FFMpegCore/FFMpegCore/FFMpeg/Arguments/MultiInputArgument.cs

namespace FFMpegCore.Arguments
{
    /// <summary>
    /// Represents input parameters for multiple files
    /// </summary>
    public class MultiInputArgument : IInputArgument
    {
        public readonly bool VerifyExists;
        public readonly IEnumerable<string> FilePaths;

        public MultiInputArgument(bool verifyExists, IEnumerable<string> filePaths)
        {
            VerifyExists = verifyExists;
            FilePaths = filePaths;
        }

        public MultiInputArgument(IEnumerable<string> filePaths, bool verifyExists) : this(verifyExists, filePaths) { }

        public void Pre()
        {
            if (VerifyExists)
            {
                var missingFiles = new List<string>();
                foreach (var filePath in FilePaths)
                {
                    if (!File.Exists(filePath))
                    {
                        missingFiles.Add(filePath);
                    }
                }

                if (missingFiles.Any())
                {
                    throw new FileNotFoundException($"The following input files were not found: {string.Join(", ", missingFiles)}");
                }
            }
        }

        public Task During(CancellationToken cancellationToken = default) => Task.CompletedTask;
        public void Post() { }

        /// <summary>
        /// Generates a combined input argument text for all file paths
        /// </summary>
        public string Text => string.Join(" ", FilePaths.Select(filePath => $"-i \"{filePath}\""));
    }
}