-- probe_win.lua -- final, breakpoint-free observation of the injected window.
--
-- No bpset/wpset at all: this script only reads RAM markers and takes PNG
-- snapshots on a trigger file ("<prefix> <count> <stride>").  The payload does
-- the work; the script just looks.
local machine = manager.machine
local dir = os.getenv("MSG_DIR") or "."
local trigger = os.getenv("MSG_TRIGGER") or (dir .. "/trigger")
local screen = nil
for _, s in pairs(machine.screens) do screen = s; break end
local cpu = machine.devices[':maincpu']
local space = cpu.spaces['program']
local f = 0
local job = nil

local function u32(a)
	local ok, v = pcall(function() return space:read_u32(a) end)
	if ok then return v end
	return 0xdeadbeef
end

local function consume_trigger()
	local fh = io.open(trigger, "r")
	if not fh then return end
	local text = fh:read("*a") or ""
	fh:close(); os.remove(trigger)
	local prefix, count, stride = text:match("(%S+)%s+(%d+)%s+(%d+)")
	if not prefix then return end
	job = { prefix = prefix, left = tonumber(count), stride = tonumber(stride), next = f }
	print(string.format("probe_win: frame %d job %s x%d every %d",
		f, prefix, job.left, job.stride))
end

emu.register_frame_done(function()
	f = f + 1
	consume_trigger()
	if job and screen and f >= job.next then
		local out = string.format("%s/%s_frame%05d.png", dir, job.prefix, f)
		local ok = pcall(function() return screen:snapshot(out) end)
		print(string.format("probe_win: frame %d %s ok=%s", f, out, tostring(ok)))
		job.left = job.left - 1
		job.next = f + job.stride
		if job.left <= 0 then job = nil end
	end
	if f % 100 == 0 then
		print(string.format("probe_win: f=%d stage=%d strlen=%d win_low=%04X",
			f, u32(0x01890140), u32(0x01890160), u32(0x01890120)))
	end
end, "vt1200-gui-probe-win")