inabox/InABox.Poster.CSV/CSVPosterEngine.cs

using CsvHelper;
using InABox.Core;
using InABox.Core.Postable;
using InABox.Scripting;
using Microsoft.Win32;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace InABox.Poster.CSV
{
    public class CSVPosterEngine<TPostable> : PosterEngine<TPostable, ICSVPoster<TPostable>, CSVPosterSettings>
        where TPostable : Entity, IPostable, IRemotable, IPersistent, new()
    {
        private ScriptDocument? _script;
        private bool _hasCheckedScript;

        private ScriptDocument? GetScriptDocument()
        {
            if (_hasCheckedScript)
            {
                return _script;
            }

            var settings = GetSettings();
            if (settings.ScriptEnabled && !string.IsNullOrWhiteSpace(settings.Script))
            {
                var document = new ScriptDocument(settings.Script);
                document.Properties.Add(new ScriptProperty("Results", null));
                if (!document.Compile())
                {
                    throw new Exception("Script failed to compile!");
                }
                _script = document;
            }
            else
            {
                _script = null;
            }

            _hasCheckedScript = true;
            return _script;
        }

        public override bool BeforePost(IDataModel<TPostable> model)
        {
            if(GetScriptDocument() is ScriptDocument script)
            {
                return script.Execute(methodname: "BeforePost", parameters: new object[] { model });
            }
            else
            {
                return Poster.BeforePost(model);
            }
        }

        protected override IPostResult<TPostable> DoProcess(IDataModel<TPostable> model)
        {
            var settings = GetSettings();

            ICSVExport<TPostable> results;
            if (GetScriptDocument() is ScriptDocument script)
            {
                if (!script.Execute(methodname: "Process", parameters: new object[] { model }))
                {
                    throw new Exception("Post Failed.");
                }

                var resultsObject = script.GetValue("Results");
                results = (resultsObject as ICSVExport<TPostable>)
                    ?? throw new Exception($"Script 'Results' property expected to be ICSVExport<{typeof(TPostable)}>, got {resultsObject}");
            }
            else
            {
                results = Poster.Process(model);
            }

            var dlg = new SaveFileDialog()
            {
                FileName = settings.DefaultOutputFile,
                Filter = "CSV Files (*.csv)|*.csv"
            };

            if(dlg.ShowDialog() == true)
            {
                using var writer = new StreamWriter(dlg.FileName);
                using var csv = new CsvWriter(writer, CultureInfo.InvariantCulture);
                csv.Context.RegisterClassMap(results.ClassMap.ClassMap);

                var method = typeof(CsvWriter).GetMethods()
                    .Where(x => x.Name == nameof(CsvWriter.WriteRecords) && x.GetGenericArguments().Length == 1).First()
                    .MakeGenericMethod(results.Type);
                method.Invoke(csv, new object?[] { results.Records });
                return results;
            }
            else
            {
                throw new PostCancelledException();
            }
        }

        public override void AfterPost(IDataModel<TPostable> model, IPostResult<TPostable> result)
        {
            if (GetScriptDocument() is ScriptDocument script)
            {
                // Ignoring 'result', because this is actually the 'Results' field of the script class.
                script.Execute(methodname: "AfterPost", parameters: new object[] { model });
            }
            else
            {
                Poster.AfterPost(model, result);
            }
        }
    }
}