using Omika.Diagnostics.Security;

namespace Omika.Diagnostics.Tests;

/// <summary>Tests de la génération/hachage de la clé d'accès serveur client (T19, §27-§32).</summary>
public class DiagnosticApiKeyGeneratorTests
{
    [Fact]
    public void GenerateKey_HasPrefix_AndDecodesTo32Bytes()
    {
        string key = DiagnosticApiKeyGenerator.GenerateKey();

        Assert.StartsWith(DiagnosticApiKeyGenerator.KeyPrefix, key);
        string base64Url = key[DiagnosticApiKeyGenerator.KeyPrefix.Length..];
        byte[] bytes = DecodeBase64Url(base64Url);
        Assert.Equal(DiagnosticApiKeyGenerator.KeyBytes, bytes.Length);
    }

    [Fact]
    public void GenerateKey_ProducesUniqueKeys()
    {
        HashSet<string> keys = Enumerable.Range(0, 100).Select(_ => DiagnosticApiKeyGenerator.GenerateKey()).ToHashSet();
        Assert.Equal(100, keys.Count);
    }

    [Fact]
    public void Hash_IsDeterministic_And64HexChars()
    {
        string hash1 = DiagnosticApiKeyGenerator.Hash("omkdiag_test");
        string hash2 = DiagnosticApiKeyGenerator.Hash("omkdiag_test");

        Assert.Equal(hash1, hash2);
        Assert.Equal(64, hash1.Length);
        Assert.Matches("^[0-9A-F]{64}$", hash1);
    }

    [Fact]
    public void Verify_ReturnsTrue_ForMatchingKey()
    {
        string key = DiagnosticApiKeyGenerator.GenerateKey();
        string hash = DiagnosticApiKeyGenerator.Hash(key);

        Assert.True(DiagnosticApiKeyGenerator.Verify(key, hash));
    }

    [Fact]
    public void Verify_ReturnsFalse_ForWrongKey()
    {
        string hash = DiagnosticApiKeyGenerator.Hash("omkdiag_real_key");
        Assert.False(DiagnosticApiKeyGenerator.Verify("omkdiag_other_key", hash));
    }

    [Fact]
    public void Verify_ReturnsFalse_ForMalformedHash()
    {
        Assert.False(DiagnosticApiKeyGenerator.Verify("omkdiag_x", "not-a-hex-hash"));
    }

    [Fact]
    public void Verify_ReturnsFalse_ForEmptyInputs()
    {
        Assert.False(DiagnosticApiKeyGenerator.Verify("", "0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF"));
        Assert.False(DiagnosticApiKeyGenerator.Verify("omkdiag_x", ""));
    }

    [Fact]
    public void DisplayPrefix_ReturnsFirst8Chars()
    {
        string prefix = DiagnosticApiKeyGenerator.DisplayPrefix("omkdiag_abcdefgh", 8);
        Assert.Equal("omkdiag_", prefix);
        Assert.Equal(8, prefix.Length);
    }

    private static byte[] DecodeBase64Url(string value)
    {
        string base64 = value.Replace('-', '+').Replace('_', '/');
        switch (base64.Length % 4)
        {
            case 2: base64 += "=="; break;
            case 3: base64 += "="; break;
        }

        return Convert.FromBase64String(base64);
    }
}