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

local hud     = include("hud")
local rotate  = include("rotate")
local utility = include("utility")

-- TODO: Add crosshair indicators for rotating around edges.
-- TODO: Replace `on_rightclick` of intended nodes?
-- TODO: Allow right-clicking while holding sneak with an empty hand to invert rotation.
-- TODO: Add some more comments.

-- Distance at which we want to rotate by "pushing" on an edge.
local EDGE_DISTANCE = 1.5 / 16 -- 1.5 texels (at 16² texture resolution)

-- Contains a per-player state that holds information, created by a raycast
-- done in `playerstep`, about the node this player might rotate. This is used
-- to decide what to do when a rightclick occurs and to update the their HUD.
local rotating_state = {}

-- Register rotatable nodes.
do
    local function nodecore_filtered_lookup(eq_func)
        local lookup = {}
        for i = 0, 23 do
            local facedir = nodecore.facedirs[i]
            for j = 1, #lookup 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
        rotate.register_rotatable("nc_optics:lens" .. lens_state, LENS_FILTERED_LOOKUP) end
    for _, prism_state in ipairs({ "", "_on", "_gated" }) do
        rotate.register_rotatable("nc_optics:prism" .. prism_state, PRISM_FILTERED_LOOKUP) end

    rotate.register_rotatable("nc_doors:panel_plank" , PANEL_FILTERED_LOOKUP)
    rotate.register_rotatable("nc_doors:panel_cobble", PANEL_FILTERED_LOOKUP)
end

-- Calculates the state for the specified `player` and player `data`.
-- This state contains information about how the player would rotate a block.
local function calculate_rotating_state(player, data)
    local state = {}

    local pointed_thing = data.raycast()
    if (not pointed_thing) or pointed_thing.type ~= "node" then return end

    state.pos  = pointed_thing.under
    state.node = minetest.get_node(state.pos)
    if not rotate.is_rotatable(state.node) then return end

    if vector.equals(pointed_thing.above, pointed_thing.under) then return end
    state.face = pointed_thing.above - pointed_thing.under

    local edge, distance = utility.find_closest_edge(state.node, pointed_thing)
    -- FIXME: Something in `find_closest_edge` is causing an unexpected edge to be returned, hence the additional check.
    if edge and distance <= EDGE_DISTANCE and state.face:multiply(edge):length() ~= 0 then
        state.axis = state.face:cross(edge):normalize()
        state.mode = "edge"
    else
        state.axis = state.face
        state.mode = "face"
    end

    state.invert = player:get_player_control().sneak

    local degrees = state.invert and 90 or -90
    state.facedir = rotate.rotate_facedir(state.node.param2, state.axis, degrees)
    state.facedir = rotate.fix_rotatable_facedir(state.node, state.facedir)
    state.success = state.facedir and state.facedir ~= state.node.param2

    return state
end

nodecore.register_playerstep({
    label = "extended rotating update",
    action = function(player, data)
        local name = player:get_player_name()
        rotating_state[name] = calculate_rotating_state(player, data)
        hud.update_player_hud(player, rotating_state[name])
    end,
})

minetest.register_on_leaveplayer(function(player)
    local name = player:get_player_name()
    rotating_state[name] = nil
end)

minetest.register_on_punchnode(function(pos, node, puncher, pointed_thing)
    if not minetest.is_player(puncher) then return end
    local name  = puncher:get_player_name()
    local state = rotating_state[name]
    if not state then return end

    -- Make sure we're still the same node that we raycasted in `playerstep`.
    if not vector.equals(pos, state.pos) then return end
    if node.name ~= state.node.name or node.param2 ~= state.node.param2 then return end

    -- Only continue if the node can actually be sucessfully rotated.
    if not state.success then return end

    minetest.swap_node(pos, nodecore.underride({ param2 = state.facedir }, node))
end)