using Microsoft.Extensions.Logging;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config;
using ZB.MOM.WW.Secrets.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests;

/// <summary>
///     Follow-up #2 + G-2a — pins the five resolution forms supported by
///     <see cref="GalaxySecretRef.ResolveApiKeyAsync"/>: <c>env:NAME</c>, <c>file:PATH</c>,
///     <c>dev:KEY</c>, <c>secret:NAME</c> (via the shared <see cref="ISecretResolver"/>), and
///     the literal-string fallback. The <c>secret:</c> arm is fail-closed — an absent secret
///     throws rather than leaking the ref string as the key. (The resolver was extracted from
///     <c>GalaxyDriver</c> to the shared <c>GalaxySecretRef</c> in Driver.Galaxy.Contracts so the
///     runtime driver and the AdminUI browser share one copy.)
/// </summary>
public sealed class GalaxyDriverApiKeyResolverTests
{
    /// <summary>Name the fake resolver knows; matches the SecretName-normalized form.</summary>
    private const string KnownSecretName = "galaxy/inst1/apikey";

    /// <summary>The value the fake resolver returns for <see cref="KnownSecretName"/>.</summary>
    private const string KnownSecretValue = "key-from-secret-store";

    /// <summary>A fake resolver: returns a known value for one known name, null otherwise.</summary>
    private static ISecretResolver FakeResolver() => new StubSecretResolver();

    /// <summary>Verifies that a literal string is returned unchanged.</summary>
    [Fact]
    public async Task Literal_string_is_returned_unchanged()
    {
        (await GalaxySecretRef.ResolveApiKeyAsync("plain-text-key", FakeResolver()))
            .ShouldBe("plain-text-key");
    }

    /// <summary>Verifies that env: prefix resolves to an environment variable.</summary>
    [Fact]
    public async Task Env_prefix_resolves_to_environment_variable()
    {
        const string name = "OTOPCUA_TEST_GALAXY_API_KEY";
        Environment.SetEnvironmentVariable(name, "key-from-env");
        try
        {
            (await GalaxySecretRef.ResolveApiKeyAsync($"env:{name}", FakeResolver()))
                .ShouldBe("key-from-env");
        }
        finally
        {
            Environment.SetEnvironmentVariable(name, null);
        }
    }

    /// <summary>Verifies that unset environment variables throw with a descriptive message.</summary>
    [Fact]
    public async Task Env_prefix_unset_variable_throws_with_descriptive_message()
    {
        const string name = "OTOPCUA_TEST_GALAXY_API_KEY_UNSET";
        Environment.SetEnvironmentVariable(name, null);

        var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
            GalaxySecretRef.ResolveApiKeyAsync($"env:{name}", FakeResolver()));
        ex.Message.ShouldContain(name);
        ex.Message.ShouldContain("unset");
    }

    /// <summary>Verifies that file: prefix resolves to trimmed file contents.</summary>
    [Fact]
    public async Task File_prefix_resolves_to_trimmed_file_contents()
    {
        var path = Path.Combine(Path.GetTempPath(), $"galaxy-key-{Guid.NewGuid():N}.txt");
        File.WriteAllText(path, "  key-from-file  \n");
        try
        {
            (await GalaxySecretRef.ResolveApiKeyAsync($"file:{path}", FakeResolver()))
                .ShouldBe("key-from-file");
        }
        finally
        {
            File.Delete(path);
        }
    }

    /// <summary>Verifies that file: prefix with missing path throws.</summary>
    [Fact]
    public async Task File_prefix_missing_path_throws()
    {
        var path = Path.Combine(Path.GetTempPath(), $"does-not-exist-{Guid.NewGuid():N}.txt");
        var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
            GalaxySecretRef.ResolveApiKeyAsync($"file:{path}", FakeResolver()));
        ex.Message.ShouldContain(path);
        ex.Message.ShouldContain("doesn't exist");
    }

    // ===== G-2a: secret: arm — resolves through the shared ISecretResolver, fail-closed =====

    /// <summary>Verifies that secret: prefix resolves through the ISecretResolver.</summary>
    [Fact]
    public async Task Secret_prefix_resolves_through_secret_resolver()
    {
        (await GalaxySecretRef.ResolveApiKeyAsync($"secret:{KnownSecretName}", FakeResolver()))
            .ShouldBe(KnownSecretValue);
    }

    /// <summary>Verifies that an absent secret throws (fail-closed) and does NOT leak the ref string.</summary>
    [Fact]
    public async Task Secret_prefix_absent_secret_throws_fail_closed()
    {
        const string missingRef = "secret:galaxy/missing/apikey";

        var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
            GalaxySecretRef.ResolveApiKeyAsync(missingRef, FakeResolver()));

        // Fail-closed: must throw, must reference the secret + "absent"/"fail-closed", and
        // must NOT return the ref string as the key.
        ex.Message.ShouldContain("galaxy/missing/apikey");
        ex.Message.ShouldContain("absent");
    }

    /// <summary>Verifies that the secret: arm does not consult the logger's literal warning.</summary>
    [Fact]
    public async Task Secret_prefix_does_not_emit_literal_warning()
    {
        var logger = new CaptureLogger();
        await GalaxySecretRef.ResolveApiKeyAsync($"secret:{KnownSecretName}", FakeResolver(), logger);
        logger.Entries.ShouldNotContain(e => e.Level == LogLevel.Warning);
    }

    // ===== Driver.Galaxy-010 regression: literal arm warns + dev: prefix path =====

    /// <summary>Verifies that literal strings emit a warning when a logger is supplied.</summary>
    [Fact]
    public async Task Literal_string_emits_warning_when_logger_supplied()
    {
        // A literal API key on a production deployment means the cleartext key sits
        // in the DriverConfig JSON. The resolver must surface a warning so an
        // operator who committed one by accident sees it at startup.
        var logger = new CaptureLogger();
        var key = await GalaxySecretRef.ResolveApiKeyAsync("plain-text-key", FakeResolver(), logger);

        key.ShouldBe("plain-text-key");
        logger.Entries.ShouldContain(e =>
            e.Level == LogLevel.Warning && e.Message.Contains("literal", StringComparison.OrdinalIgnoreCase));
    }

    /// <summary>Verifies that dev: prefix returns literal text without emitting warnings.</summary>
    [Fact]
    public async Task Dev_prefix_returns_literal_without_warning()
    {
        // An explicit dev: prefix signals the operator knowingly opted into a literal
        // key (dev / parity rig). The resolver must accept it AND suppress the
        // warning so production logs aren't polluted on a deliberate dev choice.
        var logger = new CaptureLogger();
        var key = await GalaxySecretRef.ResolveApiKeyAsync("dev:plain-text-key", FakeResolver(), logger);

        key.ShouldBe("plain-text-key");
        logger.Entries.ShouldNotContain(e => e.Level == LogLevel.Warning);
    }

    /// <summary>Verifies that env: prefix does not emit literal string warnings.</summary>
    [Fact]
    public async Task Env_prefix_does_not_emit_literal_warning()
    {
        const string name = "OTOPCUA_TEST_GALAXY_API_KEY_NOWARN";
        Environment.SetEnvironmentVariable(name, "v");
        try
        {
            var logger = new CaptureLogger();
            await GalaxySecretRef.ResolveApiKeyAsync($"env:{name}", FakeResolver(), logger);
            logger.Entries.ShouldNotContain(e => e.Level == LogLevel.Warning);
        }
        finally
        {
            Environment.SetEnvironmentVariable(name, null);
        }
    }

    /// <summary>Verifies that a null resolver is rejected (ArgumentNullException).</summary>
    [Fact]
    public async Task Null_resolver_throws()
    {
        await Should.ThrowAsync<ArgumentNullException>(() =>
            GalaxySecretRef.ResolveApiKeyAsync("plain-text-key", resolver: null!));
    }

    /// <summary>A test logger that captures log entries for verification.</summary>
    private sealed class CaptureLogger : ILogger
    {
        /// <summary>Gets the list of captured log entries with their levels and messages.</summary>
        public List<(LogLevel Level, string Message)> Entries { get; } = new();

        /// <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)
            => Entries.Add((logLevel, formatter(state, exception)));
    }

    /// <summary>A fake ISecretResolver returning one known value; null for every other name.</summary>
    private sealed class StubSecretResolver : ISecretResolver
    {
        /// <inheritdoc />
        public Task<string?> GetAsync(SecretName name, CancellationToken ct) =>
            Task.FromResult<string?>(
                string.Equals(name.Value, KnownSecretName, StringComparison.Ordinal)
                    ? KnownSecretValue
                    : null);
    }

    /// <summary>Verifies that file: prefix with empty file throws.</summary>
    [Fact]
    public async Task File_prefix_empty_file_throws()
    {
        var path = Path.Combine(Path.GetTempPath(), $"galaxy-key-empty-{Guid.NewGuid():N}.txt");
        File.WriteAllText(path, "   \n  ");
        try
        {
            var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
                GalaxySecretRef.ResolveApiKeyAsync($"file:{path}", FakeResolver()));
            ex.Message.ShouldContain("empty");
        }
        finally
        {
            File.Delete(path);
        }
    }
}