preset = arg or "" -- must be done before requiring strict!
local globalize = require("strict")

-- configuration.

local cfg = require("config")
local gcfg = require("gameconfig")

-- state.

local params_fn
local std_fn

local epoch_i = 0
local base_params
local trial_i = -1 -- NOTE: trial 0 is an unperturbed trial, if enabled.
local trial_neg = true
local trial_params --= {}
local trial_rewards = {}
local trials_remaining = 0
local es -- evolution strategy.

local trial_frames = 0
local total_frames = 0
local lagless_count = 0
local decisions_made = 0

local force_start = false
local force_start_old = false

local startsave = savestate.create(1)
local any_random = cfg.starting_world == 0 or cfg.starting_level == 0

local poketime = false
local max_time

local jp

local screen_scroll_delta
local reward

local powerup_old
local status_old
local coins_old
local score_old

local state_saved = false
local reset = true

local state_old = ''
local last_trial_state

-- localize some stuff.

local abs = math.abs
local assert = assert
local ceil = math.ceil
local collectgarbage = collectgarbage
local exp = math.exp
local floor = math.floor
local insert = table.insert
local ipairs = ipairs
local log = math.log
local max = math.max
local min = math.min
local open = io.open
local pairs = pairs
local pow = math.pow
local print = print
local random = math.random
local randomseed = math.randomseed
local remove = table.remove
local select = select
local sort = table.sort
local sqrt = math.sqrt
local unpack = table.unpack or unpack

local band = bit.band
local bor = bit.bor
local bxor = bit.bxor
local bnot = bit.bnot
local lshift = bit.lshift
local rshift = bit.rshift
local arshift = bit.arshift
local rol = bit.rol
local ror = bit.ror

local emu = emu
local gui = gui

local util = require("util")
local argmax = util.argmax
local argsort = util.argsort
local calc_mean_dev = util.calc_mean_dev
local clamp = util.clamp
local copy = util.copy
local empty = util.empty
local lerp = util.lerp
local softchoice = util.softchoice
local unperturbed_rank = util.unperturbed_rank
local exists = util.exists

local game = require("smb")
game.overlay = cfg.enable_overlay

-- utilities.

local log_map = {
    epoch = 1,
    trial_mean = 2,
    trial_std = 3,
    delta_mean = 4,
    delta_std = 5,
    step_std = 6,
    weight_mean = 7, -- TODO: rename to param_mean.
    weight_std = 8, -- TODO: rename to param_std.
    test_trial = 9,
    decisions = 10,
}

local function log_csv(t)
    if cfg.log_fn == nil then return end
    local f = open(cfg.log_fn, 'a')
    if f == nil then error("Failed to open log file "..cfg.log_fn) end
    local values = {}
    for k, v in pairs(t) do
        local i = log_map[k]
        if i == nil then error("Unexpected log key "..tostring(k)) end
        values[i] = v
    end
    for k, i in pairs(log_map) do
        if values[i] == nil then error("Missing log key "..tostring(k)) end
    end
    for i, v in ipairs(values) do
        f:write(tostring(v))
        if i ~= #values then f:write(",") end
    end
    f:write('\n')
    f:close()
end

-- network parameters.

package.loaded['nn'] = nil -- DEBUG
local nn = require("nn")

local network
local nn_x, nn_tx, nn_ty, nn_tz, nn_y, nn_z
local function make_network(input_size)
    nn_x = nn.Input({input_size})
    nn_tx = nn.Input({gcfg.tile_count})
    nn_ty = nn_tx:feed(nn.Embed(#game.valid_tiles, 2))

    nn_tz = nn_ty
    if cfg.reduce_tiles then
        nn_tz = nn_tz:feed(nn.Reshape{11, 17 * 2})
        nn_tz = nn_tz:feed(nn.DenseBroadcast(5, true))
        nn_tz = nn_tz:feed(nn.Relu())
        -- note: due to a quirk in Merge, we don't need to flatten nn_tz.
    end

    nn_y = nn.Merge()
    nn_x:feed(nn_y)
    nn_tz:feed(nn_y)

    if cfg.hidden then
        nn_y = nn_y:feed(nn.Dense(cfg.hidden_size, true))
        if cfg.deterministic then
            nn_y = nn_y:feed(nn.Relu())
        else
            nn_y = nn_y:feed(nn.Gelu())
        end
        if cfg.layernorm then nn_y = nn_y:feed(nn.LayerNorm()) end
    end

    nn_z = nn_y
    nn_z = nn_z:feed(nn.Dense(#gcfg.jp_lut), true, cfg.bias_out)
    nn_z = nn_z:feed(nn.Softmax())
    return nn.Model({nn_x, nn_tx}, {nn_z})
end

-- learning and evaluation.

local ars = require("ars")
local snes = require("snes")
local xnes = require("xnes")

local function prepare_epoch()
    trial_neg = false

    base_params = network:collect()
    if cfg.playback_mode then return end

    print('preparing epoch '..tostring(epoch_i)..'...')
    empty(trial_rewards)

    if cfg.es == 'xnes' then
        print("sigma:", es.sigma)
    elseif cfg.es == 'snes' then
        local sigma_mean, sigma_dev = calc_mean_dev(es.std)
        --print("sigma:", sigma_mean, sigma_dev)
        print("sigma 50%:", sigma_mean)
        print("sigma 95%:", sigma_mean + sigma_dev * 1.64485)
    end

    local precision
    if cfg.graycode then
        precision = (pow(cfg.deviation, 1/-0.51175585) - 8.68297257) / 1.66484392
        print(("chosen precision: %.2f"):format(precision))
    end

    local dummy
    if cfg.es == 'ars' then
        trial_params, dummy = es:ask(precision)
    elseif cfg.es == 'snes' then
        trial_params, dummy = es:ask_mix()
    else
        trial_params, dummy = es:ask()
    end

    trial_i = -1
end

local function load_next_trial()
    if cfg.negate_trials then
        trial_neg = not trial_neg
    else
        trial_neg = true
    end
    trial_i = trial_i + 1
    if trial_i == 0 and not cfg.unperturbed_trial then
        trial_neg = false
        trial_i = 1
    end
    if trial_i > 0 then
        --print('loading trial', trial_i)
        network:distribute(trial_params[trial_i])
    else
        --print("test trial")
        network:distribute(base_params)
    end
end

local function learn_from_epoch()
    print()

    local current_cost = trial_rewards[0] -- may be nil!

    if cfg.unperturbed_trial then
        local nth_place = unperturbed_rank(trial_rewards, current_cost)

        -- a rank of 1 means our gradient is uninformative.
        print(("test trial: %d out of %d"):format(nth_place, #trial_rewards))
    end

    local delta_rewards = {} -- only used for logging.
    if cfg.negate_trials then
        for i = 1, #trial_rewards, 2 do
            local ind = floor(i / 2) + 1
            local pos = trial_rewards[i + 0]
            local neg = trial_rewards[i + 1]
            delta_rewards[ind] = abs(pos - neg)
        end
    end

    local step
    if cfg.es == 'ars' and cfg.ars_lips then
        step = es:tell(trial_rewards, current_cost)
    else
        step = es:tell(trial_rewards)
    end

    local step_mean, step_dev = calc_mean_dev(step)
    print("step mean:", step_mean)
    print("step stddev:", step_dev)

    es:decay(cfg.param_decay, cfg.sigma_decay)

    base_params = es:params()

    local trial_mean, trial_std = calc_mean_dev(trial_rewards)
    local delta_mean, delta_std = calc_mean_dev(delta_rewards)
    local param_mean, param_std = calc_mean_dev(base_params)

    log_csv{
        epoch = epoch_i,
        trial_mean = trial_mean,
        trial_std = trial_std,
        delta_mean = delta_mean,
        delta_std = delta_std,
        step_std = step_dev,
        weight_mean = param_mean,
        weight_std = param_std,
        test_trial = current_cost or 0,
        decisions = decisions_made,
    }

    if cfg.enable_network then
        network:distribute(base_params)
        network:save(params_fn)

        if cfg.es == 'snes' then
            local f = assert(open(std_fn, "w"))
            for _, v in ipairs(es.std) do f:write(("%f\n"):format(v)) end
            f:close()
        end

    else
        print("note: not updating params in playable mode.")
    end

    print()
end

local function joypad_mash(button)
    local jp_mash = {
        up = false,
        down = false,
        left = false,
        right = false,
        A = false,
        B = false,
        select = false,
        start = false,
    }
    assert(jp_mash[button] == false, "invalid button: "..tostring(button), 1)
    jp_mash[button] = emu.framecount() % 2 == 1
    joypad.write(1, jp_mash)
end

local function loadlevel(world, level)
    -- TODO: move to smb.lua. rename to load_level.
    if world == 0 then world = random(1, 8) end
    if level == 0 then level = random(1, 4) end
    emu.poweron()
    while emu.framecount() < 60 do
        if emu.framecount() == 32 then
            local area = game.area_lut[world * 10 + level]
            game.W(0x75F, world - 1)
            game.W(0x75C, level - 1)
            game.W(0x760, area)
        end
        if emu.framecount() == 42 then
            game.W(0x7A0, 0) -- world screen timer (reduces startup time)
        end
        joypad_mash('start')
        emu.frameadvance()
    end
end

local function do_reset()
    local state = game.get_state()
    -- be a little more descriptive.
    if state == 'dead' and game.get_timer() == 0 then state = 'timeup' end

    if trial_i >= 0 then
        if trial_i == 0 then
            print('test trial reward:', reward, "("..state..")")
        elseif cfg.negate_trials then
            --local dir = trial_neg and "negative" or "positive"
            --print('trial', trial_i, dir, 'reward:', reward, "("..state..")")

            if trial_neg then
                local pos = trial_rewards[#trial_rewards]
                local neg = reward
                local fmt = "trial %i rewards: %+i, %+i (%s, %s)"
                print(fmt:format(floor(trial_i / 2),
                                 pos, neg, last_trial_state, state))
            end
            last_trial_state = state
        else
            print('trial', trial_i, 'reward:', reward, "("..state..")")
        end

        if trial_i == 0 or not cfg.negate_trials then
            trial_rewards[trial_i] = reward
        else
            trial_rewards[#trial_rewards + 1] = reward
        end
    end

    if epoch_i == 0 or (trial_i == #trial_params and trial_neg) then
        if epoch_i > 0 then learn_from_epoch() end
        if not cfg.playback_mode then epoch_i = epoch_i + 1 end
        prepare_epoch()
        collectgarbage()
        if any_random then
            loadlevel(cfg.starting_world, cfg.starting_level)
            state_saved = false
        end
    end

    max_time = 6 * sqrt(10 * (epoch_i - 1)) + 60
    max_time = clamp(max_time, cfg.min_time, cfg.max_time)
    max_time = ceil(max_time)

    -- TODO: game.reset(cfg.starting_lives, cfg.start_big)

    if game.get_state() == 'loading' then game.advance() end -- kind of a hack.
    reward = 0
    powerup_old = game.R(0x754)
    status_old = game.R(0x756)
    coins_old = game.R(0x7ED) * 10 + game.R(0x7EE)
    score_old = game.get_score()

    -- set number of lives. (mario gets n+1 chances)
    game.W(0x75A, cfg.starting_lives)

    if cfg.start_big then
        -- make mario "super".
        game.W(0x754, 0)
        game.W(0x756, 1)
    end

    -- end of game.reset()

    if state_saved then
        savestate.load(startsave)
    else
        savestate.save(startsave)
    end
    state_saved = true

    jp = nil
    screen_scroll_delta = 0
    trial_frames = 0
    emu.frameadvance() -- prevents emulator from quirking up.

    load_next_trial()

    reset = false
end

local function init()
    network = make_network(gcfg.input_size)
    network:reset()
    network:print()
    print("parameters:", network.n_param)

    if cfg.init_zeros then
        local W = network:collect()
        for i, w in ipairs(W) do W[i] = 0 end
        network:distribute(W)
    end

    emu.poweron()
    emu.unpause()
    local playing = cfg.playable_mode or cfg.playback_mode
    if not playing then emu.speedmode("turbo") end

    if not any_random then
        loadlevel(cfg.starting_world, cfg.starting_level)
    end

    params_fn = cfg.params_fn or ('network%07i.txt'):format(network.n_param)
    std_fn = params_fn:gsub(".txt", "")..".sigma.txt"

    if exists(params_fn) then
        network:load(params_fn)
    end

    if cfg.es == 'xnes' then
        -- if you get an out of memory error, you can't use xNES. sorry!
        -- maybe there'll be a patch for FCEUX in the future.
        es = xnes.Xnes(network.n_param, cfg.epoch_trials,
                       cfg.base_rate, cfg.deviation, cfg.negate_trials)
    elseif cfg.es == 'snes' then
        es = snes.Snes(network.n_param, cfg.epoch_trials,
                       cfg.base_rate, cfg.deviation, cfg.negate_trials)
        -- TODO: clean this up into an interface:
        es.min_refresh = cfg.min_refresh

        if exists(std_fn) then
            local f = assert(open(std_fn, "r"))
            for i=1, network.n_param do
                es.std[i] = assert(tonumber(assert(f:read())))
            end
            f:close()
        end
    elseif cfg.es == 'ars' then
        es = ars.Ars(network.n_param, cfg.epoch_trials, cfg.epoch_top_trials,
                     cfg.base_rate, cfg.deviation, cfg.negate_trials,
                     cfg.momentum)
    else
        error("Unknown evolution strategy specified: " + tostring(cfg.es))
    end

    es.param_rate = cfg.param_rate
    es.sigma_rate = cfg.sigma_rate
    es.covar_rate = cfg.covar_rate
    es.rate_init = cfg.sigma_rate -- just for SNES?

    es:params(network:collect())
end

local function prepare_reset()
    if cfg.playback_mode then return end
    reset = true
end

local function draw_framecount(x, y, frames)
    local tf0 = frames % 1000
    local tf1 = (frames % 1000000 - tf0) / 1000
    local tf2 = (frames - tf0 - tf1) / 1000000
    gui.text(x, y, ("%03i,%03i,%03i"):format(tf2,tf1,tf0), '#FFFFFF', '#0000003F')
end

local function doit(dummy)
    local ingame_paused = game.get_state() == "paused"

    -- every few frames mario stands still, forcibly decrease the timer.
    -- this includes having the game paused.
    -- TODO: more robust. doesn't detect moonwalking against a wall.
    -- well, that shouldn't happen anymore now that i've disabled left+right.
    local timer = game.get_timer()
    if ingame_paused or random() > 1 - cfg.timer_loser and game.R(0x1D) == 0 and game.R(0x57) == 0 then
        timer = timer - 1
    end
    if not cfg.playback_mode then
        timer = clamp(timer, 0, max_time)
        if cfg.enable_network then
            game.set_timer(timer)
        end
    end

    draw_framecount(12, 215, decisions_made)

    screen_scroll_delta = screen_scroll_delta + game.R(0x775)

    if dummy == true then
        -- don't invoke AI this frame. (keep holding the old inputs)
        gui.text(89, 16, ("%+5i"):format(reward), '#FFFFFF', '#0000003F')
        return
    end

    empty(game.sprite_input)
    empty(game.tile_input)
    empty(game.extra_input)

    local controllable = game.R(0x757) == 0 and game.R(0x758) == 0
    local x, y = game.getxy(0, 0x86, 0xCE, 0x6D, 0xB5)
    local powerup = game.R(0x754)
    local status = game.R(0x756)
    game.mark_sprite(x + 8, y + 24, -powerup - 1)
    -- TODO: this will have to do until sprite type embed is added:
    insert(game.extra_input, (status - 1) * 256)

    local vx, vy = game.S(0x57), game.S(0x9F)
    insert(game.extra_input, vx * 16)
    insert(game.extra_input, vy * 16)

    if cfg.time_inputs then
        for i=2,5 do
            local v = band(trial_frames, lshift(1, i)) == 0 and -181 or 181
            insert(game.extra_input, v)
        end
    end

    game.handle_enemies()
    game.handle_fireballs()
    --game.handle_blocks() -- blocks being hit. not interactable; we don't care!
    game.handle_hammers()
    game.handle_misc()
    game.handle_tiles()

    local coins = game.R(0x7ED) * 10 + game.R(0x7EE)
    local coins_delta = coins - coins_old
    -- handle wrap-around.
    if coins_delta < 0 then coins_delta = 100 + coins - coins_old end
    -- remember that 0 is big mario and 1 is small mario.
    local powerup_delta = powerup_old - powerup
    -- 2 is fire mario.
    local status_delta = clamp(status - status_old, -1, 1)
    local flagpole_bonus = game.R(0xE) == 4 and cfg.frameskip or 0
    --local reward_delta = screen_scroll_delta + status_delta * 256 + flagpole_bonus
    local score_delta = game.get_score() - score_old
    if score_delta < 0 then score_delta = 0 end
    local reward_delta = screen_scroll_delta + cfg.score_multiplier * (score_delta + flagpole_bonus)
    screen_scroll_delta = 0

    if cfg.decrement_reward and reward_delta == 0 then reward_delta = reward_delta - 1 end

    if not ingame_paused and game.get_state() ~= 'win_walking' then
        -- note that we exclude points gained walking into the castle.
        -- this way, we avoid adding the timer-based fireworks to our reward,
        -- which are basically unwanted noise due to the way they trigger.
        if flagpole_bonus > 0 or controllable then
            reward = reward + reward_delta
        end
    end

    --gui.text(72, 12, ("%+4i"):format(reward_delta), '#FFFFFF', '#0000003F')
    gui.text(89, 16, ("%+5i"):format(reward), '#FFFFFF', '#0000003F')

    if game.get_state() == 'dead' and state_old ~= 'dead' then
        --print("dead. lives remaining:", game.R(0x75A, 0))
        if game.R(0x75A, 0) == 0 then prepare_reset() end
    end
    if game.get_state() == 'lose' then
        -- this shouldn't happen if we catch the deaths as above.
        print("ran out of lives.")
        prepare_reset()
    end

    -- lose a point for every frame paused.
    --if ingame_paused then reward = reward - 1 end
    if ingame_paused then reward = reward - 402; prepare_reset() end

    -- if we've run out of time while the game is paused...
    -- that's cheating! unpause.
    force_start = ingame_paused and timer == 0

    local X = {}
    for i, v in ipairs(game.sprite_input) do insert(X, v / 256) end
    for i, v in ipairs(game.extra_input) do insert(X, v / 256) end
    nn.reshape(X, 1, gcfg.input_size)
    nn.reshape(game.tile_input, 1, gcfg.tile_count)

    trial_frames = trial_frames + cfg.frameskip
    if cfg.enable_network and game.get_state() == 'playing' or ingame_paused then
        total_frames = total_frames + cfg.frameskip

        local outputs = network:forward({[nn_x]=X, [nn_tx]=game.tile_input})

        local eps = lerp(cfg.eps_start, cfg.eps_stop, total_frames / cfg.eps_frames)
        if cfg.det_epsilon and random() < eps then
            local i = floor(random() * #gcfg.jp_lut) + 1
            jp = copy(gcfg.jp_lut[i], jp)
        else
            local choose = cfg.deterministic and argmax or softchoice
            local ind = choose(unpack(outputs[nn_z]))
            jp = copy(gcfg.jp_lut[ind], jp)
        end

        if force_start then
            jp = {
                up      = false,
                down    = false,
                left    = false,
                right   = false,
                A       = false,
                B       = false,
                start   = force_start_old,
                select  = false,
            }
        else
            decisions_made = decisions_made + 1
        end
    end

    coins_old = coins
    powerup_old = powerup
    status_old = status
    force_start_old = force_start
    state_old = game.get_state()
    score_old = game.get_score()
end

init()

while true do
    gui.text(4, 12, game.get_state(), '#FFFFFF', '#0000003F')

    while gcfg.bad_states[game.get_state()] do
        -- mash the start button until we have control.
        joypad_mash('start')
        prepare_reset()

        game.advance()
        gui.text(4, 12, game.get_state(), '#FFFFFF', '#0000003F')

        while game.get_state() == "loading" do game.advance() end -- kind of a hack.
        state_old = game.get_state()
    end

    if reset then
        do_reset()
        lagless_count = 0
    end

    if not cfg.enable_network then
        -- infinite time cheat. super handy for testing.
        if game.R(0xE) == 8 then
            game.set_timer(667)
            poketime = true
        elseif poketime then
            poketime = false
            game.set_timer(1)
        end

        -- infinite lives.
        game.W(0x75A, 1)
    end

    local doot = jp == nil or lagless_count % cfg.frameskip == 0
    doit(not doot)

    -- jp might still be nil if we're not ingame or we're not playing.
    if jp ~= nil then joypad.write(1, jp) end

    game.advance() -- remember, this skips lag frames.
    lagless_count = lagless_count + 1
end