#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <stdexcept>
#include <utility>
#include <algorithm>
#include <optional>
#include <string_view>
#include <cstdint>
#include <cstring>
#include <cstdlib>
#include <cctype>
#include <cassert>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/fcntl.h>
#include <sys/wait.h>
#include "../board.h"

using namespace std;


static const char *matchcachedir = "comp_cache";
static const char *playerlogdir = "comp_playerlogs";
static const char *gamelogdir = "comp_gamelogs";
static const int num_matches = 5;
static const int timeout_msec = 60000;


static char hexchar(int n) {
	return "0123456789ABCDEF"[n];
}

static string makeSafe(const string_view str) {
	string res;
	res.reserve(str.size() + 3);

	for (char c : str) {
		if (isalnum(c)) {
			res += c;
		} else {
			res += '_';
			res += hexchar((c >> 4) & 0xf);
			res += hexchar(c & 0xf);
		}
	}

	return res;
}

// Only creates a single component
static void mkdirp(const string_view name) {
	if (mkdir(name.data(), 0755) < 0) {
		if (errno != EEXIST) {
			perror("mkdir");
			exit(1);
		}
	}
}

static int64_t gettimestamp() {
	struct timeval tv;
	gettimeofday(&tv, nullptr);
	return tv.tv_sec * 1000000LL + tv.tv_usec;
}

struct Player;

// 'win' is for player 1
struct MatchResult {
	enum class Win {
		win, loss, tie, timeout
	};

	Win win;
	size_t ms1 = 0, ms2 = 0;

	int score() const;
	string describe(const Player &p1, const Player &p2) const;
	MatchResult inverted() const;
};

struct Player {
	string fname, safename;
	vector<MatchResult> results;

	Player(const string &fname)
			: fname(fname), safename(makeSafe(fname)) {}
};

int MatchResult::score() const {
	switch (win) {
		case Win::win: return 3;
		case Win::loss: return 1;
		case Win::tie: return 2;
		case Win::timeout: return 0;
		default: assert(false);
	}
}

string MatchResult::describe(const Player &p1, const Player &p2) const {
	string prefix;
	switch (win) {
		case Win::win: prefix = p1.fname + " won: "; break;
		case Win::loss: prefix = p2.fname + " won: "; break;
		case Win::tie: prefix = "tie: "; break;
		case Win::timeout: prefix = "timeout: "; break;
	}
	return prefix + to_string(score()) + "-" + to_string(inverted().score());
}

MatchResult MatchResult::inverted() const {
	MatchResult r;
	switch (win) {
		case Win::win: r.win = Win::loss; break;
		case Win::loss: r.win = Win::win; break;
		case Win::tie: r.win = Win::tie; break;
		case Win::timeout: r.win = Win::timeout; break;
	}
	r.ms2 = ms1; r.ms1 = ms2;
	return r;
}

class StopCompetitionError : public runtime_error {
public:
	StopCompetitionError()
			: runtime_error("StopCompetitionError") {}
	explicit StopCompetitionError(const string &what_arg)
			: runtime_error(what_arg) {}
	explicit StopCompetitionError(const char *what_arg)
			: runtime_error(what_arg) {}
};

class Process {
	string execname;
	optional<string> stderrRedirect;
	pid_t pid = -1;
	int infd = -1, outfd = -1;

	string readBuf;

public:
	Process(const string_view execname)
			: execname(execname) {}

	void redirectStderr(const string_view fname) {
		stderrRedirect = fname;
	}

	void run() {
		int stderrfd = -1;
		if (stderrRedirect) {
			stderrfd = open(stderrRedirect->data(), O_WRONLY|O_CREAT|O_TRUNC, 0644);
			if (stderrfd < 0) {
				perror("open");
				cout << endl << "ERROR: Cannot open player log file '" << *stderrRedirect << "'" << endl;
				throw StopCompetitionError();
			}
		}

		int pipefds[2];
		if (pipe(pipefds) < 0) {
			perror("pipe");
			exit(1);
		}
		infd = pipefds[1];
		int child_in = pipefds[0];

		if (pipe(pipefds) < 0) {
			perror("pipe");
			exit(1);
		}
		outfd = pipefds[0];
		int child_out = pipefds[1];

		pid = fork();
		if (pid < 0) {
			perror("fork");
			exit(1);
		}

		if (pid == 0) {
			if (stderrRedirect) dup2(stderrfd, STDERR_FILENO);
			dup2(child_in, STDIN_FILENO);
			dup2(child_out, STDOUT_FILENO);
			close(infd);
			close(outfd);

			execlp(execname.data(), execname.data(), NULL);
			cerr << endl << "ERROR: Error executing player file '" << execname << "'" << endl;
			exit(255);
		}

		if (stderrfd >= 0) close(stderrfd);
		close(child_in);
		close(child_out);
	}

	void wait() {
		while (true) {
			int status;
			if (waitpid(pid, &status, 0) < 0) {
				if (errno == EINTR) continue;
				perror("waitpid");
				break;
			}
			if (WIFEXITED(status)) break;
		}
	}

	void stop() {
		if (pid != -1) kill(pid, SIGSTOP);
	}

	void unStop() {
		if (pid != -1) kill(pid, SIGCONT);
	}

	bool writeLine(const string_view line) {
		string str;
		str.reserve(line.size() + 1);
		str += line;
		str += '\n';

		size_t cursor = 0;
		while (cursor < str.size()) {
			ssize_t nw = write(infd, str.data() + cursor, str.size() - cursor);
			if (nw < 0) {
				if (errno == EINTR) continue;
				perror("write");
				return false;
			}
			cursor += nw;
		}

		return true;
	}

	optional<string> readLine() {
		size_t idx = readBuf.find('\n');
		if (idx != string::npos) {
			string res = readBuf.substr(0, idx);
			readBuf = readBuf.substr(idx + 1);
			return res;
		}

		while (true) {
			string s(1024, '\0');
			ssize_t nr = read(outfd, &s[0], s.size());
			if (nr < 0) {
				if (errno == EINTR) continue;
				perror("read");
				return nullopt;
			}
			s.resize(nr);

			idx = s.find('\n');
			if (idx != string::npos) {
				string res = readBuf + s.substr(0, idx);
				readBuf = s.substr(idx + 1);
				return res;
			}

			readBuf += s;
		}
	}

	void terminate() {
		if (pid != -1) kill(pid, SIGTERM);
	}
};

static string gameCodeName(const Player &p1, const Player &p2, int index) {
	return p1.safename + "-" + p2.safename + "-" + to_string(index);
}

static string playerLogPath(const Player &p1, const Player &p2, int index, int who) {
	return string(playerlogdir) + "/" + gameCodeName(p1, p2, index) + "-" + to_string(who) + ".txt";
}

static string matchCachePath(const Player &p1, const Player &p2, int index) {
	return string(matchcachedir) + "/" + gameCodeName(p1, p2, index) + ".txt";
}

static string gameLogPath(const Player &p1, const Player &p2, int index) {
	return string(gamelogdir) + "/" + gameCodeName(p1, p2, index) + ".txt";
}

static optional<MatchResult> readMatchCache(const Player &p1, const Player &p2, int index) {
	ifstream f(matchCachePath(p1, p2, index));
	if (!f) return nullopt;

	MatchResult mres;
	string word;
	f >> word >> mres.ms1 >> mres.ms2;
	if (!f) return nullopt;

	if (word == "win") mres.win = MatchResult::Win::win;
	else if (word == "loss") mres.win = MatchResult::Win::loss;
	else if (word == "tie") mres.win = MatchResult::Win::tie;
	else if (word == "timeout") mres.win = MatchResult::Win::timeout;
	else return nullopt;

	return mres;
}

static void writeMatchCache(const Player &p1, const Player &p2, int index, const MatchResult &mres) {
	string path = matchCachePath(p1, p2, index);
	ofstream f(path);
	if (!f) {
		cout << endl << "ERROR: Cannot open match cache file '" << path << "'" << endl;
		throw StopCompetitionError();
	}

	switch (mres.win) {
		case MatchResult::Win::win: f << "win"; break;
		case MatchResult::Win::loss: f << "loss"; break;
		case MatchResult::Win::tie: f << "tie"; break;
		case MatchResult::Win::timeout: f << "timeout"; break;
	}

	f << ' ' << mres.ms1 << ' ' << mres.ms2 << endl;
}

static void recordResult(Player &p1, Player &p2, const MatchResult &result) {
	p1.results.push_back(result);
	p2.results.push_back(result.inverted());
}

static void playMatch(Player &p1, Player &p2, int index) {
	cout << p1.fname << " - " << p2.fname << ": " << flush;

	if (optional<MatchResult> optres = readMatchCache(p1, p2, index)) {
		cout << optres->describe(p1, p2) << " (cached)" << endl;
		recordResult(p1, p2, *optres);
		return;
	}

	MatchResult mres;


	string gamelog_path = gameLogPath(p1, p2, index);
	ofstream gamelog(gamelog_path);
	if (!gamelog) {
		cout << endl << "ERROR opening game log file " << gamelog_path << endl;
		throw StopCompetitionError();
	}

	gamelog << "Player 1: " << p1.fname << "\n"
	        << "Player 2: " << p2.fname << "\n\n" << flush;

	Process procs[2] = {Process(p1.fname), Process(p2.fname)};
	procs[0].redirectStderr(playerLogPath(p1, p2, index, 1));
	procs[1].redirectStderr(playerLogPath(p1, p2, index, 2));
	procs[0].run();
	procs[1].run();

	Board board = Board::makeInitial();
	string lastMove = "Start";

	while (true) {
		for (int i = 0; i < 2; i++) {
			if (!procs[i].writeLine(lastMove)) {
				cout << endl << "ERROR writing move to player " << i+1 << endl;
				throw StopCompetitionError();
			}

			procs[i].unStop();
			int64_t start = gettimestamp();
			optional<string> oline = procs[i].readLine();
			if (!oline) {
				cout << endl << "ERROR reading move from player " << i+1 << endl;
				throw StopCompetitionError();
			}

			lastMove = *oline;
			(i == 0 ? mres.ms1 : mres.ms2) += gettimestamp() - start;
			procs[i].stop();

			gamelog << "P" << i+1 << ": " << lastMove << endl;

			if (mres.ms1 / 1000 > timeout_msec || mres.ms2 / 1000 > timeout_msec) {
				mres.win = MatchResult::Win::timeout;
				goto match_done;
			}

			optional<Move> omv = Move::parse(lastMove);
			if (!omv) {
				cout << endl << "ERROR in player " << i+1 << ": unreadable move '" << lastMove << "'" << endl;
				throw StopCompetitionError();
			}
			if (!board.isValid(*omv, i == 0 ? -1 : 1)) {
				cout << endl << "ERROR in player " << i+1 << ": invalid move " << *omv << endl;
				throw StopCompetitionError();
			}

			int outcome = board.applyCW(*omv);
			if (outcome != 0) {
				if (outcome == 1) mres.win = MatchResult::Win::loss;
				else if (outcome == -1) mres.win = MatchResult::Win::win;
				else assert(false);
				goto match_done;
			}

			stringstream ss;
			ss << *omv;
			lastMove = ss.str();
		}
	}

match_done:
	for (int i = 0; i < 2; i++) {
		bool success = procs[i].writeLine("Stop");
		procs[i].unStop();
		if (success) usleep(10000);
		procs[i].terminate();
	}
	for (int i = 0; i < 2; i++) {
		procs[i].wait();
	}

	cout << mres.describe(p1, p2) << endl;

	gamelog << "\nResult: " << mres.describe(p1, p2) << "\n"
	        << "P1 took " << mres.ms1 / 1000000.0 << " seconds\n"
	        << "P2 took " << mres.ms2 / 1000000.0 << " seconds\n" << flush;

	writeMatchCache(p1, p2, index, mres);
	recordResult(p1, p2, mres);
}

static void playerPit(Player &p1, Player &p2) {
	for (int i = 0; i < num_matches; i++) {
		playMatch(p1, p2, i + 1);
	}
}

static void fullCompetition(vector<Player> &players) {
	for (size_t p1i = 0; p1i < players.size(); p1i++) {
		for (size_t p2i = p1i + 1; p2i < players.size(); p2i++) {
			playerPit(players[p1i], players[p2i]);
			playerPit(players[p2i], players[p1i]);
		}
	}
}

int main(int argc, char **argv) {
	if (argc <= 1) {
		cerr << "Usage: " << argv[0] << " <players...>" << endl;
		return 1;
	}

	vector<Player> players;
	for (int i = 0; i < argc - 1; i++) {
		players.emplace_back(argv[i+1]);
	}

	mkdirp(matchcachedir);
	mkdirp(playerlogdir);
	mkdirp(gamelogdir);

	fullCompetition(players);

	vector<pair<string, int>> scores;
	for (const Player &player : players) {
		int score = 0;
		for (const MatchResult &result : player.results) {
			score += result.score();
		}
		scores.emplace_back(player.fname, score);
	}

	sort(scores.begin(), scores.end(),
			[](const pair<string, int> &a, const pair<string, int> &b) { return a.second > b.second; });

	size_t maxlen = strlen("Player");
	for (const Player &player : players) {
		maxlen = max(maxlen, player.fname.size());
	}

	cout << endl << setw(maxlen) << "Player" << " | " << "Score" << endl;
	cout << string(maxlen, '-') << "-+------" << endl;

	for (const auto &p : scores) {
		cout << setw(maxlen) << p.first << " | " << p.second << endl;
	}
}