package main

import (
	"crypto/ecdh"
	"testing"
)

// The worked example from RFC 8291 §5. Reproducing it exactly pins every step
// of the derivation — the ECDH, both HKDF extractions, the record padding and
// the RFC 8188 header layout — against the spec rather than against ourselves.
func TestEncryptPayloadRFC8291Vector(t *testing.T) {
	const (
		plaintext    = "When I grow up, I want to be a watermelon"
		authSecret   = "BTBZMqHH6r4Tts7J_aSIgg"
		receiverPub  = "BCVxsr7N_eNgVRqvHtD0zTZsEc6-VV-JvLexhqUzORcxaOzi6-AYWXvTBHm4bjyPjs7Vd8pZGH6SRpkNtoIAiw4"
		senderPriv   = "yfWPiYE-n46HLnH0KqZOF1fJJU3MYrct3AELtAQ-oRw"
		saltB64      = "DGv6ra1nlYgDCS1FRnbzlw"
		wantCiphered = "DGv6ra1nlYgDCS1FRnbzlwAAEABBBP4z9KsN6nGRTbVYI_c7VJSPQTBtkgcy27ml" +
			"mlMoZIIgDll6e3vCYLocInmYWAmS6TlzAC8wEqKK6PBru3jl7A_yl95bQpu6cVPT" +
			"pK4Mqgkf1CXztLVBSt2Ks3oZwbuwXPXLWyouBWLVWGNWQexSgSxsj_Qulcy4a-fN"
	)

	var sub Subscription
	sub.Endpoint = "https://push.example.net/push/JzLQ3raZJfFBR0aqvOMsLrt54w4rJUsV"
	sub.Keys.P256dh = receiverPub
	sub.Keys.Auth = authSecret

	salt, err := b64.DecodeString(saltB64)
	if err != nil {
		t.Fatalf("decode salt: %v", err)
	}
	seed, err := b64.DecodeString(senderPriv)
	if err != nil {
		t.Fatalf("decode sender key: %v", err)
	}
	eph, err := ecdh.P256().NewPrivateKey(seed)
	if err != nil {
		t.Fatalf("sender key: %v", err)
	}

	got, err := encryptPayload(sub, []byte(plaintext), salt, eph)
	if err != nil {
		t.Fatalf("encryptPayload: %v", err)
	}
	if b64.EncodeToString(got) != wantCiphered {
		t.Errorf("ciphertext mismatch\n got: %s\nwant: %s", b64.EncodeToString(got), wantCiphered)
	}
}

// A VAPID key must survive the round trip through its on-disk form, since the
// public half is pinned by every subscription made while it was in use.
func TestVAPIDKeyRoundTrip(t *testing.T) {
	key, err := newVAPIDKey()
	if err != nil {
		t.Fatalf("generate: %v", err)
	}
	raw, err := key.marshal()
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}
	back, err := parseVAPIDKey(raw)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if back.Public != key.Public {
		t.Errorf("public key changed across round trip: %s != %s", back.Public, key.Public)
	}
	if _, err := back.authHeader("https://push.example.net/push/abc", vapidSubject); err != nil {
		t.Errorf("authHeader: %v", err)
	}
}