-- Internal.lua - The core of mesecons
--
-- For more practical developer resources see mesecons.tk
--
-- Function overview
-- mesecon:get_effector(nodename)     --> Returns the mesecons.effector -specifictation in the nodedef by the nodename
-- mesecon:get_receptor(nodename)     --> Returns the mesecons.receptor -specifictation in the nodedef by the nodename
-- mesecon:get_conductor(nodename)    --> Returns the mesecons.conductor-specifictation in the nodedef by the nodename
-- mesecon:get_any_inputrules (node)  --> Returns the rules of a node if it is a conductor or an effector
-- mesecon:get_any_outputrules (node) --> Returns the rules of a node if it is a conductor or a receptor

-- RECEPTORS
-- mesecon:is_receptor(nodename)     --> Returns true if nodename is a receptor
-- mesecon:is_receptor_on(nodename)  --> Returns true if nodename is an receptor with state = mesecon.state.on
-- mesecon:is_receptor_off(nodename) --> Returns true if nodename is an receptor with state = mesecon.state.off
-- mesecon:receptor_get_rules(node)  --> Returns the rules of the receptor (mesecon.rules.default if none specified)

-- EFFECTORS
-- mesecon:is_effector(nodename)     --> Returns true if nodename is an effector
-- mesecon:is_effector_on(nodename)  --> Returns true if nodename is an effector with nodedef.mesecons.effector.action_off
-- mesecon:is_effector_off(nodename) --> Returns true if nodename is an effector with nodedef.mesecons.effector.action_on
-- mesecon:effector_get_rules(node)  --> Returns the input rules of the effector (mesecon.rules.default if none specified)

-- SIGNALS
-- mesecon:activate(pos, node)     --> Activates   the effector node at the specific pos (calls nodedef.mesecons.effector.action_on)
-- mesecon:deactivate(pos, node)   --> Deactivates the effector node at the specific pos (calls nodedef.mesecons.effector.action_off)
-- mesecon:changesignal(pos, node) --> Changes     the effector node at the specific pos (calls nodedef.mesecons.effector.action_change)

-- RULES
-- mesecon:add_rules(name, rules) | deprecated? --> Saves rules table by name
-- mesecon:get_rules(name, rules) | deprecated? --> Loads rules table with name

-- CONDUCTORS
-- mesecon:is_conductor(nodename)     --> Returns true if nodename is a conductor
-- mesecon:is_conductor_on(nodename)  --> Returns true if nodename is a conductor with state = mesecon.state.on
-- mesecon:is_conductor_off(nodename) --> Returns true if nodename is a conductor with state = mesecon.state.off
-- mesecon:get_conductor_on(offstate) --> Returns the onstate  nodename of the conductor with the name offstate
-- mesecon:get_conductor_off(onstate) --> Returns the offstate nodename of the conductor with the name onstate
-- mesecon:conductor_get_rules(node)  --> Returns the input+output rules of a conductor (mesecon.rules.default if none specified)

-- HIGH-LEVEL Internals
-- mesecon:is_power_on(pos)             --> Returns true if pos emits power in any way
-- mesecon:is_power_off(pos)            --> Returns true if pos does not emit power in any way
-- mesecon:turnon(pos)                  --> Returns true  whatever there is at pos. Calls itself for connected nodes (if pos is a conductor) --> recursive
-- mesecon:turnoff(pos)                 --> Turns off whatever there is at pos. Calls itself for connected nodes (if pos is a conductor) --> recursive
-- mesecon:connected_to_receptor(pos)   --> Returns true if pos is connected to a receptor directly or via conductors; calls itself if pos is a conductor --> recursive
-- mesecon:rules_link(output, input, dug_outputrules) --> Returns true if outputposition + outputrules = inputposition and inputposition + inputrules = outputposition (if the two positions connect)
-- mesecon:rules_link_anydir(outp., inp., d_outpr.)   --> Same as rules mesecon:rules_link but also returns true if output and input are swapped
-- mesecon:is_powered(pos)              --> Returns true if pos is powered by a receptor or a conductor
-- mesecon:updatenode(pos) | deprecated --> Updates the state of pos and surroundings e.g. when newly placed by a piston

-- RULES ROTATION helpsers
-- mesecon:rotate_rules_right(rules)
-- mesecon:rotate_rules_left(rules)
-- mesecon:rotate_rules_up(rules)
-- mesecon:rotate_rules_down(rules)
-- These functions return rules that have been rotated in the specific direction

-- General
function mesecon:get_effector(nodename)
	if  minetest.registered_nodes[nodename]
	and minetest.registered_nodes[nodename].mesecons
	and minetest.registered_nodes[nodename].mesecons.effector then
		return minetest.registered_nodes[nodename].mesecons.effector
	end
end

function mesecon:get_receptor(nodename)
	if  minetest.registered_nodes[nodename]
	and minetest.registered_nodes[nodename].mesecons
	and minetest.registered_nodes[nodename].mesecons.receptor then
		return minetest.registered_nodes[nodename].mesecons.receptor
	end
end

function mesecon:get_conductor(nodename)
	if  minetest.registered_nodes[nodename]
	and minetest.registered_nodes[nodename].mesecons
	and minetest.registered_nodes[nodename].mesecons.conductor then
		return minetest.registered_nodes[nodename].mesecons.conductor
	end
end

function mesecon:get_any_outputrules (node)
	if mesecon:is_conductor(node.name) then
		return mesecon:conductor_get_rules(node)
	elseif mesecon:is_receptor(node.name) then
		return mesecon:receptor_get_rules(node)
	end
	return false
end

function mesecon:get_any_inputrules (node)
	if mesecon:is_conductor(node.name) then
		return mesecon:conductor_get_rules(node)
	elseif mesecon:is_effector(node.name) then
		return mesecon:effector_get_rules(node)
	end
	return false
end

-- Receptors
-- Nodes that can power mesecons
function mesecon:is_receptor_on(nodename)
	local receptor = mesecon:get_receptor(nodename)
	if receptor and receptor.state == mesecon.state.on then
		return true
	end
	return false
end

function mesecon:is_receptor_off(nodename)
	local receptor = mesecon:get_receptor(nodename)
	if receptor and receptor.state == mesecon.state.off then
		return true
	end
	return false
end

function mesecon:is_receptor(nodename)
	local receptor = mesecon:get_receptor(nodename)
	if receptor then
		return true
	end
	return false
end

function mesecon:receptor_get_rules(node)
	local receptor = mesecon:get_receptor(node.name)
	if receptor then
		local rules = receptor.rules
		if type(rules) == 'function' then
			return rules(node)
		elseif rules then
			return rules
		end
	end
	return mesecon.rules.default
end

-- Effectors
-- Nodes that can be powered by mesecons
function mesecon:is_effector_on(nodename)
	local effector = mesecon:get_effector(nodename)
	if effector and effector.action_off then
		return true
	end
	return false
end

function mesecon:is_effector_off(nodename)
	local effector = mesecon:get_effector(nodename)
	if effector and effector.action_on then
		return true
	end
	return false
end

function mesecon:is_effector(nodename)
	local effector = mesecon:get_effector(nodename)
	if effector then
		return true
	end
	return false
end

function mesecon:effector_get_rules(node)
	local effector = mesecon:get_effector(node.name)
	if effector then
		local rules = effector.rules
		if type(rules) == 'function' then
			return rules(node)
		elseif rules then
			return rules
		end
	end
	return mesecon.rules.default
end

--Signals

function mesecon:activate(pos, node)
	local effector = mesecon:get_effector(node.name)
	if effector and effector.action_on then
		effector.action_on (pos, node)
	end
end

function mesecon:deactivate(pos, node)
	local effector = mesecon:get_effector(node.name)
	if effector and effector.action_off then
		effector.action_off (pos, node)
	end
end

function mesecon:changesignal(pos, node)
	local effector = mesecon:get_effector(node.name)
	if effector and effector.action_change then
		effector.action_change (pos, node)
	end
end

--Rules

function mesecon:add_rules(name, rules)
	mesecon.rules[name] = rules
end

function mesecon:get_rules(name)
	return mesecon.rules[name]
end

-- Conductors

function mesecon:is_conductor_on(nodename)
	local conductor = mesecon:get_conductor(nodename)
	if conductor and conductor.state == mesecon.state.on then
		return true
	end
	return false
end

function mesecon:is_conductor_off(nodename)
	local conductor = mesecon:get_conductor(nodename)
	if conductor and conductor.state == mesecon.state.off then
		return true
	end
	return false
end

function mesecon:is_conductor(nodename)
	local conductor = mesecon:get_conductor(nodename)
	if conductor then
		return true
	end
	return false
end

function mesecon:get_conductor_on(offstate)
	local conductor = mesecon:get_conductor(offstate)
	if conductor then
		return conductor.onstate
	end
	return false
end

function mesecon:get_conductor_off(onstate)
	local conductor = mesecon:get_conductor(onstate)
	if conductor then
		return conductor.offstate
	end
	return false
end

function mesecon:conductor_get_rules(node)
	local conductor = mesecon:get_conductor(node.name)
	if conductor then
		local rules = conductor.rules
		if type(rules) == 'function' then
			return rules(node)
		elseif rules then
			return rules
		end
	end
	return mesecon.rules.default
end

-- some more general high-level stuff

function mesecon:is_power_on(pos)
	local node = minetest.env:get_node(pos)
	if mesecon:is_conductor_on(node.name) or mesecon:is_receptor_on(node.name) then
		return true
	end
	return false
end

function mesecon:is_power_off(pos)
	local node = minetest.env:get_node(pos)
	if mesecon:is_conductor_off(node.name) or mesecon:is_receptor_off(node.name) then
		return true
	end
	return false
end

function mesecon:turnon(pos)
	local node = minetest.env:get_node(pos)

	if mesecon:is_conductor_off(node.name) then
		local rules = mesecon:conductor_get_rules(node)
		minetest.env:add_node(pos, {name = mesecon:get_conductor_on(node.name)})

		for _, rule in ipairs(rules) do
			local np = mesecon:addPosRule(pos, rule)

			if mesecon:rules_link(pos, np) then
				mesecon:turnon(np)
			end
		end
	end

	if mesecon:is_effector(node.name) then
		mesecon:changesignal(pos, node)
		if mesecon:is_effector_off(node.name) then
			mesecon:activate(pos, node)
		end
	end
end

function mesecon:turnoff(pos)
	local node = minetest.env:get_node(pos)

	if mesecon:is_conductor_on(node.name) then
		local rules = mesecon:conductor_get_rules(node)
		minetest.env:add_node(pos, {name = mesecon:get_conductor_off(node.name)})

		for _, rule in ipairs(rules) do
			local np = mesecon:addPosRule(pos, rule)

			if mesecon:rules_link(pos, np) then
				mesecon:turnoff(np)
			end
		end
	end

	if mesecon:is_effector(node.name) then
		mesecon:changesignal(pos, node)
		if mesecon:is_effector_on(node.name)
		and not mesecon:is_powered(pos) then
			mesecon:deactivate(pos, node)
		end
	end
end


function mesecon:connected_to_receptor(pos, checked)
	checked = checked or {}

	-- find out if node has already been checked (to prevent from endless loop)
	for _, cp in ipairs(checked) do
		if mesecon:cmpPos(cp, pos) then
			return false, checked
		end
	end

	-- add current position to checked
	table.insert(checked, {x=pos.x, y=pos.y, z=pos.z})

	local node = minetest.env:get_node(pos)

	if mesecon:is_conductor(node.name) then
		-- Check if conductors around are connected
		local rules = mesecon:conductor_get_rules(node)

		for _, rule in ipairs(rules) do
			local np = mesecon:addPosRule(pos, rule)
			if mesecon:rules_link(np, pos) then
				connected, checked = mesecon:connected_to_receptor(np, checked)
				if connected then
					return true
				end
			end
		end
	elseif mesecon:is_receptor_on(node.name) then
		return true
	end

	return false, checked
end

function mesecon:rules_link(output, input, dug_outputrules) --output/input are positions (outputrules optional, used if node has been dug)
	local outputnode = minetest.env:get_node(output)
	local inputnode = minetest.env:get_node(input)
	local outputrules = dug_outputrules or mesecon:get_any_outputrules (outputnode)
	local inputrules = mesecon:get_any_inputrules (inputnode)

	if not outputrules or not inputrules then
		return
	end

	for _, outputrule in ipairs(outputrules) do
		-- Check if output sends to input
		if mesecon:cmpPos(mesecon:addPosRule(output, outputrule), input) then
			for _, inputrule in ipairs(inputrules) do
				-- Check if input accepts from output
				if  mesecon:cmpPos(mesecon:addPosRule(input, inputrule), output) then
					return true
				end
			end
		end
	end
	return false
end

function mesecon:rules_link_anydir(pos1, pos2)
	return mesecon:rules_link(pos1, pos2) or mesecon:rules_link(pos2, pos1)
end

function mesecon:is_powered(pos)
	local node = minetest.env:get_node(pos)
	local rules = mesecon:get_any_inputrules(node)
	if not rules then return false end

	for _, rule in ipairs(rules) do
		local np = mesecon:addPosRule(pos, rule)
		local nn = minetest.env:get_node(np)

		if (mesecon:is_conductor_on (nn.name) or mesecon:is_receptor_on (nn.name))
		and mesecon:rules_link(np, pos) then
			return true
		end
	end
	
	return false
end

function mesecon:updatenode(pos)
	if mesecon:is_powered(pos) then
		mesecon:turnon(pos)
	else
		mesecon:turnoff(pos)
	end
end

--Rules rotation Functions:
function mesecon:rotate_rules_right(rules)
	local nr={};
	for i, rule in ipairs(rules) do
		nr[i]={}
		nr[i].z=rule.x
		nr[i].x=-rule.z
		nr[i].y=rule.y
	end
	return nr
end

function mesecon:rotate_rules_left(rules)
	local nr={};
	for i, rule in ipairs(rules) do
		nr[i]={}
		nr[i].z=-rules[i].x
		nr[i].x=rules[i].z
		nr[i].y=rules[i].y
	end
	return nr
end

function mesecon:rotate_rules_down(rules)
	local nr={};
	for i, rule in ipairs(rules) do
		nr[i]={}
		nr[i].y=rule.x
		nr[i].x=-rule.y
		nr[i].z=rule.z
	end
	return nr
end

function mesecon:rotate_rules_up(rules)
	local nr={};
	for i, rule in ipairs(rules) do
		nr[i]={}
		nr[i].y=-rule.x
		nr[i].x=rule.y
		nr[i].z=rule.z
	end
	return nr
end