#ifndef OSMIUM_IO_DETAIL_READ_WRITE_HPP
#define OSMIUM_IO_DETAIL_READ_WRITE_HPP

/*

This file is part of Osmium (https://osmcode.org/libosmium).

Copyright 2013-2025 Jochen Topf <jochen@topf.org> and others (see README).

Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

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, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

*/

#include <osmium/io/writer_options.hpp>
#include <osmium/util/file.hpp>

#include <cassert>
#include <cerrno>
#include <cstddef>
#include <fcntl.h>
#include <string>
#include <system_error>

namespace osmium {

    namespace io {

        /**
         * @brief Namespace for Osmium internal use
         */
        namespace detail {

            /**
             * Open file for writing. If the file exists, it is truncated, if
             * not, it is created. If the file name is empty or "-", no file
             * is opened and the stdout file descriptor (1) is returned.
             *
             * @param filename Name of file to be opened.
             * @param allow_overwrite If the file exists, should it be overwritten?
             * @returns File descriptor of open file.
             * @throws system_error if the file can't be opened.
             */
            inline int open_for_writing(const std::string& filename, const osmium::io::overwrite allow_overwrite = osmium::io::overwrite::no) {
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

                if (filename.empty() || filename == "-") {
#ifdef _WIN32
                    _setmode(1, _O_BINARY);
#endif
                    return 1; // stdout
                }

                int flags = O_WRONLY | O_CREAT; // NOLINT(hicpp-signed-bitwise)
                if (allow_overwrite == osmium::io::overwrite::allow) {
                    flags |= O_TRUNC; // NOLINT(hicpp-signed-bitwise)
                } else {
                    flags |= O_EXCL; // NOLINT(hicpp-signed-bitwise)
                }
#ifdef _WIN32
                flags |= O_BINARY; // NOLINT(hicpp-signed-bitwise)
#endif
                const int fd = ::open(filename.c_str(), flags, 0666);
                if (fd < 0) {
                    throw std::system_error{errno, std::system_category(), std::string("Open failed for '") + filename + "'"};
                }
                return fd;
            }

            /**
             * Open file for reading. If the file name is empty or "-", no file
             * is opened and the stdin file descriptor (0) is returned.
             *
             * @param filename Name of file to be opened.
             * @returns File descriptor of open file.
             * @throws system_error if the file can't be opened.
             */
            inline int open_for_reading(const std::string& filename) {
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

                if (filename.empty() || filename == "-") {
#ifdef _WIN32
                    _setmode(0, _O_BINARY);
#endif
                    return 0; // stdin
                }

#ifdef _WIN32
                const int flags = O_RDONLY | O_BINARY;
#else
                const int flags = O_RDONLY;
#endif
                const int fd = ::open(filename.c_str(), flags);
                if (fd < 0) {
                    throw std::system_error{errno, std::system_category(), std::string("Open failed for '") + filename + "'"};
                }
                return fd;
            }

            /**
             * Writes the given number of bytes from the output_buffer to the file descriptor.
             * This is just a wrapper around write(2), because write(2) can write less than
             * the given number of bytes.
             *
             * @param fd File descriptor.
             * @param output_buffer Buffer with data to be written. Must be at least size bytes long.
             * @param size Number of bytes to write.
             * @throws std::system_error On error.
             */
            inline void reliable_write(const int fd, const unsigned char* output_buffer, const size_t size) {
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

                enum : std::size_t {
                    // Max 100 MByte per write
                    max_write = 100UL * 1024UL * 1024UL
                };
                size_t offset = 0;
                do {
                    auto write_count = size - offset;
                    if (write_count > max_write) {
                        write_count = max_write;
                    }

                    int64_t length = 0;
                    do {
                        length = ::write(fd, output_buffer + offset, static_cast<unsigned int>(write_count));
                        if (length < 0 && errno != EINTR) {
                            throw std::system_error{errno, std::system_category(), "Write failed"};
                        }
                    } while (length < 0);
                    offset += static_cast<size_t>(length);
                } while (offset < size);
            }

            /**
             * Writes the given number of bytes from the output_buffer to the file descriptor.
             * This is just a wrapper around write(2), because write(2) can write less than
             * the given number of bytes.
             *
             * @param fd File descriptor.
             * @param output_buffer Buffer with data to be written. Must be at least size bytes long.
             * @param size Number of bytes to write.
             * @throws std::system_error On error.
             */
            inline void reliable_write(const int fd, const char* output_buffer, const size_t size) {
                reliable_write(fd, reinterpret_cast<const unsigned char*>(output_buffer), size);
            }

            /**
             * Reads a maximum of size bytes from the file descriptor into the
             * input_buffer. This is just a wrapper around read(2) catching
             * errors.
             *
             * @param fd File descriptor.
             * @param input_buffer Buffer for data to be read. Must be at least size bytes long.
             * @param size Maximum number of bytes to read.
             * @returns the number of bytes read
             * @throws std::system_error On error.
             */
            inline int64_t reliable_read(const int fd, char* input_buffer, const unsigned int size) {
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

                int64_t nread = 0;

                do {
#ifdef _WIN32
                    nread = _read(fd, input_buffer, size);
#else
                    nread = ::read(fd, input_buffer, size);
#endif
                    if (nread < 0 && errno != EINTR) {
                        throw std::system_error{errno, std::system_category(), "Read failed"};
                    }
                } while (nread < 0);

                return nread;
            }

            /**
             * Read exactly size bytes from fd into buffer. In contrast to reliable_read,
             * this function will continue reading until either EOF or an error is encountered.
             *
             * @pre buffer Buffer for data to be read. Must be at least size bytes long.
             * @returns true if size bytes could be read
             *          false if EOF was encountered
             */
            inline bool read_exactly(int fd, char* buffer, unsigned int size) {
                unsigned int to_read = size;

                while (to_read > 0) {
                    auto const read_size = reliable_read(fd, buffer + (size - to_read), to_read);
                    if (read_size == 0) { // EOF
                        return false;
                    }
                    assert(read_size <= to_read);
                    to_read -= static_cast<unsigned int>(read_size);
                }

                return true;
            }

            inline void reliable_fsync(const int fd) {
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

#ifdef _WIN32
                if (_commit(fd) != 0) {
#else
                if (::fsync(fd) != 0) {
#endif
                    throw std::system_error{errno, std::system_category(), "Fsync failed"};
                }
            }

            inline void reliable_close(const int fd) {
                if (fd < 0) {
                    return;
                }
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

#ifdef _WIN32
                if (_close(fd) != 0) {
#else
                if (::close(fd) != 0) {
#endif
                    throw std::system_error{errno, std::system_category(), "Close failed"};
                }
            }

            inline int reliable_dup(const int fd) {
#ifdef _MSC_VER
                osmium::detail::disable_invalid_parameter_handler diph;
#endif

#ifdef _WIN32
                const int fd2 = _dup(fd);
#else
                const int fd2 = ::dup(fd);
#endif
                if (fd2 < 0) {
                    throw std::system_error{errno, std::system_category(), "Dup failed"};
                }
                return fd2;
            }

            /**
             * Tell the kernel to remove all pages from this file from the
             * buffer cache. Used when reading a large file that will not be
             * needed again soon. Keeps the buffer cache clear for other
             * things.
             */
#if defined(__linux__) || defined(__FreeBSD__)
            inline void remove_buffered_pages(int fd) noexcept {
                if (fd > 0) {
                    ::posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
                }
#else
            inline void remove_buffered_pages(int /*fd*/) noexcept {
#endif
            }

            /**
             * Tell the kernel to remove all pages from this file up to the
             * specified size from the buffer cache. Used when reading a large
             * file that will not be needed again soon. Keeps the buffer cache
             * clear for other things.
             */
#if defined(__linux__) || defined(__FreeBSD__)
            inline void remove_buffered_pages(int fd, std::size_t size) noexcept {
                constexpr const std::size_t block_size = 4096;
                // Make sure to keep the last 10 blocks around, so were are
                // definitely not removing something which might be needed
                // again soon.
                if (fd > 0 && size > 10 * block_size) {
                    size -= 10 * block_size;
                    ::posix_fadvise(fd, 0, (size - 1) & ~(block_size - 1), POSIX_FADV_DONTNEED);
                }
#else
            inline void remove_buffered_pages(int /*fd*/, std::size_t /*size*/) noexcept {
#endif
            }

        } // namespace detail

    } // namespace io

} // namespace osmium

#endif // OSMIUM_IO_DETAIL_READ_WRITE_HPP
