-- Distance from center to side of the laser beam square. Not really the radius, but it sounds cooler. :P
local LASER_RADIUS = -1/16

local COLSTRING_IDS = {
	[lzr_globals.COLOR_NONE] = "_", -- nothing
	[lzr_globals.COLOR_RED] = "R", -- red
	[lzr_globals.COLOR_GREEN] = "G", -- green
	[lzr_globals.COLOR_YELLOW] = "Y", -- yellow (R+G)
	[lzr_globals.COLOR_BLUE] = "B", -- blue
	[lzr_globals.COLOR_MAGENTA] = "M", -- magenta (R+B)
	[lzr_globals.COLOR_CYAN] = "C", -- cyan (G+B)
	[lzr_globals.COLOR_WHITE] = "W", -- white (R+G+B)
}

-- The maximum possible colorcode
local MAX_COLORCODE = 7

-- DATA FORMATS:
--[[ colorcode:
A number representing a laser color.
It ranges from 0 to 7.
Value 0 stands for 'no color', the absense of a laser.
There are 3 primary colors:
* 1 = red
* 2 = green
* 4 = blue
The other values are reserved for secondary colors that
result from adding the values from 2 primary colors
that have been additive color mixing.
See lzr_globals for the full list of colorcodes.
]]

--[[ dirstring: A representation of 3 axes (XYZ) which each have
a colorcode converted to a string.
The 3 characters stand for these directions, in order: X, Y, Z
Example: "140" = red on X axis, blue on Y axis and no laser in the Z axis
]]

--[[ dirs table: Like dirstring, but in table format. It's a table
with 3 numbers, each of them is a colorcode.
The same order of axes is used like for dirstring.
Example: { 1, 4, 0 } -- X = red, Y = blue, Z = no laser
]]

-- Converts a dirstring to a dirs table
function lzr_laser.dirstring_to_dirs(dirstring)
	local dirs = {}
	for d=1, 3 do
		local dirnum = tonumber(string.sub(dirstring, d, d))
		if not dirnum then
			error("[lzr_laser] dirstring_to_dirs: Invalid dirstring! Character #"..d.." is not a digit.")
		elseif dirnum >= 0 and dirnum <= MAX_COLORCODE then
			dirs[d] = dirnum
		else
			error("[lzr_laser] dirstring_to_dirs: Invalid dirstring! Character #"..d.." is outside the valid digit value range (0-"..MAX_COLORCODE..").")
		end
	end
	return dirs
end

-- Converts a dirstring into a "colstring", a string
-- of letters each representing a color
function lzr_laser.dirstring_to_colstring(dirstring)
	local dirs = {}
	local colstr = ""
	for d=1, string.len(dirstring) do
		local dirnum = tonumber(string.sub(dirstring, d, d))
		if not dirnum then
			error("[lzr_laser] dirstring_to_dirs: Invalid dirstring! Character #"..d.." is not a digit.")
		elseif dirnum >= 0 or dirnum <= MAX_COLORCODE then
			colstr = colstr .. COLSTRING_IDS[dirnum]
		else
			error("[lzr_laser] dirstring_to_dirs: Invalid dirstring! Character #"..d.." is outside the valid digit value range (0-7).")
		end
	end
	return colstr
end



-- Converts a dirs table to a dirstring
function lzr_laser.dirs_to_dirstring(dirs)
	local dirstring = ""
	for d=1, 3 do
		if dirs[d] >= 0 or dirs[d] <= MAX_COLORCODE then
			dirstring = dirstring .. tostring(dirs[d])
		else
			error("[lzr_laser] dirs_to_dirstring: Invalid dirs!")
		end
	end
	return dirstring
end

function lzr_laser.vector_to_dirs(dir_vector)
	local dirs = {0,0,0}
	if dir_vector.x ~= 0 then
		dirs[1] = 1
	end
	if dir_vector.y ~= 0 then
		dirs[2] = 1
	end
	if dir_vector.z ~= 0 then
		dirs[3] = 1
	end
	return dirs
end

function lzr_laser.vector_and_color_to_dirs(dir_vector, color)
	local dirs = {0,0,0}
	if dir_vector.x ~= 0 then
		dirs[1] = color
	end
	if dir_vector.y ~= 0 then
		dirs[2] = color
	end
	if dir_vector.z ~= 0 then
		dirs[3] = color
	end
	return dirs
end

-- Convert number to string in binary form
-- * num: Number
-- * minLength: Minimum number of characters the string must have, will
--              fill string with leading zeroes if needed (default: 1)
-- Returns: string
function lzr_laser.dec2bin(num, minLength)
	if not minLength then
		minLength = 1
	end
	local t = {}
	local rem
	while num > 0 do
		rem = math.fmod(num,2)
		t[#t+1] = rem
		num = (num-rem)/2
	end
	local bin = table.concat(t)
	bin = string.reverse(bin)
	local length = string.len(bin)
	if length < minLength then
		bin = string.rep("0", minLength - length) .. bin
	end
	return bin
end

-- Takes 2 binary numbers (as strings!)
-- and returns the 'bitwise or' of them (also as string).
-- Both strings MUST be of equal length.
function lzr_laser.bitwise_or(bin1, bin2)
	local len = string.len(bin1)
	local out = ""
	for i=1, len do
		if string.sub(bin1, i, i) == "1" or string.sub(bin2, i, i) == "1" then
			out = out .. "1"
		else
			out = out .. "0"
		end
	end
	return out
end

-- Lookup table for dirstring_or
local colorcode_bor_lookup = {}
for i=0, MAX_COLORCODE do
	colorcode_bor_lookup[tostring(i)] = {}
	for j=0, MAX_COLORCODE do
		colorcode_bor_lookup[tostring(i)][tostring(j)] = tostring(bit.bor(i, j))
	end
end

-- Takes two dirstrings (with digits from 0 to 7)
-- and does a bitwise or on each digit on them
-- and returns the result.
-- Example: "001" and "003" give "003"
function lzr_laser.dirstring_or(dirstring1, dirstring2)
	local len = string.len(dirstring1)
	local out = ""
	for i=1, len do
		local d1 = string.sub(dirstring1, i, i)
		local d2 = string.sub(dirstring2, i, i)
		-- We use a lookup table for improved performance
		-- since this function is called for every
		-- laser step in the laser propagation
		-- algorithm.
		local res = colorcode_bor_lookup[d1][d2]
		out = out .. tostring(res)
	end
	return out
end

-- Generates a line of particles between two positions
-- * pos1, pos2: Start and end position
-- * texture: Particle texture file name
-- * amount: (optional) number of particles per step
-- * spread: (optional) how far to spread out particles from the perfect line
-- * vspread: (optional) maximum random velocity of particles
-- * size: (optional) particle size multiplier
-- * steps: (optional) how many iterations to use (more = more detailed but slower)
function lzr_laser.particle_line(pos1, pos2, texture, amount, spread, vspread, size, steps)
	if not amount then amount = 10 end
	if not spread then spread = 0.1 end
	if not vspread then vspread = 0.01 end
	if not size then size = 0.4 end
	if not steps then steps = 30 end

	local pos = vector.copy(pos1)
	for i=0,steps-1 do
		pos.x = pos1.x + (pos2.x - pos1.x) * (i/steps)
		pos.y = pos1.y + (pos2.y - pos1.y) * (i/steps)
		pos.z = pos1.z + (pos2.z - pos1.z) * (i/steps)
		minetest.add_particlespawner({
			amount = amount,
			time = 0.001,
			minpos = vector.subtract(pos, vector.new(spread, spread, spread)),
			maxpos = vector.add(pos, vector.new(spread, spread, spread)),
			minvel = vector.new(-vspread, -vspread, -vspread),
			maxvel = vector.new(vspread, vspread, vspread),
			minsize = size,
			maxsize = size,
			texture = texture,
			minexptime = 1.5,
			maxexptime = 1.7,
		})
	end
end

local dirstring_lookup = {}
function lzr_laser.laser_group_to_dirstring(laser_group)
	return dirstring_lookup[laser_group]
end
function lzr_laser.colors_to_laser_group(color_x, color_y, color_z)
	return color_x + color_y * 8 + color_z * 64
end

-- Create a lookup table for laser_group_to_distring for performance
for x=0,MAX_COLORCODE do
for y=0,MAX_COLORCODE do
for z=0,MAX_COLORCODE do
	local val = lzr_laser.colors_to_laser_group(x,y,z)
	dirstring_lookup[val] = x .. y .. z
end
end
end

-- Returns true if the given laser block (by nodename)
-- is active.
function lzr_laser.is_laser_block_active(nodename)
	local def = minetest.registered_nodes[nodename]
	if not def then
		return false
	end
	local element_group = def._lzr_element_group
	if not element_group then
		return false
	end
	if minetest.get_item_group(nodename, element_group) == 2 then
		return true
	else
		return false
	end
end

-- Convert a 'pos string' to a list of positions.
-- A 'pos string' is a string containing of positions,
-- each in the `minetest.pos_to_string` format, and each
-- position is separated by a semicolon.
lzr_laser.pos_string_to_positions = function(pos_str)
	local strs = string.split(pos_str, ";")
	local posses  = {}
	if strs then
		for s=1, #strs do
			local stpos = minetest.string_to_pos(strs[s])
			if not stpos then
				minetest.log("error", "[lzr_laser] Invalid pos_string syntax of node at "..minetest.pos_to_string(stpos)..": "..tostring(pos_str))
				return {}
			end
			table.insert(posses, stpos)
		end
	end
	return posses
end

-- Convert a list of positions to a 'pos string'.
-- See `lzr_laser.pos_string_to_positions` for a definition
-- of 'pos string'.
lzr_laser.positions_to_pos_string = function(positions)
	local to_str = ""
	for p=1, #positions do
		to_str = to_str .. minetest.pos_to_string(positions[p])
		if p < #positions then
			to_str = to_str .. ";"
		end
	end
	return to_str
end


local temp_waypoints = {}
local add_temp_waypoint = function(player, texture, wpos, size, z_index_add)
	size = size or 1
	local id = player:hud_add({
		type = "image_waypoint",
		text = texture,
		offset = { x = 0, y = 0 },
		scale = { x = 8 * size, y = 8 * size },
		z_index = -290 + (z_index_add or 0),
		world_pos = wpos,
	})
	if not id then
		return
	end
	local job = minetest.after(1.7, function(player)
		if player and player:is_player() then
			for i=1, #temp_waypoints do
				if temp_waypoints[i].id == id then
					table.remove(temp_waypoints, i)
					break
				end
			end
			player:hud_remove(id)
		end
	end, player)
	table.insert(temp_waypoints, {id=id, job=job})
end
local remove_temp_waypoints = function(player)
	for t=1, #temp_waypoints do
		player:hud_remove(temp_waypoints[t].id)
		temp_waypoints[t].job:cancel()
	end
	temp_waypoints = {}
end

-- Show information in the HUD of the trigger
-- with the given trigger ID. This shows waypoints
-- of senders/receivers associated to the trigger
-- particle paths towards those associated triggers
-- and other icons.
-- `trigger_id`: Trigger ID
-- `player`: Player doing the trigger
-- `show_trigger_type`: If `true`, also show icons for the sender/receiver type (default: false)
lzr_laser.show_trigger_info = function(trigger_id, player, show_trigger_type)
	remove_temp_waypoints(player)
	local trigger = lzr_triggers.get_trigger(trigger_id)
	local tpos
	if type(trigger.location) == "table" then
		tpos = trigger.location
	elseif trigger.location == "player" then
		tpos = player:get_pos()
		tpos = vector.offset(0, 1, 0)
	else
		return
	end

	local tpos = trigger.location
	local receivers = lzr_triggers.get_receivers(trigger_id)
	local senders = lzr_triggers.get_senders(trigger_id)
	if #receivers > 0 and #senders > 0 then
		add_temp_waypoint(player, "lzr_triggers_icon_sender_receiver.png", tpos)
	end
	if #receivers > 0 then
		if #senders == 0 then
			add_temp_waypoint(player, "lzr_triggers_icon_sender.png", tpos)
		end
		for r=1, #receivers do
			local rtrig = lzr_triggers.get_trigger(receivers[r])
			if not rtrig then
				local rpos = minetest.string_to_pos(receivers[r])
				if rpos then
					add_temp_waypoint(player, "lzr_laser_particle_unknown.png^[opacity:127", rpos)
				end
				minetest.log("error", "[lzr_laser] Receiver '"..receivers[r].." for trigger '"..trigger_id.."' does not exist!")
			else
				local rloc = rtrig.location
				if rloc == "player" then
					rloc = player:get_pos()
					rloc = vector.offset(rloc, 0, 1, 0)
				end
				add_temp_waypoint(player, "lzr_triggers_icon_receiver.png^[opacity:127", rloc)
				if show_trigger_type then
					-- Small icon for receiver type
					local rloc_receiver_type = vector.offset(rloc, 0.125, 0.125, 0.125)
					add_temp_waypoint(player, lzr_triggers.RECEIVER_TYPE_ICONS[rtrig.receiver_type].."^[opacity:127", rloc_receiver_type, 0.4, 1)
				end
				lzr_laser.particle_line(tpos, rloc, "lzr_laser_particle_signal_marker.png", 1, 0, 0)
			end
		end
		if show_trigger_type then
			-- Small icon for signal type
			local tpos_signal_type = vector.offset(tpos, -0.125, -0.125, -0.125)
			add_temp_waypoint(player, lzr_triggers.SIGNAL_TYPE_ICONS[trigger.signal_type], tpos_signal_type, 0.4, 1)
		end
	end
	if #senders > 0 then
		if #receivers == 0 then
			add_temp_waypoint(player, "lzr_triggers_icon_receiver.png", tpos)
		end
		for s=1, #senders do
			local strig = lzr_triggers.get_trigger(senders[s])
			if not strig then
				local spos = minetest.string_to_pos(senders[s])
				if spos then
					add_temp_waypoint(player, "lzr_laser_particle_unknown.png^[opacity:127", spos)
				end
				minetest.log("error", "[lzr_laser] Sender '"..senders[s].." for trigger '"..trigger_id.."' does not exist!")
			else
				local sloc = strig.location
				if sloc == "player" then
					sloc = player:get_pos()
					sloc = vector.offset(sloc, 0, 1, 0)
				end
				add_temp_waypoint(player, "lzr_triggers_icon_sender.png^[opacity:127", sloc)
				if show_trigger_type then
					-- Small icon for signal type
					local sloc_signal_type = vector.offset(sloc, -0.125, -0.125, -0.125)
					add_temp_waypoint(player, lzr_triggers.SIGNAL_TYPE_ICONS[strig.signal_type].."^[opacity:127", sloc_signal_type, 0.4, 1)
				end
				lzr_laser.particle_line(tpos, sloc, "lzr_laser_particle_signal_marker.png", 1, 0, 0)
			end
		end
		if show_trigger_type then
			-- Small icon for receiver type
			local tpos_receiver_type = vector.offset(tpos, 0.125, 0.125, 0.125)
			add_temp_waypoint(player, lzr_triggers.RECEIVER_TYPE_ICONS[trigger.receiver_type], tpos_receiver_type, 0.4, 1)
		end
	end
end