#include "sys.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdexcept>
#include <system_error>

#include "logger.h"
#include "globals.h"

namespace sys {

FileInfo fileInfo(const std::string &path) {
	FileInfo finfo;

	struct stat st;
	if (stat(path.c_str(), &st) < 0) {
		throw std::runtime_error("stat '" + path + "': " + strerror(errno));
	}

	finfo.mTimeSec = st.st_mtim.tv_sec;
	finfo.mTimeNsec = st.st_mtim.tv_nsec;
	finfo.isDir = S_ISDIR(st.st_mode);
	return finfo;
}

bool fileExists(const std::string &path) {
	struct stat st;
	if (stat(path.c_str(), &st) < 0) {
		if (errno == ENOENT) {
			return false;
		} else {
			throw std::runtime_error("stat '" + path + "': " + strerror(errno));
		}
	}

	return true;
}

void mkdirp(const std::string &path) {
	// TODO: Implement this in C++ instead
	std::vector<std::string> argv;
	argv.push_back("mkdir");
	argv.push_back("-p");
	argv.push_back("--");
	argv.push_back(path);
	execute(argv, nullptr, global::verbose >= 2);
}

void execute(const std::vector<std::string> &args, std::string *output, bool print) {
	if (print) {
		std::string str;
		for (size_t i = 0; i < args.size(); ++i) {
			if (i != 0) {
				str += " ";
			}
			str += args[i];
		}
		logger::log(str);
	}

	// argv[0] should be interpreted as a shell command, because being able to run
	// CC='gcc --sysroot=/blah' is used by some systems.
	std::string command = std::string(args[0]) + " \"$@\"";
	std::vector<const char *> argv;
	argv.push_back("/bin/sh"); // TODO: Use $SHELL?
	argv.push_back("-c");
	argv.push_back(command.c_str());
	argv.push_back("--");
	for (size_t i = 1; i < args.size(); ++i) {
		argv.push_back(args[i].c_str());
	}

	argv.push_back(nullptr);

	int fds[2];
	if (pipe(fds) < 0) {
		throw std::runtime_error(std::string("fork: ") + strerror(errno));
	}

	pid_t child = fork();
	if (child == 0) {
		close(fds[0]);
		dup2(fds[1], 1);

		// So, from what I've read, execvp should never modify its argv; so this should be fine?
		if (execvp(argv[0], (char *const *)argv.data()) < 0) {
			perror(argv[0]);
			abort();
		}

		// This shouldn't happen
		exit(0);
	} else if (child < 0) {
		throw std::runtime_error(std::string("fork: ") + strerror(errno));
	}

	close(fds[1]);

	if (output == nullptr) {
		close(fds[0]);
	} else {
		char buf[1025];
		while (true) {
			ssize_t num = read(fds[0], buf, sizeof(buf) - 1);
			if (num < 0 && errno != EAGAIN) {
				close(fds[0]);
				throw std::runtime_error(
					std::string("read: ") + strerror(errno) +
					" (fd: " + std::to_string(fds[0]) + ")");
			} else if (num < 0) {
				continue;
			}

			if (num == 0) {
				close(fds[0]);
				break;
			}

			buf[num] = '\0';
			*output += buf;
		}
	}

	int wstatus;
	waitpid(child, &wstatus, 0);
	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0) {
		throw std::runtime_error(std::string(args[0]) +
				" exited with code " + std::to_string(WEXITSTATUS(wstatus)));
	}

	if (WTERMSIG(wstatus)) {
		throw std::runtime_error(std::string(args[0]) +
				" terminated due to " + strsignal(WTERMSIG(wstatus)));
	}

	if (output != nullptr && output->back() == '\n') {
		output->pop_back();
	}
}

void readDir(const std::string &path, std::vector<std::string> &files) {
	DIR *d = opendir(path.c_str());
	if (d == NULL) {
		throw std::runtime_error("opendir '" + path + "': " + strerror(errno));
	}

	struct dirent *ent;
	while ((ent = readdir(d)) != NULL) {
		if (ent->d_name[0] == '.')
			continue;
		files.emplace_back(ent->d_name);
	}

	closedir(d);
}

void chdir(const std::string &path) {
	if (::chdir(path.c_str()) < 0) {
		throw std::runtime_error("chdir '" + path + "': " + strerror(errno));
	}
}

std::string cwd() {
	std::vector<char> buf;
	buf.reserve(128);
	while (1) {
		char *res = getcwd(buf.data(), buf.capacity());
		if (res == NULL) {
			if (errno == ERANGE) {
				buf.reserve(buf.capacity() * 2);
			} else {
				throw std::system_error(EFAULT, std::generic_category());
			}
		} else {
			std::string str(buf.data());
			return str;
		}
	}
}

void symlink(const std::string &from, const std::string &to) {
	// TODO: Implement this in C++ instead
	std::vector<std::string> argv;
	argv.push_back("ln");
	argv.push_back("-s");
	argv.push_back("-f");
	argv.push_back("--");
	argv.push_back(from);
	argv.push_back(to);
	sys::execute(argv, nullptr, global::verbose > 2);
}

}