// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

using System.Collections.Concurrent;

namespace McpServer;

public static class AskStatus
{
    public const string Pending = "pending";
    public const string Answered = "answered";
}

public static class ApprovalStatus
{
    public const string Pending = "pending";
    public const string Approved = "approved";
    public const string Rejected = "rejected";
}

// Immutable so readers always see a consistent (Status, Reply) snapshot — no locks,
// no Volatile, no torn state. Transitions go through ConcurrentDictionary.TryUpdate
// in State.PendingAsks: build a new record, swap atomically against the old one.
public sealed record PendingAsk(string UserId, string Status = AskStatus.Pending, string? Reply = null);

/// <summary>
/// In-memory state shared between the Teams bot handlers and the MCP tools.
/// A server restart clears everything — pending asks and approvals in flight will be lost.
/// </summary>
public sealed class State
{
    /// <summary>User AAD object id -> personal conversationId. Populated on first incoming 1:1 message.</summary>
    public ConcurrentDictionary<string, string> Conversations { get; } = new();

    /// <summary>requestId -> PendingAsk.</summary>
    public ConcurrentDictionary<string, PendingAsk> PendingAsks { get; } = new();

    /// <summary>approvalId -> approval status. Values: "pending", "approved", "rejected".</summary>
    public ConcurrentDictionary<string, string> Approvals { get; } = new();

    /// <summary>
    /// requestId -> TCS completed when the user replies (or the ask is superseded).
    /// Lets <c>wait_for_reply</c> return sub-millisecond after the answer lands instead of polling.
    /// </summary>
    public ConcurrentDictionary<string, TaskCompletionSource<PendingAsk>> ReplyWaiters { get; } = new();

    /// <summary>
    /// approvalId -> TCS completed with the final status when the user clicks Approve/Reject.
    /// Lets <c>wait_for_approval</c> return sub-millisecond after the decision lands instead of polling.
    /// </summary>
    public ConcurrentDictionary<string, TaskCompletionSource<string>> ApprovalWaiters { get; } = new();

    /// <summary>
    /// Service URL used by proactive sends and <c>conversations.create</c>. Updated from
    /// the first incoming activity; falls back to the default Teams endpoint until then.
    /// </summary>
    public Uri ServiceUrl { get; set; } = new Uri("https://smba.trafficmanager.net/teams/");
}