package amf

import (
	"math"
	"encoding/binary"
	"errors"
)

// reverse of the decode in amf/decode,go
// see that file for what most of this means
func Encode(amf_root_obj AMFObj) ([]byte, error) {
	tmp_buffer := make([]byte, 1024)
	bytes_encoded := 0

	for i := 0; i < len(amf_root_obj); i++ {
		if err := encode_next(amf_root_obj[i], &tmp_buffer, &bytes_encoded); err != nil {
			return tmp_buffer[:bytes_encoded], err
		}
	}
	return tmp_buffer[:bytes_encoded], nil
}

func encode_marker(marker_val uint8, tmp_buffer *[]byte, bytes_encoded *int) {
	(*tmp_buffer)[*bytes_encoded] = marker_val
	*bytes_encoded++
}

func encode_number(num_to_enc float64, tmp_buffer *[]byte, bytes_encoded *int) {
	binary.BigEndian.PutUint64((*tmp_buffer)[*bytes_encoded:*bytes_encoded + 8], math.Float64bits(num_to_enc))
	*bytes_encoded += 8
}

func encode_string(str_to_enc string, tmp_buffer *[]byte, bytes_encoded *int) {
	str_len := len(str_to_enc)
	binary.BigEndian.PutUint16((*tmp_buffer)[*bytes_encoded:*bytes_encoded + 2], uint16(str_len))
	*bytes_encoded += 2
	copy((*tmp_buffer)[*bytes_encoded:*bytes_encoded + str_len], str_to_enc)
	*bytes_encoded += str_len
}

func encode_object(obj_to_enc AMFObj, tmp_buffer *[]byte, bytes_encoded *int) {
	for prop, value := range obj_to_enc {
		encode_string(prop.(string), tmp_buffer, bytes_encoded)
		encode_next(value, tmp_buffer, bytes_encoded)
	}
}

func encode_next(amf_obj interface{}, tmp_buffer *[]byte, bytes_encoded *int) (error) {
	switch amf_obj.(type) {
	case float64:
		encode_marker(0, tmp_buffer, bytes_encoded)
		encode_number(amf_obj.(float64), tmp_buffer, bytes_encoded)
	case string:
		encode_marker(2, tmp_buffer, bytes_encoded)
		encode_string(amf_obj.(string), tmp_buffer, bytes_encoded)
	case AMFObj:
		encode_marker(3, tmp_buffer, bytes_encoded)
		encode_object(amf_obj.(AMFObj), tmp_buffer, bytes_encoded)
		encode_string("", tmp_buffer, bytes_encoded)
		encode_marker(9, tmp_buffer, bytes_encoded)
	case nil:
		encode_marker(5, tmp_buffer, bytes_encoded)
	default:
		return errors.New("Type not implemented")
	}
	return nil
}