Playa/extensions/Volcanic.AgenticCore.Extensions.GoogleCalendar/GoogleCalendarOptions.cs

namespace Volcanic.AgenticCore.Extensions.GoogleCalendar;

/// <summary>
/// Configures the Google Calendar extension. The OAuth client is process-wide (one Google Cloud app for the bot);
/// accounts are per chat. Empty strings count as unset.
/// </summary>
public sealed record GoogleCalendarOptions
{
    /// <summary>OAuth client id (type "TVs and Limited Input devices"). Else <c>GOOGLE_CLIENT_ID</c>.</summary>
    public string? ClientId { get; init; }
    /// <summary>OAuth client secret. Else <c>GOOGLE_CLIENT_SECRET</c>.</summary>
    public string? ClientSecret { get; init; }
    /// <summary>
    /// Root of per-chat token directories (<c>&lt;root&gt;/&lt;chat key&gt;/token.json</c>). Unset (the default): each chat's token
    /// lives in its workspace, <c>&lt;cwd&gt;/.volcanic/google-calendar/token.json</c>.
    /// </summary>
    public string? TokenDirectory { get; init; }
    /// <summary>Environment lookup; defaults to <see cref="Environment.GetEnvironmentVariable(string)"/>.</summary>
    public Func<string, string?>? GetEnv { get; init; }
    /// <summary>HTTP client for Google; tests pass one over a fake handler.</summary>
    public HttpClient? Http { get; init; }
    /// <summary>Clock for polling and token expiry; tests pass a fake.</summary>
    public TimeProvider? Time { get; init; }
    /// <summary>Per-chat connection state. Defaults to <see cref="GoogleCalendarConnections.Shared"/>.</summary>
    public GoogleCalendarConnections? Connections { get; init; }

    private Func<string, string?> Env => GetEnv ?? Environment.GetEnvironmentVariable;

    internal string? EffectiveClientId => NonEmpty(ClientId) ?? NonEmpty(Env("GOOGLE_CLIENT_ID"));
    internal string? EffectiveClientSecret => NonEmpty(ClientSecret) ?? NonEmpty(Env("GOOGLE_CLIENT_SECRET"));

    /// <summary>True when both the client id and the secret are set (here or in the environment): the extension registers its tool and commands.</summary>
    public bool IsConfigured => EffectiveClientId is not null && EffectiveClientSecret is not null;

    /// <summary>The configured token root, or null to keep each chat's token in its workspace.</summary>
    internal string? EffectiveTokenDirectory => NonEmpty(TokenDirectory);

    /// <summary>The settings a connection needs, or null when the client id or secret is missing.</summary>
    internal GoogleCalendarSettings? Resolve() =>
        EffectiveClientId is { } id && EffectiveClientSecret is { } secret
            ? new GoogleCalendarSettings(id, secret, EffectiveTokenDirectory, Http ?? GoogleHttp.Default, Time ?? TimeProvider.System)
            : null;

    public override string ToString() =>
        $"GoogleCalendarOptions {{ ClientId = {ClientId}, ClientSecret = {(string.IsNullOrEmpty(ClientSecret) ? "" : "***")}, TokenDirectory = {TokenDirectory} }}";

    internal static string? NonEmpty(string? value) => string.IsNullOrWhiteSpace(value) ? null : value.Trim();
}

/// <summary>Resolved, validated configuration shared by every chat's connection.</summary>
internal sealed record GoogleCalendarSettings(string ClientId, string ClientSecret, string? TokenRoot, HttpClient Http, TimeProvider Time)
{
    public override string ToString() => $"GoogleCalendarSettings {{ ClientId = {ClientId}, TokenRoot = {TokenRoot} }}";
}

internal static class GoogleHttp
{
    /// <summary>One client for the process: connections of all chats share it.</summary>
    public static readonly HttpClient Default = new() { Timeout = TimeSpan.FromSeconds(60) };
}