package luajit

import "fmt"

// ArgSpec defines an argument specification for validation
type ArgSpec struct {
	Name     string
	Type     string
	Required bool
	Check    func(*State, int) bool
}

// Common argument checkers
var (
	CheckString = func(s *State, i int) bool { return s.IsString(i) }
	CheckNumber = func(s *State, i int) bool { return s.IsNumber(i) }
	CheckBool   = func(s *State, i int) bool { return s.IsBoolean(i) }
	CheckTable  = func(s *State, i int) bool { return s.IsTable(i) }
	CheckFunc   = func(s *State, i int) bool { return s.IsFunction(i) }
	CheckAny    = func(s *State, i int) bool { return true }
)

// CheckArgs validates function arguments against specifications
func (s *State) CheckArgs(specs ...ArgSpec) error {
	for i, spec := range specs {
		argIdx := i + 1
		if argIdx > s.GetTop() {
			if spec.Required {
				return fmt.Errorf("missing argument %d: %s", argIdx, spec.Name)
			}
			break
		}

		if s.IsNil(argIdx) && !spec.Required {
			continue
		}

		if !spec.Check(s, argIdx) {
			return fmt.Errorf("argument %d (%s) must be %s", argIdx, spec.Name, spec.Type)
		}
	}
	return nil
}

// CheckMinArgs checks for minimum number of arguments
func (s *State) CheckMinArgs(min int) error {
	if s.GetTop() < min {
		return fmt.Errorf("expected at least %d arguments, got %d", min, s.GetTop())
	}
	return nil
}

// CheckExactArgs checks for exact number of arguments
func (s *State) CheckExactArgs(count int) error {
	if s.GetTop() != count {
		return fmt.Errorf("expected exactly %d arguments, got %d", count, s.GetTop())
	}
	return nil
}