using Telegram.Bot.Types;
using Volcanic.AgenticCore.Extensions.Mcp.Remote;
using Volcanic.AgenticCore.Features.Extensions;
using Volcanic.AgenticCore.Features.Processes;

namespace Volcanic.AgenticCore.Telegram;

/// <summary>
/// Remote MCP servers per chat (<see cref="RemoteMcpExtension"/>). Keys are sealed with <c>MCP_ENCRYPTION_SECRET</c>, or
/// the bot token when that is unset; agent processes see neither (both match the default deny-list).
/// </summary>
public static class RemoteMcpSetup
{
    public const string SecretVariable = "MCP_ENCRYPTION_SECRET";

    public static readonly IReadOnlyList<BotCommand> Menu =
    [
        new() { Command = "mcp_list", Description = "Remote MCP servers of this chat" },
        new() { Command = "mcp_add", Description = "Add an MCP server: /mcp_add <name> <url>" },
        new() { Command = "mcp_remove", Description = "Remove an MCP server: /mcp_remove <name>" },
        new() { Command = "mcp_tools", Description = "Show or limit a server's tools" },
    ];

    public const string HelpLines =
        "\n/mcp_list, /mcp_add <name> <url>, /mcp_remove <name>, /mcp_tools <name> [a,b|all] – this chat's remote MCP servers";

    public static IReadOnlyList<BotCommand> MenuFor(IReadOnlyList<BotCommand> menu) => [.. menu, .. Menu];

    /// <summary>The dedicated secret, else the bot token. Adds the dedicated one to the redacted secret values.</summary>
    public static RemoteMcpOptions Options(TelegramOptions telegram, Func<string, string?> getEnv, ProcessEnvironmentOptions processEnvironment)
    {
        ArgumentNullException.ThrowIfNull(telegram);
        ArgumentNullException.ThrowIfNull(getEnv);
        ArgumentNullException.ThrowIfNull(processEnvironment);
        var dedicated = getEnv(SecretVariable) is { } value && !string.IsNullOrWhiteSpace(value) ? value.Trim() : null;
        if (dedicated is not null) processEnvironment.SecretValues.Add(dedicated);
        return new RemoteMcpOptions { Secret = dedicated ?? (string.IsNullOrWhiteSpace(telegram.BotToken) ? null : telegram.BotToken) };
    }

    public static string Describe(Func<string, string?> getEnv) =>
        string.IsNullOrWhiteSpace(getEnv(SecretVariable))
            ? $"Remote MCP: keys sealed with the bot token (set {SecretVariable} to keep them across a token change)"
            : $"Remote MCP: keys sealed with {SecretVariable}";

    /// <summary>A command whose message holds a key: the router deletes it from the chat after handing it over.</summary>
    public static bool CarriesKey(string command, string args) =>
        command == "mcp_add" && (args.Contains("--bearer", StringComparison.Ordinal) || args.Contains("--header", StringComparison.Ordinal));

    /// <summary>A new extension instance per chat session.</summary>
    public static ExtensionRegistration Registration(RemoteMcpOptions options) =>
        new(RemoteMcpExtension.ExtensionName, _ => new RemoteMcpExtension(options), "telegram");
}