GlobalData.cs

public static class GlobalData
{
  public static List<Quote> Quotes { get; set; }
}

public static class Extensions {
    public static string CleanString(this string str) {
        if (str == null) return "";
        var result = str.Trim().Trim('"');
        result = String.Join(' ', result.Split(' ', StringSplitOptions.RemoveEmptyEntries));
        return result;
    }

    public static Quote GetQuote1(this MittalInput json) {
        var quote = new Quote();
        quote.QuoteText = json.Content.CleanString();

        if (json.Author != null) {
            var authorData  = json.Author.Split(',');
            quote.Author = authorData[0].CleanString();
            if (authorData.Length > 1){
              quote.Book = authorData[1].CleanString();
              quote.Source = "Book";
            }
        }
        else quote.Author = "Unknown";

        quote.Language = "english";
        
        quote.Categories = String.Join(",", json.Tags.Select(x => x.ToLower().CleanString()).Distinct());
        quote.DataSet = "mittal";
        return quote;
    }

    public static Quote GetQuote2(this QuotableInput json) {
        var quote = new Quote();
        quote.QuoteText = json.Content.CleanString();

        if (json.Author != null) {
            var authorData  = json.Author.Split(',');
            quote.Author = authorData[0].CleanString();
            if (authorData.Length > 1){
              quote.Book = authorData[1].CleanString();
              quote.Source = "Book";
            }
        }
        else quote.Author = "Unknown";

        quote.Language = "english";
        
        quote.Categories = String.Join(",", json.Tags.Select(x => x.ToLower().CleanString()).Distinct());
        quote.DataSet = "quotable";
        return quote;
    }

    public static Quote GetQuote3(this ManannInput data) {
        var quote = new Quote();
        quote.QuoteText = data.quote.CleanString();

        if (data.author != null) {
            var authorData  = data.author.Split(',');
            quote.Author = authorData[0].CleanString();
            if (authorData.Length > 1){
              quote.Book = authorData[1].CleanString();
              quote.Source = "Book";
            }
        }
        else quote.Author = "Unknown";

        quote.Language = "english";
        
        quote.Categories = String.Join(",", data.category.Split(',', StringSplitOptions.RemoveEmptyEntries).Select(x => x.ToLower().CleanString()).Distinct());
        quote.DataSet = "manann";
        return quote;
    }
}