ARC

--[[
ARC: AR Client
Uses Plethora overlay glasses and modems to display 3D signage transmitted from local "beacons"
]]

local m = peripheral.find "modem"
local mods = peripheral.wrap "back"

if not m then error "Modem required." end
if not mods then error "Is this even on a neural interface?" end
if not mods.canvas3d then error "Overlay glasses required." end

local canv = mods.canvas3d()

local object_channel = 666

m.open(object_channel)

local x, y, z

-- convert position to string for use as table key
local function serialize_position(p)
    return string.format("%f,%f,%f", p[1], p[2], p[3])
end

-- Generate a string representation of a table, for easy comparison. Not really hashing, I guess.
local function hash_table(x)
    if type(x) == "table" then
        local out = ""
        for k, v in pairs(x) do
            if type(k) ~= "string" or not k:match "^_" then -- ignore keys beginning with _
                out = out .. hash_table(k) .. ":" .. hash_table(v) .. ";"
            end
        end
        return out
    else
        return tostring(x)
    end
end

-- honestly not that elegant, but it works
-- TODO: do this more efficiently/nicely somehow?
local function tables_match(x, y)
    return hash_table(x) == hash_table(y)
end

local objects = {}
local timers = {}

local function redraw(object)
    local frame = object._frame
    frame.clear()
end

local function process_object(object)
    local pos = serialize_position(object.position)
    if objects[pos] then
        if not tables_match(object, objects[pos]) then
            print("redrawing", pos)
            objects[pos] = object
            redraw(objects[pos])
        end
        local t = os.startTimer(20)
        timers[t] = pos
    else
        print("new object at", pos)
        if x then
            local frame =
        else
            print("GPS error, cannot create object")
        end
    end
end

local function main_loop()
    while true do
        local event, timer, channel, reply_channel, message, distance = os.pullEvent()
        if event == "modem_message" and channel == object_channel and distance and type(message) == "table" then -- ensure message is from this dimension and otherwise valid
            for _, object in pairs(msg) do
                local ok, err = pcall(process_object, object)
                if not ok then printError(err) end
            end
        elseif event == "timer" then
            local objpos = timers[timer]
            if objpos then
                local obj = objects[objpos]
                if obj then
                    print(objpos, "timed out")
                    obj._frame.remove()
                    objects[objpos] = nil
                end
            end
        end
    end
end

-- Request location every second
local function GPS_loop()
    while true do
        x, y, z = gps.locate()
        sleep(1)
    end
end

parallel.waitForAll(GPS_loop, main_loop)