ersatztv/ErsatzTV.Core/FFmpeg/SubtitleBuilder.cs

using System.IO;
using System.Text;
using System.Threading.Tasks;
using ErsatzTV.Core.Interfaces.FFmpeg;
using LanguageExt;
using static LanguageExt.Prelude;

namespace ErsatzTV.Core.FFmpeg
{
    public class SubtitleBuilder
    {
        private readonly ITempFilePool _tempFilePool;
        private string _content;
        private Option<IDisplaySize> _resolution = None;
        private Option<string> _fontName;
        private Option<int> _fontSize;
        private Option<string> _primaryColor;
        private Option<string> _outlineColor;
        private Option<int> _alignment;
        private int _marginRight;
        private int _marginLeft;
        private int _marginV;
        private Option<int> _borderStyle;
        private Option<int> _shadow;

        public SubtitleBuilder(ITempFilePool tempFilePool)
        {
            _tempFilePool = tempFilePool;
        }

        public SubtitleBuilder WithResolution(IDisplaySize resolution)
        {
            _resolution = Some(resolution);
            return this;
        }

        public SubtitleBuilder WithFontName(string fontName)
        {
            _fontName = fontName;
            return this;
        }

        public SubtitleBuilder WithFontSize(int fontSize)
        {
            _fontSize = fontSize;
            return this;
        }

        public SubtitleBuilder WithPrimaryColor(string primaryColor)
        {
            _primaryColor = primaryColor;
            return this;
        }

        public SubtitleBuilder WithOutlineColor(string outlineColor)
        {
            _outlineColor = outlineColor;
            return this;
        }

        public SubtitleBuilder WithAlignment(int alignment)
        {
            _alignment = alignment;
            return this;
        }

        public SubtitleBuilder WithMarginRight(int marginRight)
        {
            _marginRight = marginRight;
            return this;
        }

        public SubtitleBuilder WithMarginLeft(int marginLeft)
        {
            _marginLeft = marginLeft;
            return this;
        }
        
        public SubtitleBuilder WithMarginV(int marginV)
        {
            _marginV = marginV;
            return this;
        }

        public SubtitleBuilder WithBorderStyle(int borderStyle)
        {
            _borderStyle = borderStyle;
            return this;
        }

        public SubtitleBuilder WithShadow(int shadow)
        {
            _shadow = shadow;
            return this;
        }

        public SubtitleBuilder WithFormattedContent(string content)
        {
            _content = content;
            return this;
        }
        
        public async Task<string> BuildFile()
        {
            string fileName = _tempFilePool.GetNextTempFile(TempFileCategory.Subtitle);

            var sb = new StringBuilder();
            sb.AppendLine("[Script Info]");
            sb.AppendLine("ScriptType: v4.00+");
            sb.AppendLine("WrapStyle: 0");
            sb.AppendLine("ScaledBorderAndShadow: yes");
            sb.AppendLine("YCbCr Matrix: None");

            foreach (IDisplaySize resolution in _resolution)
            {
                sb.AppendLine($"PlayResX: {resolution.Width}");
                sb.AppendLine($"PlayResY: {resolution.Height}");
            }

            sb.AppendLine("[V4+ Styles]");
            sb.AppendLine("Format: Name, Fontname, Fontsize, PrimaryColour, OutlineColour, BorderStyle, Shadow, Alignment, Encoding");
            sb.AppendLine($"Style: Default,{await _fontName.IfNoneAsync("")},{await _fontSize.IfNoneAsync(32)},{await _primaryColor.IfNoneAsync("")},{await _outlineColor.IfNoneAsync("")},{await _borderStyle.IfNoneAsync(0)},{await _shadow.IfNoneAsync(0)}, {await _alignment.IfNoneAsync(0)},1");

            sb.AppendLine("[Events]");
            sb.AppendLine("Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text");
            sb.AppendLine($"Dialogue: 0,0:00:00.00,99:99:99.99,Default,,{_marginLeft},{_marginRight},{_marginV},,{_content}");

            if (!string.IsNullOrWhiteSpace(_content))
            {
                sb.AppendLine(_content);
            }

            await File.WriteAllTextAsync(fileName, sb.ToString());

            return fileName;
        }
    }
}