package web

// Header represents an HTTP header with key and value
type Header struct {
	Key   string
	Value string
}

// Common HTTP header keys
const (
	HeaderContentType      = "Content-Type"
	HeaderContentLength    = "Content-Length"
	HeaderHost             = "Host"
	HeaderAccept           = "Accept"
	HeaderUserAgent        = "User-Agent"
	HeaderAcceptEncoding   = "Accept-Encoding"
	HeaderAcceptLanguage   = "Accept-Language"
	HeaderConnection       = "Connection"
	HeaderCookie           = "Cookie"
	HeaderSetCookie        = "Set-Cookie"
	HeaderLocation         = "Location"
	HeaderAuthorization    = "Authorization"
	HeaderCacheControl     = "Cache-Control"
	HeaderOrigin           = "Origin"
	HeaderReferer          = "Referer"
	HeaderTransferEncoding = "Transfer-Encoding"
)

// Pre-allocated common headers
var (
	// Content type headers
	HeaderContentTypeJSON      = Header{Key: HeaderContentType, Value: "application/json"}
	HeaderContentTypeHTML      = Header{Key: HeaderContentType, Value: "text/html"}
	HeaderContentTypePlain     = Header{Key: HeaderContentType, Value: "text/plain"}
	HeaderContentTypeXML       = Header{Key: HeaderContentType, Value: "application/xml"}
	HeaderContentTypeForm      = Header{Key: HeaderContentType, Value: "application/x-www-form-urlencoded"}
	HeaderContentTypeMultipart = Header{Key: HeaderContentType, Value: "multipart/form-data"}

	// Connection headers
	HeaderConnectionClose     = Header{Key: HeaderConnection, Value: "close"}
	HeaderConnectionKeepAlive = Header{Key: HeaderConnection, Value: "keep-alive"}
)

// FindHeader looks for a header by key in a slice of headers
func FindHeader(headers []Header, key string) (string, bool) {
	for _, h := range headers {
		if h.Key == key {
			return h.Value, true
		}
	}
	return "", false
}

// SetHeader sets a header value in a slice of headers
func SetHeader(headers *[]Header, key string, value string) {
	for i, h := range *headers {
		if h.Key == key {
			(*headers)[i].Value = value
			return
		}
	}
	*headers = append(*headers, Header{Key: key, Value: value})
}