module;

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

module io;

import std;

namespace brc {

std::string read_file(const std::filesystem::path& path) {
	auto file = std::ifstream(path);
	if (!file.is_open()) {
		throw std::runtime_error(std::format("could not open file: {}", path.string()));
	}
	auto stream = std::stringstream();
	stream << file.rdbuf();
	return stream.str();
}

mapped_file::mapped_file(const std::filesystem::path& path) {
	const auto file_size = std::filesystem::file_size(path);

	fd = open(path.generic_string().data(), O_RDONLY);
	data = mmap(nullptr, file_size, PROT_READ, MAP_PRIVATE, fd, 0);
	length = file_size;

	if (data == MAP_FAILED) {
		close(fd);
		throw std::runtime_error("failed to map file");
	}
}

mapped_file::mapped_file(mapped_file&& other) noexcept
	: fd(other.fd), data(std::exchange(other.data, nullptr)), length(other.length) {}

mapped_file& mapped_file::operator=(mapped_file&& other) noexcept {
	if (&other == this) {
		return *this;
	}

	auto moved = std::move(other);

	std::swap(moved.fd, this->fd);
	std::swap(moved.data, this->data);
	std::swap(moved.length, this->length);

	return *this;
}

mapped_file::~mapped_file() {
	if (data != nullptr) {
		munmap(data, length);
		close(fd);
	}
}

mapped_file::operator std::string_view() const noexcept {
	return std::string_view(reinterpret_cast<const char*>(data), length);
}

std::size_t mapped_file::size() const noexcept { return length; }

}  // namespace brc