#include "FunctionInfo.hpp"
#include "Utility.hpp"
#include <algorithm>
#include <format>
#include <optional>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>

std::regex decl_rgx(R"(^  (\S+) (\S+)(?: \[)?(\d+?)?\]?;$)"); // capturing type, name and array size
std::regex ass_rgx(R"(^ +?(\w+) = (.+);)"); // OwO
std::regex if_rgx(R"(if \((.+)\) )");
std::regex usg_rgx(R"(,"(Usage: [^;]+).?"[, \)])"); // .? is a workaround to prevent raw string from closing
std::regex usg_vld_rgx(R"(Usage: .+?\((.*?)\))");
std::regex lua_is_rgx(R"(lua_is(.+?)\(L,(\w+?)\))");
std::regex lua_to_rgx(R"(lua_to(.+?)\(L,(\w+?)[,\)])");
std::regex lua_push_rgx(R"(lua_push(.+?)\(())");
std::regex dowhl_cond_rgx(R"(while \((.+)\);)");

std::optional<int> prsi_lcls(std::string str, std::unordered_map<std::string, int>& lcls)
{	// looks up local variables, before it tries to call prsi
	if (lcls.count(str)) return lcls[str];
	return prsi(str);
}

__forceinline std::optional<int> slv_step(std::stack<int>& vals, std::stack<Op>& ops)
{
	int v2 = vals.top();
	vals.pop();
	int v1 = vals.top();
	vals.pop();
	Op op = ops.top();
	ops.pop();
	switch (op)
	{
	case LOR:
		return v1 || v2;
	case LAND:
		return v1 && v2;
	case BOR:
		return v1 | v2;
	case BXOR:
		return v1 ^ v2;
	case BAND:
		return v1 & v2;
	case EQ:
		return v1 == v2;
	case UEQ:
		return v1 != v2;
	case LT:
		return v1 < v2;
	case LTE:
		return v1 <= v2;
	case BT:
		return v1 > v2;
	case BTE:
		return v1 >= v2;
	case PLS:
		return v1 + v2;
	case MIN:
		return v1 - v2;
	case MUL:
		return v1 * v2;
	case DIV:
		if (v2 == 0) return std::nullopt;
		return v1 / v2;
	case MOD:
		if (v2 == 0) return std::nullopt;
		return v1 % v2;
	}
	return std::nullopt; // unsupported op
}

__forceinline std::optional<int> push_op(std::stack<int>& vals, std::stack<Op>& ops, Op op)
{
	while (ops.size() >= 1 && op_prec(ops.top()) >= op_prec(op))
	{	// last op has greater or same precedence
		auto res = slv_step(vals, ops);
		if (!res.has_value()) return std::nullopt;
		vals.push(res.value());
	}
	ops.push(op);
}

std::regex lua_is_quick(R"(^lua_is\S+?\(L,\S+?\)$)");
std::regex sstrcmpi_quick(R"(^SStrCmpI\(\S+?,\S+?,\S+?\)$)");

std::optional<int> eval(std::string& infix, locals& lcls)
{
	std::smatch match;
	if (std::regex_search(infix, match, lua_is_quick)) return 1;
	if (std::regex_search(infix, match, sstrcmpi_quick)) return 1;

	if (infix.find_first_of(' ') == std::string::npos)
	{	// TODO performance escape hatch for simple infix strings - might actually be counter productive... have to check
		return prsi_lcls(infix, lcls);
	}

	std::stack<int> vals;
	std::stack<Op> ops;
	int tk_start = 0;
	std::string tk;
	bool was_brr;
	for (int tk_end = 0; tk_end < infix.length(); tk_end++)
	{
		was_brr = false;
		switch (infix[tk_end])
		{
		case ' ':
			tk = infix.substr(tk_start, tk_end - tk_start);
			tk_start = tk_end + 1;
			break;
		case '(':
			tk = "";
			ops.push(Op::BRL);
			tk_start = tk_end + 1;
			continue;
		case ')':
			tk = infix.substr(tk_start, tk_end - tk_start);
			tk_start = tk_end + 1;
			was_brr = true;
			break;
		}
		if (tk == "" && tk_end == infix.length() - 1)
		{	// last token
			tk = infix.substr(tk_start, tk_end - tk_start + 1);
		}
		if (tk == "" && !was_brr) continue; // empty token, nothing to do

		if (tk == "||") push_op(vals, ops, LOR);
		else if (tk == "&&") push_op(vals, ops, LAND);
		else if (tk == "|") push_op(vals, ops, BOR);
		else if (tk == "^") push_op(vals, ops, BXOR);
		else if (tk == "&") push_op(vals, ops, BAND);
		else if (tk == "==") push_op(vals, ops, EQ);
		else if (tk == "!=") push_op(vals, ops, UEQ);
		else if (tk == "<") push_op(vals, ops, LT);
		else if (tk == "<=") push_op(vals, ops, LTE);
		else if (tk == ">") push_op(vals, ops, BT);
		else if (tk == ">=") push_op(vals, ops, BTE);
		else if (tk == "+") push_op(vals, ops, PLS);
		else if (tk == "-") push_op(vals, ops, MIN);
		else if (tk == "*") push_op(vals, ops, MUL);
		else if (tk == "/") push_op(vals, ops, DIV);
		else if (tk == "%") push_op(vals, ops, MOD);
		else if (tk != "")
		{
			auto pr = prsi_lcls(tk, lcls);
			if (!pr.has_value()) return std::nullopt;
			vals.push(pr.value());
		}
		if (was_brr)
		{
			while (ops.top() != BRL)
			{
				auto res = slv_step(vals, ops);
				if (!res.has_value()) return std::nullopt;
				vals.push(res.value());
			}
			ops.pop(); // popping left brace
		}
		tk = "";
	}
	while (!ops.empty())
	{
		auto res = slv_step(vals, ops);
		if (!res.has_value()) return std::nullopt;
		vals.push(res.value());
	}
	if (vals.size() != 1 || !ops.empty()) return std::nullopt;
	return vals.top();
}

bool FunctionInfo::prc_varmap_rgx(bool prc_in, const std::string& ln_in, std::regex& rgx, locals& lcls)
{
	std::string ln = ln_in;
	varmap& params = prc_in ? in : out;
	bool fnd = false;
	while (std::regex_search(ln, match, rgx))
	{
		fnd = true;
		int lua_idx;
		std::string lua_type;
		lua_type = match[1];
		if (lua_type == "lstring") lua_type = "string"; // lstring is a string!
		else if (lua_type == "fstring") lua_type = "string"; // frsting is a string!
		if (&rgx == &lua_push_rgx)
		{	// push parsing uses a global index starting with 1
			lua_idx = out.size() + 1;
		}
		else lua_idx = prsi_lcls(match[2], lcls).value();
		if (lua_idx == -1)
		{	// -1 means there wasn't a literal used for accessing the index, so i can not parse it
			if (&rgx == &lua_push_rgx) out_cnt = -1;
			else in_cnt = -1; // TODO might be possible to parse when evaluating variables
			return fnd;
		}
		params[lua_idx].push_back(lua_type); // always push lua type for now
		ln = match.suffix();
	}
	return fnd;
}

void FunctionInfo::chk_vld()
{	// run all checks, so we have the full picture
	bool vld = true;
	if (prs_msg.size() > 0) vld = false; // parsing messages up until this point are hard errors
	if (in_cnt > -1)
	{	// in varmap is not dynamic
		if (!usg.empty())
		{	// check against usage string
			if (std::regex_search(usg, match, usg_vld_rgx))
			{
				std::string usg_params = match[1];
				int comma_cnt = 0;
				for (char c : usg_params) comma_cnt += c == ',';
				if (in_cnt == 0 && !usg_params.empty() || in_cnt != comma_cnt + 1)
				{
					prs_msg.push_back(std::format("in param count ({}) does not match usage string ({})", in_cnt, !usg_params.empty() * (comma_cnt + 1)));
					vld = false;
				}
			}
			else prs_msg.push_back("usage string is malformed"); // do not consider this for validity
		}
		for (int i = 1; i <= in_cnt; i++)
		{	// lua indexes start with 1
			if (!in.contains(i))
			{
				prs_msg.push_back("in param index not in order");
				vld = false;
				break;
			}
		}
	}
	if (out_cnt != -1 && out_cnt != out.size())
	{
		prs_msg.push_back(std::format("out param count ({}) does not match return value ({})", out.size(), out_cnt));
		vld = false;
	}
	prs_vld = vld;
}

void FunctionInfo::cln_varmap(bool prc_in)
{
	varmap& params = prc_in ? in : out;
	int cnt = prc_in ? in_cnt : out_cnt;
	if (cnt == -1)
	{
		params.clear(); // dynamic varmap does not need entries
		return;
	}
	for (auto& [lua_index, lua_types] : params)
	{
		std::sort(lua_types.begin(), lua_types.end());
		lua_types.erase(std::unique(lua_types.begin(), lua_types.end()), lua_types.end());
	}
	if (prc_in) in_cnt = in.size(); // input count can only be inferred by in varmap size
}

bool FunctionInfo::nil_in_varmap(bool prc_in) const
{
	const varmap& params = prc_in ? in : out;
	for (auto& [key, value] : params)
		if (std::find(value.begin(), value.end(), "nil") != value.end())
			return true;
	return false;
}

std::string FunctionInfo::str() const
{
	std::string str = std::format("{:X} {}{}\n", addr, nm, prs_vld ? "" : " (invalid)");
	if (!usg.empty()) str += "  " + usg + "\n";
	str += "  in:  " + str_varmap(true) + "\n";
	str += "  out: " + str_varmap(false);
	for (const std::string& err : prs_msg) str += "\n  " + err;
	return str;
}

std::string FunctionInfo::str_varmap(bool prc_in) const
{
	int cnt = prc_in ? in_cnt : out_cnt;
	switch (cnt)
	{
	case -1:
		return "dynamic";
	case 0:
		return "0 ()";
	}
	const varmap& params = prc_in ? in : out;
	if (params.size() > 0)
	{	// cnt and params.size() might differ - lua_push* calls can be undetected
		std::string str = std::to_string(cnt) + " (";
		for (const auto& [lua_index, lua_types] : params)
		{
			for (const auto& lua_type : lua_types) str += lua_type + "/";
			str.pop_back(); // remove last slash
			str += ", ";
		}
		str[str.length() - 2] = ')'; // replace last comma with closing bracket
		str.pop_back(); // remove space after last comma
		return str;
	}
	return std::to_string(cnt) + " ()";
}

FunctionInfo::FunctionInfo()
{
}

FunctionInfo::FunctionInfo(std::vector<std::string> src)
{	
	addr = std::stoi(&src[0][13], 0, 16); // no use of prsi - values occur once -> no caching wanted
	nm = src[1].substr(13, src[1].find_first_of('(') - 13);

	locals lcls; // local variables
	std::set<std::string> track_types = { "BOOL", "int", "uint", "undefined4"}; // only track locals of these types
	std::string type;
	int idx = 2;
	if (!src[idx].starts_with("  return "))
	{	// process local variable declarations
		for (; idx < src.size(); idx++)
		{
			std::string& ln = src[idx];
			if (std::regex_search(ln, match, decl_rgx))
			{
				if (!track_types.count(match[1])) continue; // not interested in type
				lcls[match[2]] = 0; // track with init value 0
			}
			else break; // found no more declaration
		}
	}
	
	std::string ind; // indentation - keeping track of current block level
	std::string lp_utl = ""; // currently in a loop until this line is reached
	std::string skp_ass_utl = "";
	std::string skp_push_utl = ""; // skip push parsing until this ln has been reached
	std::string cond;
	std::optional<int> er; // eval result
	bool is_if_ln;
	bool enc_usg = false; // encountered usg
	uint ret_val; // return value
	std::string infix;
	lp_track lp_track; // keeps track where the loop started
	std::unordered_map<std::string, bool> push_track; // keeps track if on this indent level a push has happened
	for (; idx < src.size(); idx++) // skip right to the lines which matter
	{
		std::string& ln = src[idx];
		is_if_ln = false;

		int i = 2;
		while (i < ln.length())
		{
			if (ln[i] != ' ') break;
			i += 2;
		}
		ind = ln.substr(0, i);

		switch (ln[i])
		{
		case '}':
			if (lp_track.find(ind) != lp_track.end())
			{	// closing bracket of a loop
				lp_track[ind].iter--;
				if (lp_track[ind].iter < 0)
				{	// max iterations exceeded
					prs_msg.push_back(std::format("max iterations exceeded in: {}", idx + 1));
				}
			}
			if (std::regex_search(ln, match, dowhl_cond_rgx))
			{
				lp_track[ind].iter--;
				if (lp_track[ind].iter < 0)
				{	// max iterations exceeded
					prs_msg.push_back(std::format("max iterations exceeded in: {}", idx + 1));
				}
				else
				{
					infix = match[1];
					auto er = eval(infix, lcls);
					if (er.has_value() && er.value() != 0)
					{	// condition was parsable and evaluated to true

						idx = lp_track[ind].idx;
						continue;
					}
				}
				if (lp_track.find(ind) != lp_track.end()) lp_track.erase(ind);
				break;
			}
			break;
		case 'c':
		case 'd':
			if (lnsw(ln, i, "do {"))
			{	// setting loop end, if not already in a loop
				lp_track[ind] = { idx + (lnew(ln, "{")) - 1, MAX_ITER};
				break;
			}
			if (lnsw(ln, i, "case ") || lnsw(ln, i, "default:"))
			{
				if (push_track[ind]) ssie(skp_push_utl, ind + "}");
				else push_track[ind] = false; // only execute if a previous case didn't already contain a push
				break;
			}
			break;
		case 'f':
			if (lnsw(ln, i, "for ("))
			{
				lp_track[ind] = { idx + (lnew(ln, "{")) - 1, MAX_ITER};
				break;
			}
			break;
		case 'i': // check for if
			if (lnsw(ln, i, "if "))
			{	// enough characters left to be if statement
				is_if_ln = true;
				break;
			}
			break;
		case 'e':
			if (lnsw(ln, i, "else "))
			{	// enough characters left to be if statement
				if (push_track[ind])
				{
					ssie(skp_ass_utl, lnew(ln, "{") ? ind + "}" : "\1");
					ssie(skp_push_utl, lnew(ln, "{") ? ind + "}" : "\1");
				}
				else if (lnsw(ln, i + 5, "if ")) is_if_ln = true;
				break;
			}
			break;
		case 'g':
			if (!out.empty() && lnsw(ln, i, "goto "))
			{
				ssie(skp_push_utl, std::string(ln.substr(i + 5, ln.length() - i - 6)) + ":");
				break;
			}
			break;
		case 'r': // check for return
			if (out_cnt == -1) break; // this function has a dynamic number of outputs, no need for further processing
			if (lnsw(ln, i, "return "))
			{	// enough characters left to be the simplest return
				cond = std::string(&ln[i + 7], ln.length() - i - 8);
				er = eval(cond, lcls);
				if (er.has_value()) ret_val = er.value();
				else ret_val = -1;
				// check if already encountered return value (except 0) matches; dynamic if not
				if (ret_val != 0)
				{	// TODO probably need to check if i am currently skipping push
					out_cnt = (out_cnt == 0 || out_cnt == ret_val) ? ret_val : -1;
					if (ret_val == out.size())
					{	// found a return statement and return value matches output param count
						ssie(skp_push_utl, "\1skip2end");
					}
				}
				break;
			}
			break;
		case 'w':
			if (lnsw(ln, i, "while ("))
			{	// setting loop end, if not already in a loop
				lp_track[ind] = { idx + (lnew(ln, "{")) - 1, MAX_ITER};
				break;
			}
			break;
		}

		if (is_if_ln)
		{
			std::regex_search(ln, match, if_rgx);
			cond = match[1];
			er = eval(cond, lcls);
			if(!er.has_value() || er.value() != 0) push_track[ind] = true;
			else
			{
				push_track[ind] = false;
				skp_ass_utl = lnew(ln, "{") ? ind + "}" : "\1";
				skp_push_utl = lnew(ln, "{") ? ind + "}" : "\1";
			}
		}

		if (skp_ass_utl.empty() && std::regex_search(ln, match, ass_rgx) && lcls.count(match[1])) // only process assignment for variables i still care about
		{	// assignment regex matched and local variable with the name is tracked
			infix = match[2];
			auto er = eval(infix, lcls);
			if (er.has_value()) lcls[match[1]] = er.value();
			else lcls.erase(match[1]);
		}

		if (!enc_usg)
		{	// usage string can only occur once anyway
			//if (auto match = ctre::match<usage_regex>(ln))
			if (std::regex_search(ln, match, usg_rgx))
			{	// found usg string
				usg = match[1];
				size_t found = -1; // so the first find uses 0 through the increment
				while ((found = usg.find("\\\"", found + 1)) != std::string::npos) usg.replace(found, 2, "\"");
				enc_usg = true;
				ssie(skp_push_utl, "\1"); // sometimes lua_pushfstring is used before lua_error; do not consider this an output!
			}
		}

		if (in_cnt != -1)
		{
			prc_varmap_rgx(true, ln, lua_is_rgx, lcls);
			prc_varmap_rgx(true, ln, lua_to_rgx, lcls);
		}
		if (out_cnt != -1 && skp_push_utl.empty() && prc_varmap_rgx(false, ln, lua_push_rgx, lcls))
		{
			std::string lvl = is_if_ln ? ind : ind.substr(0, ind.length() - 2); // do not subtract 1 block level, if this was a simple if ln
			while (lvl >= "  ")
			{	// if a push was found, track it for this and all lower block levels
				push_track[lvl] = true;
				lvl = lvl.substr(0, lvl.length() - 2);
			}
		}

		if (!lp_utl.empty() && ln.starts_with(lp_utl)) lp_utl = "";
		if (lp_utl == "\1") lp_utl = "";
		if (!skp_ass_utl.empty() && ln.starts_with(skp_ass_utl))  skp_ass_utl = "";
		if (skp_ass_utl == "\1")  skp_ass_utl = "";
		if (!skp_push_utl.empty() && ln.starts_with(skp_push_utl)) skp_push_utl = ""; // reset skip since ln has been reached now
		if (skp_push_utl == "\1") skp_push_utl = ""; // reset temporary skip which was used for 1 ln
	}

	cln_varmap(true); // clean inputs
	cln_varmap(false); // clean outputs
	chk_vld(); // check validity of parsed data
}