// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// 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 is present in all copies. The
// full license for this software is available in the LICENSE file.

#include <ircd/m/m.h>

/// ID of the room which indexes all users (an instance of the room is
/// provided below).
const ircd::m::room::id::buf
users_room_id
{
	"users", ircd::my_host()
};

/// The users room is the database of all users. It primarily serves as an
/// indexing mechanism and for top-level user related keys. Accounts
/// registered on this server will be among state events in this room.
/// Users do not have access to this room, it is used internally.
///
ircd::m::room
ircd::m::user::users
{
	users_room_id
};

/// ID of the room which stores ephemeral tokens (an instance of the room is
/// provided below).
const ircd::m::room::id::buf
tokens_room_id
{
	"tokens", ircd::my_host()
};

/// The tokens room serves as a key-value lookup for various tokens to
/// users, etc. It primarily serves to store access tokens for users. This
/// is a separate room from the users room because in the future it may
/// have an optimized configuration as well as being more easily cleared.
///
ircd::m::room
ircd::m::user::tokens
{
	tokens_room_id
};

bool
ircd::m::exists(const user::id &user_id)
{
	return user::users.has("ircd.user", user_id);
}

bool
ircd::m::my(const user &user)
{
	return my(user.user_id);
}

/// Register the user by creating a room !@user:myhost and then setting a
/// an `ircd.account` state event in the `users` room.
///
/// Each of the registration options becomes a key'ed state event in the
/// user's room.
///
/// Once this call completes the registration was successful; otherwise
/// throws.
void
ircd::m::user::activate(const json::members &contents)
try
{
	const auto room_id{this->room_id()};
	m::room room
	{
		create(room_id, me.user_id, "user")
	};

	send(room, user_id, "ircd.account.options", "registration", contents);
	send(users, me.user_id, "ircd.user", user_id,
	{
		{ "active", true }
	});
}
catch(const m::ALREADY_MEMBER &e)
{
	throw m::error
	{
		http::CONFLICT, "M_USER_IN_USE", "The desired user ID is already in use."
	};
}

void
ircd::m::user::deactivate(const json::members &contents)
{
	//TODO: XXX
}

void
ircd::m::user::password(const string_view &password)
try
{
	char buf[64];
	const auto supplied
	{
		gen_password_hash(buf, password)
	};

	const user::room user_room{*this};
	send(user_room, user_id, "ircd.password", user_id,
	{
		{ "sha256", supplied }
	});
}
catch(const m::ALREADY_MEMBER &e)
{
	throw m::error
	{
		http::CONFLICT, "M_USER_IN_USE", "The desired user ID is already in use."
	};
}

bool
ircd::m::user::is_password(const string_view &password)
const noexcept try
{
	char buf[64];
	const auto supplied
	{
		gen_password_hash(buf, password)
	};

	bool ret{false};
	const user::room user_room{*this};
	user_room.get("ircd.password", user_id, [&supplied, &ret]
	(const m::event &event)
	{
		const json::object &content
		{
			json::at<"content"_>(event)
		};

		const auto &correct
		{
			unquote(content.at("sha256"))
		};

		ret = supplied == correct;
	});

	return ret;
}
catch(const m::NOT_FOUND &e)
{
	return false;
}
catch(const std::exception &e)
{
	log::critical
	{
		"user::is_password(): %s %s", string_view{user_id}, e.what()
	};

	return false;
}

bool
ircd::m::user::is_active()
const
{
	bool ret{false};
	users.get(std::nothrow, "ircd.user", user_id, [&ret]
	(const m::event &event)
	{
		const json::object &content
		{
			at<"content"_>(event)
		};

		ret = content.get("active") == "true";
	});

	return ret;
}

/// Generates a user-room ID into buffer; see room_id() overload.
ircd::m::id::room::buf
ircd::m::user::room_id()
const
{
	assert(!empty(user_id));
	return
	{
		user_id.local(), my_host()
	};
}

/// Generates a room MXID of the following form: `!@user:host`
///
/// This is the "user's room" essentially serving as a database mechanism for
/// this specific user. This is for users on this server's host only.
///
ircd::m::id::room
ircd::m::user::room_id(const mutable_buffer &buf)
const
{
	assert(!empty(user_id));
	return
	{
		buf, user_id.local(), my_host()
	};
}

ircd::string_view
ircd::m::user::gen_access_token(const mutable_buffer &buf)
{
	static const size_t token_max{32};
	static const auto &token_dict{rand::dict::alpha};

	const mutable_buffer out
	{
		data(buf), std::min(token_max, size(buf))
	};

	return rand::string(token_dict, out);
}

ircd::string_view
ircd::m::user::gen_password_hash(const mutable_buffer &out,
                                 const string_view &supplied_password)
{
	//TODO: ADD SALT
	const sha256::buf hash
	{
		sha256{supplied_password}
	};

	return b64encode_unpadded(out, hash);
}

//
// user::room
//

ircd::m::user::room::room(const m::user::id &user_id)
:room{m::user{user_id}}
{}

ircd::m::user::room::room(const m::user &user)
:user{user}
,room_id{user.room_id()}
{
	static_cast<m::room &>(*this) = room_id;
}