#include <windows.h>
#include <lmcons.h>
#include <string.h>
#include <stdio.h>
#include <tchar.h>
#include <strsafe.h>

#define ID_DIR	914
#define ID_BTN	879
#define ID_CBOX	806
#define ID_RES	435
#define MAX_CHARS	260
#define MAX_LENGTH	32767

TCHAR dNames[MAX_PATH];		// computer name
DWORD dLen = MAX_PATH;		// length
DWORD ldResult;

TCHAR buf[MAX_CHARS], path[MAX_CHARS], newPath[MAX_CHARS], mask[MAX_CHARS], res[MAX_LENGTH];

WIN32_FIND_DATA dirInfo;

LONG WINAPI WndProc(HWND, UINT, WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    HWND hwnd;
    MSG msg;
    WNDCLASS w;
    memset(&w, 0, sizeof(WNDCLASS));
    w.style = WS_TILED | CS_HREDRAW | CS_VREDRAW;
    w.lpfnWndProc = WndProc;
    w.hInstance = hInstance;
	w.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    w.lpszClassName = L"Lab2";
	w.hIcon = LoadIcon(NULL, IDI_EXCLAMATION);
	w.hCursor = LoadCursor(NULL, IDC_ARROW);
    RegisterClass(&w);
    hwnd = CreateWindow(L"Lab2", L"Nepryakhin 3121", WS_OVERLAPPEDWINDOW, 400, 400, 360, 360, NULL, NULL, hInstance, NULL);
	
	HWND hCbox = CreateWindow(L"Combobox", NULL, WS_BORDER | WS_CHILD | WS_VISIBLE | CBS_SORT | CBS_DROPDOWNLIST, 5, 5, 50, 240, hwnd, (HMENU)ID_CBOX, hInstance, 0);
	HWND hDir = CreateWindow(L"Edit", NULL, WS_BORDER | WS_CHILD | WS_VISIBLE | ES_LEFT, 60, 6, 200, 20, hwnd, (HMENU)ID_DIR, hInstance, 0);
	HWND hBtn = CreateWindow(L"Button", NULL, WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON | BS_CENTER, 265, 6, 80, 20, hwnd, (HMENU)ID_BTN, hInstance, 0);
	HWND hRes = CreateWindow(L"Edit", NULL, WS_BORDER | WS_CHILD | WS_VISIBLE | ES_LEFT | ES_MULTILINE | ES_READONLY | ES_AUTOVSCROLL, 5, 32, 340, 290, hwnd, (HMENU)ID_RES, hInstance, 0);

	SetWindowText(hBtn, L"Задать");
	SetWindowText(hDir, L"windows");
	SetWindowText(hRes, L"Select disk, type path of directory in textbox and click button to get all .cpp and .txt files in its oldest subdirectory.");

	ldResult = GetLogicalDriveStrings(dLen, dNames);	// get drive names
	
	if (ldResult > 0 && ldResult <= MAX_PATH)	// validation
	{
		TCHAR* sDrive = dNames;

		while (*sDrive)	// add each drive to combobox
		{
			SendMessage(hCbox, CB_ADDSTRING, 0, (LPARAM) sDrive);
			sDrive += wcslen(sDrive) + 1;
		}
	}
	
	SendMessage(hCbox, CB_SETCURSEL, 0, 0);	// select first item

    ShowWindow(hwnd,nCmdShow);
    UpdateWindow(hwnd);
	
	while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    
	return msg.wParam;
}

bool checkDir()	// only directory, exlude . and ..
{
	return ((dirInfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) && _tcscmp(dirInfo.cFileName, L".") != 0 && _tcscmp(dirInfo.cFileName, L"..") != 0);
}

bool GetAncientDir()
{
	bool result = false;	// success flag
	FILETIME cur;

	// flush memory, get first dir
	ZeroMemory(&dirInfo, sizeof(WIN32_FIND_DATA));
	StringCbPrintf(mask, MAX_CHARS, L"%s\\*", path);
	HANDLE hFind = FindFirstFile(mask, &dirInfo);

	if (checkDir())	// its ok dir
	{
		// set time as default
		cur = dirInfo.ftCreationTime;
		StringCbPrintf(newPath, MAX_CHARS, L"%s\\%s", path, dirInfo.cFileName);
		result = true;	// there is one dir at least, ok
	}

	while (FindNextFile(hFind, &dirInfo))	// for each file
		if (checkDir() && CompareFileTime(&cur, &dirInfo.ftCreationTime) > -1)	// check if its dir and its creation time
			{
				cur = dirInfo.ftCreationTime;	// new time, new path
				StringCbPrintf(newPath, MAX_CHARS, L"%s\\%s", path, dirInfo.cFileName);
				result = true;	// flag ok
			}

	FindClose(hFind);	// close handle

	return result;
}

void GetFiles(LPCWSTR ext)
{
	// flush memory, find first file with specified extension
	ZeroMemory(&dirInfo, sizeof(WIN32_FIND_DATA));
	StringCbPrintf(mask, MAX_CHARS, L"%s\\*.%s", newPath, ext);
	HANDLE hFind = FindFirstFile(mask, &dirInfo);

	if(hFind == INVALID_HANDLE_VALUE)	// no file
		StringCbPrintf(res, MAX_LENGTH, L"%s\r\nThere's no .%s files\r\n", res, ext);
	else
	{
		StringCbPrintf(res, MAX_LENGTH, L"%s\r\n.%s files:\r\n%s\r\n", res, ext, dirInfo.cFileName);	   // first one

		while (FindNextFile(hFind, &dirInfo))	// get more
			StringCbPrintf(res, MAX_LENGTH, L"%s%s\r\n", res, dirInfo.cFileName);
	}
	
	FindClose(hFind);	// close handle
}

LONG WINAPI WndProc(HWND hwnd, UINT Message, WPARAM wparam, LPARAM lparam)
{
    switch (Message){
    case WM_DESTROY: 
        PostQuitMessage(0);
        break;
	case WM_COMMAND:
		if (HIWORD(wparam) == BN_CLICKED && LOWORD(wparam) == ID_BTN)
		{
			// get combobox drive letter and directory, concatenate
			GetDlgItemText(hwnd, ID_DIR, buf, MAX_CHARS);
			GetDlgItemText(hwnd, ID_CBOX, path, MAX_CHARS);
			StringCbPrintf(path, MAX_CHARS, L"%s%s", path, buf);
			
			// flush memory and find directory
			ZeroMemory(&dirInfo, sizeof(WIN32_FIND_DATA));
			FindFirstFile(path, &dirInfo);

			// it's found
			if (dirInfo.dwFileAttributes == FILE_ATTRIBUTE_DIRECTORY)
			{
				if(!GetAncientDir())	// get oldest subdir
					StringCbPrintf(res, MAX_LENGTH, L"There is no subdirectories in %s", path);
				else
				{
					StringCbPrintf(res, MAX_LENGTH, L"Files in %s\r\n", newPath);
					GetFiles(L"txt");	// get all .txt files
					GetFiles(L"cpp");	// .cpp
				}
			}
			else
				StringCbPrintf(res, sizeof(res), L"Can't find or open directory.");
			
			// type result in textbox
			SetDlgItemText(hwnd, ID_RES, res);
		}

		break;
    default:
        return DefWindowProc(hwnd, Message, wparam, lparam);
    }

    return 0;
}