/**
 *! Exonet Protocol Version 2
 *
 * This is designed to be a fairly simple fake-networking system, allowing you to send and receive messages
 * between the exonet_protocol datums, and for atoms to react to those messages, based on the contents of the message.
 * Hopefully, this can evolve to be a more robust fake-networking system and allow for some devious network hacking in the future.
 *
 * Version 1 never existed.
 *
 * *Setting up*
 *
 * To set up the exonet link, define a variable on your desired atom it is like this;
 * 	var/datum/exonet_protocol/exonet = null
 * Afterwards, before you want to do networking, call exonet = New(src), then exonet.make_address(string), and give it a string to hash into the new IP.
 * The reason it needs a string is so you can have the addresses be persistant, assuming no-one already took it first.
 *
 * When you're no longer wanting to use the address and want to free it up, like when you want to Destroy() it, you need to call remove_address()
 *
 * *Sending messages*
 *
 * To send a message to another datum, you need to know it's EPv2 (fake IP) address.  Once you know that, call send_message(), place your
 * intended address in the first argument, then the message in the second.  For example, send_message(exonet.address, "ping") will make you
 * ping yourself.
 *
 * *Receiving messages*
 * You don't need to do anything special to receive the messages, other than give your target exonet datum an address as well.  Once something hits
 * your datum with send_message(), receive_message() is called, and the default action is to call receive_exonet_message() on the datum's holder.
 * You'll want to override receive_exonet_message() on your atom, and define what will occur when the message is received.
 * The receiving atom will receive the origin atom (the atom that sent the message), the origin address, and finally the message itself.
 * It's suggested to start with an if or switch statement for the message, to determine what to do.
 */

var/global/list/all_exonet_connections = list()

/datum/exonet_protocol
	var/address = "" //Resembles IPv6, but with only five 'groups', e.g. XXXX:XXXX:XXXX:XXXX:XXXX
	var/atom/movable/holder = null

/datum/exonet_protocol/New(var/atom/holder)
	src.holder = holder
	..()

/datum/exonet_protocol/Destroy()
	remove_address()
	holder = null
	return ..()

// Proc: make_address()
// Parameters: 1 (string - used to make into a hash that will be part of the new address)
// Description: Allocates a new address based on the string supplied.  It results in consistant addresses for each round assuming it is not already taken..
/datum/exonet_protocol/proc/make_address(var/string)
	set waitfor = FALSE		// will this break things? yes. do i care? no fuck you.
	if(string)
		var/new_address = null
		while(new_address == find_address(new_address)) //Collision test.
			var/hash = md5(string)
			var/raw_address = copytext(hash,1,25)
			var/addr_0 = "fc00" //Used for unique local address in real-life IPv6.
			var/addr_1 = hexadecimal_to_EPv2(raw_address)

			new_address = "[addr_0]:[addr_1]"
			string = "[string]0" //If we did get a collision, this should make the next attempt not have one.
			CHECK_TICK
		address = new_address
		all_exonet_connections |= src


// Proc: make_arbitrary_address()
// Parameters: 1 (new_address - the desired address)
// Description: Allocates that specific address, if it is available.
/datum/exonet_protocol/proc/make_arbitrary_address(var/new_address)
	if(new_address)
		if(new_address == find_address(new_address) )	//Collision test.
			return 0
		address = new_address
		all_exonet_connections |= src
		return 1

// Proc: hexadecimal_to_EPv2()
// Parameters: 1 (hex - a string of hexadecimals to convert)
// Description: Helper proc to add colons to a string in the right places.
/proc/hexadecimal_to_EPv2(var/hex)
	if(!hex)
		return null
	var/addr_1 = copytext(hex,1,5)
	var/addr_2 = copytext(hex,5,9)
	var/addr_3 = copytext(hex,9,13)
	var/addr_4 = copytext(hex,13,17)
	var/new_address = "[addr_1]:[addr_2]:[addr_3]:[addr_4]"
	return new_address


// Proc: remove_address()
// Parameters: None
// Description: Deallocates the address, freeing it for use.
/datum/exonet_protocol/proc/remove_address()
	address = ""
	all_exonet_connections.Remove(src)


// Proc: find_address()
// Parameters: 1 (target_address - the desired address to find)
// Description: Searches the global list all_exonet_connections for a specific address, and returns it if found, otherwise returns null.
/datum/exonet_protocol/proc/find_address(var/target_address)
	for(var/datum/exonet_protocol/exonet in all_exonet_connections)
		if(exonet.address == target_address)
			return exonet.address
	return null

// Proc: get_atom_from_address()
// Parameters: 1 (target_address - the desired address to find)
// Description: Searches an address for the atom it is attached for, otherwise returns null.
/datum/exonet_protocol/proc/get_atom_from_address(var/target_address)
	for(var/datum/exonet_protocol/exonet in all_exonet_connections)
		if(exonet.address == target_address)
			return exonet.holder
	return null

// Proc: send_message()
// Parameters: 3 (target_address - the desired address to send the message to, data_type - text stating what the content is meant to be used for,
// 		content - the actual 'message' being sent to the address)
// Description: Sends the message to target_address, by calling receive_message() on the desired datum.  Returns true if the message is recieved.
/datum/exonet_protocol/proc/send_message(var/target_address, var/data_type, var/content)
	if(!address)
		return FALSE
	var/obj/machinery/exonet_node/node = get_exonet_node()
	if(!node) // Telecomms went boom, ion storm, etc.
		return FALSE
	for(var/datum/exonet_protocol/exonet in all_exonet_connections)
		if(exonet.address == target_address)
			node.write_log(src.address, target_address, data_type, content)
			return exonet.receive_message(holder, address, data_type, content)

// Proc: receive_message()
// Parameters: 4 (origin_atom - the origin datum's holder, origin_address - the address the message originated from,
// 		data_type - text stating what the content is meant to be used for, content - the actual 'message' being sent from origin_atom)
// Description: Called when send_message() successfully reaches the intended datum.  By default, calls receive_exonet_message() on the holder atom.
/datum/exonet_protocol/proc/receive_message(var/atom/origin_atom, var/origin_address, var/data_type, var/content)
	holder.receive_exonet_message(origin_atom, origin_address, data_type, content)
	return TRUE // for send_message()

// Proc: receive_exonet_message()
// Parameters: 3 (origin_atom - the origin datum's holder, origin_address - the address the message originated from, message - the message that was sent)
// Description: Override this to make your atom do something when a message is received.
/atom/proc/receive_exonet_message(var/atom/origin_atom, var/origin_address, var/message, var/text)
	return