///
/// \file rcpp.cc
/// \author kyle 
/// \created 2023-10-12
/// \brief rcpp is a recursive copy by pattern program.
///
/// \section COPYRIGHT
///
/// Copyright 2023 K. Isom <kyle@imap.cc>
///
/// Permission to use, copy, modify, and/or distribute this software for
/// any purpose with or without fee is hereby granted, provided that
/// the above copyright notice and this permission notice appear in all
/// copies.
///
/// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
/// WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
/// WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
/// AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
/// DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
/// OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
/// TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
/// PERFORMANCE OF THIS SOFTWARE.
///


#include <filesystem>
#include <fstream>
#include <iostream>
#include <regex>


#define ALIAS_FS	namespace fs = std::filesystem
typedef std::filesystem::path	Path;


#ifdef NO_TRACE
static std::ofstream	null("/dev/null");
#define TRACE	null
#else
#define TRACE	std::cout
#endif



int
preflightDirectory(Path dst)
{
	ALIAS_FS;
	if (!fs::exists(dst)) {
		fs::create_directory(dst);
	} else if (!fs::is_directory(dst)) {
		return -1;
	}

	return 0;
}


int
preflightChecks(Path dst, Path src)
{
	ALIAS_FS;

	if (preflightDirectory(dst) != 0) {
		return -1;
	}

	if (!fs::exists(src)) {
		return -1;
	}

	if (!fs::is_regular_file(src)) {
		return -1;
	}

	return 0;
}

int
copyToPath(Path dst, Path src)
{
	ALIAS_FS;

	TRACE << "copyToPath " << dst << " " << src << "\n";

	if (preflightChecks(dst, src)) {
		return -1;
	}

	Path dstFile = dst / src.filename();
	TRACE << "destination file: " << dstFile << "\n";

	fs::copy(src, dst, fs::copy_options::update_existing);
	return 0;
}


int
maybeCopyPattern(Path dst, Path entry, std::regex &pattern)
{
	ALIAS_FS;

	TRACE << "maybeCopyPattern " << entry << "\n";
	if (!fs::is_regular_file(entry)) {
		TRACE << "\tnot a file\n";
		return 0;
	}

	if (!std::regex_search(entry.string(), pattern)) {
		TRACE << "\tpattern doesn't match\n";
		return 0;
	}

	return (copyToPath(dst, entry));
}



int
recursiveCopyPattern(Path &dst, Path &src, std::regex &pattern)
{
	ALIAS_FS;

	if (!fs::exists(src)) {
		return -1;
	} 		

	if (!fs::is_directory(src)) {
		return -1;
	}

	for (auto entry : fs::recursive_directory_iterator(src)) {
		TRACE << "found " << entry << "\n";
		if (maybeCopyPattern(dst, entry, pattern)) {
			return -1;
		}
	}

	return 0;
}


int
main(int argc, char *argv[])
{
	ALIAS_FS;

	auto regexOptions = std::regex_constants::optimize;
	if (argc < 4) {
		std::cerr << "Usage: rcpp pattern files... destination\n";
	}

	auto pattern = std::string(argv[1]);
	auto destDir = fs::absolute(fs::path(argv[argc-1]));
	bool value;
	
	TRACE << "argc: " << argc << "\n";

	auto rePattern = std::regex(pattern);
	for (int i = 2; i < argc-1; i++) {
		TRACE << "[" << i << "] consider " << argv[i] << "\n";
		auto src = fs::path(argv[i]);
		if (recursiveCopyPattern(destDir, src, rePattern) != 0) {
			TRACE << "failed\n";
		}
	}

	return 0;
}