package forward

import "net/http"

var superviseAllowedHeaders = []string{
	"Content-Type",
	"X-Ca-Appkey",
	"X-Ca-Encryption",
	"X-Ca-Nonce",
	"X-Ca-Timestamp",
	"X-Service-Id",
	"X-Service-Method",
	"X-Ca-Signature",
	"requestBody",
}

var fileAllowedHeaders = []string{
	"Content-Type",
	"X-Authorization",
}

func allowedHeaderSet(kind string) map[string]struct{} {
	list := superviseAllowedHeaders
	if kind == "file" {
		list = fileAllowedHeaders
	}
	set := make(map[string]struct{}, len(list))
	for _, name := range list {
		set[http.CanonicalHeaderKey(name)] = struct{}{}
	}
	return set
}

func copyAllowedHeaders(dst, src http.Header, kind string) {
	allow := allowedHeaderSet(kind)
	for key, values := range src {
		if _, ok := allow[http.CanonicalHeaderKey(key)]; !ok {
			continue
		}
		for _, v := range values {
			dst.Add(key, v)
		}
	}
}