// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package subtle_test

import (
	"encoding/hex"
	"testing"

	"github.com/tink-crypto/tink-go/v2/subtle"
)

func TestHKDFBasic(t *testing.T) {
	// Test vectors from RFC 5869, Appendix A.
	//
	// The name and desc fields align with the content from the RFC for easy
	// cross referencing.
	var tests = []struct {
		name    string
		desc    string
		hashAlg string
		key     string
		salt    string
		info    string
		tagSize uint32
		okm     string
	}{
		{
			name:    "TestCase1",
			desc:    "Basic test case with SHA-256",
			hashAlg: "SHA256",
			key:     "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
			salt:    "000102030405060708090a0b0c",
			info:    "f0f1f2f3f4f5f6f7f8f9",
			tagSize: 42,
			okm:     "3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865",
		},
		{
			name:    "TestCase2",
			desc:    "Test with SHA-256 and longer inputs/outputs",
			hashAlg: "SHA256",
			key: "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f" +
				"202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f" +
				"404142434445464748494a4b4c4d4e4f",
			salt: "606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f" +
				"808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f" +
				"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
			info: "b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecf" +
				"d0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeef" +
				"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
			tagSize: 82,
			okm: "b11e398dc80327a1c8e7f78c596a49344f012eda2d4efad8a050cc4c19afa97c" +
				"59045a99cac7827271cb41c65e590e09da3275600c2f09b8367793a9aca3db71" +
				"cc30c58179ec3e87c14c01d5c1f3434f1d87",
		},
		{
			name:    "TestCase3",
			desc:    "Test with SHA-256 and zero-length salt/info",
			hashAlg: "SHA256",
			key:     "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
			salt:    "",
			info:    "",
			tagSize: 42,
			okm: "8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d" +
				"9d201395faa4b61a96c8",
		},
		{
			name:    "TestCase4",
			desc:    "Basic test case with SHA-1",
			hashAlg: "SHA1",
			key:     "0b0b0b0b0b0b0b0b0b0b0b",
			salt:    "000102030405060708090a0b0c",
			info:    "f0f1f2f3f4f5f6f7f8f9",
			tagSize: 42,
			okm:     "085a01ea1b10f36933068b56efa5ad81a4f14b822f5b091568a9cdd4f155fda2c22e422478d305f3f896",
		},
		{
			name:    "TestCase5",
			desc:    "Test with SHA-1 and longer inputs/outputs",
			hashAlg: "SHA1",
			key: "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f" +
				"202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f" +
				"404142434445464748494a4b4c4d4e4f",
			salt: "606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f" +
				"808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f" +
				"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
			info: "b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecf" +
				"d0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeef" +
				"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
			tagSize: 82,
			okm: "0bd770a74d1160f7c9f12cd5912a06ebff6adcae899d92191fe4305673ba2ffe" +
				"8fa3f1a4e5ad79f3f334b3b202b2173c486ea37ce3d397ed034c7f9dfeb15c5e" +
				"927336d0441f4c4300e2cff0d0900b52d3b4",
		},
		{
			name:    "TestCase6",
			desc:    "Test with SHA-1 and zero-length salt/info",
			hashAlg: "SHA1",
			key:     "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
			salt:    "",
			info:    "",
			tagSize: 42,
			okm: "0ac1af7002b3d761d1e55298da9d0506b9ae52057220a306e07b6b87e8df21d0" +
				"ea00033de03984d34918",
		},
		{
			name:    "TestCase7",
			desc:    "Test with SHA-1, salt not provided (defaults to HashLen zero octets), zero-length info",
			hashAlg: "SHA1",
			key:     "0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c",
			salt:    "",
			info:    "",
			tagSize: 42,
			okm: "2c91117204d745f3500d636a62f64f0ab3bae548aa53d423b0d1f27ebba6f5e5" +
				"673a081d70cce7acfc48",
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			key, err := hex.DecodeString(test.key)
			if err != nil {
				t.Fatalf("%s\nhex.DecodeString(key) err = %v", test.desc, err)
			}
			salt, err := hex.DecodeString(test.salt)
			if err != nil {
				t.Fatalf("%s\nFailed decoding salt: %v", test.desc, err)
			}
			info, err := hex.DecodeString(test.info)
			if err != nil {
				t.Fatalf("%s\nFailed decoding info: %v", test.desc, err)
			}

			okm, err := subtle.ComputeHKDF(test.hashAlg, key, salt, info, test.tagSize)
			if err != nil {
				t.Errorf("%s\nsubtle.ComputeHKDF() err = %v, want nil", test.desc, err)
			}
			if got, want := hex.EncodeToString(okm), test.okm; got != want {
				t.Errorf("%s\nsubtle.ComputeHKDF() = %q, want %q", test.desc, got, want)
			}
		})
	}
}

func TestNewHMACWithInvalidInput(t *testing.T) {
	var tests = []struct {
		name    string
		hashAlg string
		tagSize uint32
	}{
		{
			name:    "invalid algorithm",
			hashAlg: "SHA0",
			tagSize: 32,
		},
		{
			name:    "tag too short",
			hashAlg: "SHA256",
			tagSize: 9,
		},
		{
			name:    "tag too big",
			hashAlg: "SHA512",
			tagSize: 16323,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			if _, err := subtle.ComputeHKDF(test.hashAlg, nil, nil, nil, test.tagSize); err == nil {
				t.Fatalf("subtle.ComputeHKDF(%q, nil, nil, nil, %d) err is nil, want not nil", test.hashAlg, test.tagSize)
			}
		})
	}
}
