package stomp

import (
	"bytes"
	"strconv"
)

const defaultHeaderLen = 5

type item struct {
	name []byte
	data []byte
}

// Header represents the header section of the STOMP message.
type Header struct {
	items []item
	itemc int
}

func newHeader() *Header {
	return &Header{
		items: make([]item, defaultHeaderLen),
	}
}

// Get returns the named header value.
func (h *Header) Get(name []byte) (b []byte) {
	for i := 0; i < h.itemc; i++ {
		if v := h.items[i]; bytes.Equal(v.name, name) {
			return v.data
		}
	}
	return
}

// GetString returns the named header value.
func (h *Header) GetString(name string) string {
	k := []byte(name)
	v := h.Get(k)
	return string(v)
}

// GetBool returns the named header value.
func (h *Header) GetBool(name string) bool {
	s := h.GetString(name)
	b, _ := strconv.ParseBool(s)
	return b
}

// GetInt returns the named header value.
func (h *Header) GetInt(name string) int {
	s := h.GetString(name)
	i, _ := strconv.Atoi(s)
	return i
}

// GetInt64 returns the named header value.
func (h *Header) GetInt64(name string) int64 {
	s := h.GetString(name)
	i, _ := strconv.ParseInt(s, 10, 64)
	return i
}

// Field returns the named header value in string format. This is used to
// provide compatibility with the SQL expression evaluation package.
func (h *Header) Field(name []byte) []byte {
	return h.Get(name)
}

// Add appens the key value pair to the header.
func (h *Header) Add(name, data []byte) {
	h.grow()
	h.items[h.itemc].name = name
	h.items[h.itemc].data = data
	h.itemc++
}

// Index returns the keypair at index i.
func (h *Header) Index(i int) (k, v []byte) {
	if i > h.itemc {
		return
	}
	k = h.items[i].name
	v = h.items[i].data
	return
}

// Len returns the header length.
func (h *Header) Len() int {
	return h.itemc
}

func (h *Header) grow() {
	if h.itemc > defaultHeaderLen-1 {
		h.items = append(h.items, item{})
	}
}

func (h *Header) reset() {
	h.itemc = 0
	h.items = h.items[:defaultHeaderLen]
	for i := range h.items {
		h.items[i].name = zeroBytes
		h.items[i].data = zeroBytes
	}
}

var zeroBytes []byte