using Google.Protobuf;
using Grpc.Core;
using Microsoft.Extensions.Logging;
using ZB.MOM.WW.Secrets.Abstractions;
using ZB.MOM.WW.Secrets.Replicator.Grpc.V1;

namespace ZB.MOM.WW.Secrets.Replicator.Grpc.Tests;

/// <summary>
/// A <see cref="CallInvoker"/> that answers the two hub RPCs from canned responses and records what
/// the client sent.
/// </summary>
/// <remarks>
/// This is what lets the tests drive the <b>real</b> <c>GrpcSecretsHubClient</c> — the generated
/// client accepts a <see cref="CallInvoker"/>, so substituting one exercises the header, the
/// deadline and the wire-to-domain conversion without a live server. A fake of the
/// <c>ISecretsHubReader</c> seam would bypass every one of those.
/// </remarks>
internal sealed class FakeSecretsHubCallInvoker : CallInvoker
{
    /// <summary>Response returned for <c>GetManifest</c>.</summary>
    public GetManifestResponse ManifestResponse { get; set; } = new();

    /// <summary>Response returned for <c>GetSecrets</c>.</summary>
    public GetSecretsResponse SecretsResponse { get; set; } = new();

    /// <summary>The options every call was invoked with, in call order.</summary>
    public List<CallOptions> Calls { get; } = [];

    /// <summary>The RPC names invoked, in call order.</summary>
    public List<string> Methods { get; } = [];

    /// <summary>The most recent <c>GetSecrets</c> request, so tests can assert what was asked for.</summary>
    public GetSecretsRequest? LastSecretsRequest { get; private set; }

    /// <summary>Returns the <c>Authorization</c> header value seen on the call at the given index.</summary>
    /// <param name="index">Zero-based call index.</param>
    /// <returns>The header value, or <see langword="null"/> when the header was not sent.</returns>
    public string? AuthorizationOn(int index) =>
        Calls[index].Headers?.GetValue("authorization");

    /// <inheritdoc />
    public override AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(
        Method<TRequest, TResponse> method, string? host, CallOptions options, TRequest request)
    {
        ArgumentNullException.ThrowIfNull(method);

        Calls.Add(options);
        Methods.Add(method.Name);

        if (request is GetSecretsRequest secretsRequest)
        {
            LastSecretsRequest = secretsRequest;
        }

        object response = method.Name switch
        {
            "GetManifest" => ManifestResponse,
            "GetSecrets" => SecretsResponse,
            _ => throw new InvalidOperationException($"unexpected RPC '{method.Name}'."),
        };

        return new AsyncUnaryCall<TResponse>(
            Task.FromResult((TResponse)response),
            Task.FromResult(new Metadata()),
            () => Status.DefaultSuccess,
            () => new Metadata(),
            () => { });
    }

    /// <inheritdoc />
    public override TResponse BlockingUnaryCall<TRequest, TResponse>(
        Method<TRequest, TResponse> method, string? host, CallOptions options, TRequest request) =>
        throw new NotSupportedException("The hub client only makes async unary calls.");

    /// <inheritdoc />
    public override AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(
        Method<TRequest, TResponse> method, string? host, CallOptions options, TRequest request) =>
        throw new NotSupportedException("The hub contract has no streaming RPC.");

    /// <inheritdoc />
    public override AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(
        Method<TRequest, TResponse> method, string? host, CallOptions options) =>
        throw new NotSupportedException("The hub contract has no streaming RPC.");

    /// <inheritdoc />
    public override AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(
        Method<TRequest, TResponse> method, string? host, CallOptions options) =>
        throw new NotSupportedException("The hub contract has no streaming RPC.");
}

/// <summary>A clock frozen at a caller-chosen instant, so a deadline assertion can be exact.</summary>
/// <param name="now">The instant every read returns.</param>
internal sealed class FixedTimeProvider(DateTimeOffset now) : TimeProvider
{
    /// <inheritdoc />
    public override DateTimeOffset GetUtcNow() => now;
}

/// <summary>Captures level and formatted message for every log entry.</summary>
/// <typeparam name="TCategory">The logger category.</typeparam>
internal sealed class RecordingLogger<TCategory> : ILogger<TCategory>
{
    /// <summary>Formatted messages logged at <see cref="LogLevel.Information"/>.</summary>
    public List<string> Information { get; } = [];

    /// <summary>Formatted messages logged at <see cref="LogLevel.Warning"/>.</summary>
    public List<string> Warnings { get; } = [];

    /// <summary>Count of information entries.</summary>
    public int InformationCount => Information.Count;

    /// <summary>Count of warning entries.</summary>
    public int WarningCount => Warnings.Count;

    /// <inheritdoc />
    public IDisposable? BeginScope<TState>(TState state) where TState : notnull => null;

    /// <inheritdoc />
    public bool IsEnabled(LogLevel logLevel) => true;

    /// <inheritdoc />
    public void Log<TState>(
        LogLevel logLevel,
        EventId eventId,
        TState state,
        Exception? exception,
        Func<TState, Exception?, string> formatter)
    {
        ArgumentNullException.ThrowIfNull(formatter);

        string message = formatter(state, exception);

        switch (logLevel)
        {
            case LogLevel.Information:
                Information.Add(message);
                break;
            case LogLevel.Warning:
                Warnings.Add(message);
                break;
            default:
                break;
        }
    }
}

/// <summary>Builders for well-formed wire messages that individual tests then damage.</summary>
internal static class TestWire
{
    /// <summary>A well-formed wire row.</summary>
    /// <param name="name">The secret name.</param>
    /// <param name="marker">A byte written into the ciphertext so the row is identifiable.</param>
    /// <returns>The wire row.</returns>
    public static SecretRow Row(string name, byte marker) => new()
    {
        Name = name,
        ContentType = nameof(SecretContentType.Text),
        Ciphertext = ByteString.CopyFrom(marker),
        Nonce = ByteString.CopyFrom((byte)1),
        Tag = ByteString.CopyFrom((byte)2),
        WrappedDek = ByteString.CopyFrom((byte)3),
        WrapNonce = ByteString.CopyFrom((byte)4),
        WrapTag = ByteString.CopyFrom((byte)5),
        KekId = "sha256:test",
        Revision = 0,
        IsDeleted = false,
        CreatedUtc = FixedInstant.ToString("O"),
        UpdatedUtc = FixedInstant.ToString("O"),
    };

    /// <summary>A well-formed manifest entry matching <see cref="Row"/>.</summary>
    /// <param name="name">The secret name.</param>
    /// <returns>The wire manifest entry.</returns>
    public static ManifestEntry Entry(string name) => new()
    {
        Name = name,
        Revision = 0,
        UpdatedUtc = FixedInstant.ToString("O"),
        IsDeleted = false,
    };

    /// <summary>The timestamp every builder stamps, so rows differ only where a test makes them differ.</summary>
    public static readonly DateTimeOffset FixedInstant =
        new(2026, 8, 7, 1, 2, 3, TimeSpan.Zero);
}