--!native
local pearlin = {}
local vector = require(game:GetService("ServerStorage").vector)

function pearlin.fade(t)
    return ((6 * t - 15) * t + 10) * t * t * t
end

function pearlin.lerp(t, a1, a2)
    return a1 + t * (a2 - a1)
end

function pearlin.getConstVector(v)
    v = v or 0
    local h = bit32.band(v, 3)
    if h == 0 then
        return vector.new(1.0, 1.0)
    elseif h == 1 then
        return vector.new(-1.0, 1.0)
    elseif h == 2 then
        return vector.new(-1.0, -1.0)
    else
        return vector.new(1.0, -1.0)
    end
end

function pearlin.createNDarray(n, tbl)
    tbl = tbl or {}
    if n == 0 then
        return tbl
    end
    setmetatable(tbl, {
        __index = function(t, k)
            local new = pearlin.createNDarray(n - 1)
            t[k] = new
            return new
        end,
    })
    return tbl
end

function pearlin.createANDarray(n, tbl, func)
    tbl = tbl or {}
    if n == 0 then
        return setmetatable(tbl, { __newindex = func })
    end
    setmetatable(tbl, {
        __index = function(t, k)
            local new = pearlin.createANDarray(n - 1, nil, func)
            t[k] = new
            return new
        end,
    })
    return tbl
end

function pearlin.shuffle(tbl)
    local temp
    for e = (#tbl - 1), 1, -1 do
        local index = math.floor((math.random() * (e - 1)) + 0.5)
        temp = tbl[e]
        tbl[e] = tbl[index]
        tbl[index] = temp
    end
end

function pearlin.makeperm()
    local P = {}
    for i = 0, 8192 do
        table.insert(P, i)
    end
    pearlin.shuffle(P)
    for i = 0, 8192 do
        table.insert(P, i)
    end
    return P
end
local P = pearlin.makeperm()
function pearlin.noise2d(x, y)
    local X = math.floor(x)
    local Y = math.floor(y)
    local xf = x - math.floor(x)
    local yf = y - math.floor(y)
    local topRight = vector.new(xf - 1.0, yf - 1.0)
    local topLeft = vector.new(xf, yf - 1.0)
    local bottomRight = vector.new(xf - 1.0, yf)
    local bottomLeft = vector.new(xf, yf)
    local valueTopRight = P[P[X + 1] + Y + 1]
    local valueTopLeft = P[P[X] + Y + 1]
    local valueBottomRight = P[P[X + 1] + Y]
    local valueBottomLeft = P[P[X] + Y]
    local dotTopRight = topRight:dot(pearlin.getConstVector(valueTopRight))
    local dotTopLeft = topLeft:dot(pearlin.getConstVector(valueTopLeft))
    local dotBottomRight = bottomRight:dot(pearlin.getConstVector(valueBottomRight))
    local dotBottomLeft = bottomLeft:dot(pearlin.getConstVector(valueBottomLeft))
    local u = pearlin.fade(xf)
    local v = pearlin.fade(yf)
    return pearlin.lerp(u, pearlin.lerp(v, dotBottomLeft, dotTopLeft), pearlin.lerp(v, dotBottomRight, dotTopRight))
end

local function hash(str)
    local h = 5381
    for c in str:gmatch(".") do
        h = math.fmod((bit32.lshift(h, 5) + h) + string.byte(c), 2147483648)
    end
    return h
end

function pearlin.calcseed(inputstr)
    if tonumber(inputstr) then
        return inputstr
    else
        return hash(inputstr)
    end
end

function pearlin.noise(x, y, amp, seed, offsetx, offsety)
    math.randomseed(seed or os.time())
    offsetx = offsetx or 0
    offsety = offsety or 0 -- whats the math.randomseed() for
    local tbl = pearlin.createNDarray(2)
    local defamp = amp or 0.01
    for a = 1 + offsety, y + offsety do
        for b = 1 + offsetx, x + offsetx do
            local n = ((pearlin.noise2d(a * defamp)) + 1) * 0.5
            n = n + 1.0
            n = n * 0.5
            tbl[a - offsety][b - offsetx] = n
        end
    end
    return tbl
end

return pearlin