using System.IO;

namespace GermanApp.Domain.Interfaces;

/// <summary>
/// Domain interface for Coqui TTS text-to-speech service.
/// This is part of the Domain layer.
/// </summary>
public interface ITtsService
{
    /// <summary>
    /// Generates audio from text.
    /// </summary>
    /// <param name="text">Text to convert to speech</param>
    /// <param name="speaker">Speaker ID/voice (optional)</param>
    /// <param name="language">Language code (default: de)</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Audio data as bytes</returns>
    Task<byte[]> GenerateAudioAsync(
        string text,
        string? speaker = null,
        string language = "de",
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Generates audio and saves to a file.
    /// </summary>
    /// <param name="text">Text to convert to speech</param>
    /// <param name="outputPath">Path to save the audio file</param>
    /// <param name="speaker">Speaker ID/voice (optional)</param>
    /// <param name="language">Language code (default: de)</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Path to the generated audio file</returns>
    Task<string> GenerateAudioToFileAsync(
        string text,
        string outputPath,
        string? speaker = null,
        string language = "de",
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Generates audio as a stream.
    /// </summary>
    /// <param name="text">Text to convert to speech</param>
    /// <param name="speaker">Speaker ID/voice (optional)</param>
    /// <param name="language">Language code (default: de)</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Audio stream</returns>
    Task<Stream> GenerateAudioStreamAsync(
        string text,
        string? speaker = null,
        string language = "de",
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Tests the Coqui TTS model and configuration.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>True if model is loaded and working</returns>
    Task<bool> TestModelAsync(CancellationToken cancellationToken = default);

    /// <summary>
    /// Gets the current TTS model information.
    /// </summary>
    /// <returns>Model name and path</returns>
    Task<(string ModelName, string? ModelPath)> GetModelInfoAsync();

    /// <summary>
    /// Gets list of available voices/speakers for the current model.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of available speaker IDs</returns>
    Task<IReadOnlyList<string>> GetAvailableSpeakersAsync(CancellationToken cancellationToken = default);

    /// <summary>
    /// Cleans up old audio files from storage.
    /// </summary>
    /// <param name="olderThan">Delete files older than this timespan</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Number of files deleted</returns>
    Task<int> CleanupOldFilesAsync(
        TimeSpan olderThan,
        CancellationToken cancellationToken = default);
}