlags_NoModal))
    {
        if(isPosSet_)
        {
            SetNextWindowPos(ImVec2(static_cast<float>(posX_), static_cast<float>(posY_)));
        }
        SetNextWindowSize(ImVec2(static_cast<float>(width_), static_cast<float>(height_)));
    }
    else
    {
        if(isPosSet_)
        {
            SetNextWindowPos(ImVec2(static_cast<float>(posX_), static_cast<float>(posY_)), ImGuiCond_FirstUseEver);
        }
        SetNextWindowSize(ImVec2(static_cast<float>(width_), static_cast<float>(height_)), ImGuiCond_FirstUseEver);
    }
    if(flags_ & ImGuiFileBrowserFlags_NoModal)
    {
        if(!BeginPopup(openLabel_.c_str()))
        {
            return;
        }
    }
    else if(!BeginPopupModal(openLabel_.c_str(), nullptr,
                             flags_ & ImGuiFileBrowserFlags_NoTitleBar ? ImGuiWindowFlags_NoTitleBar : 0))
    {
        return;
    }

    isOpened_ = true;
    ScopeGuard endPopup([] { EndPopup(); });

    std::filesystem::path newDir; bool shouldSetNewDir = false;

    if(editDir_)
    {
        if(setFocusToEditDir_) // Automatically set the text box to be focused on appearing
        {
            SetKeyboardFocusHere();
        }

        PushItemWidth(-1);
        const bool enter = InputText(
            "##directory", currDirBuffer_.data(), currDirBuffer_.size(),
            ImGuiInputTextFlags_CallbackResize | ImGuiInputTextFlags_EnterReturnsTrue | ImGuiInputTextFlags_AutoSelectAll,
            ExpandInputBuffer, &currDirBuffer_);
        PopItemWidth();

        if(!IsItemActive() && !setFocusToEditDir_)
        {
            editDir_ = false;
        }
        setFocusToEditDir_ = false;

        if(enter)
        {
            std::filesystem::path enteredDir = u8StrToPath(currDirBuffer_.data());
            if(is_directory(enteredDir))
            {
                newDir = std::move(enteredDir);
                shouldSetNewDir = true;
            }
            else if(is_directory(enteredDir.parent_path()))
            {
                newDir = enteredDir.parent_path();
                shouldSetNewDir = true;
            }
            else
            {
                statusStr_ = "[" + std::string(currDirBuffer_.data()) + "] is not a valid directory";
            }
        }
    }
    else
    {
        // display elements in pwd

#ifdef _WIN32
        const char currentDrive = static_cast<char>(currentDirectory_.c_str()[0]);
        const char driveStr[] = { currentDrive, ':', '\0' };

        PushItemWidth(4 * GetFontSize());
        if(BeginCombo("##select_drive", driveStr))
        {
            ScopeGuard guard([&] { EndCombo(); });

            for(int i = 0; i < 26; ++i)
            {
                if(!(drives_ & (1 << i)))
                {
                    continue;
                }

                const char driveCh = static_cast<char>('A' + i);
                const char selectableStr[] = { driveCh, ':', '\0' };
                const bool selected = currentDrive == driveCh;

                if(Selectable(selectableStr, selected) && !selected)
                {
                    char newPwd[] = { driveCh, ':', '\\', '\0' };
                    SetDirectory(newPwd);
                }
            }
        }
        PopItemWidth();

        SameLine();
#endif

        int secIdx = 0, newDirLastSecIdx = -1;
        for(const auto &sec : currentDirectory_)
        {
#ifdef _WIN32
            if(secIdx == 1)
            {
                ++secIdx;
                continue;
            }
#endif

            PushID(secIdx);
            if(secIdx > 0)
            {
                SameLine();
            }
            if(SmallButton(u8StrToStr(sec.u8string()).c_str()))
            {
                newDirLastSecIdx = secIdx;
            }
            PopID();

            ++secIdx;
        }

        if(newDirLastSecIdx >= 0)
        {
            int i = 0;
            std::filesystem::path dstDir;
            for(const auto &sec : currentDirectory_)
            {
                if(i++ > newDirLastSecIdx)
                {
                    break;
                }
                dstDir /= sec;
            }

#ifdef _WIN32
            if(newDirLastSecIdx == 0)
            {
                dstDir /= "\\";
            }
#endif

            SetDirectory(dstDir);
        }

        if(flags_ & ImGuiFileBrowserFlags_EditPathString)
        {
            SameLine();

            if(SmallButton("#"))
            {
                const auto currDirStr = u8StrToStr(currentDirectory_.u8string());
                currDirBuffer_.resize(currDirStr.size() + 1);
                std::memcpy(currDirBuffer_.data(), currDirStr.data(), currDirStr.size());
                currDirBuffer_.back() = '\0';

                editDir_ = true;
                setFocusToEditDir_ = true;
            }
            else
            {
                ToolTip("Edit the current path");
            }
        }
    }

    SameLine();
    if(SmallButton("*"))
    {
#ifdef _WIN32
        drives_ = GetDrivesBitMask();
#endif

        UpdateFileRecords();

        std::set<std::filesystem::path> newSelectedFilenames;
        for(auto &name : selectedFilenames_)
        {
            const auto it = std::find_if(
                fileRecords_.begin(), fileRecords_.end(), [&](const FileRecord &record)
                {
                    return name == record.name;
                });
            if(it != fileRecords_.end())
            {
                newSelectedFilenames.insert(name);
            }
        }

        if((flags_ & ImGuiFileBrowserFlags_EnterNewFilename) && !inputNameBuffer_.empty() && inputNameBuffer_[0])
        {
            newSelectedFilenames.insert(u8StrToPath(inputNameBuffer_.data()));
        }
    }
    else
    {
        ToolTip("Refresh");
    }

    bool focusOnInputText = false;
    if(flags_ & ImGuiFileBrowserFlags_CreateNewDir)
    {
        SameLine();
        if(SmallButton("+"))
        {
            OpenPopup(openNewDirLabel_.c_str());
            newDirNameBuffer_[0] = '\0';
        }
        else
        {
            ToolTip("Create a new directory");
        }

        if(BeginPopup(openNewDirLabel_.c_str()))
        {
            ScopeGuard endNewDirPopup([] { EndPopup(); });

            InputText(
                "name", newDirNameBuffer_.data(), newDirNameBuffer_.size(),
                ImGuiInputTextFlags_CallbackResize, ExpandInputBuffer, &newDirNameBuffer_);
            focusOnInputText |= IsItemFocused();
            SameLine();

            if(Button("ok") && newDirNameBuffer_[0] != '\0')
            {
                ScopeGuard closeNewDirPopup([] { CloseCurrentPopup(); });
                if(create_directory(currentDirectory_ / u8StrToPath(newDirNameBuffer_.data())))
                {
                    UpdateFileRecords();
                }
                else
                {
                    statusStr_ = "failed to create " + std::string(newDirNameBuffer_.data());
                }
            }
        }
    }

    // browse files in a child window

    float reserveHeight = GetFrameHeightWithSpacing();
    if(flags_ & ImGuiFileBrowserFlags_EnterNewFilename)
    {
        reserveHeight += GetFrameHeightWithSpacing();
    }

    {
        BeginChild("ch", ImVec2(0, -reserveHeight), true,
                   (flags_ & ImGuiFileBrowserFlags_NoModal) ? ImGuiWindowFlags_AlwaysHorizontalScrollbar : 0);
        ScopeGuard endChild([] { EndChild(); });

        const bool shouldHideRegularFiles =
            (flags_ & ImGuiFileBrowserFlags_HideRegularFiles) && (flags_ & ImGuiFileBrowserFlags_SelectDirectory);

        for(unsigned int rscIndex = 0; rscIndex < fileRecords_.size(); ++rscIndex)
        {
            const auto &rsc = fileRecords_[rscIndex];
            if(!rsc.isDir && shouldHideRegularFiles)
            {
                continue;
            }
            if(!rsc.isDir && !IsExtensionMatched(rsc.extension))
            {
                continue;
            }
            if(!rsc.name.empty() && rsc.name.c_str()[0] == '$')
            {
                continue;
            }

            const bool selected = selectedFilenames_.find(rsc.name) != selectedFilenames_.end();
            
#if IMGUI_VERSION_NUM >= 19100
            const ImGuiSelectableFlags selectableFlag = ImGuiSelectableFlags_NoAutoClosePopups;
#else
            const ImGuiSelectableFlags selectableFlag = ImGuiSelectableFlags_DontClosePopups;
#endif

            if(Selectable(rsc.showName.c_str(), selected, selectableFlag))
            {
                const bool wantDir = flags_ & ImGuiFileBrowserFlags_SelectDirectory;
                const bool canSelect = rsc.name != ".." && rsc.isDir == wantDir;
                const bool rangeSelect =
                    canSelect && GetIO().KeyShift &&
                    rangeSelectionStart_ < fileRecords_.size() &&
                    (flags_ & ImGuiFileBrowserFlags_MultipleSelection) &&
                    IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows);
                const bool multiSelect =
                    !rangeSelect && GetIO().KeyCtrl &&
                    (flags_ & ImGuiFileBrowserFlags_MultipleSelection) &&
                    IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows);

                if(rangeSelect)
                {
                    const unsigned int first = (std::min)(rangeSelectionStart_, rscIndex);
                    const unsigned int last = (std::max)(rangeSelectionStart_, rscIndex);
                    selectedFilenames_.clear();
                    for(unsigned int i = first; i <= last; ++i)
                    {
                        if(fileRecords_[i].isDir != wantDir)
                        {
                            continue;
                        }
                        if(!wantDir && !IsExtensionMatched(fileRecords_[i].extension))
                        {
                            continue;
                        }
                        selectedFilenames_.insert(fileRecords_[i].name);
                    }
                }
                else if(selected)
                {
                    if(!multiSelect)
                    {
                        selectedFilenames_ = { rsc.name };
                        rangeSelectionStart_ = rscIndex;
                    }
                    else
                    {
                        selectedFilenames_.erase(rsc.name);
                    }
                    if(flags_ & ImGuiFileBrowserFlags_EnterNewFilename)
                    {
                        AssignToArrayStyleString(inputNameBuffer_, "");
                    }
                }
                else if(canSelect)
                {
                    if(multiSelect)
                    {
                        selectedFilenames_.insert(rsc.name);
                    }
                    else
                    {
                        selectedFilenames_ = { rsc.name };
                    }
                    if(flags_ & ImGuiFileBrowserFlags_EnterNewFilename)
                    {
                        const auto rscName = u8StrToStr(rsc.name.u8string());
                        AssignToArrayStyleString(inputNameBuffer_, rscName);
                    }
                    rangeSelectionStart_ = rscIndex;
                }
            }

            if(IsMouseDoubleClicked(ImGuiMouseButton_Left) && IsItemHovered(ImGuiHoveredFlags_None))
            {
                if(rsc.isDir)
                {
                    shouldSetNewDir = true;
                    newDir = (rsc.name != "..") ? (currentDirectory_ / rsc.name) : currentDirectory_.parent_path();
                }
                else if(!(flags_ & ImGuiFileBrowserFlags_SelectDirectory))
                {
                    selectedFilenames_ = { rsc.name };
                    isOk_ = true;
                    CloseCurrentPopup();
                }
            }
            else if(IsKeyPressed(ImGuiKey_GamepadFaceDown) && IsItemHovered()) 
            {
                if(rsc.isDir)
                {
                    shouldSetNewDir = true;
                    newDir = (rsc.name != "..") ? (currentDirectory_ / rsc.name) : currentDirectory_.parent_path();
                    SetKeyboardFocusHere(-1);
                }
                else if(!(flags_ & ImGuiFileBrowserFlags_SelectDirectory))
                {
                    selectedFilenames_ = { rsc.name };
                    isOk_ = true;
                    CloseCurrentPopup();
                }
            }
        }
    }

    if(shouldSetNewDir)
    {
        SetDirectory(newDir);
    }

    if(flags_ & ImGuiFileBrowserFlags_EnterNewFilename)
    {
        PushID(this);
        ScopeGuard popTextID([] { PopID(); });

        if(inputNameBuffer_.empty())
        {
            inputNameBuffer_.resize(1, '\0');
        }

        PushItemWidth(-1);
        if(InputText(
            "", inputNameBuffer_.data(), inputNameBuffer_.size(),
            ImGuiInputTextFlags_CallbackResize, ExpandInputBuffer, &inputNameBuffer_))
        {
            if(inputNameBuffer_[0] != '\0')
            {
                selectedFilenames_ = { u8StrToPath(inputNameBuffer_.data()) };
            }
            else
            {
                selectedFilenames_.clear();
            }
        }
        focusOnInputText |= IsItemFocused();
        PopItemWidth();
    }

    if(!focusOnInputText && !editDir_)
    {
        const bool selectAll = (flags_ & ImGuiFileBrowserFlags_MultipleSelection) &&
                               IsKeyPressed(ImGuiKey_A) && (IsKeyDown(ImGuiKey_LeftCtrl) ||
                               IsKeyDown(ImGuiKey_RightCtrl));
        if(selectAll)
        {
            const bool needDir = flags_ & ImGuiFileBrowserFlags_SelectDirectory;
            selectedFilenames_.clear();
            for(size_t i = 1; i < fileRecords_.size(); ++i)
            {
                auto &record = fileRecords_[i];
                if(record.isDir == needDir &&
                   (needDir || IsExtensionMatched(record.extension)))
                {
                    selectedFilenames_.insert(record.name);
                }
            }
        }
    }

    const bool isEnterPressed =
        (flags_ & ImGuiFileBrowserFlags_ConfirmOnEnter) &&
        IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows) &&
        IsKeyPressed(ImGuiKey_Enter);
    if(!(flags_ & ImGuiFileBrowserFlags_SelectDirectory))
    {
        BeginDisabled(selectedFilenames_.empty());
        const bool ok = Button("ok");
        EndDisabled();
        if((ok || isEnterPressed) && !selectedFilenames_.empty())
        {
            isOk_ = true;
            CloseCurrentPopup();
        }
    }
    else
    {
        if(Button(" ok ") || isEnterPressed)
        {
            isOk_ = true;
            CloseCurrentPopup();
        }
    }

    SameLine();

    const bool shouldClose =
        Button("cancel") || shouldClose_ ||
        ((flags_ & ImGuiFileBrowserFlags_CloseOnEsc) &&
        IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows) &&
        IsKeyPressed(ImGuiKey_Escape));
    if(shouldClose)
    {
        CloseCurrentPopup();
    }

    if(!statusStr_.empty() && !(flags_ & ImGuiFileBrowserFlags_NoStatusBar))
    {
        SameLine();
        Text("%s", statusStr_.c_str());
        if (ImGui::IsItemHovered())
        {
            ImGui::BeginTooltip();            
            ImGui::PushTextWrapPos(300.0f);
            ImGui::Text("%s", statusStr_.c_str());
            ImGui::PopTextWrapPos();
            ImGui::EndTooltip();
        }
    }

    if(!typeFilters_.empty())
    {
        SameLine();
        PushItemWidth(8 * GetFontSize());
        if(BeginCombo(
            "##type_filters", typeFilters_[typeFilterIndex_].c_str()))
        {
            ScopeGuard guard([&] { EndCombo(); });

            for(size_t i = 0; i < typeFilters_.size(); ++i)
            {
                bool selected = i == typeFilterIndex_;
                if(Selectable(typeFilters_[i].c_str(), selected) && !selected)
                {
                    typeFilterIndex_ = static_cast<unsigned int>(i);
                }
            }
        }
        PopItemWidth();
    }
}

inline bool ImGui::FileBrowser::HasSelected() const noexcept
{
    return isOk_;
}

inline bool ImGui::FileBrowser::SetDirectory(const std::filesystem::path &dir)
{
    const std::filesystem::path preferredFallback = this->GetDirectory();
    return SetCurrentDirectoryInternal(dir, preferredFallback);
}

inline const std::filesystem::path &ImGui::FileBrowser::GetDirectory() const noexcept
{
    return currentDirectory_;
}

inline std::filesystem::path ImGui::FileBrowser::GetSelected() const
{
    // when isOk_ is true, selectedFilenames_ may be empty if SelectDirectory
    // is enabled. return pwd in that case.
    if(selectedFilenames_.empty())
    {
        return currentDirectory_;
    }
    return currentDirectory_ / *selectedFilenames_.begin();
}

inline std::vector<std::filesystem::path> ImGui::FileBrowser::GetMultiSelected() const
{
    if(selectedFilenames_.empty())
    {
        return { currentDirectory_ };
    }

    std::vector<std::filesystem::path> ret;
    ret.reserve(selectedFilenames_.size());
    for(auto &s : selectedFilenames_)
    {
        ret.push_back(currentDirectory_ / s);
    }

    return ret;
}

inline void ImGui::FileBrowser::ClearSelected()
{
    selectedFilenames_.clear();
    if((flags_ & ImGuiFileBrowserFlags_EnterNewFilename))
    {
        AssignToArrayStyleString(inputNameBuffer_, "");
    }
    isOk_ = false;
}

inline void ImGui::FileBrowser::SetTypeFilters(const std::vector<std::string> &_typeFilters)
{
    typeFilters_.clear();

    // remove duplicate filter names due to case unsensitivity on windows

#ifdef _WIN32

    std::vector<std::string> typeFilters;
    for(auto &rawFilter : _typeFilters)
    {
        std::string lowerFilter = ToLower(rawFilter);
        const auto it = std::find(typeFilters.begin(), typeFilters.end(), lowerFilter);
        if(it == typeFilters.end())
        {
            typeFilters.push_back(std::move(lowerFilter));
        }
    }

#else

    auto &typeFilters = _typeFilters;

#endif

    // insert auto-generated filter
    hasAllFilter_ = false;
    if(typeFilters.size() > 1)
    {
        hasAllFilter_  = true;
        std::string allFiltersName = std::string();
        for(size_t i = 0; i < typeFilters.size(); ++i)
        {
            if(typeFilters[i] == std::string_view(".*"))
            {
                hasAllFilter_ = false;
                break;
            }

            if(i > 0)
            {
                allFiltersName += ",";
            }
            allFiltersName += typeFilters[i];
        }

        if(hasAllFilter_)
        {
            typeFilters_.push_back(std::move(allFiltersName));
        }
    }

    std::copy(typeFilters.begin(), typeFilters.end(), std::back_inserter(typeFilters_));
    typeFilterIndex_ = 0;
}

inline void ImGui::FileBrowser::SetCurrentTypeFilterIndex(int index)
{
    typeFilterIndex_ = static_cast<unsigned int>(index);
}

inline void ImGui::FileBrowser::SetInputName(std::string_view input)
{
    assert((flags_ & ImGuiFileBrowserFlags_EnterNewFilename) &&
           "SetInputName can only be called when ImGuiFileBrowserFlags_EnterNewFilename is enabled");
    customizedInputName_ = input;
}

inline std::string ImGui::FileBrowser::ToLower(const std::string &s)
{
    std::string ret = s;
    for(char &c : ret)
    {
        c = static_cast<char>(std::tolower(c));
    }
    return ret;
}

inline void ImGui::FileBrowser::ToolTip(const std::string_view &s)
{
    if (!ImGui::IsItemHovered())
    {
        return;
    }
    ImGui::SetTooltip("%s", s.data());
}

inline void ImGui::FileBrowser::UpdateFileRecords()
{
    fileRecords_ = { FileRecord{ true, "..", "[D] ..", "" } };

    const auto getDirectoryIterator = [&]() -> std::filesystem::directory_iterator
    {
        try
        {            
            return std::filesystem::directory_iterator(currentDirectory_);
        }
        catch (const std::filesystem::filesystem_error& err)
        {            
            statusStr_ = std::string("error: ") + err.what();
            if (!(flags_ & ImGuiFileBrowserFlags_SkipItemsCausingError))
            {
                throw;
            }
            return {};
        }
    };

    for(auto &p : getDirectoryIterator())
    {
        FileRecord rcd;
        try
        {
            if(p.is_regular_file())
            {
                rcd.isDir = false;
            }
            else if(p.is_directory())
            {
                rcd.isDir = true;
            }
            else
            {
                continue;
            }

            rcd.name = p.path().filename();
            if(rcd.name.empty())
            {
                continue;
            }

            rcd.extension = p.path().filename().extension();
            rcd.showName = (rcd.isDir ? "[D] " : "[F] ") + u8StrToStr(p.path().filename().u8string());
        }
        catch(...)
        {
            if(!(flags_ & ImGuiFileBrowserFlags_SkipItemsCausingError))
            {
                throw;
            }
            continue;
        }
        fileRecords_.push_back(rcd);
    }

    // The default lexicographical order does not meet our sorting requirements.
    // We want [b0, a0, A1] to be sorted into something like [a0, A1, b0] instead of [a0, b0, A1].
    // Therefore, here we compute a custom key for each filename for sorting.
    if(fileRecords_.size() > 2)
    {
        std::vector<std::vector<uint32_t>> keys;
        keys.reserve(fileRecords_.size());
        for(auto &fileRecord : fileRecords_)
        {
            const auto name = u8StrToStr(fileRecord.name.u8string());
            auto& key = keys.emplace_back();
            key.reserve(name.size() + 1);
            key.emplace_back(!fileRecord.isDir);
            for(char c : name)
            {
                if('A' <= c && c <= 'Z')
                {
                    key.emplace_back(2 * (c + 'a' - 'A') + 1);
                }
                else
                {
                    key.emplace_back(2 * c);
                }
            }
        }

        std::vector<uint32_t> fileRecordRemapIndices;
        fileRecordRemapIndices.reserve(fileRecords_.size());
        for(uint32_t i = 0; i < fileRecords_.size(); ++i)
        {
            fileRecordRemapIndices.push_back(i);
        }

        std::sort(
            fileRecordRemapIndices.begin() + 1, fileRecordRemapIndices.end(), [&](uint32_t li, uint32_t ri)
            {
                return keys[li] < keys[ri];
            });

        std::vector<FileRecord> remappedFileRecords;
        remappedFileRecords.reserve(fileRecords_.size());
        for(const uint32_t index : fileRecordRemapIndices)
        {
            remappedFileRecords.emplace_back(std::move(fileRecords_[index]));
        }

        fileRecords_ = std::move(remappedFileRecords);
    }

    ClearRangeSelectionState();
}

inline void ImGui::FileBrowser::SetCurrentDirectoryUncatched(const std::filesystem::path &pwd)
{
    currentDirectory_ = absolute(pwd);
    UpdateFileRecords();

    bool shouldClearInputNameBuffer = true;

    if((flags_ & ImGuiFileBrowserFlags_EnterNewFilename) &&
       selectedFilenames_.size() == 1 &&
       !customizedInputName_.empty() &&
       !inputNameBuffer_.empty() &&
       std::strcmp(inputNameBuffer_.data(), customizedInputName_.data()) == 0)
    {
        shouldClearInputNameBuffer = false;
    }

    if(shouldClearInputNameBuffer)
    {
        selectedFilenames_.clear();
        AssignToArrayStyleString(inputNameBuffer_, "");
    }
}

inline bool ImGui::FileBrowser::SetCurrentDirectoryInternal(
    const std::filesystem::path &dir, const std::filesystem::path &preferredFallback)
{
    try
    {
        SetCurrentDirectoryUncatched(dir);
        return true;
    }
    catch(const std::exception &err)
    {
        statusStr_ = std::string("error: ") + err.what();
    }
    catch(...)
    {
        statusStr_ = "unknown error";
    }

    if(preferredFallback != defaultDirectory_)
    {
        try
        {
            SetCurrentDirectoryUncatched(preferredFallback);
        }
        catch(...)
        {
            SetCurrentDirectoryUncatched(defaultDirectory_);
        }
    }
    else
    {
        SetCurrentDirectoryUncatched(defaultDirectory_);
    }

    return false;
}

inline bool ImGui::FileBrowser::IsExtensionMatched(const std::filesystem::path &_extension) const
{
#ifdef _WIN32
    std::filesystem::path extension = ToLower(u8StrToStr(_extension.u8string()));
#else
    auto &extension = _extension;
#endif

    // no type filters
    if(typeFilters_.empty())
    {
        return true;
    }

    // invalid type filter index
    if(static_cast<size_t>(typeFilterIndex_) >= typeFilters_.size())
    {
        return true;
    }

    // all type filters
    if(hasAllFilter_ && typeFilterIndex_ == 0)
    {
        for(size_t i = 1; i < typeFilters_.size(); ++i)
        {
            if(extension == typeFilters_[i])
            {
                return true;
            }
        }
        return false;
    }

    // universal filter
    if(typeFilters_[typeFilterIndex_] == std::string_view(".*"))
    {
        return true;
    }

    // regular filter
    return extension == typeFilters_[typeFilterIndex_];
}

inline void ImGui::FileBrowser::ClearRangeSelectionState()
{
    rangeSelectionStart_ = 9999999;
    const bool dir = flags_ & ImGuiFileBrowserFlags_SelectDirectory;
    for(unsigned int i = 1; i < fileRecords_.size(); ++i)
    {
        if(fileRecords_[i].isDir == dir)
        {
            if(!dir && !IsExtensionMatched(fileRecords_[i].extension))
            {
                continue;
            }
            rangeSelectionStart_ = i;
            break;
        }
    }
}

inline void ImGui::FileBrowser::AssignToArrayStyleString(std::vector<char> &arr, std::string_view content)
{
    if(content.empty())
    {
        if(!arr.empty())
        {
            arr[0] = '\0';
        }
        return;
    }

    if(arr.size() < content.size() + 1)
    {
        arr.resize(content.size() + 1);
    }
    std::memcpy(arr.data(), content.data(), content.size());
    arr[content.size()] = '\0';
}

inline int ImGui::FileBrowser::ExpandInputBuffer(ImGuiInputTextCallbackData *callbackData)
{
    if(callbackData && callbackData->EventFlag & ImGuiInputTextFlags_CallbackResize)
    {
        auto buffer = static_cast<std::vector<char>*>(callbackData->UserData);
        size_t newSize = buffer->size();
        while(newSize < static_cast<size_t>(callbackData->BufSize))
        {
            newSize <<= 1;
        }
        buffer->resize(newSize, '\0');
        callbackData->Buf = buffer->data();
        callbackData->BufDirty = true;
    }
    return 0;
}

#if defined(__cpp_lib_char8_t)
inline std::string ImGui::FileBrowser::u8StrToStr(std::u8string s)
{
    std::string result;
    result.resize(s.length());
    std::memcpy(result.data(), s.data(), s.length());
    return result;
}
#endif

inline std::string ImGui::FileBrowser::u8StrToStr(std::string s)
{
    return s;
}

inline std::filesystem::path ImGui::FileBrowser::u8StrToPath(const char *str)
{
#if defined(__cpp_lib_char8_t)
    // With C++20/23, it's impossible to efficiently convert a `char*` string to a `char8_t*` string without violating
    // the strict aliasing rule. Bad joke!
    const size_t len = std::strlen(str);
    std::u8string u8Str;
    u8Str.resize(len);
    std::memcpy(u8Str.data(), str, len);
    return std::filesystem::path(u8Str);
#else
    // u8path is deprecated in C++20
    return std::filesystem::u8path(str);
#endif
}

#ifdef _WIN32

inline std::uint32_t ImGui::FileBrowser::GetDrivesBitMask()
{
    std::uint32_t ret = 0;
    for(int i = 0; i < 26; ++i)
    {
        const char rootName[4] = { static_cast<char>('A' + i), ':', '\\', '\0' };
        try{
            if (std::filesystem::exists(rootName))
            {
                ret |= (1 << i);
            }
        }
        catch (const std::filesystem::filesystem_error &)
        {
            // Ignore invalid paths or inaccessible drives, e.g., empty CD drives or network shares
        }
    }
    return ret;
}

#endif