---

dens = $int(Density, 60, 5, 100)$
maxL = $int(Max Layers, 5, 1, 8)$
skyOnly = $boolean(Sky Only, true)$
denySlabs = $boolean(Deny Slabs, true)$
denyStairs = $boolean(Deny Stairs, true)$
denyLeaves = $boolean(Deny Leaves, true)$
deny1 = $blockState(Deny 1, barrier)$
deny2 = $blockState(Deny 2, glass)$
deny3 = $blockState(Deny 3, oak_planks)$
l1 = $blockState(L1, snow)$
l2 = $blockState(L2, snow)$
l3 = $blockState(L3, snow)$
l4 = $blockState(L4, snow)$
l5 = $blockState(L5, snow)$
l6 = $blockState(L6, snow)$
l7 = $blockState(L7, snow)$
l8 = $blockState(L8, snow)$

function isOpen(b)
    if b == blocks.air then return true end
    if b == blocks.cave_air then return true end
    if b == blocks.void_air then return true end
    return false
end

function hardBan(b)
    if b == blocks.packed_ice then return true end
    if b == blocks.blue_ice then return true end
    if b == blocks.deepslate then return true end
    if b == blocks.cobbled_deepslate then return true end
    if b == blocks.polished_deepslate then return true end
    if b == blocks.chiseled_deepslate then return true end
    if b == blocks.deepslate_bricks then return true end
    if b == blocks.cracked_deepslate_bricks then return true end
    if b == blocks.deepslate_tiles then return true end
    if b == blocks.cracked_deepslate_tiles then return true end
    if b == blocks.reinforced_deepslate then return true end
    if b == blocks.infested_deepslate then return true end
    if b == blocks.deepslate_coal_ore then return true end
    if b == blocks.deepslate_iron_ore then return true end
    if b == blocks.deepslate_copper_ore then return true end
    if b == blocks.deepslate_gold_ore then return true end
    if b == blocks.deepslate_redstone_ore then return true end
    if b == blocks.deepslate_emerald_ore then return true end
    if b == blocks.deepslate_lapis_ore then return true end
    if b == blocks.deepslate_diamond_ore then return true end
    if b == blocks.lantern then return true end
    if b == blocks.soul_lantern then return true end
    return false
end

function denied(b, st)
    if hardBan(b) then return true end
    if b == deny1 or st == deny1 then return true end
    if b == deny2 or st == deny2 then return true end
    if b == deny3 or st == deny3 then return true end
    if isBlockTagged then
        if denySlabs and isBlockTagged(b, "slabs") then return true end
        if denyStairs and isBlockTagged(b, "stairs") then return true end
        if denyLeaves and isBlockTagged(b, "leaves") then return true end
        if isBlockTagged(b, "fences") then return true end
        if isBlockTagged(b, "walls") then return true end
        if isBlockTagged(b, "fence_gates") then return true end
    end
    return false
end

function okGround(b, st)
    if isOpen(b) then return false end
    if b == blocks.water then return false end
    if b == blocks.snow then return false end
    if b == blocks.snow_block then return false end
    if denied(b, st) then return false end
    if isSolid(b) == false then return false end
    return true
end

function layerOf(st)
    if getBlockProperty then
        v = getBlockProperty(st, "layers")
        if v == "1" or v == 1 then return 1 end
        if v == "2" or v == 2 then return 2 end
        if v == "3" or v == 3 then return 3 end
        if v == "4" or v == 4 then return 4 end
        if v == "5" or v == 5 then return 5 end
        if v == "6" or v == 6 then return 6 end
        if v == "7" or v == 7 then return 7 end
        if v == "8" or v == 8 then return 8 end
    end
    if st == l8 then return 8 end
    if st == l7 then return 7 end
    if st == l6 then return 6 end
    if st == l5 then return 5 end
    if st == l4 then return 4 end
    if st == l3 then return 3 end
    if st == l2 then return 2 end
    return 1
end

function snowOf(n)
    if n < 1 then n = 1 end
    if n > 8 then n = 8 end
    if withBlockProperty then
        return withBlockProperty(blocks.snow, "layers=" .. n)
    end
    if n == 1 then return l1 end
    if n == 2 then return l2 end
    if n == 3 then return l3 end
    if n == 4 then return l4 end
    if n == 5 then return l5 end
    if n == 6 then return l6 end
    if n == 7 then return l7 end
    return l8
end

function clearAbove(px, py, pz)
    if skyOnly == false then
        return true
    end
    t = 1
    while t <= 120 do
        if isOpen(getBlock(px, py + t, pz)) == false then
            return false
        end
        t = t + 1
    end
    return true
end

function sideIsEdge(px, py, pz)
    base = getBlock(px, py - 1, pz)
    baseSt = getBlockState(px, py - 1, pz)
    if isOpen(base) then
        return true
    end
    if denied(base, baseSt) then
        return true
    end
    if isSolid(base) == false then
        return true
    end
    side = getBlock(px, py, pz)
    sideSt = getBlockState(px, py, pz)
    if side ~= blocks.snow and denied(side, sideSt) then
        return true
    end
    return false
end

function edgeLimit(px, py, pz)
    bad = 0
    if sideIsEdge(px + 1, py, pz) then bad = bad + 1 end
    if sideIsEdge(px - 1, py, pz) then bad = bad + 1 end
    if sideIsEdge(px, py, pz + 1) then bad = bad + 1 end
    if sideIsEdge(px, py, pz - 1) then bad = bad + 1 end
    if bad >= 2 then
        return 1
    end
    if bad == 1 then
        return 2
    end
    return maxL
end

function putSnow(px, py, pz, n)
    if n < 1 then
        return
    end
    cap = edgeLimit(px, py, pz)
    if n > cap then
        n = cap
    end
    if n > maxL then
        n = maxL
    end
    if n > 8 then
        n = 8
    end
    if n < 1 then
        return
    end
    setBlock(px, py, pz, snowOf(n))
end

function ensureAtLeast(px, py, pz, n)
    if n < 1 then
        return
    end
    if clearAbove(px, py, pz) == false then
        return
    end
    n = n
    cap = edgeLimit(px, py, pz)
    if n > cap then
        n = cap
    end
    here = getBlock(px, py, pz)
    if here == blocks.snow then
        cur = layerOf(getBlockState(px, py, pz))
        if cur < n then
            putSnow(px, py, pz, n)
        end
        return
    end
    if isOpen(here) then
        base = getBlock(px, py - 1, pz)
        baseSt = getBlockState(px, py - 1, pz)
        if okGround(base, baseSt) then
            putSnow(px, py, pz, n)
        end
        return
    end
    if denied(here, getBlockState(px, py, pz)) then
        return
    end
    if okGround(here, getBlockState(px, py, pz)) == false then
        return
    end
    above = getBlock(px, py + 1, pz)
    if above == blocks.snow then
        cur = layerOf(getBlockState(px, py + 1, pz))
        if cur < n then
            putSnow(px, py + 1, pz, n)
        end
        return
    end
    if isOpen(above) then
        putSnow(px, py + 1, pz, n)
    end
end

function slopeAround(px, py, pz, peak)
    if peak < 3 then
        return
    end
    need = peak - 1
    if need < 1 then
        need = 1
    end
    ensureAtLeast(px + 1, py, pz, need)
    ensureAtLeast(px - 1, py, pz, need)
    ensureAtLeast(px, py, pz + 1, need)
    ensureAtLeast(px, py, pz - 1, need)
end

function addLayer(px, py, pz, current_limit)
    n = layerOf(getBlockState(px, py, pz)) + 1
    if n > current_limit then
        return
    end
    if n > maxL then
        return
    end
    if n > 8 then
        return
    end
    cap = edgeLimit(px, py, pz)
    if n > cap then
        n = cap
    end
    putSnow(px, py, pz, n)
    slopeAround(px, py, pz, n)
end

nse = getSimplexNoise(x * 0.15, 3, z * 0.15, 23)
if nse * 100 > dens then
    return nil
end

noise_max = 1 + (nse * 100) / (dens / maxL)
noise_max = noise_max - noise_max % 1
if noise_max < 1 then
    noise_max = 1
end
if noise_max > maxL then
    noise_max = maxL
end

firstH = 1
if nse > 0.40 then
    firstH = 2
end
if nse > 0.68 then
    firstH = 3
end
if firstH > noise_max then
    firstH = noise_max
end
if firstH > maxL then
    firstH = maxL
end

b = getBlock(x, y, z)
st = getBlockState(x, y, z)
up = getBlock(x, y + 1, z)
dn = getBlock(x, y - 1, z)
dnSt = getBlockState(x, y - 1, z)

if b == blocks.snow then
    if clearAbove(x, y, z) == false then
        return nil
    end
    addLayer(x, y, z, noise_max)
    return nil
end

if isOpen(b) == false then
    if denied(b, st) then
        return nil
    end
    if up == blocks.snow then
        if clearAbove(x, y + 1, z) == false then
            return nil
        end
        addLayer(x, y + 1, z, noise_max)
        return nil
    end
    if isOpen(up) == false then
        return nil
    end
    if okGround(b, st) == false then
        return nil
    end
    if clearAbove(x, y, z) == false then
        return nil
    end
    putSnow(x, y + 1, z, firstH)
    slopeAround(x, y + 1, z, firstH)
    return nil
end

if dn == blocks.snow then
    if clearAbove(x, y - 1, z) == false then
        return nil
    end
    addLayer(x, y - 1, z, noise_max)
    return nil
end

if okGround(dn, dnSt) == false then
    return nil
end
if clearAbove(x, y - 1, z) == false then
    return nil
end
putSnow(x, y, z, firstH)
slopeAround(x, y, z, firstH)
return nil