using Volcanic.AgenticCore.Telegram.Speech;
using Volcanic.AgenticCore.Telegram.Triggers;

namespace Volcanic.AgenticCore.Telegram;

/// <summary>The <c>Telegram</c> configuration section.</summary>
public sealed class TelegramOptions
{
    public const string SectionName = "Telegram";
    public const string DefaultModel = "claude-code/claude-opus-5-5";

    /// <summary>Bot token from @BotFather. Also read from <c>TELEGRAM_BOT_TOKEN</c>.</summary>
    public string BotToken { get; set; } = "";

    /// <summary>Telegram user ids allowed to talk to the bot. Required: the agent runs shell commands.</summary>
    public List<long> AllowedUserIds { get; set; } = [];

    /// <summary>
    /// The Telegram user id that may run <c>/impersonate &lt;user_id&gt;</c> (see <see cref="Chats.Impersonation"/>); null
    /// turns the command off. Also read from <c>ADMIN_USER_ID</c>.
    /// </summary>
    public long? AdminUserId { get; set; }

    /// <summary>Each chat works in <c>&lt;WorkspaceRoot&gt;/&lt;chatId&gt;</c>.</summary>
    public string WorkspaceRoot { get; set; } = Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".volcanic", "telegram-workspaces");

    /// <summary><c>provider/model-id</c> every chat uses.</summary>
    public string Model { get; set; } = DefaultModel;

    /// <summary>Minimum time between two edits of a streaming reply (Telegram rate-limits edits).</summary>
    public TimeSpan EditInterval { get; set; } = TimeSpan.FromSeconds(1.5);

    /// <summary>How often the "typing…" action is repeated while the agent runs (Telegram shows it for 5 s).</summary>
    public TimeSpan TypingInterval { get; set; } = TimeSpan.FromSeconds(4);

    /// <summary>
    /// How long a chat's inbox waits after a message for more before sending the batch to the agent as one request (a
    /// forward and its comment, an album). Zero sends on the next timer tick.
    /// </summary>
    public TimeSpan InputDebounce { get; set; } = TimeSpan.FromMilliseconds(600);

    /// <summary>First delay after a failed poll; doubles per consecutive failure up to <see cref="ReconnectMaxDelay"/>.</summary>
    public TimeSpan ReconnectInitialDelay { get; set; } = TimeSpan.FromSeconds(1);

    public TimeSpan ReconnectMaxDelay { get; set; } = TimeSpan.FromSeconds(60);

    /// <summary>Image documents up to this size are also shown to the model inline (base64 stays under providers' 5 MB cap).</summary>
    public long InlineImageMaxBytes { get; set; } = 3_750_000;

    /// <summary>Speech to text for voice notes and audio (<c>Telegram:Speech</c>).</summary>
    public SpeechOptions Speech { get; set; } = new();

    /// <summary>Group watching with Jev topic triggers (<c>Telegram:Triggers</c>); off without an OpenRouter key.</summary>
    public TriggerOptions Triggers { get; set; } = new();

    /// <summary>IANA zone for chats that haven't set one with <c>/timezone</c>; empty = the machine's zone. Also <c>DEFAULT_TIMEZONE</c>.</summary>
    public string? DefaultTimeZone { get; set; }

    /// <summary>The configured default zone, or null when unset (then <see cref="TimeZoneInfo.Local"/> applies).</summary>
    public TimeZoneInfo? ConfiguredTimeZone() =>
        !string.IsNullOrWhiteSpace(DefaultTimeZone) && Chats.ChatTimeZones.TryParse(DefaultTimeZone, out var zone, out _) ? zone : null;

    /// <summary>Reads the environment-variable shortcuts the README documents, when the section leaves them empty.</summary>
    public void ApplyEnvironment(Func<string, string?> getEnv)
    {
        if (string.IsNullOrWhiteSpace(BotToken)) BotToken = getEnv("TELEGRAM_BOT_TOKEN") ?? "";
        if (AllowedUserIds.Count == 0 && getEnv("TELEGRAM_ALLOWED_USER_IDS") is { Length: > 0 } ids)
        {
            foreach (var part in ids.Split([',', ';', ' '], StringSplitOptions.RemoveEmptyEntries))
                if (long.TryParse(part, out var id)) AllowedUserIds.Add(id);
        }

        if (AdminUserId is null && long.TryParse(getEnv("ADMIN_USER_ID")?.Trim(), out var admin)) AdminUserId = admin;

        // Speech: the environment fills only empty settings, and an empty variable counts as unset.
        Speech ??= new SpeechOptions();
        if (string.IsNullOrWhiteSpace(Speech.ApiKey) && getEnv("OPENAI_API_KEY") is { } key && !string.IsNullOrWhiteSpace(key))
            Speech.ApiKey = key.Trim();
        if (string.IsNullOrWhiteSpace(Speech.Model) && getEnv("STT_MODEL") is { } model && !string.IsNullOrWhiteSpace(model))
            Speech.Model = model.Trim();
        Triggers ??= new TriggerOptions();
        Triggers.ApplyEnvironment(getEnv);
        if (string.IsNullOrWhiteSpace(DefaultTimeZone) && getEnv("DEFAULT_TIMEZONE") is { } tz && !string.IsNullOrWhiteSpace(tz))
            DefaultTimeZone = tz.Trim();
    }

    /// <summary>Configuration problems that must stop the host, empty when valid.</summary>
    public IReadOnlyList<string> Validate()
    {
        var errors = new List<string>();
        if (string.IsNullOrWhiteSpace(BotToken))
            errors.Add("Telegram bot token is missing: set TELEGRAM_BOT_TOKEN or Telegram:BotToken.");
        if (AllowedUserIds.Count == 0)
            errors.Add("No allowed users: set TELEGRAM_ALLOWED_USER_IDS (comma separated) or Telegram:AllowedUserIds. " +
                       "The bot runs shell commands, so it refuses to start open to everyone.");
        if (AdminUserId is <= 0) errors.Add("Telegram:AdminUserId (ADMIN_USER_ID) must be a positive Telegram user id.");
        if (string.IsNullOrWhiteSpace(WorkspaceRoot)) errors.Add("Telegram:WorkspaceRoot is empty.");
        if (string.IsNullOrWhiteSpace(Model) || !Model.Contains('/')) errors.Add("Telegram:Model must be 'provider/model-id'.");
        if (EditInterval <= TimeSpan.Zero || TypingInterval <= TimeSpan.Zero) errors.Add("Telegram intervals must be positive.");
        if (ReconnectInitialDelay <= TimeSpan.Zero || ReconnectMaxDelay < ReconnectInitialDelay)
            errors.Add("Telegram reconnect delays must be positive with max >= initial.");
        if (InputDebounce < TimeSpan.Zero) errors.Add("Telegram:InputDebounce must not be negative.");
        if (InlineImageMaxBytes <= 0) errors.Add("Telegram:InlineImageMaxBytes must be positive.");
        // On Linux "/v1" parses as an absolute file:// URI; the scheme check rejects it.
        if (!Uri.TryCreate(Speech?.BaseUrl, UriKind.Absolute, out var sttUri) || sttUri.Scheme is not ("http" or "https"))
            errors.Add("Telegram:Speech:BaseUrl must be an absolute http(s) URL.");
        if (!string.IsNullOrWhiteSpace(DefaultTimeZone) && !Chats.ChatTimeZones.TryParse(DefaultTimeZone, out _, out var zoneError))
            errors.Add("Telegram:DefaultTimeZone: " + zoneError);
        (Triggers ?? new TriggerOptions()).Validate(errors);
        return errors;
    }

    public bool IsAllowed(long? userId) => userId is { } id && AllowedUserIds.Contains(id);
}