// libnmdc project libnmdc.go
package libnmdc

import (
	"errors"
	"fmt"
	"regexp"
	"strings"
	"time"
)

const (
	DEFAULT_CLIENT_TAG   string        = "libnmdc.go"
	DEFAULT_HUB_NAME     string        = "(unknown)"
	SEND_KEEPALIVE_EVERY time.Duration = 29 * time.Second
	AUTO_RECONNECT_AFTER time.Duration = 30 * time.Second
)

var rx_protocolMessage *regexp.Regexp
var rx_publicChat *regexp.Regexp
var rx_incomingTo *regexp.Regexp
var ErrNotConnected error = errors.New("Not connected")

func init() {
	rx_protocolMessage = regexp.MustCompile("(?ms)^[^|]*\\|")
	rx_publicChat = regexp.MustCompile("(?ms)^<([^>]*)> (.*)$")
	rx_incomingTo = regexp.MustCompile("(?ms)^([^ ]+) From: ([^ ]+) \\$<([^>]*)> (.*)")
}

func NMDCUnescape(encoded string) string {
	v1 := strings.Replace(encoded, "&#36;", "$", -1)
	v2 := strings.Replace(v1, "&#124;", "|", -1)
	return strings.Replace(v2, "&amp;", "&", -1)
}

func NMDCEscape(plaintext string) string {
	v1 := strings.Replace(plaintext, "&", "&amp;", -1)
	v2 := strings.Replace(v1, "|", "&#124;", -1)
	return strings.Replace(v2, "$", "&#36;", -1)
}

func NMDCUnlock(lock []byte) string {

	nibble_swap := func(b byte) byte {
		return ((b << 4) & 0xF0) | ((b >> 4) & 0x0F)
	}

	chr := func(b byte) string {
		if b == 0 || b == 5 || b == 36 || b == 96 || b == 124 || b == 126 {
			return fmt.Sprintf("/%%DCN%04d%%/", b)
		} else {
			return string(b)
		}
	}

	key := chr(nibble_swap(lock[0] ^ lock[len(lock)-2] ^ lock[len(lock)-3] ^ 5))
	for i := 1; i < len(lock); i += 1 {
		key += chr(nibble_swap(lock[i] ^ lock[i-1]))
	}

	return key
}