local function approx_cossim(dim)
    return math.pow(1.521 * dim - 0.521, -0.5026)
end

local cfg = {
    defer_prints = true,

    playable_mode = false,
    start_big = false, --true
    starting_lives = 0, --1

    init_zeros = true, -- instead of he_normal noise or whatever.
    frameskip = 4,
    -- true greedy epsilon has both deterministic and det_epsilon set.
    deterministic = false, -- use argmax on outputs instead of random sampling.
    det_epsilon = false, -- take random actions with probability eps.

    graycode = false,
    epoch_trials = 5,
    epoch_top_trials = 2, -- new with ARS.
    unperturbed_trial = false, -- do a trial without any noise.
    negate_trials = true, -- try pairs of normal and negated noise directions.
    time_inputs = true, -- binary inputs of global frame count
    -- ^ note that this now doubles the effective trials.
    deviation = 0.32,
    --learning_rate = 0.01 / approx_cossim(7051)
    learning_rate = 0.32,
    --learning_rate = 0.0032 / approx_cossim(66573)
    --learning_rate = 0.0056 / approx_cossim(66573)
    weight_decay = 0.0032,

    cap_time = 200, --400
    timer_loser = 1/2,
    decrement_reward = false, -- bad idea, encourages mario to kill himself

    playback_mode = false,
}

-- TODO: so, uhh..
-- what happens when playback_mode is true but unperturbed_trial is false?

cfg.epoch_top_trials = math.min(cfg.epoch_trials, cfg.epoch_top_trials)

cfg.eps_start = 1.0 * cfg.frameskip / 64
cfg.eps_stop  = 0.1 * cfg.eps_start
cfg.eps_frames = 1000000
cfg.enable_overlay = cfg.playable_mode
cfg.enable_network = not cfg.playable_mode

return setmetatable(cfg, {
    __index = function(t, n)
        error("cannot use undeclared config '" .. tostring(n) .. "'", 2)
    end
})