local ipairs, ItemStack, minetest, vector, include, nodecore
    = ipairs, ItemStack, minetest, vector, include, nodecore

rawset(_G, "nc_extended_rotating", {})
nc_extended_rotating.hud      = include("hud")
nc_extended_rotating.registry = include("registry")
nc_extended_rotating.rotate   = include("rotate")
nc_extended_rotating.utility  = include("utility") -- Depends on `rotate`.
nc_extended_rotating.entity   = include("entity")  -- Depends on `utility`.
nc_extended_rotating.state    = include("state")   -- Depends on `registry`, `rotate` and `utility`.

local update_entity_hint    = nc_extended_rotating.entity.update_entity_hint
local update_player_hud     = nc_extended_rotating.hud.update_player_hud
local is_rotatable          = nc_extended_rotating.registry.is_rotatable
local register_rotatable    = nc_extended_rotating.registry.register_rotatable;
local rotate_node           = nc_extended_rotating.rotate.rotate_node
local update_rotating_state = nc_extended_rotating.state.update_rotating_state
local get_rotating_state    = nc_extended_rotating.state.get_rotating_state

-- TODO: Fix HUD showing rotation hint when we wouldn't / can't rotate.
-- TODO: Simplify registration and `on_rightclick` replacement into one call.
-- TODO: Add some more comments.

nodecore.register_playerstep({
    label = "nc_extended_rotating:update",
    action = function(player, data)
        local state = update_rotating_state(player, data)
        update_player_hud(player, state)
        update_entity_hint(player, state)
    end,
})

-- Register rotatable nodes from NodeCore.
do
    local function nodecore_filtered_lookup(eq_func)
        local lookup = {}
        for i = 0, 23 do
            local facedir = nodecore.facedirs[i]
            for j = 0, #lookup - 1 do
                local other = nodecore.facedirs[lookup[j]]
                if eq_func(facedir, other) then lookup[i] = j; break end
            end
            lookup[i] = lookup[i] or i
        end
        return lookup
    end

    local LENS_FILTERED_LOOKUP = nodecore_filtered_lookup(
        function(a, b) return vector.equals(a.f, b.f) end)
    local PRISM_FILTERED_LOOKUP = nodecore_filtered_lookup(
        function(a, b) return vector.equals(a.f, b.r) and vector.equals(a.r, b.f) end)
    local PANEL_FILTERED_LOOKUP = nodecore_filtered_lookup(
        function(a, b) return vector.equals(a.f, b.r) and vector.equals(a.r, b.f) end)

    for _, lens_state in ipairs({ "", "_on", "_glow", "_glow_start" }) do
        register_rotatable("nc_optics:lens" .. lens_state, nil, LENS_FILTERED_LOOKUP) end
    for _, prism_state in ipairs({ "", "_on", "_gated" }) do
        register_rotatable("nc_optics:prism" .. prism_state, nil, PRISM_FILTERED_LOOKUP) end

    -- Register all existing door panels.
    nodecore.register_on_register_item({
        retroactive = true,
        func = function(name, def)
            -- NOTE: This function is actually called BEFORE the item is registered with Minetest.
            --       Because of this, looking up the node definition by name does not work.
            name = name:gsub("^:", "") -- Fix for older versions of NodeCore.
            if def.groups and def.groups.door_panel and (not def.groups.door)
                then register_rotatable(name, def, PANEL_FILTERED_LOOKUP) end
        end,
    })
end

local function handle_rightclick(pos, node, clicker)
    local state = get_rotating_state(clicker, pos, node)
    if (not state) or (not state.success) then return end
    rotate_node(pos, node, state.facedir)
end

-- Replace `on_rightclick` of rotatable nodes from NodeCore.
do
    local function replace_optics_on_rightclick(name)
        local def = minetest.registered_nodes[name]
        def.on_rightclick = handle_rightclick
    end

    -- Panels can't have their `on_rightclick` overridden completely.
    -- We need to call the default implementation when holding a "pin".
    local function replace_panel_on_rightclick(name, pin)
        local def = minetest.registered_nodes[name]
        local default_rightclick = def.on_rightclick
        def.on_rightclick = function(pos, node, clicker, item_stack, ...)
            if nodecore.protection_test(pos, clicker) or ItemStack(item_stack):get_name() == pin
                then return default_rightclick(pos, node, clicker, item_stack, ...)
                else return handle_rightclick(pos, node, clicker)
            end
        end
    end

    for _, lens_state in ipairs({ "", "_on", "_glow", "_glow_start" }) do
        replace_optics_on_rightclick("nc_optics:lens" .. lens_state) end
    for _, lens_state in ipairs({ "", "_on", "_gated" }) do
        replace_optics_on_rightclick("nc_optics:prism" .. lens_state) end

    -- Replace `on_rightclick` for all existing doors' panels.
    nodecore.register_on_register_item({
        retroactive = true,
        func = function(name, def)
            if def.groups and def.groups.door then
                local panel = def.drop_in_place.name             -- The panel version of the door.
                local pin   = def.drop_non_silktouch or def.drop -- Dropped item is the door's pin.
                replace_panel_on_rightclick(panel, pin)
            end
        end,
    })
end

-- Override `nc_scaling`'s default empty hand right-click behavior so we can use it
-- to rotate things when holding sneak, which doesn't trigger a node's `on_rightclick`.
local default_on_place = minetest.registered_items[""].on_place
minetest.registered_items[""].on_place = function(item_stack, placer, pointed_thing, ...)
    if pointed_thing.type == "node" then
        -- Player must sneak in order for this to run.
        -- Non-sneak is handled by node's `on_rightclick`.
        if minetest.is_player(placer) and placer:get_player_control().sneak then
            local pos  = pointed_thing.under
            local node = minetest.get_node(pos)
            if is_rotatable(node) then
                handle_rightclick(pos, node, placer)
                return -- Skip default behavior.
            end
        end
    end
    -- Call the default function, so we can still get the "scaling" functionality.
    default_on_place(item_stack, placer, pointed_thing, ...)
end