--[[
	Copyright (c) 2023 Scott Lembcke and Howling Moon Software

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	SOFTWARE.

	TODO:
	* Print short function arguments as part of stack location.
	* Properly handle being reentrant due to coroutines.
]]

---@diagnostic disable
-- notify 汉化 并根据fk/lua 5.4实际情况魔改

local dbg

-- ** FreeKill **: local the deleted global var here
local io = io
local os = os
local load = load

-- Use ANSI color codes in the prompt by default.
local COLOR_GRAY = ""
local COLOR_RED = ""
local COLOR_BLUE = ""
local COLOR_YELLOW = ""
local COLOR_RESET = ""
local GREEN_CARET = " => "

local function pretty(obj, max_depth)
	if max_depth == nil then max_depth = dbg.pretty_depth end

	-- Returns true if a table has a __tostring metamethod.
	local function coerceable(tbl)
		local meta = getmetatable(tbl)
		return (meta and meta.__tostring)
	end

	local function recurse(obj, depth)
		if type(obj) == "string" then
			-- Dump the string so that escape sequences are printed.
			return string.format("%q", obj)
		elseif type(obj) == "table" and depth < max_depth and not coerceable(obj) then
			local str = "{"

			for k, v in pairs(obj) do
				local pair = pretty(k, 0).." = "..recurse(v, depth + 1)
				str = str..(str == "{" and pair or ", "..pair)
			end

			return str.."}"
		else
			-- tostring() can fail if there is an error in a __tostring metamethod.
			local success, value = pcall(function() return tostring(obj) end)
			return (success and value or "<!!__tostring 元方法出错!!>")
		end
	end

	return recurse(obj, 0)
end

-- The stack level that cmd_* functions use to access locals or info
-- The structure of the code very carefully ensures this.
local CMD_STACK_LEVEL = 6

-- Location of the top of the stack outside of the debugger.
-- Adjusted by some debugger entrypoints.
local stack_top = 0

-- The current stack frame index.
-- Changed using the up/down commands
local stack_inspect_offset = 0

-- LuaJIT has an off by one bug when setting local variables.
local LUA_JIT_SETLOCAL_WORKAROUND = 0

-- Default dbg.read function
local function dbg_read(prompt)
	dbg.write(prompt)
	io.flush()
	return io.read()
end

-- Default dbg.write function
local function dbg_write(str)
	io.write(str)
end

local function dbg_writeln(str, ...)
	if select("#", ...) == 0 then
		dbg.write((str or "<NULL>").."\n")
	else
		dbg.write(string.format(str.."\n", ...))
	end
end

local function format_loc(file, line) return COLOR_BLUE..file..COLOR_RESET..":"..COLOR_YELLOW..line..COLOR_RESET end
local function format_stack_frame_info(info)
	local filename = info.source:match("@(.*)")
	local source = filename and dbg.shorten_path(filename) or info.short_src
	local namewhat = (info.namewhat == "" and "chunk at" or info.namewhat)
	local name = (info.name and "'"..COLOR_BLUE..info.name..COLOR_RESET.."'" or format_loc(source, info.linedefined))
	return format_loc(source, info.currentline)..", 在"..namewhat.." "..name
end

local repl

-- Return false for stack frames without source,
-- which includes C frames, Lua bytecode, and `loadstring` functions
local function frame_has_line(info) return info.currentline >= 0 end

local function hook_factory(repl_threshold)
	return function(offset, reason)
		return function(event, _)
			-- Skip events that don't have line information.
			if not frame_has_line(debug.getinfo(2)) then return end

			-- Tail calls are specifically ignored since they also will have tail returns to balance out.
			if event == "call" then
				offset = offset + 1
			elseif event == "return" and offset > repl_threshold then
				offset = offset - 1
			elseif event == "line" and offset <= repl_threshold then
				repl(reason)
			end
		end
	end
end

local hook_step = hook_factory(1)
local hook_next = hook_factory(0)
local hook_finish = hook_factory(-1)

-- Create a table of all the locally accessible variables.
-- Globals are not included when running the locals command, but are when running the print command.
local function local_bindings(offset, include_globals)
	local level = offset + stack_inspect_offset + CMD_STACK_LEVEL
	local func = debug.getinfo(level).func
	local bindings = {}

	-- Retrieve the upvalues
	do local i = 1; while true do
		local name, value = debug.getupvalue(func, i)
		if not name then break end
		bindings[name] = value
		i = i + 1
	end end

	-- Retrieve the locals (overwriting any upvalues)
	do local i = 1; while true do
		local name, value = debug.getlocal(level, i)
		if not name then break end
		bindings[name] = value
		i = i + 1
	end end

	-- Retrieve the varargs (works in Lua 5.2 and LuaJIT)
	local varargs = {}
	do local i = 1; while true do
		local name, value = debug.getlocal(level, -i)
		if not name then break end
		varargs[i] = value
		i = i + 1
	end end
	if #varargs > 0 then bindings["..."] = varargs end

	if include_globals then
		-- In Lua 5.2, you have to get the environment table from the function's locals.
		local env = (_VERSION <= "Lua 5.1" and getfenv(func) or bindings._ENV)
		return setmetatable(bindings, {__index = env or _G})
	else
		return bindings
	end
end

-- Used as a __newindex metamethod to modify variables in cmd_eval().
local function mutate_bindings(_, name, value)
	local FUNC_STACK_OFFSET = 3 -- Stack depth of this function.
	local level = stack_inspect_offset + FUNC_STACK_OFFSET + CMD_STACK_LEVEL

	-- Set a local.
	do local i = 1; repeat
		local var = debug.getlocal(level, i)
		if name == var then
			dbg_writeln(COLOR_YELLOW.."debugger.lua"..GREEN_CARET.."设置了局部变量 "..COLOR_BLUE..name..COLOR_RESET)
			return debug.setlocal(level + LUA_JIT_SETLOCAL_WORKAROUND, i, value)
		end
		i = i + 1
	until var == nil end

	-- Set an upvalue.
	local func = debug.getinfo(level).func
	do local i = 1; repeat
		local var = debug.getupvalue(func, i)
		if name == var then
			dbg_writeln(COLOR_YELLOW.."debugger.lua"..GREEN_CARET.."设置了上值 "..COLOR_BLUE..name..COLOR_RESET)
			return debug.setupvalue(func, i, value)
		end
		i = i + 1
	until var == nil end

	-- Set a global.
	dbg_writeln(COLOR_YELLOW.."debugger.lua"..GREEN_CARET.."设置了全局变量 "..COLOR_BLUE..name..COLOR_RESET)
	_G[name] = value
end

-- Compile an expression with the given variable bindings.
local function compile_chunk(block, env)
	local source = "debugger.lua REPL"
	local chunk = nil

	if _VERSION <= "Lua 5.1" then
		chunk = loadstring(block, source)
		if chunk then setfenv(chunk, env) end
	else
		-- The Lua 5.2 way is a bit cleaner
		chunk = load(block, source, "t", env)
	end

	if not chunk then dbg_writeln(COLOR_RED.."错误: 无法编译代码:\n"..COLOR_RESET..block) end
	return chunk
end

local SOURCE_CACHE = {}

local function where(info, context_lines)
	local source = SOURCE_CACHE[info.source]
	if not source then
		source = {}
		local filename = info.source:match("@(.*)")
		if filename then
			pcall(function() for line in io.lines(filename) do table.insert(source, line) end end)
		elseif info.source then
			for line in info.source:gmatch("(.-)\n") do table.insert(source, line) end
		end
		SOURCE_CACHE[info.source] = source
	end

	if source and source[info.currentline] then
		for i = info.currentline - context_lines, info.currentline + context_lines do
			local tab_or_caret = (i == info.currentline and  GREEN_CARET or "    ")
			local line = source[i]
			if line then dbg_writeln(COLOR_GRAY.."% 4d"..tab_or_caret.."%s", i, line) end
		end
	else
		dbg_writeln(COLOR_RED.."错误: 源码不可用: "..COLOR_BLUE..info.short_src);
	end

	return false
end

-- Wee version differences
local unpack = unpack or table.unpack
local pack = function(...) return {n = select("#", ...), ...} end

local function cmd_step()
	stack_inspect_offset = stack_top
	return true, hook_step
end

local function cmd_next()
	stack_inspect_offset = stack_top
	return true, hook_next
end

local function cmd_finish()
	local offset = stack_top - stack_inspect_offset
	stack_inspect_offset = stack_top
	return true, offset < 0 and hook_factory(offset - 1) or hook_finish
end

local function cmd_print(expr)
	local env = local_bindings(1, true)
	local chunk = compile_chunk("return "..expr, env)
	if chunk == nil then return false end

	-- Call the chunk and collect the results.
	local results = pack(pcall(chunk, unpack(rawget(env, "...") or {})))

	-- The first result is the pcall error.
	if not results[1] then
		dbg_writeln(COLOR_RED.."错误:"..COLOR_RESET.." "..results[2])
	else
		local output = ""
		for i = 2, results.n do
			output = output..(i ~= 2 and ", " or "")..dbg.pretty(results[i])
		end

		if output == "" then output = "<无返回值>" end
		dbg_writeln(COLOR_BLUE..expr.. GREEN_CARET..output)
	end

	return false
end

local function cmd_eval(code)
	local env = local_bindings(1, true)
	local mutable_env = setmetatable({}, {
		__index = env,
		__newindex = mutate_bindings,
	})

	local chunk = compile_chunk(code, mutable_env)
	if chunk == nil then return false end

	-- Call the chunk and collect the results.
	local success, err = pcall(chunk, unpack(rawget(env, "...") or Util.DummyTable))
	if not success then
		dbg_writeln(COLOR_RED.."错误:"..COLOR_RESET.." "..tostring(err))
	end

	return false
end

local function cmd_down()
	local offset = stack_inspect_offset
	local info

	repeat -- Find the next frame with a file.
		offset = offset + 1
		info = debug.getinfo(offset + CMD_STACK_LEVEL)
	until not info or frame_has_line(info)

	if info then
		stack_inspect_offset = offset
		dbg_writeln("目前所在的栈帧: "..format_stack_frame_info(info))
		if tonumber(dbg.auto_where) then where(info, dbg.auto_where) end
	else
		info = debug.getinfo(stack_inspect_offset + CMD_STACK_LEVEL)
		dbg_writeln("已经位于栈底。")
	end

	return false
end

local function cmd_up()
	local offset = stack_inspect_offset
	local info

	repeat -- Find the next frame with a file.
		offset = offset - 1
		if offset < stack_top then info = nil; break end
		info = debug.getinfo(offset + CMD_STACK_LEVEL)
	until frame_has_line(info)

	if info then
		stack_inspect_offset = offset
		dbg_writeln("目前所在的栈帧: "..format_stack_frame_info(info))
		if tonumber(dbg.auto_where) then where(info, dbg.auto_where) end
	else
		info = debug.getinfo(stack_inspect_offset + CMD_STACK_LEVEL)
		dbg_writeln("已经位于栈顶。")
	end

	return false
end

local function cmd_where(context_lines)
	local info = debug.getinfo(stack_inspect_offset + CMD_STACK_LEVEL)
	return (info and where(info, tonumber(context_lines) or 5))
end

local function cmd_trace()
	dbg_writeln("目前在栈帧 %d", stack_inspect_offset - stack_top)
	local i = 0; while true do
		local info = debug.getinfo(stack_top + CMD_STACK_LEVEL + i)
		if not info then break end

		local is_current_frame = (i + stack_top == stack_inspect_offset)
		local tab_or_caret = (is_current_frame and  GREEN_CARET or "    ")
		dbg_writeln(COLOR_GRAY.."% 4d"..COLOR_RESET..tab_or_caret.."%s", i, format_stack_frame_info(info))
		i = i + 1
	end

	return false
end

local function cmd_locals()
	local bindings = local_bindings(1, false)

	-- Get all the variable binding names and sort them
	local keys = {}
	for k, _ in pairs(bindings) do table.insert(keys, k) end
	table.sort(keys)

	for _, k in ipairs(keys) do
		local v = bindings[k]

		-- Skip the debugger object itself, "(*internal)" values, and Lua 5.2's _ENV object.
		if not rawequal(v, dbg) and k ~= "_ENV" and not k:match("%(.*%)") then
			dbg_writeln("  "..COLOR_BLUE..k.. GREEN_CARET..dbg.pretty(v))
		end
	end

	return false
end

local function cmd_help()
	dbg.write(""
		..COLOR_BLUE.."  <回车>"..GREEN_CARET.."重复执行上一条命令\n"
		..COLOR_BLUE.."  c"..COLOR_YELLOW.."(ontinue)"..GREEN_CARET.."继续执行代码\n"
		..COLOR_BLUE.."  s"..COLOR_YELLOW.."(tep)"..GREEN_CARET.."单步执行下一行 (会深入到函数中)\n"
		..COLOR_BLUE.."  n"..COLOR_YELLOW.."(ext)"..GREEN_CARET.."单步执行下一行 (不深入到函数调用)\n"
		..COLOR_BLUE.."  f"..COLOR_YELLOW.."(inish)"..GREEN_CARET.."一直执行直到此函数返回\n"
		..COLOR_BLUE.."  u"..COLOR_YELLOW.."(p)"..GREEN_CARET.."上移一个栈帧\n"
		..COLOR_BLUE.."  d"..COLOR_YELLOW.."(own)"..GREEN_CARET.."下移一个栈帧\n"
		..COLOR_BLUE.."  w"..COLOR_YELLOW.."(here) "..COLOR_BLUE.."[行数]"..GREEN_CARET.."打印出当前行周围的代码\n"
		..COLOR_BLUE.."  e"..COLOR_YELLOW.."(val) "..COLOR_BLUE.."[语句]"..GREEN_CARET.."执行一个语句\n"
		..COLOR_BLUE.."  p"..COLOR_YELLOW.."(rint) "..COLOR_BLUE.."[表达式]"..GREEN_CARET.."求出表达式的值，并打印出结果\n"
		..COLOR_BLUE.."  t"..COLOR_YELLOW.."(race)"..GREEN_CARET.."打印函数调用栈\n"
		..COLOR_BLUE.."  l"..COLOR_YELLOW.."(ocals)"..GREEN_CARET.."打印函数参数、局部变量和上值\n"
		..COLOR_BLUE.."  h"..COLOR_YELLOW.."(elp)"..GREEN_CARET.."打印这条消息\n"
		-- ..COLOR_BLUE.."  q"..COLOR_YELLOW.."(uit)"..GREEN_CARET.."结束调试，继续执行代码\n"
	)
	return false
end

local last_cmd = false

local commands = {
	["^c$"] = function() return true end,
	["^s$"] = cmd_step,
	["^n$"] = cmd_next,
	["^f$"] = cmd_finish,
	["^p%s+(.*)$"] = cmd_print,
	["^e%s+(.*)$"] = cmd_eval,
	["^u$"] = cmd_up,
	["^d$"] = cmd_down,
	["^w%s*(%d*)$"] = cmd_where,
	["^t$"] = cmd_trace,
	["^l$"] = cmd_locals,
	["^h$"] = cmd_help,
	["^q$"] = function() dbg.exit(0); return true end,
}

local function match_command(line)
	for pat, func in pairs(commands) do
		-- Return the matching command and capture argument.
		if line:find(pat) then return func, line:match(pat) end
	end
end

-- Run a command line
-- Returns true if the REPL should exit and the hook function factory
local function run_command(line)
	-- GDB/LLDB exit on ctrl-d
	if line == nil then dbg.exit(1); return true end

	-- Re-execute the last command if you press return.
	if line == "" then line = last_cmd or "h" end

	local command, command_arg = match_command(line)
	if command then
		last_cmd = line
		-- unpack({...}) prevents tail call elimination so the stack frame indices are predictable.
		return unpack({command(command_arg)})
	elseif dbg.auto_eval then
		return unpack({cmd_eval(line)})
	else
		dbg_writeln(COLOR_RED.."错误:"..COLOR_RESET.." 无法识别命令 '%s'。\n输入 'h' 并按下回车键来查看命令列表。", line)
		return false
	end
end

repl = function(reason)
	-- Skip frames without source info.
	while not frame_has_line(debug.getinfo(stack_inspect_offset + CMD_STACK_LEVEL - 3)) do
		stack_inspect_offset = stack_inspect_offset + 1
	end

	local info = debug.getinfo(stack_inspect_offset + CMD_STACK_LEVEL - 3)
	reason = reason and (COLOR_YELLOW.."由于 "..COLOR_RED..reason..GREEN_CARET.." 中断执行\n") or ""
	dbg_writeln(reason..format_stack_frame_info(info))

	if tonumber(dbg.auto_where) then where(info, dbg.auto_where) end

	repeat
		local success, done, hook = pcall(run_command, dbg.read(COLOR_RED.."(dbg) "..COLOR_RESET))
		if success then
			debug.sethook(hook and hook(0), "crl")
		else
			local message = COLOR_RED.."INTERNAL DEBUGGER.LUA ERROR. ABORTING\n:"..COLOR_RESET.." "..done
			dbg_writeln(message)
			error(message)
		end
	until done
end

-- Make the debugger object callable like a function.
dbg = setmetatable({}, {
	__call = function(_, condition, top_offset, source)
		if condition then return end

		top_offset = (top_offset or 0)
		stack_inspect_offset = top_offset
		stack_top = top_offset

		debug.sethook(hook_next(1, source or "dbg()"), "crl")
		return
	end,
})

-- Expose the debugger's IO functions.
dbg.read = dbg_read
dbg.write = dbg_write
dbg.shorten_path = function (path) return path end
dbg.exit = function() end

dbg.writeln = dbg_writeln

dbg.pretty_depth = 3
dbg.pretty = pretty
dbg.pp = function(value, depth) dbg_writeln(dbg.pretty(value, depth)) end

dbg.auto_where = 1
dbg.auto_eval = true

local lua_error, lua_assert = error, assert

-- Works like error(), but invokes the debugger.
function dbg.error(err, level)
	level = level or 1
	dbg_writeln(COLOR_RED.."错误: "..COLOR_RESET..dbg.pretty(err))
	dbg(false, level, "dbg.error()")

	lua_error(err, level)
end

-- Works like assert(), but invokes the debugger on a failure.
function dbg.assert(condition, message)
	if not condition then
		dbg_writeln(COLOR_RED.."错误:"..COLOR_RESET..message)
		dbg(false, 1, "dbg.assert()")
	end

	return lua_assert(condition, message)
end

-- Works like pcall(), but invokes the debugger on an error.
function dbg.call(f, ...)
	return xpcall(f, function(err)
		dbg_writeln(COLOR_RED.."错误: "..COLOR_RESET..dbg.pretty(err))
		dbg(false, 1, "dbg.call()")

		return err
	end, ...)
end

-- Error message handler that can be used with lua_pcall().
function dbg.msgh(...)
	if debug.getinfo(2) then
		dbg_writeln(COLOR_RED.."错误: "..COLOR_RESET..dbg.pretty(...))
		dbg(false, 1, "dbg.msgh()")
	else
		dbg_writeln(COLOR_RED.."debugger.lua: "..COLOR_RESET.."Lua代码中未发生错误。将在 dbg_pcall() 完成后继续执行代码。")
	end

	return ...
end

-- Assume stdin/out are TTYs unless we can use LuaJIT's FFI to properly check them.
local stdin_isatty = true
local stdout_isatty = true

-- Conditionally enable color support.
local color_maybe_supported = (stdout_isatty and os.getenv("TERM") and os.getenv("TERM") ~= "dumb")
if color_maybe_supported and not os.getenv("DBG_NOCOLOR") then
	COLOR_GRAY = string.char(27) .. "[90m"
	COLOR_RED = string.char(27) .. "[91m"
	COLOR_BLUE = string.char(27) .. "[94m"
	COLOR_YELLOW = string.char(27) .. "[33m"
	COLOR_RESET = string.char(27) .. "[0m"
	GREEN_CARET = string.char(27) .. "[92m => "..COLOR_RESET
end

return dbg
