#ifndef UNICODE
#define UNICODE
#endif

#include <Windows.h>
#include <CommCtrl.h>
#include <string>
#include <iostream>
#include <vector>
#include <unordered_map>
#include <fstream>
#include <ctime>

#define LoadFilesButtonClicked 0x1
#define SortFilesButtonClicked 0x2

#define SCREEN_WIDTH  GetSystemMetrics(SM_CXSCREEN)
#define SCREEN_HEIGHT GetSystemMetrics(SM_CYSCREEN)

struct FileData {
    std::wstring fileName;
    std::wstring fileSize;
};

//g for global
std::vector<FileData> gFilesVector;

HWND hEdit, hListViewLeft, hListViewRight, hLoadButton, hSortButton;

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

void AddColumns(HWND hListView)
{
    LVCOLUMN lvCol = { };
    lvCol.mask = LVCF_TEXT | LVCF_WIDTH | LVCF_SUBITEM;

    lvCol.cx = 50;
    lvCol.pszText = (LPWSTR)L"Index";
    ListView_InsertColumn(hListView, 0, &lvCol);

    RECT rect;
    GetWindowRect(hListView, &rect);

    lvCol.cx = (rect.right - rect.left) / 2;
    lvCol.pszText = (LPWSTR)L"File Name";
    ListView_InsertColumn(hListView, 1, &lvCol);

    lvCol.cx = (rect.right - rect.left) / 2 - 50;
    lvCol.pszText = (LPWSTR)L"File Size";
    ListView_InsertColumn(hListView, 2, &lvCol);
}

void AddItemToListView(HWND hListView, FileData* fileData)
{
    LVITEM lvItem = { };
    lvItem.mask = LVIF_TEXT;

    int index = ListView_GetItemCount(hListView);
    lvItem.iItem = index; //index should start with the next Item

    std::wstring indexStr = std::to_wstring(index + 1);
    lvItem.pszText = (LPWSTR)indexStr.c_str();
    ListView_InsertItem(hListView, &lvItem);

    ListView_SetItemText(hListView, index, 1, (LPWSTR)fileData->fileName.c_str());
    ListView_SetItemText(hListView, index, 2, (LPWSTR)fileData->fileSize.c_str());
}

std::wstring GenerateUniqueFileName(const std::wstring& baseName,
    std::unordered_map<std::wstring, int>& gNameCount)
{
    std::wstring uniqueName = baseName;
    int count = gNameCount[baseName];

    if (count > 0) {
        uniqueName = baseName + L"[" + std::to_wstring(count) + L"]";
    }

    gNameCount[baseName]++;

    return uniqueName;
}

void LogError(std::wofstream& logFile, const std::wstring& message) {
    std::time_t currentTime = std::time(nullptr);
    std::tm localTime;
    localtime_s(&localTime, &currentTime);

    wchar_t timeBuffer[80];
    wcsftime(timeBuffer, sizeof(timeBuffer) / sizeof(wchar_t), L"%Y-%m-%d %H:%M:%S", &localTime);

    logFile << L"[" << timeBuffer << L"] " << message << std::endl;
}

void LoadFilesData(HWND hListView, const std::wstring directoryPath,
    std::vector<FileData>& files, std::unordered_map<std::wstring, int>& gNameCount,
    std::wofstream& errorLogFile)
{
    WIN32_FIND_DATA data;

    std::wstring searchPath = directoryPath + L"//*";

    HANDLE hFind = FindFirstFile(searchPath.c_str(), &data);

    if (hFind == INVALID_HANDLE_VALUE) {
        DWORD errorCode = GetLastError();
        std::wstring errorMessage = L"Error when getting files from directory: " + directoryPath +
            L". Error Code: " + std::to_wstring(errorCode);
        //std::wcout << errorMessage << std::endl;
        LogError(errorLogFile, errorMessage);
        return;
    }

    do {
        if (data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
            if (wcscmp(data.cFileName, L".") != 0 && wcscmp(data.cFileName, L"..") != 0) {
                const std::wstring newDirPath = directoryPath + L"//" + data.cFileName;
                LoadFilesData(hListView, newDirPath, files, gNameCount, errorLogFile);
            }
        }
        else {
            FileData fileData;
            std::wstring baseName = data.cFileName;

            fileData.fileName = GenerateUniqueFileName(baseName, gNameCount);

            ULONGLONG fileSize = ((ULONGLONG)data.nFileSizeHigh << 32) + data.nFileSizeLow;
            fileData.fileSize = std::to_wstring(fileSize) + L" bytes";

            gFilesVector.push_back(fileData);
        }
    } while (FindNextFile(hFind, &data) != 0);

    FindClose(hFind);
}

enum class SortDirection { Ascending, Descending };

void RadixSort(std::vector<FileData>& array, SortDirection sortDirection = SortDirection::Ascending)
{
    if (array.size() < 2)
        return;

    int maxLength = 0;
    for (const auto& item : array) {
        int size = static_cast<int>(item.fileSize.length());
        maxLength = size > maxLength ? size : maxLength;
    }

    wchar_t maxChar = 0;
    for (const auto& item : array) {
        for (const auto& ch : item.fileSize) {
            maxChar = ch > maxChar ? ch : maxChar;
        }
    }
    maxChar++;

    std::vector<FileData> output(array.size());
    std::vector<int> count(maxChar, 0);

    for (int digit = maxLength - 1; digit >= 0; digit--)
    {
        std::fill(count.begin(), count.end(), 0);

        for (const auto& item : array)
        {
            int bucketIndex = digit < item.fileSize.length() ? item.fileSize[digit] : 0;
            count[bucketIndex]++;
        }

        for (int i = 1; i < maxChar; i++)
        {
            count[i] += count[i - 1];
        }

        if (sortDirection == SortDirection::Ascending)
        {
            for (int i = array.size() - 1; i >= 0; i--)
            {
                int bucketIndex = digit < array[i].fileSize.length() ? array[i].fileSize[digit] : 0;
                output[--count[bucketIndex]] = array[i];
            }
        }
        else
        {
            for (int i = 0; i < array.size(); i++)
            {
                int bucketIndex = digit < array[i].fileSize.length() ? array[i].fileSize[digit] : 0;
                output[--count[bucketIndex]] = array[i];
            }
        }

        for (int i = 0; i < array.size(); i++)
        {
            array[i] = output[i];
        }
    }
}

void SortListView(HWND hListView)
{
    if (gFilesVector.size() > 0) {
        ListView_DeleteAllItems(hListView);

        RadixSort(gFilesVector);

        SendMessage(hListView, WM_SETREDRAW, FALSE, 0);

        size_t size = gFilesVector.size();

        for (auto i = 0; i < size; i++) {
            AddItemToListView(hListView, &gFilesVector[i]);
        }

        SendMessage(hListView, WM_SETREDRAW, TRUE, 0);
    }
    else {
        MessageBox(hListView, L"Fill your left table!", L"Error", MB_ICONERROR);
    }
}

void PrepareListView(HWND hListView)
{
    wchar_t directoryPath[MAX_PATH] = { 0 };
    GetWindowTextW(hEdit, directoryPath, MAX_PATH);

    WIN32_FIND_DATA data;

    std::wstring searchPath = std::wstring(directoryPath) + L"\\*";

    HANDLE hFind = FindFirstFile(searchPath.c_str(), &data);

    if (hFind == INVALID_HANDLE_VALUE || searchPath == L"\\*") {
        MessageBox(hListView, L"Enter existing directory path!", L"Error", MB_ICONERROR);
        return;
    }

    ListView_DeleteAllItems(hListView);

    std::wofstream errorLogFile(L"D://errors.log.txt", std::ios::app);

    gFilesVector = { };
    std::unordered_map<std::wstring, int> gNameCount = { };

    SendMessage(hListView, WM_SETREDRAW, FALSE, 0);

    LoadFilesData(hListView, directoryPath, gFilesVector, gNameCount, errorLogFile);

    int size = static_cast<int>(gFilesVector.size());

    for (int i = 0; i < size; i++) {
        AddItemToListView(hListView, &gFilesVector[i]);
    }

    SendMessage(hListView, WM_SETREDRAW, TRUE, 0);
}

int WINAPI wWinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE hPrevInstance,
    _In_ PWSTR pCmdLine, _In_ int nCmdShow)
{
    /*if (AllocConsole()) {
        FILE* fp;
        freopen_s(&fp, "CONOUT$", "w", stdout);
    }*/

    const wchar_t CLASS_NAME[] = L"WINAPI_LAB1";

    WNDCLASS wc = { };
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = hInstance;
    wc.lpszClassName = CLASS_NAME;

    RegisterClass(&wc);

    HWND hwnd = CreateWindowEx(0, CLASS_NAME, L"WINAPI_LAB1", WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, SCREEN_WIDTH, SCREEN_HEIGHT,
        NULL, NULL, hInstance, NULL
    );

    if (hwnd == NULL)
    {
        return 0;
    }

    ShowWindow(hwnd, SW_SHOWMAXIMIZED);

    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);

        FillRect(hdc, &ps.rcPaint, (HBRUSH)(COLOR_WINDOW + 1));
        EndPaint(hwnd, &ps);
    }
    return 0;

    case WM_CREATE:
    {
        hListViewLeft = CreateWindowEx(0, WC_LISTVIEW, L"",
            WS_CHILD | WS_VISIBLE | WS_BORDER | LVS_REPORT,
            10, 40, SCREEN_WIDTH / 2 - 10, SCREEN_HEIGHT - 120,
            hwnd, NULL, NULL, NULL);

        hListViewRight = CreateWindowEx(0, WC_LISTVIEW, L"",
            WS_CHILD | WS_VISIBLE | WS_BORDER | LVS_REPORT,
            10 + SCREEN_WIDTH / 2, 40, SCREEN_WIDTH / 2 - 50, SCREEN_HEIGHT - 120,
            hwnd, NULL, NULL, NULL);

        AddColumns(hListViewLeft);
        AddColumns(hListViewRight);

        hEdit = CreateWindowEx(0, WC_EDIT, L"",
            WS_CHILD | WS_VISIBLE | WS_BORDER,
            10, 10, SCREEN_WIDTH - 400, 20,
            hwnd, NULL, NULL, NULL);

        hLoadButton = CreateWindowEx(0, WC_BUTTON, L"Load Files",
            WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON | WS_TABSTOP,
            SCREEN_WIDTH - 380, 8, 120, 25,
            hwnd, (HMENU)LoadFilesButtonClicked, NULL, NULL);

        hSortButton = CreateWindowEx(0, WC_BUTTON, L"Sort Files",
            WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON | WS_TABSTOP,
            SCREEN_WIDTH - 160, 8, 120, 25,
            hwnd, (HMENU)SortFilesButtonClicked, NULL, NULL);

    }
    break;

    case WM_COMMAND:
    {
        int wmId = LOWORD(wParam);
        int wmEvent = HIWORD(wParam);

        switch (wmId)
        {
            case LoadFilesButtonClicked:
            {
                if (wmEvent == BN_CLICKED) {
                    PrepareListView(hListViewLeft);
                    //GetDlgItem(hwnd, LoadFilesButtonClicked); – GETS HWND OF Window element
                }
                break;
            }

            case SortFilesButtonClicked:
            {
                if (wmEvent == BN_CLICKED) {
                    SortListView(hListViewRight);
                }
                break;
            }
        }
    }
    break;

    case WM_CLOSE:
        /*if (MessageBox(hwnd, L"Really quit?", L"My application", MB_OKCANCEL) == IDOK) {
            DestroyWindow(hwnd);
        }*/
        PostQuitMessage(0);
        break;

    case WM_DESTROY:
        return 0;

    default:
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
    }
    return 0;
}