package x25519

import (
	"bytes"
	"encoding/hex"
	"testing"
)

var (
	// Test vector from https://tools.ietf.org/html/rfc7748#section-6.1
	aliceSK      = "77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a"
	alicePK      = "8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a"
	bobSK        = "5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb"
	bobPK        = "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f"
	sharedSecret = "4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742"
)

func TestStardardKey(t *testing.T) {
	askhex, err := hex.DecodeString(aliceSK)
	if err != nil {
		t.Fatal(err)
	}

	ask := Get(askhex)
	apk := ask.Public()
	if alicePK != hex.EncodeToString(apk[:]) {
		t.Fatal("public key failed")
	}

	bskhex, err := hex.DecodeString(bobSK)
	if err != nil {
		t.Fatal(err)
	}

	bsk := Get(bskhex)
	bpk := bsk.Public()
	if bobPK != hex.EncodeToString(bpk[:]) {
		t.Fatal("public key failed")
	}

	s1, err := ask.Shared(bpk)
	if err != nil {
		t.Fatal(err)
	}
	s2, err := bsk.Shared(apk)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(s1, s2) {
		t.Fatal("shared secret failed")
	}
	if hex.EncodeToString(s1) != sharedSecret {
		t.Fatal("shared secret failed")
	}
}

func TestGenerateKey(t *testing.T) {
	for i := 0; i < 100; i++ {
		ourSK, _ := New(nil)
		theirSK, _ := New(nil)
		s1, err := ourSK.Shared(theirSK.Public())
		if err != nil {
			t.Fatal(err)
		}
		s2, err := theirSK.Shared(ourSK.Public())
		if err != nil {
			t.Fatal(err)
		}
		if !bytes.Equal(s1, s2) {
			t.Fatal("computed shared secrets differs")
		}
	}
}