-- ^ and : need escaping if they are in parentheses...
local texmod_escape = function(s)
    local p_c = 0                -- parentheses_count
    local n_s = ""
    for i = 0, #s do
        local c = s:sub(i,i)
        if c == "(" then
            p_c = p_c + 1
        elseif c == ")" then
            p_c = p_c - 1
        elseif c == "^" and p_c > 0 then
            c = ("\\"):rep(math.pow(2, p_c-1)) .. c
        elseif c == ":" and p_c > 0 then
            c = ("\\"):rep(math.pow(2, p_c-1)) .. c
        end
        n_s = n_s .. c
    end
    return n_s
end

hidden_doors.create_door_texture = function (texture, resolution)
    -- in case of a high-res texturepack, but a low-res texture from another mod, we need to upscale the given texture
    texture = "doors_trapdoor.png^[opacity:0^" .. texture

    local base = "doors_door_wood.png^[opacity:0"
    -- in case of a low-res texturepack, but a high-res texture from another mod we have to upscale the door image
    if resolution and resolution > 16 then
        local width = resolution * 38 / 16
        local height = resolution * 2
        base = base .. ("^[fill:%i,%i:0,0:#0000)"):format(width, height)
    end

    -- ------------------------------------------------------------------------------------------------------------
    -- see snippet_create_texture.lua for the idea behind this

    -- flip the texture around y, place it onto the base texture, flip the whole texture again
    local t_2 = ("%s^[combine:0x0:0,0=(%s^[transform6)^[transform6"):format(base, texture)
    -- t1 can be placed and is already in the correct position
    local t_12 = ("%s^[combine:0x0:0,0=(%s)"):format(t_2, texture)

    -- idea: flip t_12 around y and rotate 2x
    -- first rotation brings the textures to places 1 & 3
    local t_34_rot = ("%s^[combine:0x0:0,0=(%s^[transform6^[transform3)"):format(base, t_12)
    local t_34 = ("%s^[combine:0x0:0,0=(%s^[transform3)"):format(base, t_34_rot)

    -- 5 & 6 are only the sides of the door, it should be good enough to mirror t_12
    local t_56 = ("%s^[transform4"):format(t_12)

    -- t_34 and t_56 overlap, make sure t_34 is on top
    local img = ("%s^[combine:0x0:0,0=(%s):0,0=(%s):0,0=(%s)"):format(base, t_56, t_34, t_12)

    return texmod_escape(img)
    -- return texmod_escape(img)
end

hidden_doors.create_inventory_image = function (texture, resolution)
    -- in case of a high-res texturepack, but a low-res texture from another mod, we need to upscale the given texture
    texture = "doors_trapdoor.png^[opacity:0^" .. texture

    local base = "doors_door_wood.png^[opacity:0"
    -- in case of a low-res texturepack, but a high-res texture from another mod we have to upscale the door image
    if resolution and resolution > 16 then
        base = base .. ("^[fill:%i,%i:0,0:#0000)"):format(resolution, resolution * 2)
    end

    -- flip the texture around y, place it onto the base texture, flip the whole texture again
    local t_2 = ("%s^[combine:0x0:0,0=(%s^[transform6)^[transform6"):format(base, texture)
    -- t1 can be placed and is already in the correct position
    local t_12 = ("%s^[combine:0x0:0,0=%s"):format(t_2, texture)

    return texmod_escape(t_12)
end


hidden_doors.register_from_node = function (name, basenode, resolution, recipe)
    local basedef = core.registered_nodes[basenode]
    if not basedef then print(basenode) return end

    doors.register(name, {
        description = ("hidden %s door"):format(basedef.description),
        inventory_image = hidden_doors.create_inventory_image(basedef.tiles[1], resolution),
        tiles = {{ name = hidden_doors.create_door_texture(basedef.tiles[1], resolution), backface_culling = true }},
        groups = {
            door = 1,
            dig_immediate = basedef.groups.dig_immediate,
            crumbly = basedef.groups.crumbly,
            cracky = basedef.groups.cracky,
            snappy = basedef.groups.snappy,
            choppy = basedef.groups.choppy,
        },
        sound_open = (basedef.groups.crumbly and "hidden_doors_stone_door_open.ogg"),
        sound_close = (basedef.groups.crumbly and "hidden_doors_stone_door_close.ogg"),
    })
end