-- license:BSD-3-Clause
-- copyright-holders:Carl
-- This includes a library of functions to be used at the Lua console as cf.getspaces() etc...
local exports = {}
exports.name = "cheatfind"
exports.version = "0.0.1"
exports.description = "Cheat finder helper library"
exports.license = "The BSD 3-Clause License"
exports.author = { name = "Carl" }

local cheatfind = exports

function cheatfind.startplugin()
	local cheat = {}
	local watches = {}

	-- return table of devices and spaces
	function cheat.getspaces()
		local spaces = {}
		for tag, device in pairs(manager:machine().devices) do
			if device.spaces then
				spaces[tag] = {}
				for name, space in pairs(device.spaces) do
					spaces[tag][name] = space
				end
			end
		end
		return spaces
	end

	-- return table of ram devices
	function cheat.getram()
		local ram = {}
		for tag, device in pairs(manager:machine().devices) do
			if device:shortname() == "ram" then
				ram[tag] = {}
				ram[tag].dev = device
				ram[tag].size = emu.item(device.items["0/m_size"]):read(0)
			end
		end
		return ram
	end

	-- save data block
	function cheat.save(space, start, size)
		local data = { block = "", start = start, size = size, space = space }
		if space.shortname then
			if space:shortname() == "ram" then
				data.block = emu.item(space.items["0/m_pointer"]):read_block(start, size)
				if not data.block then
					return nil
				end
			end
		else
			local block = ""
			for i = start, start + size do
				block = block .. string.pack("B", space:read_u8(i))
			end
			data.block = block
		end
		return data
	end

	-- compare two data blocks, format is as lua string.unpack, bne and beq val is table of masks
	function cheat.comp(olddata, newdata, oper, format, val, bcd)
		local ret = {}
		local ref = {} -- this is a helper for comparing two match lists
		local bitmask = nil

		local function bne(a, b, val, addr)
			if val == 0 then
				bitmask = a ~ b
				return bitmask ~= 0
			elseif not val[addr] then
				return false
			else
				bitmask = (a ~ b) & val[addr]
				return bitmask ~= 0
			end
		end

		local function beq(a, b, val, addr)
			if val == 0 then
				bitmask = ~a ~ b
				return bitmask ~= 0
			elseif not val[addr] then
				return false
			else
				bitmask = (~a ~ b) & val[addr]
				return bitmask ~= 0
			end
		end

		local cfoper = { 
			lt = function(a, b, val) return (a < b and val == 0) or (val > 0 and (a + val) == b) end,
			gt = function(a, b, val) return (a > b and val == 0) or (val > 0 and (a - val) == b) end,
			eq = function(a, b, val) return a == b end,
			ne = function(a, b, val) return (a ~= b and val == 0) or
				(val > 0 and ((a - val) == b or (a + val) == b)) end,
			bne = bne, beq = beq }

		local function check_bcd(val)
			local a = val + 0x0666666666666666
			a = a ~ val
			return (a & 0x1111111111111110) == 0
		end

		local function frombcd(val)
			local result = 0
			local mul = 1
			while val ~= 0 do
				result = result + ((val % 16) * mul)
				val = val >> 4
				mul = mul * 10
			end
			return result
		end

		if olddata.start ~= newdata.start or olddata.size ~= newdata.size or not cfoper[oper] then
			return {} 
		end
		if not val then
			val = 0
		end
		for i = 1, olddata.size do
			local old = string.unpack(format, olddata.block, i)
			local new = string.unpack(format, newdata.block, i)
			local oldc, newc = old, new
			local comp = false
			local addr = olddata.start + i - 1
			if not bcd or (check_bcd(old) and check_bcd(new)) then
				if bcd then
					oldc = frombcd(old)
					newc = frombcd(new)
				end
				if cfoper[oper](oldc, newc, val, addr) then
					ret[#ret + 1] = { addr = addr,
					oldval = old,
					newval = new,
					bitmask = bitmask }
					ref[ret[#ret].addr] = #ret
				end
			end
		end
		return ret, ref
	end

	local function check_val(oper, val, matches)
		if oper ~= "beq" and oper ~= "bne" then
			return val
		elseif not matches or not matches[1].bitmask then
			return nil
		end
		local masks = {}
		for num, match in pairs(matches) do
			masks[match.addr] = match.bitmask
		end
		return masks
	end

	-- compare two blocks and filter by table of previous matches
	function cheat.compnext(olddata, newdata, oldmatch, oper, format, val, bcd)
		local matches, refs = cheat.comp(olddata, newdata, oper, format, check_val(oper, val, oldmatch), bcd)
		local nonmatch = {}
		local oldrefs = {}
		for num, match in pairs(oldmatch) do
			oldrefs[match.addr] = num
		end
		for addr, ref in pairs(refs) do
			if not oldrefs[addr] then
				nonmatch[ref] = true
				refs[addr] = nil
			else
				matches[ref].oldval = oldmatch[oldrefs[addr]].oldval
			end
		end
		local resort = {}
		for num, match in pairs(matches) do
			if not nonmatch[num] then
				resort[#resort + 1] = match
			end
		end
		return resort 
	end
			 

	-- compare a data block to the current state
	function cheat.compcur(olddata, oper, format, val, bcd)
		local newdata = cheat.save(olddata.space, olddata.start, olddata.size, olddata.space)
		return cheat.comp(olddata, newdata, oper, format, check_val(oper, val, oldmatch), bcd)
	end

	-- compare a data block to the current state and filter
	function cheat.compcurnext(olddata, oldmatch, oper, format, val, bcd)
		local newdata = cheat.save(olddata.space, olddata.start, olddata.size, olddata.space)
		return cheat.compnext(olddata, newdata, oldmatch, oper, format, check_val(oper, val, oldmatch), bcd)
	end


	_G.cf = cheat

	local devtable = {}
	local devsel = 1
	local devcur = 1
	local formtable = { "<B", ">B", "<b", ">b", "<H", ">H", "<h", ">h", "<L", ">L", "<l", ">l", "<J", ">J", "<j", ">j" }
	local formname = { "little u8", "big u8", "little s8", "big s8", "little u16", "big u16", "little s16", "big s16",
			   "little u32", "big u32", "little s32", "big s32", "little u64", "big u64", "little s64", "big s64" }
	local width = 1
	local bcd = 0
	local optable = { "lt", "gt", "eq", "ne", "beq", "bne" }
	local opsel = 1
	local value = 0
	local leftop = 1
	local rightop = 0
	local matches = {}
	local matchsel = 1
	local menu_blocks = {}
	local midx = { region = 1, init = 2, undo = 3, save = 4, lop = 6, op = 7, rop = 8, val = 9,
		       width = 11,  bcd = 12, comp = 13, match = 15, watch = 0 }

	local function start()
		devtable = {}
		devsel = 1
		devcur = 1
		width = 1
		bcd = 0
		opsel = 1
		value = 0
		leftop = 1
		rightop = 1
		matches = {}
		matchsel = 1
		menu_blocks = {}

		local space_table = cheat.getspaces()
		for tag, list in pairs(space_table) do
			if list.program then
				local ram = {}
				for num, entry in pairs(list.program.map) do
					if entry.writetype == "ram" then
						ram[#ram + 1] = { offset = entry.offset, size = entry.endoff - entry.offset }
					end
				end
				if next(ram) then
					devtable[#devtable + 1] = { tag = tag, space = list.program, ram = ram }
				end
			end
		end
		space_table = cheat.getram()
		for tag, ram in pairs(space_table) do
			devtable[#devtable + 1] = { tag = tag, space = ram.dev, ram = {{ offset = 0, size = ram.size }} }
		end
	end

	emu.register_start(start)

	local function menu_populate()
		local menu = {}

		local function menu_lim(val, min, max, menuitem)
			if val == min then
				menuitem[3] = "r"
			elseif val == max then
				menuitem[3] = "l"
			else
				menuitem[3] = "lr"
			end
		end

		menu[midx.region] = { "CPU or RAM", devtable[devsel].tag, 0 }
		if #devtable == 1 then
			menu[midx.region][3] = 0
		else
			menu_lim(devsel, 1, #devtable, menu[midx.region])
		end
		menu[midx.init] = { "Start new search", "", 0 }
		if #menu_blocks ~= 0 then
			menu[midx.undo] = { "Undo last search -- #" .. #matches, "", 0 }
			menu[midx.save] = { "Save current -- #" .. #menu_blocks[1] + 1, "", 0 }
			menu[midx.save + 1] = { "---", "", "off" }
			menu[midx.lop] = { "Left operand", leftop, "" }
			menu_lim(leftop, 1, #menu_blocks[1] + 1, menu[midx.lop])
			if leftop == #menu_blocks[1] + 1 then
				menu[midx.lop][2] = "All"
			end
			menu[midx.op] = { "Operator", optable[opsel], "" }
			menu_lim(opsel, 1, #optable, menu[midx.op])
			menu[midx.rop] = { "Right operand", rightop, "" }
			menu_lim(rightop, 1, #menu_blocks[1] + 1, menu[midx.rop])
			if rightop == #menu_blocks[1] + 1 then
				menu[midx.rop][2] = "Current"
			end
			menu[midx.val] = { "Value", value, "" }
			menu_lim(value, 0, 100, menu[midx.val]) -- max value?
			if value == 0 then
				menu[midx.val][2] = "Any"
			end
			menu[midx.val + 1] = { "---", "", "off" }
			menu[midx.width] = { "Data Format", formname[width], 0 }
			menu_lim(width, 1, #formtable, menu[midx.width])
			menu[midx.bcd] = { "BCD", "Off", 0 }
			menu_lim(bcd, 0, 1, menu[midx.bcd])
			if bcd == 1 then
				menu[midx.bcd][2] = "On"
			end
			menu[midx.comp] = { "Compare", "", 0 }
			if #matches ~= 0 then
				menu[midx.comp + 1] = { "---", "", "off" }
				menu[midx.match] = { "Match block", matchsel, "" }
				if #matches[#matches] == 1 then
					menu[midx.match][3] = 0
				else
					menu_lim(matchsel, 1, #matches[#matches], menu[midx.match])
				end
				for num2, match in ipairs(matches[#matches][matchsel]) do
					if #menu > 50 then
						break
					end
					local numform = ""
					local bitwidth = formtable[width]:sub(2, 2):lower()
					if bitwidth == "h" then
						numform = " %04x"
					elseif bitwidth == "l" then
						numform = " %08x"
					elseif bitwidth == "j" then
						numform = " %016x"
					else
						numform = " %02x"
					end
					menu[#menu + 1] = { string.format("%08x" .. numform .. numform, match.addr, match.oldval, 
					                                  match.newval), "", 0 }
					if not match.mode then
						match.mode = 1
					end
					if match.mode == 1 then
						menu[#menu][2] = "Test"
					elseif match.mode == 2 then
						menu[#menu][2] = "Write"
					else
						menu[#menu][2] = "Watch"
					end
					menu_lim(match.mode, 1, 3, menu[#menu])
				end
			end
			if #watches ~= 0 then
				menu[#menu + 1] = { "Clear Watches", "", 0 }
				midx.watch = #menu
			end
		end
		return menu
	end

	local function menu_callback(index, event)
		local ret = false

		local function incdec(val, min, max)
			if event == "left" and val ~= min then
				val = val - 1
				ret = true
			elseif event == "right" and val ~= max then
				val = val + 1
				ret = true
			end
			return val
		end

		if index == midx.region then
			if (event == "left" or event == "right") and #menu_blocks ~= 0 then
				manager:machine():popmessage("Changes to this only take effect when \"Start new search\" is selected")
			end
			devsel = incdec(devsel, 1, #devtable)
			return true
		elseif index == midx.init then
			if event == "select" then
				menu_blocks = {}
				matches = {}
				for num, region in ipairs(devtable[devcur].ram) do
					menu_blocks[num] = {}
					menu_blocks[num][1] = cheat.save(devtable[devcur].space, region.offset, region.size)
				end
				manager:machine():popmessage("Data cleared and current state saved")
				watches = {}
				leftop = 1
				rightop = 2
				ret = true
			end
			devcur = devsel
		elseif index == midx.undo then
			if event == "select" and #matches > 0 then
				matches[#matches] = nil
			end
			ret = true
		elseif index == midx.save then
			if event == "select" then
				for num, region in ipairs(devtable[devcur].ram) do
					menu_blocks[num][#menu_blocks[num] + 1] = cheat.save(devtable[devcur].space, region.offset, region.size)
				end
				manager:machine():popmessage("Current state saved")
				ret = true
			end
		elseif index == midx.op then
			opsel = incdec(opsel, 1, #optable)
			if event == "left" or event == "right" or event == "comment" then
				if optable[opsel] == "lt" then
					manager:machine():popmessage("Left less than right, value is difference")
				elseif optable[opsel] == "gt" then
					manager:machine():popmessage("Left greater than right, value is difference")
				elseif optable[opsel] == "eq" then
					manager:machine():popmessage("Left equal to right, value is ignored")
				elseif optable[opsel] == "ne" then
					manager:machine():popmessage("Left not equal to right, value is difference")
				elseif optable[opsel] == "beq" then
					manager:machine():popmessage("Left equal to right with bitmask, value is ignored")
				elseif optable[opsel] == "bne" then
					manager:machine():popmessage("Left not equal to right with bitmask, value is ignored")
				end
			end
		elseif index == midx.val then
			value = incdec(value, 0, 100)
		elseif index == midx.lop then
			leftop = incdec(leftop, 1, #menu_blocks[1])
		elseif index == midx.rop then
			rightop = incdec(rightop, 1, #menu_blocks[1] + 1)
		elseif index == midx.width then
			width = incdec(width, 1, #formtable)
		elseif index == midx.bcd then
			bcd = incdec(bcd, 0, 1)
		elseif index == midx.comp then
			if event == "select" then
				for num = 1, #menu_blocks do
					if #matches == 0 then
						matches[1] = {}
						if rightop == #menu_blocks[1] + 1 then
							matches[1][num] = cheat.compcur(menu_blocks[num][leftop], optable[opsel],
										formtable[width], value, bcd == 1)
						else
							matches[1][num] = cheat.comp(menu_blocks[num][leftop], menu_blocks[num][rightop],
										   optable[opsel], formtable[width], value, bcd == 1)
						end
					else
						lastmatch = matches[#matches]
						matches[#matches + 1] = {}
						if rightop == #menu_blocks[1] + 1 then
							matches[#matches][num] = cheat.compcurnext(menu_blocks[num][leftop], lastmatch[num],
											optable[opsel], formtable[width], value, bcd == 1)
						else
							matches[#matches][num] = cheat.compnext(menu_blocks[num][leftop], menu_blocks[num][rightop],
											lastmatch[num], optable[opsel], formtable[width], value, bcd == 1)
						end
					end


				end
				ret = true
			end
		elseif index == midx.match then
			matchsel = incdec(matchsel, 0, #matches[#matches])
		elseif index == midx.watch then
			watches = {}
			ret = true
		elseif index > midx.match then 
			local match = matches[#matches][matchsel][index - midx.match]
			match.mode = incdec(match.mode, 1, 3)
			if event == "select" then
				local dev = devtable[devcur]
				local cheat = { desc = string.format("Test cheat at addr %08x", match.addr), script = {} }
				local wid = formtable[width]:sub(2, 2):lower()
				if wid == "h" then
					wid = "u16"
				elseif wid == "l" then
					wid = "u32"
				elseif wid == "j" then
					wid = "u64"
				else
					wid = "u8"
				end
				
				if dev.space.shortname then
					cheat.ram = dev.tag
					cheat.script.on = "ram:write(" .. match.addr .. "," .. match.newval .. ")"
				else
					cheat.space = { cpu = { tag = dev.tag, type = "program" } }
					cheat.script.on = "cpu:write_" .. wid .. "(" .. match.addr .. "," .. match.newval .. ")"
				end
				if match.mode == 1 then
					if not _G.ce then
						manager:machine():popmessage("Cheat engine not available")
					else
						_G.ce.inject(cheat)
					end
				elseif match.mode == 2 then
					local filename = string.format("%s_%08x_cheat.json", emu.romname(), match.addr)
					local json = require("json")
					local file = io.open(filename, "w")
					file:write(json.stringify(cheat))
					file:close()
					manager:machine():popmessage("Cheat written to " .. filename)
				else
					local func = "return space:read"
					local env = { space = devtable[devcur].space }
					if not dev.space.shortname then
						func = func .. "_" .. wid
					end
					func = func .. "(" .. match.addr .. ")"
					watches[#watches + 1] = { addr = match.addr, func = load(func, func, "t", env) }
				end
			end
		end
		devsel = devcur
		return ret
	end
	emu.register_menu(menu_callback, menu_populate, "Cheat Finder")
	emu.register_frame_done(function () 
			local tag, screen = next(manager:machine().screens)
			local height = manager:machine():ui():get_line_height()
			for num, watch in ipairs(watches) do
				screen:draw_text("left", num * height, string.format("%08x %08x", watch.addr, watch.func()))
			end
		end)
end

return exports