local ns = {
    beacons = {},
    teleports = {}
}

minetest.register_entity(":teleport_box", {
    initial_properties = {
        visual = "mesh",
        mesh = "teleport_box.gltf",
        textures = {"teleport_box.png"},
        visual_size = vector.new(1,1,1) *5,
        static_save = false,
        use_texture_alpha = true,
        backface_culling = false,
        pointable = false,
        glow = 14
    },
    on_activate = function(e)
        e.object:set_armor_groups{immortal = 1}
    end,
    on_step = function(e, dtime)
        
    end
})

minetest.register_entity(":teleport_beacon", {
    initial_properties = {
        visual = "mesh",
        mesh = "teleport_beacon.gltf",
        textures = {"teleport_beacon.png"},
        use_texture_alpha = true,
        backface_culling = false,
        pointable = false,
        glow = 14
    },
    on_activate = function(e, name)
        if name then e.owner = name end
        if not ns.beacons[e.owner] or ns.beacons[e.owner].marker then
            e.object:remove()
            return
        end
        ns.beacons[e.owner].marker = e.object
        e.object:set_armor_groups{immortal = 1}
        e.object:set_animation({x=1,y=1}, 1.5, 0, false)
    end,
    get_staticdata = function(e)
        return e.owner
    end
})

-- HACK: Override the builtin item to be teleportable, so that
-- entity teleportation can remain opt-in.
local def = table.copy(minetest.registered_entities["__builtin:item"])
def._teleportable = true
minetest.register_entity(":__builtin:item", def)

function ns.do_teleport(from, to, radius)
    for obj in minetest.objects_in_area(from:offset(-radius, -radius, -radius), from:offset(radius, radius, radius)) do
        if obj:is_player() or obj:get_luaentity()._teleportable then
            obj:set_pos(obj:get_pos() -from +to)
        end
    end
end

function ns.begin_teleport(from, to, radius)
    ns.teleports[to:to_string()] = true
    radius = radius or 2.5
    local box1 = minetest.add_entity(from, "teleport_box")
    local box2 = minetest.add_entity(to, "teleport_box")
    box1:set_animation({x=0,y=1.25}, 1, 0, false)
    box2:set_animation({x=0,y=1.25}, 1, 0, false)
    minetest.after(1, function()
        box1:set_animation({x=1.25,y=2.25}, 1, 0, true)
        box2:set_animation({x=1.25,y=2.25}, 1, 0, true)
    end)
    minetest.after(10, function()
        box1:set_animation({x=2.25,y=2.5}, 1, 0, false)
        box2:set_animation({x=2.25,y=2.5}, 1, 0, false)
        minetest.after(0.25, function()
            box1:set_animation({x=2.5,y=2.5}, 1, 0, false)
            box2:set_animation({x=2.5,y=2.5}, 1, 0, false)
            box1:set_properties{use_texture_alpha = false}
            box2:set_properties{use_texture_alpha = false}
        end)
        minetest.after(1, function()
            ns.do_teleport(from, to, radius)
            minetest.after(0.5, function()
                box1:set_animation({x=2.5,y=3}, 1, 0, false)
                box2:set_animation({x=2.5,y=3}, 1, 0, false)
                minetest.after(0.5, function()
                    box1:remove()
                    box2:remove()
                    ns.teleports[to:to_string()] = nil
                end)
            end)
        end)
    end)
end

function ns.place_beacon(name, pos)
    if ns.beacons[name] and ns.beacons[name].marker then
        ns.beacons[name].marker:remove()
    end
    ns.beacons[name] = {
        pos = pos
    }
    local obj = minetest.add_entity(pos, "teleport_beacon", name)
    obj:set_animation({x=0,y=1}, 1.5, 0, false)
end
    
minetest.register_craftitem(":teleport", {
    inventory_image = "rgt_acacia_planks.png",
    on_place = function(s, p, pt)
        ns.place_beacon(p:get_player_name(), pt.above)
    end,
    on_use = function(s, p, pt)
        local name = p:get_player_name()
        if not pt.above then return end
        if ns.beacons[name] then
            if ns.teleports[ns.beacons[name].pos:to_string()] then
                tell(name, "This destination is currently is use by another spell.")
            else
                ns.begin_teleport(pt.above, ns.beacons[name].pos)
            end
        else
            tell(name, "No beacon placed.")
        end
    end
})