package luajit

/*
#include <lua.h>
#include <lauxlib.h>
*/
import "C"
import "fmt"

// LuaError represents an error from the Lua state
type LuaError struct {
	Code    int
	Message string
}

func (e *LuaError) Error() string {
	return fmt.Sprintf("lua error (code=%d): %s", e.Code, e.Message)
}

// Stack management constants from lua.h
const (
	LUA_MINSTACK      = 20      // Minimum Lua stack size
	LUA_MAXSTACK      = 1000000 // Maximum Lua stack size
	LUA_REGISTRYINDEX = -10000  // Pseudo-index for the Lua registry
	LUA_GLOBALSINDEX  = -10002  // Pseudo-index for globals table
)

// GetStackTrace returns the current Lua stack trace
func (s *State) GetStackTrace() string {
	s.GetGlobal("debug")
	if !s.IsTable(-1) {
		s.Pop(1)
		return "debug table not available"
	}

	s.GetField(-1, "traceback")
	if !s.IsFunction(-1) {
		s.Pop(2) // Remove debug table and non-function
		return "debug.traceback not available"
	}

	s.Call(0, 1)
	trace := s.ToString(-1)
	s.Pop(1) // Remove the trace

	return trace
}