// Copyright Epic Games, Inc. All Rights Reserved.

#include <zenutil/consoletui.h>

#include <zencore/zencore.h>

#if ZEN_PLATFORM_WINDOWS
#	include <zencore/windows.h>
#else
#	include <poll.h>
#	include <signal.h>
#	include <sys/ioctl.h>
#	include <termios.h>
#	include <unistd.h>
#endif

#include <algorithm>
#include <atomic>
#include <cerrno>
#include <cstdio>
#include <cstring>

namespace zen {

//////////////////////////////////////////////////////////////////////////
// Platform-specific terminal helpers

#if ZEN_PLATFORM_WINDOWS

static bool
CheckIsInteractiveTerminal()
{
	DWORD dwMode = 0;
	return GetConsoleMode(GetStdHandle(STD_INPUT_HANDLE), &dwMode) && GetConsoleMode(GetStdHandle(STD_OUTPUT_HANDLE), &dwMode);
}

static void
EnableVirtualTerminal()
{
	HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
	DWORD  dwMode  = 0;
	if (GetConsoleMode(hStdOut, &dwMode))
	{
		SetConsoleMode(hStdOut, dwMode | ENABLE_VIRTUAL_TERMINAL_PROCESSING);
	}
}

// RAII guard: sets the console output code page for the lifetime of the object and
// restores the original on destruction. Required for UTF-8 glyphs to render correctly
// via printf/fflush since the default console code page is not UTF-8.
class ConsoleCodePageGuard
{
public:
	explicit ConsoleCodePageGuard(UINT NewCP) : m_OldCP(GetConsoleOutputCP()) { SetConsoleOutputCP(NewCP); }
	~ConsoleCodePageGuard() { SetConsoleOutputCP(m_OldCP); }

private:
	UINT m_OldCP;
};

static char s_LastChar = 0;

#else  // POSIX

static bool
CheckIsInteractiveTerminal()
{
	return isatty(STDIN_FILENO) && isatty(STDOUT_FILENO);
}

static void
EnableVirtualTerminal()
{
	// ANSI escape codes are native on POSIX terminals; nothing to do
}

// SIGWINCH (terminal resize) flag — set by signal handler, consumed by TuiReadKey()
static volatile sig_atomic_t s_GotSigWinch = 0;

static void
SigWinchHandler(int /*Sig*/)
{
	s_GotSigWinch = 1;
}

// RAII guard: switches the terminal to raw/unbuffered input mode and restores
// the original attributes on destruction.
class RawModeGuard
{
public:
	RawModeGuard()
	{
		if (tcgetattr(STDIN_FILENO, &m_OldAttrs) != 0)
		{
			return;
		}

		struct termios Raw = m_OldAttrs;
		Raw.c_iflag &= ~static_cast<tcflag_t>(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
		Raw.c_cflag |= CS8;
		Raw.c_lflag &= ~static_cast<tcflag_t>(ECHO | ICANON | IEXTEN | ISIG);
		Raw.c_cc[VMIN]	= 1;
		Raw.c_cc[VTIME] = 0;
		if (tcsetattr(STDIN_FILENO, TCSANOW, &Raw) == 0)
		{
			m_Valid = true;
		}

		// Install SIGWINCH handler for terminal resize detection
		s_GotSigWinch		= 0;
		struct sigaction Sa = {};
		Sa.sa_handler		= SigWinchHandler;
		Sa.sa_flags			= SA_RESTART;
		sigaction(SIGWINCH, &Sa, &m_OldSigAction);
	}

	~RawModeGuard()
	{
		if (m_Valid)
		{
			tcsetattr(STDIN_FILENO, TCSANOW, &m_OldAttrs);
		}
		sigaction(SIGWINCH, &m_OldSigAction, nullptr);
	}

	bool IsValid() const { return m_Valid; }

private:
	struct termios	 m_OldAttrs		= {};
	struct sigaction m_OldSigAction = {};
	bool			 m_Valid		= false;
};

static int
ReadByteWithTimeout(int TimeoutMs)
{
	struct pollfd Pfd
	{
		STDIN_FILENO, POLLIN, 0
	};
	if (poll(&Pfd, 1, TimeoutMs) > 0 && (Pfd.revents & POLLIN))
	{
		unsigned char c = 0;
		if (read(STDIN_FILENO, &c, 1) == 1)
		{
			return static_cast<int>(c);
		}
	}
	return -1;
}

// State for fullscreen live mode (alternate screen + raw input)
static struct termios s_SavedAttrs = {};
static bool			  s_InLiveMode = false;

static char s_LastChar = 0;

#endif	// ZEN_PLATFORM_WINDOWS / POSIX

//////////////////////////////////////////////////////////////////////////
// Public API

uint32_t
TuiConsoleColumns(uint32_t Default)
{
#if ZEN_PLATFORM_WINDOWS
	CONSOLE_SCREEN_BUFFER_INFO Csbi = {};
	if (GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &Csbi))
	{
		return static_cast<uint32_t>(Csbi.dwSize.X);
	}
#else
	struct winsize Ws = {};
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &Ws) == 0 && Ws.ws_col > 0)
	{
		return static_cast<uint32_t>(Ws.ws_col);
	}
#endif
	return Default;
}

void
TuiEnableOutput()
{
	EnableVirtualTerminal();
#if ZEN_PLATFORM_WINDOWS
	SetConsoleOutputCP(CP_UTF8);
#endif
}

bool
TuiIsStdoutTty()
{
#if ZEN_PLATFORM_WINDOWS
	static bool Cached = [] {
		DWORD dwMode = 0;
		return GetConsoleMode(GetStdHandle(STD_OUTPUT_HANDLE), &dwMode) != 0;
	}();
	return Cached;
#else
	static bool Cached = isatty(STDOUT_FILENO) != 0;
	return Cached;
#endif
}

bool
IsTuiAvailable()
{
	static bool Cached = CheckIsInteractiveTerminal();
	return Cached;
}

// Compute visible width of a string, skipping ANSI escape sequences.
static int
VisibleWidth(const std::string& Text)
{
	int	 Width	  = 0;
	bool InEscape = false;
	for (char c : Text)
	{
		if (InEscape)
		{
			if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
			{
				InEscape = false;  // Final byte of escape sequence
			}
		}
		else if (c == '\033')
		{
			InEscape = true;
		}
		else
		{
			++Width;
		}
	}
	return Width;
}

// Truncate a string that may contain ANSI escape sequences to a visible width.
// Appends "..." if truncated. Ensures ANSI state is reset after truncation.
static std::string
TruncateAnsi(const std::string& Text, int MaxVisible)
{
	if (MaxVisible <= 0)
	{
		return {};
	}

	int	 Visible  = 0;
	bool InEscape = false;
	for (size_t i = 0; i < Text.size(); ++i)
	{
		char c = Text[i];
		if (InEscape)
		{
			if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
			{
				InEscape = false;
			}
		}
		else if (c == '\033')
		{
			InEscape = true;
		}
		else
		{
			++Visible;
			if (Visible >= MaxVisible - 2)	// Leave room for "..."
			{
				return Text.substr(0, i + 1) + "\033[0m...";
			}
		}
	}
	return Text;
}

// Word-wrap a single line to fit within Width visible columns.
// ANSI escape codes pass through without counting toward width.
// Returns one or more lines.
static std::vector<std::string>
WrapLine(const std::string& Line, uint32_t Width)
{
	if (Width == 0)
	{
		return {Line};
	}

	// Fast path: line already fits
	if (VisibleWidth(Line) <= static_cast<int>(Width))
	{
		return {Line};
	}

	// Measure leading whitespace for continuation indent so wrapped lines
	// align with the original text.
	int IndentChars = 0;
	for (char c : Line)
	{
		if (c == ' ')
		{
			++IndentChars;
		}
		else if (c == '\t')
		{
			IndentChars += 4;
		}
		else
		{
			break;
		}
	}
	// Cap indent to half the width to avoid degenerate cases
	int ContinuationIndent = std::min(IndentChars, static_cast<int>(Width) / 2);

	std::vector<std::string> Result;
	std::string				 CurrentLine;
	int						 CurrentVisible = 0;
	int						 EffectiveWidth = static_cast<int>(Width);
	bool					 InEscape		= false;
	bool					 HasWords		= false;  // True once a word has been appended to CurrentLine

	// Track the current "word" being accumulated
	std::string Word;
	int			WordVisible = 0;

	auto FlushWord = [&]() {
		if (Word.empty())
		{
			return;
		}

		// Would this word overflow?
		int SpaceNeeded = WordVisible;
		if (HasWords)
		{
			SpaceNeeded += 1;  // space before word
		}

		if (HasWords && CurrentVisible + SpaceNeeded > EffectiveWidth)
		{
			// Wrap: emit current line, start new continuation line
			Result.push_back(CurrentLine);
			CurrentLine	   = std::string(ContinuationIndent, ' ');
			CurrentVisible = ContinuationIndent;
			EffectiveWidth = static_cast<int>(Width);
			HasWords	   = false;
		}

		// Force-break words wider than the available space
		if (WordVisible > EffectiveWidth - CurrentVisible)
		{
			// Append character by character
			bool WordEscape = false;
			for (char c : Word)
			{
				if (WordEscape)
				{
					CurrentLine += c;
					if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
					{
						WordEscape = false;
					}
				}
				else if (c == '\033')
				{
					CurrentLine += c;
					WordEscape = true;
				}
				else
				{
					if (CurrentVisible >= EffectiveWidth)
					{
						Result.push_back(CurrentLine);
						CurrentLine	   = std::string(ContinuationIndent, ' ');
						CurrentVisible = ContinuationIndent;
						HasWords	   = false;
					}
					CurrentLine += c;
					++CurrentVisible;
				}
			}
			HasWords = true;
			Word.clear();
			WordVisible = 0;
			return;
		}

		// Append with space separator
		if (HasWords)
		{
			CurrentLine += ' ';
			++CurrentVisible;
		}
		CurrentLine += Word;
		CurrentVisible += WordVisible;
		HasWords = true;

		Word.clear();
		WordVisible = 0;
	};

	for (size_t i = 0; i < Line.size(); ++i)
	{
		char c = Line[i];

		if (InEscape)
		{
			Word += c;
			if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
			{
				InEscape = false;
			}
		}
		else if (c == '\033')
		{
			Word += c;
			InEscape = true;
		}
		else if (c == ' ' || c == '\t')
		{
			FlushWord();
		}
		else
		{
			Word += c;
			++WordVisible;
		}
	}

	FlushWord();

	if (!CurrentLine.empty() || Result.empty())
	{
		Result.push_back(CurrentLine);
	}

	return Result;
}

std::vector<std::string>
TuiWrapLines(const std::vector<std::string>& Lines, uint32_t Width)
{
	std::vector<std::string> Result;
	for (const std::string& Line : Lines)
	{
		std::vector<std::string> Wrapped = WrapLine(Line, Width);
		Result.insert(Result.end(), Wrapped.begin(), Wrapped.end());
	}
	return Result;
}

// Case-insensitive substring match
static bool
ContainsCaseInsensitive(const std::string& Haystack, const std::string& Needle)
{
	if (Needle.empty())
	{
		return true;
	}
	auto It = std::search(Haystack.begin(), Haystack.end(), Needle.begin(), Needle.end(), [](char A, char B) {
		return std::tolower(static_cast<unsigned char>(A)) == std::tolower(static_cast<unsigned char>(B));
	});
	return It != Haystack.end();
}

int
TuiPickOne(std::string_view				Title,
		   std::span<const std::string> Items,
		   int							InitialSelection,
		   std::string*					InOutFilter,
		   std::span<const std::string> SearchTexts)
{
	TuiEnterAlternateScreen();

	const int	  TotalCount	= static_cast<int>(Items.size());
	constexpr int kIndicatorLen = 3;  // " ▶ " or "   " — 3 display columns

	// When SearchTexts is provided, filter against it instead of display labels
	bool UseSearchTexts = !SearchTexts.empty();

	// Filter state — seed from caller if provided
	std::string		 Filter = InOutFilter ? *InOutFilter : std::string{};
	std::vector<int> Visible;		 // Indices into Items that match the current filter
	int				 CursorPos = 0;	 // Index into Visible
	int				 ScrollTop = 0;	 // First visible index in the viewport

	auto RebuildVisible = [&] {
		Visible.clear();
		for (int i = 0; i < TotalCount; ++i)
		{
			const std::string& Haystack = (UseSearchTexts && i < static_cast<int>(SearchTexts.size())) ? SearchTexts[i] : Items[i];
			if (ContainsCaseInsensitive(Haystack, Filter))
			{
				Visible.push_back(i);
			}
		}
		CursorPos = 0;
		ScrollTop = 0;
	};

	RebuildVisible();

	// Apply initial selection: find it in the Visible list
	if (InitialSelection > 0 && InitialSelection < TotalCount)
	{
		for (int i = 0; i < static_cast<int>(Visible.size()); ++i)
		{
			if (Visible[i] == InitialSelection)
			{
				CursorPos = i;
				break;
			}
		}
	}

	// Layout: Row 1 = title bar, Row 2 = filter (optional), rows 3..N-1 = items, row N = hint footer
	// kFixedRows = title bar (1) + hint footer (1) = 2
	constexpr int kFixedRows = 2;

	auto GetPageSize = [&]() -> int {
		int Rows		   = static_cast<int>(TuiConsoleRows());
		int FilterOverhead = Filter.empty() ? 0 : 1;
		int Available	   = Rows - kFixedRows - FilterOverhead;
		return std::max(Available, 1);
	};

	auto EnsureCursorVisible = [&] {
		int PageSize	 = GetPageSize();
		int VisibleCount = static_cast<int>(Visible.size());
		if (CursorPos < ScrollTop)
		{
			ScrollTop = CursorPos;
		}
		else if (CursorPos >= ScrollTop + PageSize)
		{
			ScrollTop = CursorPos - PageSize + 1;
		}
		int MaxScroll = std::max(0, VisibleCount - PageSize);
		ScrollTop	  = std::clamp(ScrollTop, 0, MaxScroll);
	};

	auto Render = [&] {
		uint32_t Cols		  = TuiConsoleColumns();
		uint32_t Rows		  = TuiConsoleRows();
		int		 MaxTextLen	  = static_cast<int>(Cols) - kIndicatorLen;
		int		 VisibleCount = static_cast<int>(Visible.size());
		int		 PageSize	  = GetPageSize();

		TuiCursorHome();

		// Row 1: Title bar (reverse video)
		TuiMoveCursor(1, 1);
		TuiEraseLine();
		printf("\033[1;7m");  // bold + reverse
		printf(" %.*s", static_cast<int>(std::min(static_cast<uint32_t>(Title.size()), Cols - 1)), Title.data());
		printf("\033[0m");

		uint32_t CurrentRow = 2;

		// Optional filter bar
		if (!Filter.empty())
		{
			TuiMoveCursor(CurrentRow, 1);
			TuiEraseLine();
			printf("  \033[33mfilter:\033[0m %s", Filter.c_str());
			if (VisibleCount == 0)
			{
				printf("  \033[2m(no matches)\033[0m");
			}
			++CurrentRow;
		}

		// Item viewport
		int ViewEnd = std::min(ScrollTop + PageSize, VisibleCount);

		for (int Row = 0; Row < PageSize; ++Row)
		{
			int i = ScrollTop + Row;

			TuiMoveCursor(CurrentRow + static_cast<uint32_t>(Row), 1);
			TuiEraseLine();

			if (i < VisibleCount)
			{
				bool IsSelected = (i == CursorPos);

				if (IsSelected)
				{
					printf("\033[1;7m");
				}

				const char*		   Indicator   = IsSelected ? " \xe2\x96\xb6 " : "   ";
				const std::string& ItemText	   = Items[Visible[i]];
				int				   ItemVisible = VisibleWidth(ItemText);
				if (MaxTextLen > 0 && ItemVisible > MaxTextLen)
				{
					printf("%s%s", Indicator, TruncateAnsi(ItemText, MaxTextLen).c_str());
				}
				else
				{
					printf("%s%s", Indicator, ItemText.c_str());
				}

				if (IsSelected)
				{
					printf("\033[0m");
				}
			}
		}

		// Hint footer (last row)
		TuiMoveCursor(Rows, 1);
		TuiEraseLine();
		printf("\033[7m");
		printf(
			"  \xe2\x86\x91/\xe2\x86\x93 navigate  "
			"Enter confirm  "
			"Esc %s  "
			"Type to filter",
			Filter.empty() ? "cancel" : "clear");
		if (ScrollTop > 0 || ViewEnd < VisibleCount)
		{
			printf("  [%d-%d of %d]", ScrollTop + 1, ViewEnd, VisibleCount);
		}
		printf("\033[0m");

		TuiFlush();
	};

	EnsureCursorVisible();
	Render();

	int	 Result = -1;
	bool Done	= false;
	while (!Done)
	{
		ConsoleKey Key			= TuiReadKey();
		int		   VisibleCount = static_cast<int>(Visible.size());

		switch (Key)
		{
			case ConsoleKey::ArrowUp:
				if (VisibleCount > 0)
				{
					CursorPos = (CursorPos - 1 + VisibleCount) % VisibleCount;
					EnsureCursorVisible();
				}
				break;

			case ConsoleKey::ArrowDown:
				if (VisibleCount > 0)
				{
					CursorPos = (CursorPos + 1) % VisibleCount;
					EnsureCursorVisible();
				}
				break;

			case ConsoleKey::PageUp:
				if (VisibleCount > 0)
				{
					CursorPos = std::max(0, CursorPos - GetPageSize());
					EnsureCursorVisible();
				}
				break;

			case ConsoleKey::PageDown:
				if (VisibleCount > 0)
				{
					CursorPos = std::min(VisibleCount - 1, CursorPos + GetPageSize());
					EnsureCursorVisible();
				}
				break;

			case ConsoleKey::Enter:
				if (VisibleCount > 0)
				{
					Result = Visible[CursorPos];
				}
				Done = true;
				break;

			case ConsoleKey::Escape:
				if (!Filter.empty())
				{
					Filter.clear();
					RebuildVisible();
					EnsureCursorVisible();
				}
				else
				{
					Done = true;
				}
				break;

			case ConsoleKey::Backspace:
				if (!Filter.empty())
				{
					Filter.pop_back();
					RebuildVisible();
					EnsureCursorVisible();
				}
				break;

			case ConsoleKey::Char:
				Filter += TuiReadKeyChar();
				RebuildVisible();
				EnsureCursorVisible();
				break;

			case ConsoleKey::Resize:
				EnsureCursorVisible();
				break;

			default:
				break;
		}

		Render();
	}

	// Persist filter state for the caller
	if (InOutFilter)
	{
		*InOutFilter = std::move(Filter);
	}

	TuiExitAlternateScreen();

	return Result;
}

void
TuiEnterAlternateScreen()
{
	EnableVirtualTerminal();
#if ZEN_PLATFORM_WINDOWS
	SetConsoleOutputCP(CP_UTF8);
#endif

	printf("\033[?1049h");	// Enter alternate screen buffer
	printf("\033[?25l");	// Hide cursor
	fflush(stdout);

#if ZEN_PLATFORM_WINDOWS
	// Enable window-size events so ReadConsoleInput returns WINDOW_BUFFER_SIZE_EVENT
	{
		HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
		DWORD  dwMode = 0;
		if (GetConsoleMode(hStdin, &dwMode))
		{
			SetConsoleMode(hStdin, dwMode | ENABLE_WINDOW_INPUT);
		}
	}
#else
	if (tcgetattr(STDIN_FILENO, &s_SavedAttrs) == 0)
	{
		struct termios Raw = s_SavedAttrs;
		Raw.c_iflag &= ~static_cast<tcflag_t>(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
		Raw.c_cflag |= CS8;
		Raw.c_lflag &= ~static_cast<tcflag_t>(ECHO | ICANON | IEXTEN | ISIG);
		Raw.c_cc[VMIN]	= 1;
		Raw.c_cc[VTIME] = 0;
		if (tcsetattr(STDIN_FILENO, TCSANOW, &Raw) == 0)
		{
			s_InLiveMode = true;
		}
	}

	// Install SIGWINCH handler for terminal resize detection
	s_GotSigWinch		= 0;
	struct sigaction Sa = {};
	Sa.sa_handler		= SigWinchHandler;
	Sa.sa_flags			= SA_RESTART;
	sigaction(SIGWINCH, &Sa, nullptr);
#endif
}

void
TuiExitAlternateScreen()
{
	printf("\033[?25h");	// Show cursor
	printf("\033[?1049l");	// Exit alternate screen buffer
	fflush(stdout);

#if !ZEN_PLATFORM_WINDOWS
	if (s_InLiveMode)
	{
		tcsetattr(STDIN_FILENO, TCSANOW, &s_SavedAttrs);
		s_InLiveMode = false;
	}

	// Restore default SIGWINCH handler
	signal(SIGWINCH, SIG_DFL);
#endif
}

void
TuiCursorHome()
{
	printf("\033[H");
}

uint32_t
TuiConsoleRows(uint32_t Default)
{
#if ZEN_PLATFORM_WINDOWS
	CONSOLE_SCREEN_BUFFER_INFO Csbi = {};
	if (GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &Csbi))
	{
		return static_cast<uint32_t>(Csbi.srWindow.Bottom - Csbi.srWindow.Top + 1);
	}
#else
	struct winsize Ws = {};
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &Ws) == 0 && Ws.ws_row > 0)
	{
		return static_cast<uint32_t>(Ws.ws_row);
	}
#endif
	return Default;
}

bool
TuiPollQuit()
{
#if ZEN_PLATFORM_WINDOWS
	HANDLE hStdin  = GetStdHandle(STD_INPUT_HANDLE);
	DWORD  dwCount = 0;
	if (!GetNumberOfConsoleInputEvents(hStdin, &dwCount) || dwCount == 0)
	{
		return false;
	}
	INPUT_RECORD Record{};
	DWORD		 dwRead = 0;
	while (PeekConsoleInputA(hStdin, &Record, 1, &dwRead) && dwRead > 0)
	{
		ReadConsoleInputA(hStdin, &Record, 1, &dwRead);
		if (Record.EventType == KEY_EVENT && Record.Event.KeyEvent.bKeyDown)
		{
			WORD vk = Record.Event.KeyEvent.wVirtualKeyCode;
			char ch = Record.Event.KeyEvent.uChar.AsciiChar;
			if (vk == VK_ESCAPE || ch == 'q' || ch == 'Q')
			{
				return true;
			}
		}
	}
	return false;
#else
	// Non-blocking read: character 3 = Ctrl+C, 27 = Esc, 'q'/'Q' = quit
	int b = ReadByteWithTimeout(0);
	return (b == 3 || b == 27 || b == 'q' || b == 'Q');
#endif
}

void
TuiSetScrollRegion(uint32_t Top, uint32_t Bottom)
{
	printf("\033[%u;%ur", Top, Bottom);
}

void
TuiResetScrollRegion()
{
	printf("\033[r");
}

void
TuiMoveCursor(uint32_t Row, uint32_t Col)
{
	printf("\033[%u;%uH", Row, Col);
}

void
TuiSaveCursor()
{
	printf(
		"\033"
		"7");
}

void
TuiRestoreCursor()
{
	printf(
		"\033"
		"8");
}

void
TuiEraseLine()
{
	printf("\033[2K");
}

void
TuiWrite(std::string_view Text)
{
	fwrite(Text.data(), 1, Text.size(), stdout);
}

void
TuiFlush()
{
	fflush(stdout);
}

void
TuiShowCursor(bool Show)
{
	if (Show)
	{
		printf("\033[?25h");
	}
	else
	{
		printf("\033[?25l");
	}
}

//////////////////////////////////////////////////////////////////////////
// Public key reading

ConsoleKey
TuiReadKey()
{
#if ZEN_PLATFORM_WINDOWS
	HANDLE		 hStdin = GetStdHandle(STD_INPUT_HANDLE);
	INPUT_RECORD Record{};
	DWORD		 dwRead = 0;
	while (true)
	{
		if (!ReadConsoleInputA(hStdin, &Record, 1, &dwRead))
		{
			return ConsoleKey::Escape;
		}
		if (Record.EventType == WINDOW_BUFFER_SIZE_EVENT)
		{
			return ConsoleKey::Resize;
		}
		if (Record.EventType != KEY_EVENT || !Record.Event.KeyEvent.bKeyDown)
		{
			continue;
		}
		switch (Record.Event.KeyEvent.wVirtualKeyCode)
		{
			case VK_UP:
				return ConsoleKey::ArrowUp;
			case VK_DOWN:
				return ConsoleKey::ArrowDown;
			case VK_LEFT:
				return ConsoleKey::ArrowLeft;
			case VK_RIGHT:
				return ConsoleKey::ArrowRight;
			case VK_PRIOR:
				return ConsoleKey::PageUp;
			case VK_NEXT:
				return ConsoleKey::PageDown;
			case VK_HOME:
				return ConsoleKey::Home;
			case VK_END:
				return ConsoleKey::End;
			case VK_RETURN:
				return ConsoleKey::Enter;
			case VK_ESCAPE:
				return ConsoleKey::Escape;
			case VK_BACK:
				return ConsoleKey::Backspace;
			default:
				{
					char ch = Record.Event.KeyEvent.uChar.AsciiChar;
					if (ch >= 32 && ch < 127)
					{
						s_LastChar = ch;
						return ConsoleKey::Char;
					}
					break;
				}
		}
	}
#else
	// Check for pending SIGWINCH before blocking on read
	if (s_GotSigWinch)
	{
		s_GotSigWinch = 0;
		return ConsoleKey::Resize;
	}

	unsigned char c = 0;
	if (read(STDIN_FILENO, &c, 1) != 1)
	{
		// read() returns -1 with EINTR when interrupted by SIGWINCH
		if (errno == EINTR && s_GotSigWinch)
		{
			s_GotSigWinch = 0;
			return ConsoleKey::Resize;
		}
		return ConsoleKey::Escape;
	}

	if (c == 27)  // ESC or escape sequence
	{
		int Next = ReadByteWithTimeout(50);
		if (Next == '[')
		{
			int Code = ReadByteWithTimeout(50);
			switch (Code)
			{
				case 'A':
					return ConsoleKey::ArrowUp;
				case 'B':
					return ConsoleKey::ArrowDown;
				case 'C':
					return ConsoleKey::ArrowRight;
				case 'D':
					return ConsoleKey::ArrowLeft;
				case 'H':
					return ConsoleKey::Home;
				case 'F':
					return ConsoleKey::End;
				case '5':
					if (ReadByteWithTimeout(50) == '~')
					{
						return ConsoleKey::PageUp;
					}
					break;
				case '6':
					if (ReadByteWithTimeout(50) == '~')
					{
						return ConsoleKey::PageDown;
					}
					break;
				default:
					break;
			}
		}
		return ConsoleKey::Escape;
	}

	if (c == '\r' || c == '\n')
	{
		return ConsoleKey::Enter;
	}
	if (c == 127 || c == 8)
	{
		return ConsoleKey::Backspace;
	}
	if (c >= 32 && c < 127)
	{
		s_LastChar = c;
		return ConsoleKey::Char;
	}

	return ConsoleKey::Unknown;
#endif
}

char
TuiReadKeyChar()
{
	return s_LastChar;
}

//////////////////////////////////////////////////////////////////////////
// TuiPager — fullscreen scrollable text viewer with search and word wrapping

void
TuiPager(std::string_view Title, const std::vector<std::string>& Lines)
{
	TuiEnterAlternateScreen();

	// Word-wrapped lines and the last width they were wrapped to
	std::vector<std::string> Wrapped;
	uint32_t				 WrapWidth = 0;

	auto Rewrap = [&]() {
		uint32_t Cols = TuiConsoleColumns();
		if (Cols != WrapWidth)
		{
			Wrapped	  = TuiWrapLines(Lines, Cols);
			WrapWidth = Cols;
		}
	};

	Rewrap();

	uint32_t TopLine = 0;

	// Search state
	std::string SearchQuery;
	int32_t		SearchMatchLine = -1;
	bool		SearchFailed	= false;
	bool		SearchWrapped	= false;

	auto GetPageHeight = [&]() -> uint32_t {
		uint32_t Rows = TuiConsoleRows();
		return (Rows > 2) ? (Rows - 2) : 1;
	};

	auto ClampTop = [&]() {
		uint32_t PageH	   = GetPageHeight();
		uint32_t LineCount = static_cast<uint32_t>(Wrapped.size());
		if (LineCount <= PageH)
		{
			TopLine = 0;
		}
		else if (TopLine > LineCount - PageH)
		{
			TopLine = LineCount - PageH;
		}
	};

	auto Render = [&]() {
		uint32_t Cols	   = TuiConsoleColumns();
		uint32_t Rows	   = TuiConsoleRows();
		uint32_t PageH	   = GetPageHeight();
		uint32_t LineCount = static_cast<uint32_t>(Wrapped.size());

		TuiCursorHome();

		// Title bar
		TuiMoveCursor(1, 1);
		printf("\033[1;7m");
		TuiEraseLine();
		uint32_t LastVisible = std::min(TopLine + PageH, LineCount);
		printf(" %.*s  (lines %u-%u of %u)",
			   static_cast<int>(std::min(static_cast<uint32_t>(Title.size()), Cols - 30)),
			   Title.data(),
			   LineCount > 0 ? TopLine + 1 : 0,
			   LastVisible,
			   LineCount);
		printf("\033[0m");

		// Content lines
		for (uint32_t i = 0; i < PageH; ++i)
		{
			TuiMoveCursor(i + 2, 1);
			TuiEraseLine();

			uint32_t LineIdx = TopLine + i;
			if (LineIdx < LineCount)
			{
				const std::string& Line = Wrapped[LineIdx];

				if (SearchMatchLine >= 0 && LineIdx == static_cast<uint32_t>(SearchMatchLine))
				{
					printf("\033[43;30m");
				}

				printf("%s", Line.c_str());

				if (SearchMatchLine >= 0 && LineIdx == static_cast<uint32_t>(SearchMatchLine))
				{
					printf("\033[0m");
				}
			}
		}

		// Status bar
		TuiMoveCursor(Rows, 1);
		TuiEraseLine();
		printf("\033[7m");

		if (LineCount <= PageH)
		{
			printf(" (All)");
		}
		else if (TopLine == 0)
		{
			printf(" (Top)");
		}
		else if (TopLine + PageH >= LineCount)
		{
			printf(" (End)");
		}
		else
		{
			uint32_t Pct = (TopLine * 100) / (LineCount - PageH);
			printf(" (%u%%)", Pct);
		}

		if (!SearchQuery.empty())
		{
			if (SearchFailed)
			{
				printf("  \033[0;7;31mno match:\033[0;7m %s", SearchQuery.c_str());
			}
			else if (SearchWrapped)
			{
				printf("  search (wrapped): %s", SearchQuery.c_str());
			}
			else
			{
				printf("  search: %s", SearchQuery.c_str());
			}
		}
		else
		{
			printf("  Esc:quit  Type to search  Enter:next match");
		}

		printf("\033[0m");
		TuiFlush();
	};

	auto FindNext = [&](uint32_t StartLine, bool Wrap) -> bool {
		if (SearchQuery.empty())
		{
			return false;
		}

		uint32_t LineCount = static_cast<uint32_t>(Wrapped.size());
		for (uint32_t i = 0; i < LineCount; ++i)
		{
			uint32_t Idx = (StartLine + i) % LineCount;
			if (Idx < StartLine && !Wrap)
			{
				break;
			}

			if (ContainsCaseInsensitive(Wrapped[Idx], SearchQuery))
			{
				SearchMatchLine = static_cast<int32_t>(Idx);
				SearchFailed	= false;
				SearchWrapped	= Wrap && (Idx < StartLine);

				uint32_t PageH = GetPageHeight();
				if (static_cast<uint32_t>(SearchMatchLine) < TopLine || static_cast<uint32_t>(SearchMatchLine) >= TopLine + PageH)
				{
					TopLine = static_cast<uint32_t>(SearchMatchLine);
					if (TopLine > 3)
					{
						TopLine -= 3;
					}
					else
					{
						TopLine = 0;
					}
					ClampTop();
				}
				return true;
			}
		}

		SearchFailed	= true;
		SearchWrapped	= false;
		SearchMatchLine = -1;
		return false;
	};

	ClampTop();
	Render();

	bool Done = false;
	while (!Done)
	{
		ConsoleKey Key = TuiReadKey();

		SearchFailed  = false;
		SearchWrapped = false;

		uint32_t PageH	   = GetPageHeight();
		uint32_t LineCount = static_cast<uint32_t>(Wrapped.size());

		switch (Key)
		{
			case ConsoleKey::ArrowUp:
				if (TopLine > 0)
				{
					--TopLine;
				}
				break;

			case ConsoleKey::ArrowDown:
				if (TopLine + PageH < LineCount)
				{
					++TopLine;
				}
				break;

			case ConsoleKey::PageUp:
				if (TopLine >= PageH)
				{
					TopLine -= PageH;
				}
				else
				{
					TopLine = 0;
				}
				break;

			case ConsoleKey::PageDown:
				TopLine += PageH;
				ClampTop();
				break;

			case ConsoleKey::Home:
				TopLine = 0;
				break;

			case ConsoleKey::End:
				if (LineCount > PageH)
				{
					TopLine = LineCount - PageH;
				}
				break;

			case ConsoleKey::Char:
				SearchQuery += TuiReadKeyChar();
				FindNext(TopLine, true);
				break;

			case ConsoleKey::Backspace:
				if (!SearchQuery.empty())
				{
					SearchQuery.pop_back();
					if (!SearchQuery.empty())
					{
						FindNext(TopLine, true);
					}
					else
					{
						SearchMatchLine = -1;
					}
				}
				break;

			case ConsoleKey::Enter:
				{
					uint32_t Start = (SearchMatchLine >= 0) ? static_cast<uint32_t>(SearchMatchLine) + 1 : TopLine;
					FindNext(Start, true);
					break;
				}

			case ConsoleKey::Escape:
				if (!SearchQuery.empty())
				{
					SearchQuery.clear();
					SearchMatchLine = -1;
				}
				else
				{
					Done = true;
				}
				break;

			case ConsoleKey::Resize:
				Rewrap();
				ClampTop();
				break;

			default:
				break;
		}

		Render();
	}

	TuiExitAlternateScreen();
}

}  // namespace zen