#include <iostream>
#include <tuple>
#include <cstdlib>
#include "referee.h"

// Timeout in milliseconds for the feature negotiation at the start of the
// protocol. If the referee hasn't sent anything after this timeout, we assume
// the referee isn't capable of sending feature lines.
#define FEATURE_TIMEOUT 200


Referee::Referee(bool verbose, const string_view execname, const vector<string> &players)
		: verbose(verbose)
		, proc(execname)
		, refereeExecname(execname)
		, numPlayers(players.size()) {

	proc.run();

	reftag = "REF(" + to_string(proc.getPid()) + ") ";

	if (verbose) {
		cout << reftag << "starting for:";
		for (const string &p : players) cout << " " << p;
		cout << endl;
	}

	queryFeatures();

	if (!features.version2) {
		cout << reftag << "does not support protocol version 2!" << endl;
		exit(1);
	}

	proc.writeLine(to_string(players.size()), false);
	for (const string &p : players) {
		proc.writeLine(p, false);
	}
}

Referee::~Referee() {
	if (verbose) {
		cout << reftag << "stopping" << endl;
	}
	proc.wait();
	proc.terminate();
}

Referee::Event Referee::nextEvent() {
	optional<string> ocommand = proc.readLine();
	if (!ocommand) {
		cout << reftag << "Unexpected EOF before 'end' command!" << endl;
		exit(1);
	}

	string &command = *ocommand;

	if (verbose) {
		cout << reftag << "read <" << command << ">" << endl;
	}

	auto getPlayer = [this](const string &command, const char *commandName, int prefixLen) {
		int player;
		try {
			player = stoi(command.substr(prefixLen));
		} catch (...) {
			cout << reftag << "Protocol violation in '" << commandName << "' command!" << endl;
			exit(1);
		}

		if (player < 0 || player >= numPlayers) {
			cout << reftag << "Invalid player index " << player << " mentioned in '" << commandName << "' command!" << endl;
			exit(1);
		}

		size_t afterIndex = command.find(' ', prefixLen);
		if (afterIndex != string::npos) afterIndex++;

		return make_pair(player, afterIndex);
	};

	if (command.substr(0, 5) == "read ") {
		int player = getPlayer(command, "read", 5).first;
		return ReadEvent{
			player,
			[this](const string &line) {
				if (verbose) {
					cout << reftag << "write <" << line << ">" << endl;
				}

				if (!proc.writeLine(line, false)) {
					cout << reftag << "Referee exited unexpectedly after 'read' command!" << endl;
					exit(1);
				}
			}
		};
	} else if (command.substr(0, 6) == "write ") {
		int player;
		size_t afterIndex;
		tie(player, afterIndex) = getPlayer(command, "write", 6);

		if (afterIndex == string::npos) {
			cout << reftag << "Protocol violation in 'write' command: no line!" << endl;
			exit(1);
		}

		return WriteEvent{player, false, command.substr(afterIndex)};
	} else if (command.substr(0, 11) == "writemaybe ") {
		int player;
		size_t afterIndex;
		tie(player, afterIndex) = getPlayer(command, "writemaybe", 11);

		if (afterIndex == string::npos) {
			cout << reftag << "Protocol violation in 'writemaybe' command: no line!" << endl;
			exit(1);
		}

		return WriteEvent{player, true, command.substr(afterIndex)};
	} else if (command.substr(0, 8) == "gamelog ") {
		int player;
		size_t afterIndex;
		tie(player, afterIndex) = getPlayer(command, "gamelog", 8);

		if (afterIndex == string::npos) {
			cout << reftag << "Protocol violation in 'gamelog' command: no line!" << endl;
			exit(1);
		}

		return GamelogEvent{player, command.substr(afterIndex)};
	} else if (command.substr(0, 4) == "end ") {
		size_t cursor = 4;

		vector<int> scores;
		while (cursor < command.size()) {
			size_t idx = command.find(' ', cursor);
			if (idx == string::npos) idx = command.size();

			string substr = command.substr(cursor, idx - cursor);

			int score;
			try {
				score = stoi(substr);
			} catch (...) {
				cout << reftag << "Protocol violation in 'end' command: invalid scores!" << endl;
				exit(1);
			}

			scores.push_back(score);

			cursor = idx + 1;
		}

		proc.terminate();
		return EndEvent{move(scores)};
	} else if (command.substr(0, 6) == "error ") {
		int player;
		size_t afterIndex;
		tie(player, afterIndex) = getPlayer(command, "error", 6);

		if (afterIndex == string::npos) {
			cout << reftag << "Protocol violation in 'error' command: no message!" << endl;
			exit(1);
		}

		proc.terminate();
		return ErrorEvent{player, command.substr(afterIndex)};
	} else {
		cout << reftag << "Protocol violation: unknown command '" << command << "'!" << endl;
		exit(1);
	}
}

void Referee::queryFeatures() {
	bool first = true;

	while (true) {
		optional<string> line;
		if (first) {
			line = proc.readLineTimeout(FEATURE_TIMEOUT);
			if (!line) {
				cout << "Referee '" << refereeExecname << "' does not support feature detection!" << endl;
				exit(1);
			}

			first = false;
		} else {
			line = proc.readLine();
		}

		if (!line) {
			cout << reftag << "EOF!" << endl;
			exit(1);
		}

		if (verbose) {
			cout << reftag << "read <" << *line << ">" << endl;
		}

		if (*line == "feature_end") {
			return;
		} else if (line->substr(0, 8) == "feature ") {
			string featname = line->substr(8);
			if (featname == "version_2") features.version2 = true;
			else {
				cerr << reftag << "Referee requested unsupported feature '" << featname << "'" << endl;
				exit(1);
			}
		} else {
			cerr << reftag << "Referee protocol violation in feature negotiation" << endl;
			exit(1);
		}
	}
}

void Referee::terminate() {
	proc.terminate();
}