package policy

import (
	"errors"
	"net/netip"

	"go.starlark.net/starlark"
)

// MDA implements starlark.Value and starlark.HasAttrs
// so it can be exposed as the `mda` global object in the script.
type MDA struct {
	parsedListeners []ListenerConfig
}

func (m *MDA) String() string       { return "<module mda>" }
func (m *MDA) Type() string         { return "module" }
func (m *MDA) Freeze()              {}
func (m *MDA) Truth() starlark.Bool { return true }
func (m *MDA) Hash() (uint32, error) {
	return 0, errors.New("unhashable")
}

func (m *MDA) Attr(name string) (starlark.Value, error) {
	switch name {
	case "listen":
		return starlark.NewBuiltin("listen", m.mdaListen), nil
	}
	return nil, nil
}
func (m *MDA) AttrNames() []string {
	return []string{"listen"}
}

// mdaListen handles mda.listen(address="...", role="...")
func (m *MDA) mdaListen(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
	var address, role, tlsCertFile, tlsKeyFile string

	// starlark.UnpackArgs maps Starlark arguments to Go variables safely
	err := starlark.UnpackArgs(
		b.Name(),
		args,
		kwargs,
		"address", &address,
		"role", &role,
		"tls_cert_file", &tlsCertFile,
		"tls_key_file", &tlsKeyFile)
	if err != nil {
		return nil, err
	}

	addrPort, err := netip.ParseAddrPort(address)
	if err != nil {
		return nil, err
	}

	// Save to our Go state
	m.parsedListeners = append(m.parsedListeners, ListenerConfig{
		Address:     addrPort,
		Role:        role,
		TLSCertFile: tlsCertFile,
		TLSKeyFile:  tlsKeyFile,
	})

	return starlark.None, nil
}