/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2018-2020, 2022 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2015-2016 Attila Molnar <attilamolnar@hush.com>
 *
 * This file is part of InspIRCd.  InspIRCd is free software: you can
 * redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation, version 2.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


#pragma once

namespace Numeric
{
	class WriteNumericSink;
	class WriteRemoteNumericSink;

	template <char Sep, bool SendEmpty, typename Sink>
	class GenericBuilder;

	template <char Sep = ',', bool SendEmpty = false>
	class Builder;

	template <unsigned int NumStaticParams, bool SendEmpty, typename Sink>
	class GenericParamBuilder;

	template <unsigned int NumStaticParams, bool SendEmpty = false>
	class ParamBuilder;
}

class Numeric::WriteNumericSink
{
	LocalUser* const user;

 public:
	WriteNumericSink(LocalUser* u)
		: user(u)
	{
	}

	void operator()(Numeric& numeric) const
	{
		user->WriteNumeric(numeric);
	}
};

class Numeric::WriteRemoteNumericSink
{
	User* const user;

 public:
	WriteRemoteNumericSink(User* u)
		: user(u)
	{
	}

	void operator()(Numeric& numeric) const
	{
		user->WriteRemoteNumeric(numeric);
	}
};

template <char Sep, bool SendEmpty, typename Sink>
class Numeric::GenericBuilder
{
	Sink sink;
	Numeric numeric;
	const std::string::size_type max;

	bool HasRoom(const std::string::size_type additional) const
	{
		return (numeric.GetParams().back().size() + additional <= max);
	}

 public:
	GenericBuilder(Sink s, unsigned int num, bool addparam = true, size_t additionalsize = 0)
		: sink(s)
		, numeric(num)
		, max(ServerInstance->Config->Limits.MaxLine - ServerInstance->Config->GetServerName().size() - additionalsize - 10)
	{
		if (addparam)
			numeric.push(std::string());
	}

	Numeric& GetNumeric() { return numeric; }

	void Add(const std::string& entry)
	{
		if (!HasRoom(entry.size()))
			Flush();
		numeric.GetParams().back().append(entry).push_back(Sep);
	}

	void Add(const std::string& entry1, const std::string& entry2)
	{
		if (!HasRoom(entry1.size() + entry2.size()))
			Flush();
		numeric.GetParams().back().append(entry1).append(entry2).push_back(Sep);
	}

	void Flush()
	{
		std::string& data = numeric.GetParams().back();
		if (IsEmpty())
		{
			if (!SendEmpty)
				return;
		}
		else
		{
			data.erase(data.size()-1);
		}

		sink(numeric);
		data.clear();
	}

	bool IsEmpty() const { return (numeric.GetParams().back().empty()); }
};

template <char Sep, bool SendEmpty>
class Numeric::Builder : public GenericBuilder<Sep, SendEmpty, WriteNumericSink>
{
 public:
	Builder(LocalUser* user, unsigned int num, bool addparam = true, size_t additionalsize = 0)
		: ::Numeric::GenericBuilder<Sep, SendEmpty, WriteNumericSink>(WriteNumericSink(user), num, addparam, additionalsize + user->nick.size())
	{
	}
};

template <unsigned int NumStaticParams, bool SendEmpty, typename Sink>
class Numeric::GenericParamBuilder
{
	Sink sink;
	Numeric numeric;
	std::string::size_type currlen;
	std::string::size_type max;

	bool HasRoom(const std::string::size_type additional) const
	{
		return (currlen + additional <= max);
	}

 public:
	GenericParamBuilder(Sink s, unsigned int num, size_t additionalsize)
		: sink(s)
		, numeric(num)
		, currlen(0)
		, max(ServerInstance->Config->Limits.MaxLine - ServerInstance->Config->GetServerName().size() - additionalsize - 10)
	{
	}

	void AddStatic(const std::string& entry)
	{
		max -= (entry.length() + 1);
		numeric.GetParams().push_back(entry);
	}

	void Add(const std::string& entry)
	{
		if (!HasRoom(entry.size()))
			Flush();

		currlen += entry.size() + 1;
		numeric.GetParams().push_back(entry);
	}

	void Flush()
	{
		if ((!SendEmpty) && (IsEmpty()))
			return;

		sink(numeric);
		currlen = 0;
		numeric.GetParams().erase(numeric.GetParams().begin() + NumStaticParams, numeric.GetParams().end());
	}

	bool IsEmpty() const { return (numeric.GetParams().size() <= NumStaticParams); }
};

template <unsigned int NumStaticParams, bool SendEmpty>
class Numeric::ParamBuilder : public GenericParamBuilder<NumStaticParams, SendEmpty, WriteNumericSink>
{
 public:
	ParamBuilder(LocalUser* user, unsigned int num)
		: ::Numeric::GenericParamBuilder<NumStaticParams, SendEmpty, WriteNumericSink>(WriteNumericSink(user), num, user->nick.size())
	{
	}
};

namespace Numerics
{
	class CannotSendTo;
	class ChannelPrivilegesNeeded;
	class InvalidModeParameter;
	class NoSuchChannel;
	class NoSuchNick;
}

/** Builder for the ERR_CANNOTSENDTOCHAN and ERR_CANTSENDTOUSER numerics. */
class Numerics::CannotSendTo : public Numeric::Numeric
{
 public:
	CannotSendTo(Channel* chan, const std::string& message)
		: Numeric(ERR_CANNOTSENDTOCHAN)
	{
		push(chan->name);
		push(message);
	}

	CannotSendTo(Channel* chan, const std::string& what, ModeHandler* mh)
		: Numeric(ERR_CANNOTSENDTOCHAN)
	{
		push(chan->name);
		push(InspIRCd::Format("You cannot send %s to this channel whilst the +%c (%s) mode is set.",
			what.c_str(), mh->GetModeChar(), mh->name.c_str()));
	}

	CannotSendTo(Channel* chan, const std::string& what, char extban, const std::string& extbandesc)
		: Numeric(ERR_CANNOTSENDTOCHAN)
	{
		push(chan->name);
		push(InspIRCd::Format("You cannot send %s to this channel whilst %s %c: (%s) extban is set matching you.",
			what.c_str(), strchr("AEIOUaeiou", extban) ? "an" : "a", extban, extbandesc.c_str()));
	}

	CannotSendTo(User* user, const std::string& message)
		: Numeric(ERR_CANTSENDTOUSER)
	{
		push(user->registered & REG_NICK ? user->nick : "*");
		push(message);
	}

	CannotSendTo(User* user, const std::string& what, ModeHandler* mh, bool self = false)
		: Numeric(ERR_CANTSENDTOUSER)
	{
		push(user->registered & REG_NICK ? user->nick : "*");
		push(InspIRCd::Format("You cannot send %s to this user whilst %s have the +%c (%s) mode set.",
			what.c_str(), self ? "you" : "they", mh->GetModeChar(), mh->name.c_str()));
	}
};

/* Builder for the ERR_CHANOPRIVSNEEDED numeric. */
class Numerics::ChannelPrivilegesNeeded : public Numeric::Numeric
{
 public:
	ChannelPrivilegesNeeded(Channel* chan, unsigned int rank, const std::string& message)
		: Numeric(ERR_CHANOPRIVSNEEDED)
	{
		push(chan->name);

		const PrefixMode* pm = ServerInstance->Modes.FindNearestPrefixMode(rank);
		if (pm)
			push(InspIRCd::Format("You must be a channel %s or higher to %s.", pm->name.c_str(), message.c_str()));
		else
			push(InspIRCd::Format("You do not have the required channel privileges to %s.", message.c_str()));
	}
};

/* Builder for the ERR_INVALIDMODEPARAM numeric. */
class Numerics::InvalidModeParameter : public Numeric::Numeric
{
 private:
	void push_message(ModeHandler* mode, const std::string& message)
	{
		if (!message.empty())
		{
			// The caller has specified their own message.
			push(message);
			return;
		}

		const std::string& syntax = mode->GetSyntax();
		if (!syntax.empty())
		{
			// If the mode has a syntax hint we include it in the message.
			push(InspIRCd::Format("Invalid %s mode parameter. Syntax: %s.", mode->name.c_str(), syntax.c_str()));
		}
		else
		{
			// Otherwise, send it without.
			push(InspIRCd::Format("Invalid %s mode parameter.", mode->name.c_str()));
		}
	}

 public:
	InvalidModeParameter(Channel* chan, ModeHandler* mode, const std::string& parameter, const std::string& message = "")
		: Numeric(ERR_INVALIDMODEPARAM)
	{
		push(chan->name);
		push(mode->GetModeChar());
		push(parameter);
		push_message(mode, message);
	}

	InvalidModeParameter(User* user, ModeHandler* mode, const std::string& parameter, const std::string& message = "")
		: Numeric(ERR_INVALIDMODEPARAM)
	{
		push(user->registered & REG_NICK ? user->nick : "*");
		push(mode->GetModeChar());
		push(parameter);
		push_message(mode, message);
	}
};

/** Builder for the ERR_NOSUCHCHANNEL numeric. */
class Numerics::NoSuchChannel : public Numeric::Numeric
{
 public:
	NoSuchChannel(const std::string& chan)
		: Numeric(ERR_NOSUCHCHANNEL)
	{
		push(chan.empty() ? "*" : chan);
		push("No such channel");
	}
};

/** Builder for the ERR_NOSUCHNICK numeric. */
class Numerics::NoSuchNick : public Numeric::Numeric
{
 public:
	NoSuchNick(const std::string& nick)
		: Numeric(ERR_NOSUCHNICK)
	{
		push(nick.empty() ? "*" : nick);
		push("No such nick");
	}
};
