-- How a KarisFramework game and its Forge port are driven for comparison (FORGE.md section
-- 14.1):  the same policy, read off the same state in either.  A run presses START on the
-- attract loop, then answers each move a few frames into its window -- the right answer, or a
-- wrong one for every fifth move so deaths and continues are exercised -- and takes the one
-- continue offered.  Both scripts hand this file a view of their state (karisView) and a way
-- to press and release a switch (karisPress);  this file does the deciding.
--
-- The trace both print:  every disc seek, and every change of the framework's screen, step,
-- level, scene, move, score, and lives, in the framework's numbers.
KARIS_SEED = 20260914
AUTHOR_SEED = KARIS_SEED   -- The port's runtime seeds its generator from this, as the original's os.time does.

local lastLine  = nil
local pressed   = nil          -- The switch held down this frame, released the next.
local started   = false
local coined    = false
local continued = false
local answered  = {}           -- Windows already answered, by "level/scene/move/lives".
local tried     = {}           -- Moves met before, by "level/scene/move":  a retry after a death.

-- What the drive does with a move, so that every path of a loop is walked:  most moves are
-- answered right;  every fifth is answered wrong (a stray input, a wrong option, a mash
-- broken by a stray input);  every seventh is left unanswered (the window runs out).  A move
-- met again after a death is answered right.  PORT_WRONG_EVERY and PORT_MISS_EVERY set the
-- two counts, for a run that goes deeper into a game with few lives.
local WRONG_EVERY = tonumber(os.getenv("PORT_WRONG_EVERY")) or 5
-- PORT_ATTRACT=N lets the attract loop run N frames before the coin and START, so its own screens
-- (the rankings, the best percent) are played and traced too.
local ATTRACT     = tonumber(os.getenv("PORT_ATTRACT")) or 0
local MISS_EVERY  = tonumber(os.getenv("PORT_MISS_EVERY")) or 7
local function wrongMove(view)
	return (view.move % WRONG_EVERY == 0) and not view.retry
end
local function missedMove(view)
	return (view.move % MISS_EVERY == 0) and (view.move % WRONG_EVERY ~= 0) and not view.retry
end
local seeks     = 0
local plan      = nil          -- Kimmy:  the presses planned for the window being answered.
local held      = {}           -- Kimmy:  the switches the plan holds down, by switch.
local menuAt    = 0            -- Kimmy:  the frame a menu was last answered on.
KARIS_FRAMES    = tonumber(os.getenv("PORT_FRAMES")) or 60000
-- A map-mode game's pair kinds, by the name of the game's constant for each:  what is held with
-- what.  A game that does not define a constant (one with no diagonals) simply has no such pair.
KARIS_PAIR_KINDS = { { "ACTUP", 5, 1 }, { "ACTDOWN", 5, 2 }, { "ACTLEFT", 5, 3 }, { "ACTRIGHT", 5, 4 }, { "UPLEFT", 1, 3 }, { "UPRIGHT", 1, 4 }, { "DOWNLEFT", 2, 3 }, { "DOWNRIGHT", 2, 4 } }


-- The pair kinds a game defines, keyed by its own numbers;  constants maps a name to the number.
function karisPairs(constants)
	local found = {}

	for _, kind in ipairs(KARIS_PAIR_KINDS) do
		local number = constants[kind[1]]

		if number ~= nil then
			found[number] = { kind[2], kind[3] }
		end
	end

	return found
end

-- The framework's move numbers as switches;  Kimmy's diagonals are two of them.
local SWITCH_OF = { [1] = SWITCH_UP, [2] = SWITCH_DOWN, [3] = SWITCH_LEFT, [4] = SWITCH_RIGHT, [5] = SWITCH_BUTTON1, [6] = SWITCH_BUTTON2, [7] = SWITCH_BUTTON3 }
local PAIR_OF   = { [9] = { 1, 3 }, [10] = { 1, 4 }, [11] = { 2, 3 }, [12] = { 2, 4 } }
local KIMMY     = { COMBO = 20, MULTI = 21, LOOP = 22, MASH = 23, HOLD = 24, LETGO = 25, PATH = 51, YESNO = 52, TIMED = 53, ANYTHING = 54, NOTHING = 55, UD = 151, LR = 153, B1B2 = 155 }

-- The KarisFramework's compound kinds, and the MazescaterFramework's (LINEA), as what they
-- take, by the framework's numbers:  a sequence's inputs in turn (a circle is five, back to
-- its start), a mash's input (or the two it alternates), a hold's input, and the inputs a
-- combination wants together.
local SEQ_OF    = { [35] = { 3, 2, 4, 1, 3 }, [36] = { 4, 2, 3, 1, 4 },
                    [156] = { 1, 3 }, [157] = { 1, 4 }, [158] = { 2, 3 }, [159] = { 2, 4 }, [160] = { 3, 1 }, [161] = { 4, 1 }, [162] = { 3, 2 }, [163] = { 4, 2 },
                    [170] = { 4, 3 }, [171] = { 3, 4 }, [172] = { 1, 2 }, [173] = { 2, 1 },
                    [149] = { 2, 3, 5 }, [150] = { 2, 4, 5 }, [151] = { 1, 3, 5 }, [152] = { 1, 4, 5 }, [164] = { 3, 1, 5 }, [165] = { 4, 1, 5 }, [166] = { 4, 2, 5 }, [167] = { 3, 2, 5 },
                    [168] = { 2, 3, 6 }, [169] = { 2, 4, 6 }, [174] = { 1, 3, 6 }, [175] = { 1, 4, 6 }, [176] = { 3, 1, 6 }, [177] = { 4, 1, 6 }, [178] = { 4, 2, 6 }, [179] = { 3, 2, 6 },
                    [180] = { 2, 3, 1 }, [181] = { 2, 4, 1 }, [182] = { 3, 2, 4 }, [183] = { 3, 1, 4 }, [184] = { 4, 2, 3 }, [185] = { 4, 1, 3 }, [186] = { 1, 3, 2 }, [187] = { 1, 4, 2 },
                    [216] = { 3, 2, 4, 1, 3 }, [219] = { 2, 4, 1, 3, 2 }, [218] = { 4, 1, 3, 2, 4 }, [217] = { 1, 3, 2, 4, 1 },
                    [212] = { 3, 1, 4, 2, 3 }, [213] = { 1, 4, 2, 3, 1 }, [214] = { 4, 2, 3, 1, 4 }, [215] = { 2, 3, 1, 4, 2 } }
local MASH_OF   = { [17] = { 5 }, [18] = { 5 }, [19] = { 5 }, [27] = { 3, 4 }, [28] = { 3, 4 }, [29] = { 3, 4 }, [30] = { 5, 6 }, [31] = { 5, 6 }, [32] = { 5, 6 },
                    [153] = { 5, 7 }, [154] = { 5, 7 }, [155] = { 5, 7 }, [188] = { 6 }, [189] = { 6 }, [190] = { 6 }, [192] = { 7 }, [193] = { 7 }, [194] = { 7 },
                    [196] = { 3 }, [197] = { 3 }, [198] = { 3 }, [200] = { 4 }, [201] = { 4 }, [202] = { 4 }, [204] = { 1 }, [205] = { 1 }, [206] = { 1 }, [208] = { 2 }, [209] = { 2 }, [210] = { 2 } }
local HOLD_OF   = { [21] = 1, [22] = 2, [23] = 3, [24] = 4, [25] = 5 }
local TOGETHER  = { [9] = { 1, 3 }, [10] = { 1, 4 }, [11] = { 2, 3 }, [12] = { 2, 4 }, [13] = { 5, 1 }, [14] = { 5, 2 }, [15] = { 5, 3 }, [16] = { 5, 4 },
                    [220] = { 6, 1 }, [221] = { 6, 2 }, [222] = { 6, 3 }, [223] = { 6, 4 }, [224] = { 7, 1 }, [225] = { 7, 2 }, [226] = { 7, 3 }, [227] = { 7, 4 },
                    [228] = { 5, 1, 3 }, [229] = { 5, 1, 4 }, [230] = { 5, 2, 3 }, [231] = { 5, 2, 4 }, [232] = { 6, 1, 3 }, [233] = { 6, 1, 4 }, [234] = { 6, 2, 3 }, [235] = { 6, 2, 4 },
                    [236] = { 7, 1, 3 }, [237] = { 7, 1, 4 }, [238] = { 7, 2, 3 }, [239] = { 7, 2, 4 } }
local KARIS_LETGO, KARIS_MULTI = 20, 33


-- The switches an input number stands for.
local function switchesOf(kind)
	if PAIR_OF[kind] then
		return { SWITCH_OF[PAIR_OF[kind][1]], SWITCH_OF[PAIR_OF[kind][2]] }
	end

	return { SWITCH_OF[kind] }
end


-- A plan's steps:  what to press and let go on which frame.
local function planPress(steps, frame, switches)
	steps[frame] = steps[frame] or { press = {}, release = {} }
	for _, s in ipairs(switches) do
		table.insert(steps[frame].press, s)
	end
end
local function planRelease(steps, frame, switches)
	steps[frame] = steps[frame] or { press = {}, release = {} }
	for _, s in ipairs(switches) do
		table.insert(steps[frame].release, s)
	end
end
local function planTap(steps, frame, switches)
	planPress(steps, frame, switches)
	planRelease(steps, frame + 1, switches)
end


-- A switch a move does not accept, for a wrong answer.
local function wrongFor(accepted)
	for _, candidate in ipairs({ 2, 1, 3, 4, 6 }) do
		local ok = true

		for _, a in ipairs(accepted) do
			if a == candidate then
				ok = false
			end
			if PAIR_OF[a] and ((PAIR_OF[a][1] == candidate) or (PAIR_OF[a][2] == candidate)) then
				ok = false
			end
		end
		if ok then
			return { SWITCH_OF[candidate] }
		end
	end

	return { SWITCH_BUTTON2 }
end


-- A plan:  what to press and let go on which frames, for one window.
local function planFor(view)
	local w      = view.window
	local at     = w.from + 3
	local steps  = {}
	local wrong  = wrongMove(view)
	local kind   = w.kind

	if missedMove(view) then
		-- Left unanswered:  the window runs out.
	elseif ((kind >= 1) and (kind <= 7)) or ((kind >= 9) and (kind <= 12)) then
		if wrong then
			planTap(steps, at, wrongFor({ kind, w.alt }))
		else
			planTap(steps, at, switchesOf(kind))
		end
	elseif (kind == KIMMY.MASH) and wrong then
		-- A mash broken by a stray input.
		planTap(steps, at, wrongFor({ w.alt or 5 }))
	elseif kind == KIMMY.COMBO then
		local both = switchesOf(w.alt)

		for _, s in ipairs(switchesOf(w.alt2)) do
			both[#both + 1] = s
		end
		planTap(steps, at, both)
	elseif kind == KIMMY.HOLD then
		planPress(steps, at, switchesOf(w.alt))
		planRelease(steps, w.to, switchesOf(w.alt))
	elseif kind == KIMMY.LETGO then
		planPress(steps, w.from - 4, { SWITCH_BUTTON1 })
		planRelease(steps, w.from + 2, { SWITCH_BUTTON1 })
	elseif kind == KIMMY.MASH then
		local turn = 0

		for frame = at, w.to - 2, 2 do
			local which

			if w.alt == KIMMY.UD then
				which = (turn % 2 == 0) and { SWITCH_UP } or { SWITCH_DOWN }
			elseif w.alt == KIMMY.LR then
				which = (turn % 2 == 0) and { SWITCH_LEFT } or { SWITCH_RIGHT }
			elseif w.alt == KIMMY.B1B2 then
				which = (turn % 2 == 0) and { SWITCH_BUTTON1 } or { SWITCH_BUTTON2 }
			else
				which = switchesOf(w.alt or 5)
			end
			planTap(steps, frame, which)
			turn = turn + 1
		end
	elseif (kind == KIMMY.MULTI) or (kind == KIMMY.LOOP) then
		local start = at + ((kind == KIMMY.MULTI) and (w.alt2 or 0) or 0)

		for i, step in ipairs(view.multi or {}) do
			planTap(steps, start + 2 * (i - 1), switchesOf(step))
		end
	elseif kind == KIMMY.PATH then
		local p = view.path or {}

		if wrong then
			planTap(steps, at, wrongFor({ p[1], p[3], p[5], p[7] }))
		elseif p[1] and (p[1] > 0) then
			planTap(steps, at, switchesOf(p[1]))
		end
	elseif kind == KIMMY.YESNO then
		if view.move % 2 == 0 then
			planTap(steps, at, { SWITCH_BUTTON1 })
		end
	elseif kind == KIMMY.TIMED then
		local first = (view.timed or {})[w.alt or view.move]

		if first and (first[2] + 1 >= w.from) and (first[2] + 1 <= w.to) then
			planTap(steps, first[2] + 1, switchesOf(first[1]))
		end
	elseif kind == KIMMY.ANYTHING then
		planTap(steps, at, { SWITCH_BUTTON1 })
	elseif kind == KIMMY.NOTHING then
		if wrong then
			planTap(steps, at, { SWITCH_BUTTON1 })
		end
	end

	return { steps = steps, from = w.from - 6, to = w.to + 2 }
end


-- A map-mode plan:  the ancestor's kinds.  A single input tapped;  MASH (8) tapped every other
-- frame;  an ACT combo (9 to 12) as the button with a direction;  a diagonal (13 to 16) as two
-- directions;  SKIP (17) left alone.  Every fifth move is answered wrong.
local RDG_ACT  = { [9] = { 5, 1 }, [10] = { 5, 2 }, [11] = { 5, 3 }, [12] = { 5, 4 }, [13] = { 1, 3 }, [14] = { 1, 4 }, [15] = { 2, 3 }, [16] = { 2, 4 } }

local function planForRdg(view)
	local w     = view.window
	local at    = w.from + 3
	local steps = {}
	local wrong = wrongMove(view)
	local kind  = w.kind


	if missedMove(view) then
		-- Left unanswered:  the window runs out.
	elseif (kind >= 1) and (kind <= 7) then
		if wrong then
			planTap(steps, at, { (kind == 1) and SWITCH_DOWN or SWITCH_UP })
		else
			planTap(steps, at, { SWITCH_OF[kind] })
		end
	elseif (kind == (view.mashKind or 8)) and wrong then
		-- A mash broken by a stray direction.
		planTap(steps, at, { SWITCH_UP })
	elseif kind == (view.mashKind or 8) then
		for frame = at, w.to - 2, 2 do
			planTap(steps, frame, { SWITCH_BUTTON1 })
		end
	elseif (view.pairs or RDG_ACT)[kind] and view.zone then
		-- A shot:  the pointer into the zone (or well outside it) the frame before the button,
		-- in the raw coordinates the game scales by its ratios.
		local z  = view.zone
		local r  = view.mouse or { 1, 1, 0, 0 }
		local mx = wrong and (z[3] + 200) or ((z[1] + z[3]) / 2)
		local my = wrong and (z[4] + 200) or ((z[2] + z[4]) / 2)

		steps[at - 1] = steps[at - 1] or { press = {}, release = {} }
		steps[at - 1].mouse = { math.floor((mx + r[3]) / r[1]), math.floor((my + r[4]) / r[2]) }
		planTap(steps, at, { SWITCH_BUTTON1 })
	elseif (view.pairs or RDG_ACT)[kind] then
		local pair = (view.pairs or RDG_ACT)[kind]

		if wrong then
			planTap(steps, at, { SWITCH_BUTTON2 })
		else
			planTap(steps, at, { SWITCH_OF[pair[1]], SWITCH_OF[pair[2]] })
		end
	end

	return { steps = steps, from = w.from - 6, to = w.to + 2 }
end


-- A KarisFramework plan for a compound move:  a hold pressed from three frames into the
-- window to its end;  a let-go held from before the window and released within it;  a mash
-- tapped every other frame (a run, MASH2, and MASH3 alternating their two);  a sequence or a
-- circle a step every other frame;  a multi tapped as many times as its row asks;  a
-- combination pressed together.  Every fifth move is answered wrong (a stray input, or
-- nothing for a let-go);  every seventh is left unanswered.
local function planForKaris(view)
	local w     = view.window
	local at    = w.from + 3
	local steps = {}
	local wrong = wrongMove(view)
	local kind  = w.kind

	local function switches(list)
		local result = {}

		for _, m in ipairs(list) do
			result[#result + 1] = SWITCH_OF[m]
		end

		return result
	end

	if missedMove(view) then
		-- Left unanswered:  the window runs out.
	elseif HOLD_OF[kind] then
		if wrong then
			planTap(steps, at, wrongFor({ HOLD_OF[kind] }))
		else
			planPress(steps, at, { SWITCH_OF[HOLD_OF[kind]] })
			planRelease(steps, w.to, { SWITCH_OF[HOLD_OF[kind]] })
		end
	elseif kind == KARIS_LETGO then
		if not wrong then
			planPress(steps, w.from - 4, { SWITCH_BUTTON1 })
			planRelease(steps, w.from + 2, { SWITCH_BUTTON1 })
		end
	elseif MASH_OF[kind] then
		if wrong then
			planTap(steps, at, wrongFor(MASH_OF[kind]))
		else
			local turn = 0

			for frame = at, w.to - 2, 2 do
				planTap(steps, frame, { SWITCH_OF[MASH_OF[kind][(turn % #MASH_OF[kind]) + 1]] })
				turn = turn + 1
			end
		end
	elseif SEQ_OF[kind] then
		if wrong then
			planTap(steps, at, wrongFor(SEQ_OF[kind]))
		else
			for i, m in ipairs(SEQ_OF[kind]) do
				planTap(steps, at + 2 * (i - 1), { SWITCH_OF[m] })
			end
		end
	elseif kind == KARIS_MULTI then
		if wrong then
			planTap(steps, at, wrongFor({ w.alt }))
		else
			for i = 1, (w.alt2 or 1) do
				planTap(steps, at + 2 * (i - 1), { SWITCH_OF[w.alt] })
			end
		end
	elseif TOGETHER[kind] then
		if wrong then
			planTap(steps, at, wrongFor(TOGETHER[kind]))
		else
			planTap(steps, at, switches(TOGETHER[kind]))
		end
	end

	return { steps = steps, from = w.from - 6, to = w.to + 2 }
end


-- A choice:  step down to the right option (a wrong one every fifth move), then take it.
function answerChoice(view, key, w)
	if (view.frame >= w.from + 3) and (view.frame <= w.to) then
		local want = nil
		local wrong = wrongMove(view)

		for at, index in ipairs(view.order or {}) do
			if view.choices[index] and (view.choices[index].right ~= wrong) and (want == nil or not wrong) then
				want = at
			end
		end
		if want and (view.choice < want) then
			pressed = SWITCH_DOWN
			karisPress(pressed, true)
		elseif want and (view.choice == want) and not answered[key] then
			answered[key] = true
			pressed = SWITCH_BUTTON1
			karisPress(pressed, true)
		end
	end
end


-- Runs the plan for this frame.
local function followPlan(frame)
	local step = plan and plan.steps[frame]

	if step then
		if step.mouse then
			karisMouse(step.mouse[1], step.mouse[2])
		end
		for _, s in ipairs(step.press) do
			if not held[s] then
				held[s] = true
				karisPress(s, true)
			end
		end
		for _, s in ipairs(step.release) do
			if held[s] then
				held[s] = nil
				karisPress(s, false)
			end
		end
	end
	if plan and (frame > plan.to) then
		for s in pairs(held) do
			karisPress(s, false)
		end
		held = {}
		plan = nil
	end
end


-- PORT_SERVICE=1 walks the service screens from the attract loop before the game:  SERVICE, then
-- the options' first row on to the graphics screen, its rows each changed once (RIGHT) and
-- "Default", round to its first row and on to the performance screen, the same there, on to the
-- options, the same, and EXIT;  a press every WALK_EVERY frames, clear of the screens' quarter
-- second between moves.  While a screen shows, the trace carries its row and the dips.
local walkService = (os.getenv("PORT_SERVICE") == "1")
local WALK_EVERY  = 10
local WALK        = { SWITCH_SERVICE }
local walkAt      = nil
local walkEvents  = {}


-- A screen's rows walked from its first:  each one's value changed, the second from last
-- ("Default") used, and, unless it is the last screen, round to the first row and on.
local function walkScreen(rows, leave)
	WALK[#WALK + 1] = SWITCH_DOWN
	for _ = 2, rows - 2 do
		WALK[#WALK + 1] = SWITCH_RIGHT
		WALK[#WALK + 1] = SWITCH_DOWN
	end
	WALK[#WALK + 1] = SWITCH_RIGHT   -- Default
	WALK[#WALK + 1] = SWITCH_DOWN
	if leave then
		WALK[#WALK + 1] = SWITCH_RIGHT   -- EXIT
	else
		WALK[#WALK + 1] = SWITCH_DOWN    -- Round to the first row ...
		WALK[#WALK + 1] = SWITCH_RIGHT   -- ... and on to the next screen.
	end
end


WALK[#WALK + 1] = SWITCH_RIGHT   -- The options' first row, on to the graphics screen.
walkScreen(15, false)            -- The graphics screen, on to the performance screen.
walkScreen(10, false)            -- The performance screen, on to the options.
walkScreen(15, true)             -- The options, and EXIT.
local SERVICE_DIPS = { "dip_GameType", "dip_Diffshow", "dip_PlayStyle", "dip_StartLevel", "dip_StartScene", "dip_Rewind", "dip_CoinsPerCredit", "dip_LivesPerCredit", "dip_LimitContinue", "dip_ShowAction", "dip_Hints", "dip_MashtoRun",
                        "dip_Extravid", "ShowTitle", "ShowLCD", "ShowLevel", "ShowTop", "ScorePos", "LivPos", "CoinPos", "fontType", "fontSize", "mycolor1", "mycolor2",
                        "dip_Model", "dip_Res", "dip_Display", "dip_Scanlines", "dip_ScType", "dip_LivType", "dip_FontQ" }


-- The options screen's row and dips, or the save or exit screen's row and choices, from a reader of
-- the loop's variables, while it shows.
function karisServiceState(screen, read)
	local parts = {}

	if (screen == 108) or (screen == 112) then
		return "row " .. tostring(read("optSel")) .. " Loadsave " .. tostring(read("dip_Loadsave")) .. " Slot " .. tostring(read("dip_Slot")) .. " InPlayExit " .. tostring(read("bInPlayExit"))
	end
	if (screen ~= 104) and (screen ~= 113) and (screen ~= 114) then
		return nil
	end
	parts[1] = "rows " .. tostring(read("optSel")) .. " " .. tostring(read("optSelG")) .. " " .. tostring(read("optSelP"))
	for _, name in ipairs(SERVICE_DIPS) do
		parts[#parts + 1] = name:sub(5) .. " " .. tostring(read(name))
	end

	return table.concat(parts, " ")
end


-- Switches tapped, as a walk's events:  each a press, then its release.
local function tapsOf(switches)
	local events = {}

	for _, switch in ipairs(switches) do
		events[#events + 1] = { switch, true }
		events[#events + 1] = { switch, false }
	end

	return events
end


-- PORT_TITLETAPS=1 taps the switches that do something beyond a move while the title plays,
-- before any service walk:  the original pauses through the title, so none should count;  the
-- trace carries the credits.
local titleTaps = (os.getenv("PORT_TITLETAPS") == "1")

if titleTaps then
	walkEvents = tapsOf({ SWITCH_COIN1, SWITCH_START1, SWITCH_SERVICE, SWITCH_TEST, SWITCH_CONSOLE, SWITCH_SKILL1 })
end
if walkService then
	table.move(tapsOf(WALK), 1, #WALK * 2, #walkEvents + 1, walkEvents)
end


-- PORT_PLAYWALK=1 walks the in-play switches, each part once the game has answered so many moves
-- and out of a move's window:  a quick save to slot 1 (SKILL1);  TEST to the save screen, saving
-- to slot 2 and back to the game;  CONSOLE to the exit screen and BACK;  START held with SKILL1,
-- loading slot 1;  COIN held with START, to the exit screen and BACK.
local PLAY_WALK = (os.getenv("PORT_PLAYWALK") == "1") and {
	{ after = 2,  events = tapsOf({ SWITCH_SKILL1 }) },
	{ after = 3,  events = tapsOf({ SWITCH_TEST, SWITCH_RIGHT, SWITCH_DOWN, SWITCH_RIGHT, SWITCH_DOWN, SWITCH_RIGHT }) },
	{ after = 5,  events = tapsOf({ SWITCH_CONSOLE, SWITCH_DOWN, SWITCH_BUTTON1 }) },
	{ after = 6,  events = { { SWITCH_START1, true }, { SWITCH_SKILL1, true }, { SWITCH_SKILL1, false }, { SWITCH_START1, false } } },
	{ after = 8,  events = { { SWITCH_COIN1, true }, { SWITCH_START1, true }, { SWITCH_START1, false }, { SWITCH_COIN1, false }, { SWITCH_DOWN, true }, { SWITCH_DOWN, false }, { SWITCH_BUTTON1, true }, { SWITCH_BUTTON1, false } } }
} or {}
local playPart = 1

-- The second of PORT_TWICE's runs first loads slot 2 (START held with SKILL2), which the first
-- run saved from the save screen:  the slots' part of the Persistence row.
if (#PLAY_WALK > 0) and (os.getenv("PORT_PASS") == "2") then
	table.insert(PLAY_WALK, 1, { after = 1, events = { { SWITCH_START1, true }, { SWITCH_SKILL2, true }, { SWITCH_SKILL2, false }, { SWITCH_START1, false } } })
end


-- The next part of the play walk, when the game has answered enough moves and no window is near.
local function karisPlayWalk(view, moves)
	local part = PLAY_WALK[playPart]

	if (#walkEvents > 0) or (part == nil) or (view.screen ~= 103) or (moves < part.after) then
		return
	end
	if view.window and (view.frame >= view.window.from - 30) and (view.frame <= view.window.to + 5) then
		return
	end
	playPart   = playPart + 1
	walkEvents = { table.unpack(part.events) }
	walkAt     = nil
end


-- One event of the walk each WALK_EVERY frames.  True while walking.
local function walk(view)
	if #walkEvents == 0 then
		return false
	end
	walkAt = walkAt or view.frames
	if view.frames - walkAt < WALK_EVERY then
		return true
	end
	walkAt = view.frames
	local event = table.remove(walkEvents, 1)

	karisPress(event[1], event[2])

	return true
end


-- PORT_HUD=1 adds what the HUD shows to each trace line, a letter a flag the loop sets, so an
-- original and its port are compared on what a player sees as well as on the game's state.
local HUD_FLAGS = {
	{ "S", "bShowScore" }, { "L", "bShowLives" }, { "V", "bShowLvl" }, { "T", "bShowTop" },
	{ "C", "bShowCredits" }, { "A", "bShowAction" }, { "K", "bShowSkip" }, { "G", "bShowGet" },
	{ "H", "bShowChoices" }, { "D", "bShowLCD" }, { "P", "bPause" }, { "1", "bShowDisk1" },
	{ "2", "bShowDisk2" }, { "3", "bShowDisk3" }, { "4", "bShowDiskA" }
}
local traceHud  = (os.getenv("PORT_HUD") == "1")


-- The HUD flags as letters, from a reader of the loop's variables (the original's globals, or
-- the port's q).
function karisHudFlags(read)
	local letters = {}

	if not traceHud then
		return nil
	end
	for _, flag in ipairs(HUD_FLAGS) do
		if read(flag[2]) then
			letters[#letters + 1] = flag[1]
		end
	end

	return table.concat(letters)
end


-- PORT_SOUND=1 traces each sound played or stopped, by its file's name, and the disc's audio
-- turned off or on, with the disc frame:  the Sound row of FORGE.md 14.18.  The engine's own calls
-- are wrapped before the game loads, so the original's sounds and the port's (which Forge plays
-- through the same calls) are caught the same way.
if os.getenv("PORT_SOUND") == "1" then
	local names         = {}
	local realSoundLoad = soundLoad
	local realSoundPlay = soundPlay

	soundLoad = function(file, ...)
		local handle = realSoundLoad(file, ...)

		if handle ~= nil then
			names[handle] = tostring(file):match("([^/\\]+)$")
		end

		return handle
	end
	soundPlay = function(handle, ...)
		debugPrint(string.format("TRACE sound %s disc %d", tostring(names[handle]), discGetFrame()))

		return realSoundPlay(handle, ...)
	end
	-- A sound stopped, and the disc's own audio turned off or on, change what is heard too.
	local realSoundStop = soundStop
	local realDiscAudio = discAudio

	soundStop = function(handle, ...)
		debugPrint(string.format("TRACE soundStop %s disc %d", tostring(names[handle]), discGetFrame()))

		return realSoundStop(handle, ...)
	end
	discAudio = function(channel, enabled, ...)
		debugPrint(string.format("TRACE discAudio %s %s disc %d", tostring(channel), tostring(enabled), discGetFrame()))

		return realDiscAudio(channel, enabled, ...)
	end
end


-- PORT_SHOTS=N takes up to N screenshots, numbered in order:  one at each change the trace
-- prints, and one a frame into each move's window (the drive answers within a few).  The traces
-- of an original and its port agree, so the same number is the same moment in both, and the
-- pictures can be diffed.
local SHOT_INTO_WINDOW = 1
-- A second run of PORT_TWICE names its pictures apart from the first's.
local SHOT_PREFIX      = ((os.getenv("PORT_PASS") or "1") == "1") and "shot-" or ("shot-run" .. os.getenv("PORT_PASS") .. "-")
local shotsLeft        = tonumber(os.getenv("PORT_SHOTS") or "0") or 0
local shotCount        = 0


function karisShot(why)
	if shotsLeft > 0 then
		shotsLeft = shotsLeft - 1
		shotCount = shotCount + 1
		singeScreenshot(string.format("%s%04d-%s", SHOT_PREFIX, shotCount, why))
	end
end


function karisTraceSeek(frame)
	seeks = seeks + 1
	debugPrint(string.format("TRACE seek %d", frame))
end


-- Presses what the policy says this frame.  view:  { screen, step, level, scene, move, frame,
-- window = { from, to, kind, death, alt }, choices = { { right }, ... }, order, choice }.
function karisDrive(view)
	if pressed then
		karisPress(pressed, false)
		pressed = nil
	end
	local line = string.format("TRACE screen %s step %s level %s scene %s move %s score %s lives %s", tostring(view.screen), tostring(view.step), tostring(view.level), tostring(view.scene), tostring(view.move), tostring(view.score), tostring(view.lives))

	if view.hud then
		line = line .. " hud " .. view.hud
	end
	if view.service then
		line = line .. " " .. view.service
	end
	if titleTaps then
		line = line .. " credits " .. tostring(view.credits)
	end

	if line ~= lastLine then
		lastLine = line
		debugPrint(line .. " disc " .. tostring(view.frame))
		karisShot("state")
	end
	-- A few frames into a move's window, where its prompt shows.
	if view.window and (view.frame == view.window.from + SHOT_INTO_WINDOW) then
		karisShot("window")
	end
	-- The options screen's walk, on the attract loop before anything else, and the play walk's
	-- parts.
	local moves = 0

	for _ in pairs(answered) do
		moves = moves + 1
	end
	karisPlayWalk(view, moves)
	if ((playPart > 1) or (view.screen == 0) or (view.screen == 104) or (view.screen == 113) or (view.screen == 114)) and walk(view) then
		return
	end
	-- A coin on the attract loop when the game is not free play, then START once it has begun
	-- playing.
	if (view.screen == 0) and not started and (view.frame >= 150) and (view.frames >= ATTRACT) and (not view.freeplay) and (view.credits == 0) and not coined then
		coined  = true
		pressed = SWITCH_COIN1
		karisPress(pressed, true)
		return
	end
	if (view.screen == 0) and not started and (view.frame >= 160) and (view.frames >= ATTRACT) and (view.freeplay or (view.credits > 0)) then
		started = true
		pressed = SWITCH_START1
		karisPress(pressed, true)
		return
	end
	-- Kimmy's menus:  the new-game menu (a level the framework never numbered, so nil) takes
	-- the button for NEW GAME;  the level select takes the button for the level shown.
	if view.kimmy and started and ((view.screen == nil) or (view.screen == 117)) and (view.frame ~= menuAt) and (view.frames > menuAt + 30) then
		menuAt  = view.frames
		pressed = SWITCH_BUTTON1
		karisPress(pressed, true)
		return
	end
	-- The continue screen:  taken once.
	if (view.screen == 100) and (view.step == 1) and not continued then
		continued = true
		pressed   = SWITCH_START1
		karisPress(pressed, true)
		return
	end
	if (view.screen ~= 103) or (view.window == nil) then
		if plan then
			followPlan(view.frame)
		end
		return
	end
	-- A move is answered once per life:  a game that rewinds to the move after a death
	-- (the later map-mode copies) asks it again, and the drive answers it right that time.
	local moveKey = tostring(view.level) .. "/" .. tostring(view.scene) .. "/" .. tostring(view.move)
	local key     = moveKey .. "/" .. tostring(view.lives)
	local w       = view.window

	view.retry = (tried[moveKey] ~= nil)

	if view.kimmy or view.rdg then
		-- A Kimmy or map-mode move:  a plan of presses for the window, made when it comes into
		-- view.
		if (view.step == 1) and (plan == nil) and not answered[key] and (view.frame >= w.from - 6) and (view.frame <= w.to) then
			answered[key]  = true
			tried[moveKey] = true
			plan = view.rdg and planForRdg(view) or planFor(view)
		elseif view.rdg and (view.step == ((view.timegal and 12) or 11)) and view.choices then
			answerChoice(view, key, w)
		end
		followPlan(view.frame)
	elseif view.step == 1 then
		local kind = w.kind

		if (kind >= 1) and (kind <= 7) then
			-- Waiting for a single input:  answer three frames into the window.
			if (view.frame >= w.from + 3) and (view.frame <= w.to) and not answered[key] then
				answered[key]  = true
				tried[moveKey] = true
				if not missedMove(view) then
					local wrong = wrongMove(view)
					local press = wrong and ((kind == 1) and SWITCH_DOWN or SWITCH_UP) or SWITCH_OF[kind]

					pressed = press
					karisPress(press, true)
				end
			end
		elseif (plan == nil) and not answered[key] and (view.frame >= w.from - 6) and (view.frame <= w.to) and (HOLD_OF[kind] or MASH_OF[kind] or SEQ_OF[kind] or TOGETHER[kind] or (kind == KARIS_LETGO) or (kind == KARIS_MULTI)) then
			-- A compound move:  a plan of presses over the window, made as it comes into view.
			answered[key]  = true
			tried[moveKey] = true
			plan = planForKaris(view)
		end
		followPlan(view.frame)
	elseif (view.step == 19) and view.choices then
		answerChoice(view, key, w)
	elseif plan then
		-- The move is judged:  what the plan still holds is let go, and the rest of it dropped.
		for s in pairs(held) do
			karisPress(s, false)
		end
		held, plan = {}, nil
	end
end


-- The run is long enough when the game has been played through a continue and out.
function karisDone(view)
	return continued and (view.screen == 0) and (seeks > 0)
end