--basic settings
local item_drop_settings                 = {} --settings table
item_drop_settings.age                   = 1.0 --how old a dropped item (_insta_collect==false) has to be before collecting
item_drop_settings.radius_magnet         = 2.0 --radius of item magnet. MUST BE LARGER THAN radius_collect!
item_drop_settings.radius_collect        = 0.2 --radius of collection
item_drop_settings.player_collect_height = 1.0 --added to their pos y value
item_drop_settings.collection_safety     = false --do this to prevent items from flying away on laggy servers
item_drop_settings.random_item_velocity  = true --this sets random item velocity if velocity is 0
item_drop_settings.drop_single_item      = false --if true, the drop control drops 1 item instead of the entire stack, and sneak+drop drops the stack
-- drop_single_item is disabled by default because it is annoying to throw away items from the intentory screen

item_drop_settings.magnet_time           = 0.75 -- how many seconds an item follows the player before giving up

local get_gravity = function()
    return tonumber(minetest.settings:get("movement_gravity")) or 9.81
end

local check_pickup_achievements = function(object, player)
    local itemname = ItemStack(object:get_luaentity().itemstring):get_name()
    if minetest.get_item_group(itemname, "tree") ~= 0 then
        awards.unlock(player:get_player_name(), "mcl:mineWood")
    elseif itemname == "mcl_mobitems:blaze_rod" then
        awards.unlock(player:get_player_name(), "mcl:blazeRod")
    elseif itemname == "mcl_mobitems:leather" then
        awards.unlock(player:get_player_name(), "mcl:killCow")
    elseif itemname == "mcl_core:diamond" then
        awards.unlock(player:get_player_name(), "mcl:diamonds")
    end
end

local enable_physics = function(object, luaentity, ignore_check)
    if luaentity.physical_state == false or ignore_check == true then
        luaentity.physical_state = true
        object:set_properties({
            physical = true
        })
        object:set_velocity({x=0,y=0,z=0})
        object:set_acceleration({x=0,y=-get_gravity(),z=0})
    end
end

local disable_physics = function(object, luaentity, ignore_check, reset_movement)
    if luaentity.physical_state == true or ignore_check == true then
        luaentity.physical_state = false
        object:set_properties({
            physical = false
        })
        if reset_movement ~= false then
            object:set_velocity({x=0,y=0,z=0})
            object:set_acceleration({x=0,y=0,z=0})
        end
    end
end

minetest.register_globalstep(function(dtime)
    for _,player in ipairs(minetest.get_connected_players()) do
        if player:get_hp() > 0 or not minetest.settings:get_bool("enable_damage") then
            local pos = player:get_pos()
            local inv = player:get_inventory()
            local checkpos = {x=pos.x,y=pos.y + item_drop_settings.player_collect_height,z=pos.z}

            --magnet and collection
            for _,object in ipairs(minetest.get_objects_inside_radius(checkpos, item_drop_settings.radius_magnet)) do
                if not object:is_player() and object:get_luaentity() and object:get_luaentity().name == "__builtin:item" and object:get_luaentity()._magnet_timer and (object:get_luaentity()._insta_collect or (object:get_luaentity().age > item_drop_settings.age)) then
                    object:get_luaentity()._magnet_timer = object:get_luaentity()._magnet_timer + dtime
                    local collected = false
                    if object:get_luaentity()._magnet_timer >= 0 and object:get_luaentity()._magnet_timer < item_drop_settings.magnet_time and inv and inv:room_for_item("main", ItemStack(object:get_luaentity().itemstring)) then

                        -- Collection
                        if vector.distance(checkpos, object:get_pos()) <= item_drop_settings.radius_collect and not object:get_luaentity()._removed then
                            -- Ignore if itemstring is not set yet
                            if object:get_luaentity().itemstring ~= "" then
                                inv:add_item("main", ItemStack(object:get_luaentity().itemstring))
                                minetest.sound_play("item_drop_pickup", {
                                    pos = pos,
                                    max_hear_distance = 16,
                                    gain = 1.0,
                                })
                                check_pickup_achievements(object, player)


                                -- Destroy entity
                                -- This just prevents this section to be run again because object:remove() doesn't remove the item immediately.
                                object:get_luaentity()._removed = true
                                object:remove()
                                collected = true
                            end

                        -- Magnet
                        else
                            --move this to the front so players can see animation before collection
                            if not collected then
                                if object:get_luaentity()._magnet_timer > 1 then
                                    object:get_luaentity()._magnet_timer = -item_drop_settings.magnet_time
                                    object:get_luaentity()._magnet_active = false
                                elseif object:get_luaentity()._magnet_timer < 0 then
                                    object:get_luaentity()._magnet_timer = object:get_luaentity()._magnet_timer + dtime
                                end
                            end

                            object:get_luaentity()._magnet_active = true
                            object:get_luaentity()._collector_timer = 0

                            -- Move object to player
                            disable_physics(object, object:get_luaentity())

                            object:move_to(checkpos)

                            --fix eternally falling items
                            minetest.after(0, function(object)
                                local lua = object:get_luaentity()
                                if lua then
                                    object:set_acceleration({x=0, y=0, z=0})
                                end
                            end, object)


                            --this is a safety to prevent items flying away on laggy servers
                            if item_drop_settings.collection_safety == true then
                                if object:get_luaentity().init ~= true then
                                    object:get_luaentity().init = true
                                    minetest.after(1, function(args)
                                        local playername = args[1]
                                        local player = minetest.get_player_by_name(playername)
                                        local object = args[2]
                                        local lua = object:get_luaentity()
                                        if player == nil or not player:is_player() or object == nil or lua == nil or lua.itemstring == nil then
                                            return
                                        end
                                        if inv:room_for_item("main", ItemStack(object:get_luaentity().itemstring)) then
                                            inv:add_item("main", ItemStack(object:get_luaentity().itemstring))
                                            if not object:get_luaentity()._removed then
                                                minetest.sound_play("item_drop_pickup", {
                                                    pos = pos,
                                                    max_hear_distance = 16,
                                                    gain = 1.0,
                                                })
                                            end
                                            check_pickup_achievements(object, player)
                                            object:get_luaentity()._removed = true
                                            object:remove()
                                        else
                                            enable_physics(object, object:get_luaentity())
                                        end
                                    end, {player:get_player_name(), object})
                                end
                            end
                        end
                    end

                end
            end

        end
    end
end)

local minigroups = { "shearsy", "swordy", "shearsy_wool", "swordy_cobweb" }
local basegroups = { "pickaxey", "axey", "shovely" }
local materials = { "wood", "gold", "stone", "iron", "diamond" }

-- Checks if the given node would drop its useful drop if dug by a tool
-- with the given tool capabilities. Returns true if it will yield its useful
-- drop, false otherwise.
local check_can_drop = function(node_name, tool_capabilities)
    local handy = minetest.get_item_group(node_name, "handy")
    local dig_immediate = minetest.get_item_group(node_name, "dig_immediate")
    if handy == 1 or dig_immediate == 2 or dig_immediate == 3 then
        return true
    else
        local toolgroupcaps
        if tool_capabilities then
            toolgroupcaps = tool_capabilities.groupcaps
        else
            return false
        end

        -- Compare node groups with tool capabilities
        for m=1, #minigroups do
            local minigroup = minigroups[m]
            local g = minetest.get_item_group(node_name, minigroup)
            if g ~= 0 then
                local plus = minigroup .. "_dig"
                if toolgroupcaps[plus] then
                    return true
                end
            end
        end
        for b=1, #basegroups do
            local basegroup = basegroups[b]
            local g = minetest.get_item_group(node_name, basegroup)
            if g ~= 0 then
                for m=g, #materials do
                    local plus = basegroup .. "_dig_"..materials[m]
                    if toolgroupcaps[plus] then
                        return true
                    end
                end
            end
        end

        return false
    end
end

function minetest.handle_node_drops(pos, drops, digger)
    -- NOTE: This function override allows digger to be nil.
    -- This means there is no digger. This is a special case which allows this function to be called
    -- by hand. Creative Mode is intentionally ignored in this case.

    local doTileDrops = minetest.settings:get_bool("mcl_doTileDrops", true)
    if (digger ~= nil and minetest.settings:get_bool("creative_mode")) or doTileDrops == false then
        return
    end

    -- Check if node will yield its useful drop by the digger's tool
    local dug_node = minetest.get_node(pos)
    local toolcaps
    if digger ~= nil then
        local tool = digger:get_wielded_item()
        toolcaps = tool:get_tool_capabilities()

        if not check_can_drop(dug_node.name, toolcaps) then
            return
        end
    end

    --[[ Special node drops when dug by shears by reading _mcl_shears_drop
    from the node definition.
    Definition of _mcl_shears_drop:
    * true: Drop itself when dug by shears
    * table: Drop every itemstring in this table when dub by shears
    ]]
    local nodedef = minetest.registered_nodes[dug_node.name]
    if toolcaps ~= nil and toolcaps.groupcaps and toolcaps.groupcaps.shearsy_dig and nodedef._mcl_shears_drop then
        if nodedef._mcl_shears_drop == true then
            drops = { dug_node.name }
        else
            drops = nodedef._mcl_shears_drop
        end
    end

    for _,item in ipairs(drops) do
        local count
        if type(item) == "string" then
            count = ItemStack(item):get_count()
        else
            count = item:get_count()
        end
        local drop_item = ItemStack(item)
        drop_item:set_count(1)
        for i=1,count do
            local obj = core.add_item(pos, drop_item)
            if obj ~= nil then
                local x = math.random(1, 5)
                if math.random(1,2) == 1 then
                    x = -x
                end
                local z = math.random(1, 5)
                if math.random(1,2) == 1 then
                    z = -z
                end
                obj:set_velocity({x=1/x, y=obj:get_velocity().y, z=1/z})
            end
        end
    end
end

-- Drop single items by default
function minetest.item_drop(itemstack, dropper, pos)
    if dropper and dropper:is_player() then
        local v = dropper:get_look_dir()
        local p = {x=pos.x, y=pos.y+1.2, z=pos.z}
        local cs = itemstack:get_count()
        if dropper:get_player_control().sneak then
            cs = 1
        end
        local item = itemstack:take_item(cs)
        local obj = core.add_item(p, item)
        if obj then
            v.x = v.x*4
            v.y = v.y*4 + 2
            v.z = v.z*4
            obj:set_velocity(v)
            -- Force collection delay
            obj:get_luaentity()._insta_collect = false
            return itemstack
        end
    end
end

--modify builtin:item

local time_to_live = tonumber(minetest.settings:get("item_entity_ttl"))
if not time_to_live then
    time_to_live = 300
end

core.register_entity(":__builtin:item", {
    initial_properties = {
        hp_max = 1,
        physical = true,
        collide_with_objects = false,
        collisionbox = {-0.3, -0.3, -0.3, 0.3, 0.3, 0.3},
        pointable = false,
        visual = "wielditem",
        visual_size = {x = 0.4, y = 0.4},
        textures = {""},
        spritediv = {x = 1, y = 1},
        initial_sprite_basepos = {x = 0, y = 0},
        is_visible = false,
        infotext = "",
    },

    -- Itemstring of dropped item. The empty string is used when the item is not yet initialized yet.
    -- The itemstring MUST be set immediately to a non-empty string after creating the entity.
    -- The hand is NOT permitted as dropped item. ;-)
    -- Item entities will be deleted if they still have an empty itemstring on their first on_step tick.
    itemstring = '',

    -- If true, item will fall
    physical_state = true,

    -- If item entity is currently flowing in water
    _flowing = false,

    -- Number of seconds this item entity has existed so far
    age = 0,

    set_item = function(self, itemstring)
        self.itemstring = itemstring
        if self.itemstring == "" then
            -- item not yet known
            return
        end
        local stack = ItemStack(itemstring)
        local count = stack:get_count()
        local max_count = stack:get_stack_max()
        if count > max_count then
            count = max_count
            self.itemstring = stack:get_name().." "..max_count
        end
        local s = 0.2 + 0.1 * (count / max_count)
        local c = s
        local itemtable = stack:to_table()
        local itemname = nil
        local description = ""
        if itemtable then
            itemname = stack:to_table().name
        end
        local item_texture = nil
        local item_type = ""
        if core.registered_items[itemname] then
            item_texture = core.registered_items[itemname].inventory_image
            item_type = core.registered_items[itemname].type
            description = core.registered_items[itemname].description
        end
        local prop = {
            is_visible = true,
            visual = "wielditem",
            textures = {itemname},
            visual_size = {x = s, y = s},
            collisionbox = {-c, -c, -c, c, c, c},
            automatic_rotate = math.pi * 0.5,
            infotext = description,
        }
        self.object:set_properties(prop)
        if item_drop_settings.random_item_velocity == true then
            minetest.after(0, function(self)
                if not self or not self.object or not self.object:get_luaentity() then
                    return
                end
                local vel = self.object:get_velocity()
                if vel and vel.x == 0 and vel.z == 0 then
                    local x = math.random(1, 5)
                    if math.random(1,2) == 1 then
                        x = -x
                    end
                    local z = math.random(1, 5)
                    if math.random(1,2) == 1 then
                        z = -z
                    end
                    local y = math.random(2,4)
                    self.object:set_velocity({x=1/x, y=y, z=1/z})
                end
            end, self)
        end

    end,

    get_staticdata = function(self)
        return core.serialize({
            itemstring = self.itemstring,
            always_collect = self.always_collect,
            age = self.age,
            _insta_collect = self._insta_collect,
            _flowing = self._flowing,
            _removed = self._removed,
        })
    end,

    on_activate = function(self, staticdata, dtime_s)
        if string.sub(staticdata, 1, string.len("return")) == "return" then
            local data = core.deserialize(staticdata)
            if data and type(data) == "table" then
                self.itemstring = data.itemstring
                self.always_collect = data.always_collect
                if data.age then
                    self.age = data.age + dtime_s
                else
                    self.age = dtime_s
                end
                --remember collection data
                -- If true, can collect item without delay
                self._insta_collect = data._insta_collect
                self._flowing = data._flowing
                self._removed = data._removed
            end
        else
            self.itemstring = staticdata
        end
        if self._removed then
            self._removed = true
            self.object:remove()
            return
        end
        if self._insta_collect == nil then
            -- Intentionally default, since delayed collection is rare
            self._insta_collect = true
        end
        if self._flowing == nil then
            self._flowing = false
        end
        self._magnet_timer = 0
        self._magnet_active = false
        -- How long ago the last possible collector was detected. nil = none in this session
        self._collector_timer = nil
        -- Used to apply additional force
        self._force = nil
        self._forcestart = nil
        self._forcetimer = 0

        self.object:set_armor_groups({immortal = 1})
        self.object:set_velocity({x = 0, y = 2, z = 0})
        self.object:set_acceleration({x = 0, y = -get_gravity(), z = 0})
        self:set_item(self.itemstring)
    end,

    try_merge_with = function(self, own_stack, object, entity)
        if self.age == entity.age or entity._removed then
            -- Can not merge with itself and remove entity
            return false
        end

        local stack = ItemStack(entity.itemstring)
        local name = stack:get_name()
        if own_stack:get_name() ~= name or
                own_stack:get_meta() ~= stack:get_meta() or
                own_stack:get_wear() ~= stack:get_wear() or
                own_stack:get_free_space() == 0 then
            -- Can not merge different or full stack
            return false
        end

        local count = own_stack:get_count()
        local total_count = stack:get_count() + count
        local max_count = stack:get_stack_max()

        if total_count > max_count then
            return false
        end
        -- Merge the remote stack into this one

        local pos = object:get_pos()
        pos.y = pos.y + ((total_count - count) / max_count) * 0.15
        self.object:move_to(pos)

        self.age = 0 -- Handle as new entity
        own_stack:set_count(total_count)
        self:set_item(own_stack:to_string())

        entity._removed = true
        object:remove()
        return true
    end,

    on_step = function(self, dtime)
        if self._removed then
            return
        end
        self.age = self.age + dtime
        if self._collector_timer ~= nil then
            self._collector_timer = self._collector_timer + dtime
        end
        if time_to_live > 0 and self.age > time_to_live then
            self._removed = true
            self.object:remove()
            return
        end
        -- Delete corrupted item entities. The itemstring MUST be non-empty on its first step,
        -- otherwise there might have some data corruption.
        if self.itemstring == "" then
            minetest.log("warning", "Item entity with empty itemstring found at "..minetest.pos_to_string(self.object:get_pos()).. "! Deleting it now.")
            self._removed = true
            self.object:remove()
        end

        local p = self.object:get_pos()
        local node = core.get_node_or_nil(p)
        local in_unloaded = (node == nil)

        -- If no collector was found for a long enough time, declare the magnet as disabled
        if self._magnet_active and (self._collector_timer == nil or (self._collector_timer > item_drop_settings.magnet_time)) then
            self._magnet_active = false
            enable_physics(self.object, self)
            return
        end
        if in_unloaded then
            -- Don't infinetly fall into unloaded map
            disable_physics(self.object, self)
            return
        end

        -- Destroy item in lava, fire or special nodes
        local nn = node.name
        local def = minetest.registered_nodes[nn]
        local lg = minetest.get_item_group(nn, "lava")
        local fg = minetest.get_item_group(nn, "fire")
        local dg = minetest.get_item_group(nn, "destroys_items")
        if (def and (lg ~= 0 or fg ~= 0 or dg == 1)) then
            if dg ~= 2 then
                minetest.sound_play("builtin_item_lava", {pos = self.object:get_pos(), gain = 0.5})
            end
            self._removed = true
            self.object:remove()
            return
        end

        -- Push item out when stuck inside solid opaque node
        if def and def.walkable and def.groups and def.groups.opaque == 1 then
            local shootdir
            local cx = p.x % 1
            local cz = p.z % 1
            local order = {}

            -- First prepare the order in which the 4 sides are to be checked.
            -- 1st: closest
            -- 2nd: other direction
            -- 3rd and 4th: other axis
            local cxcz = function(o, cw, one, zero)
                if cw > 0 then
                    table.insert(o, { [one]=1, y=0, [zero]=0 })
                    table.insert(o, { [one]=-1, y=0, [zero]=0 })
                else
                    table.insert(o, { [one]=-1, y=0, [zero]=0 })
                    table.insert(o, { [one]=1, y=0, [zero]=0 })
                end
                return o
            end
            if math.abs(cx) > math.abs(cz) then
                order = cxcz(order, cx, "x", "z")
                order = cxcz(order, cz, "z", "x")
            else
                order = cxcz(order, cz, "z", "x")
                order = cxcz(order, cx, "x", "z")
            end

            -- Check which one of the 4 sides is free
            for o=1, #order do
                local nn = minetest.get_node(vector.add(p, order[o])).name
                local def = minetest.registered_nodes[nn]
                if def and def.walkable == false and nn ~= "ignore" then
                    shootdir = order[o]
                    break
                end
            end
            -- If none of the 4 sides is free, shoot upwards
            if shootdir == nil then
                shootdir = { x=0, y=1, z=0 }
                local nn = minetest.get_node(vector.add(p, shootdir)).name
                if nn == "ignore" then
                    -- Do not push into ignore
                    return
                end
            end

            -- Set new item moving speed accordingly
            local newv = vector.multiply(shootdir, 3)
            self.object:set_acceleration({x = 0, y = 0, z = 0})
            self.object:set_velocity(newv)

            disable_physics(self.object, self, false, false)

            if shootdir.y == 0 then
                self._force = newv
                p.x = math.floor(p.x)
                p.y = math.floor(p.y)
                p.z = math.floor(p.z)
                self._forcestart = p
                self._forcetimer = 1
            end
            return
        end

        -- This code is run after the entity got a push from above “push away” code.
        -- It is responsible for making sure the entity is entirely outside the solid node
        -- (with its full collision box), not just its center.
        if self._forcetimer > 0 then
            local cbox = self.object:get_properties().collisionbox
            local ok = false
            if self._force.x > 0 and (p.x > (self._forcestart.x + 0.5 + (cbox[4] - cbox[1])/2)) then ok = true
            elseif self._force.x < 0 and (p.x < (self._forcestart.x + 0.5 - (cbox[4] - cbox[1])/2)) then ok = true
            elseif self._force.z > 0 and (p.z > (self._forcestart.z + 0.5 + (cbox[6] - cbox[3])/2)) then ok = true
            elseif self._force.z < 0 and (p.z < (self._forcestart.z + 0.5 - (cbox[6] - cbox[3])/2)) then ok = true end
            -- Item was successfully forced out. No more pushing
            if ok then
                self._forcetimer = -1
                self._force = nil
                enable_physics(self.object, self)
            else
                self._forcetimer = self._forcetimer - dtime
            end
            return
        elseif self._force then
            self._force = nil
            enable_physics(self.object, self)
            return
        end

        -- Move item around on flowing liquids
        if def and def.liquidtype == "flowing" then

            --[[ Get flowing direction (function call from flowlib), if there's a liquid.
            NOTE: According to Qwertymine, flowlib.quickflow is only reliable for liquids with a flowing distance of 7.
            Luckily, this is exactly what we need if we only care about water, which has this flowing distance. ]]
            local vec = flowlib.quick_flow(p, node)
            -- Just to make sure we don't manipulate the speed for no reason
            if vec.x ~= 0 or vec.y ~= 0 or vec.z ~= 0 then
                -- Minecraft Wiki: Flowing speed is "about 1.39 meters per second"
                local f = 1.39
                -- Set new item moving speed into the direciton of the liquid
                local newv = vector.multiply(vec, f)
                self.object:set_acceleration({x = 0, y = 0, z = 0})
                self.object:set_velocity({x = newv.x, y = -0.22, z = newv.z})

                self.physical_state = true
                self._flowing = true
                self.object:set_properties({
                    physical = true
                })
                return
            end
        elseif self._flowing == true then
            -- Disable flowing physics if not on/in flowing liquid
            self._flowing = false
            enable_physics(self.object, self, true)
            return
        end

        -- If node is not registered or node is walkably solid and resting on nodebox
        local nn = minetest.get_node({x=p.x, y=p.y-0.5, z=p.z}).name
        local v = self.object:get_velocity()

        if not core.registered_nodes[nn] or core.registered_nodes[nn].walkable and v.y == 0 then
            if self.physical_state then
                local own_stack = ItemStack(self.object:get_luaentity().itemstring)
                -- Merge with close entities of the same item
                for _, object in ipairs(core.get_objects_inside_radius(p, 0.8)) do
                    local obj = object:get_luaentity()
                    if obj and obj.name == "__builtin:item"
                            and obj.physical_state == false then
                        if self:try_merge_with(own_stack, object, obj) then
                            return
                        end
                    end
                end
                disable_physics(self.object, self)
            end
        else
            if self._magnet_active == false then
                enable_physics(self.object, self)
            end
        end
    end,

    -- Note: on_punch intentionally left out. The player should *not* be able to collect items by punching
})

if minetest.settings:get_bool("log_mods") then
    minetest.log("action", "mcl_item_entity loaded")
end