using Robovoice.Core;

namespace Robovoice.Stt.File;

public sealed class FileSttSource : ISttSource
{
    private readonly object _lock = new();
    private string[] _lines = Array.Empty<string>();
    private int _currentIndex;
    private bool _disposed;

    public event TranscriptEventHandler? TranscriptReceived;

    public string FilePath { get; set; } = string.Empty;
    public int LineCount { get; private set; }
    public int CurrentIndex => _currentIndex;

    public void LoadFile(string path)
    {
        ObjectDisposedException.ThrowIf(_disposed, this);
        FilePath = path;
        _lines = System.IO.File.ReadAllLines(path);
        LineCount = _lines.Length;
        _currentIndex = 0;
    }

    public string? GetPendingLine()
    {
        lock (_lock)
        {
            if (_lines.Length == 0) return null;
            int idx = _currentIndex % _lines.Length;
            return _lines[idx];
        }
    }

    public void EmitNext()
    {
        ObjectDisposedException.ThrowIf(_disposed, this);
        string? line = null;
        lock (_lock)
        {
            if (_lines.Length > 0)
            {
                int idx = _currentIndex % _lines.Length;
                line = _lines[idx];
                _currentIndex++;
            }
        }

        if (!string.IsNullOrWhiteSpace(line))
        {
            TranscriptReceived?.Invoke(this, new TranscriptEventArgs
            {
                Message = new TranscriptMessage(TranscriptType.Final, line!),
            });
        }
    }

    public void Reset()
    {
        lock (_lock)
        {
            _currentIndex = 0;
        }
    }

    public Task StartAsync(CancellationToken ct = default)
    {
        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken ct = default)
    {
        return Task.CompletedTask;
    }

    public ValueTask DisposeAsync()
    {
        _disposed = true;
        return ValueTask.CompletedTask;
    }
}