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// Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "winapi-common" project.
// For details, see https://github.com/egor-tensin/winapi-common.
// Distributed under the MIT License.
#pragma once
#include <winapi/error.hpp>
#include <winapi/handle.hpp>
#include <winapi/utf8.hpp>
#include <boost/algorithm/string.hpp>
#include <windows.h>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <sstream>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>
namespace console {
class Buffer {
public:
typedef CONSOLE_SCREEN_BUFFER_INFO Info;
Buffer() : m_handle(winapi::Handle::std_out()), m_info(get_info(m_handle)) {}
Buffer(winapi::Handle&& handle) : m_handle(std::move(handle)), m_info(get_info(m_handle)) {}
int16_t get_columns() const { return m_info.dwSize.X; }
int16_t get_lines() const { return m_info.dwSize.Y; }
int16_t get_cursor_column() const { return m_info.dwCursorPosition.X; }
int16_t get_cursor_line() const { return m_info.dwCursorPosition.Y; }
void update() { m_info = get_info(m_handle); }
/*
* This is a stupid little function to read the console screen buffer.
* It's fragile and will break whenever anything happens (like, if the
* console screen is resized).
*
* The screen buffer:
* 1) doesn't preserve line breaks,
* 2) pads text lines with spaces (ASCII 0x20) for storage.
*
* Hence, the "lines" read are one-dimensional arrays, right-trimmed, and
* there's no way to learn whether the whole line printed by the user was
* read back in its entirety.
*
* For example, let the console window be 80 columns wide, and the user
* prints 85 consecutive characters 'a' using
*
* std::cout << std::string(85, 'a') << '\n';
*
* The following holds:
* 1) read_lines(-1, -1) == {"aaaaa"},
* 2) read_lines(-2, -2) == {std::string(80, 'a'), "aaaaa"}.
*
* I also don't know how it interacts with tab characters '\t', encodings,
* etc. It sucks, don't use it.
*/
std::vector<std::string> read_lines(int16_t top, int16_t bottom) const {
if (top < 0)
top = get_cursor_line() + top;
if (bottom < 0)
bottom = get_cursor_line() + bottom;
if (top < 0 || bottom < 0)
throw std::range_error{"Invalid console line"};
if (top > bottom) {
std::swap(top, bottom);
}
int16_t numof_lines = bottom - top + 1;
COORD buffer_size;
buffer_size.X = get_columns();
buffer_size.Y = numof_lines;
COORD buffer_coord;
buffer_coord.X = 0;
buffer_coord.Y = 0;
std::vector<CHAR_INFO> buffer;
buffer.resize(buffer_size.X * buffer_size.Y);
SMALL_RECT read_region;
read_region.Top = top;
read_region.Left = 0;
read_region.Bottom = bottom;
read_region.Right = buffer_size.X - 1;
if (!::ReadConsoleOutputW(
m_handle.get(), buffer.data(), buffer_size, buffer_coord, &read_region)) {
throw winapi::error::windows(GetLastError(), "ReadConsoleOutputW");
}
std::vector<std::string> result;
for (int16_t i = 0; i < numof_lines; ++i) {
std::wostringstream oss;
for (int16_t c = 0; c < buffer_size.X; ++c) {
oss << buffer[i * buffer_size.X + c].Char.UnicodeChar;
}
result.emplace_back(boost::trim_right_copy(winapi::narrow(oss.str())));
}
return result;
}
std::vector<std::string> read_last_lines(std::size_t numof_lines = 1) const {
if (numof_lines < 1 || numof_lines > INT16_MAX)
throw std::range_error{"Invalid number of lines"};
return read_lines(-static_cast<int16_t>(numof_lines), -1);
}
std::string read_last_line() const { return read_lines(-1, -1)[0]; }
std::string read_line(int16_t n) const { return read_lines(n, n)[0]; }
private:
static Info get_info(const winapi::Handle& handle) {
Info dest;
std::memset(&dest, 0, sizeof(dest));
if (!::GetConsoleScreenBufferInfo(static_cast<HANDLE>(handle), &dest)) {
throw winapi::error::windows(GetLastError(), "GetConsoleScreenBufferInfo");
}
return dest;
}
winapi::Handle m_handle;
Info m_info;
};
} // namespace console
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