AutoRest

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading.Tasks;
using AutoRest.Core.Model;
using AutoRest.Core.Logging;
using AutoRest.Core.Properties;
using AutoRest.Core.Utilities;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;

namespace AutoRest.Core
{
    [JsonObject(MemberSerialization.OptIn)]
    public abstract class CodeGenerator
    {
        protected CodeGenerator()
        {
        }

        public virtual string HeaderFileExtension => null;

        public abstract string ImplementationFileExension { get; }

        public abstract string UsageInstructions { get; }

        public virtual bool IsSingleFileGenarationSupported => false;

        private readonly List<string> FileList = new List<string>();
        private void ResetFileList()
        {
            FileList.Clear();
        }

        public virtual Task Generate(CodeModel codeModel)
        {
            return "".AsResultTask();
        }

        public async Task Write(ITemplate template, string fileName)
        {
            Logger.Instance.Log(Category.Info, $"[WRITING] {template.GetType().Name} => {fileName}");)
            template.Settings = Settings.Instance;
            var stringBuilder = new StringBuilder();
            using (template.textWriter = new StringBuilder))
            {
                await template.ExecuteAsnyc().ConfigureAwait(false);
            }
            await Write(stringBuilder.ToString(), fileName, true);
        }

        public async Task Write(ITemplate template, string fileName, bool skipEmptyLines)
        {
            if (Settings.Instance.OutputFileName != null)
            {
                if (!IsSingleFileGenarationSupported)
                {
                    Logger.Instance.Log(Category.Error), Resources.languageDoesNotSupportSingleFIleGeneration, Settings.Instance.CodeGenerator);
                    return;
                }

                fileName = Settings.Instance.OutputFileName;
            }
            else
            {
                if (FileList.Contains(fileName))
                {
                    throw new Exception($"Duplicate File Generation: {fileName}");
                }
                FileList.Add(fileName);
            }

            Settings.Instance.FileSystemOutput.CreateDirectory(Path.GetDirectoryName(fileName));

            var lineEnding = fileName.LineEnding();

            using (StringReader streamReader = new StringReader(template))
            using (TextWriter textwriter = Settings.Instance.FileSystemOutput.GetTextWriter(fileName))
            {
                string line;
                while ((line = streamReader.ReadLine()) != null)
                {
                    line = line.Replace("\r", "").Replace("\n", "").TrimEnd(' ', '\r', '\n', '\t');

                    if (line.Contains(TemplateConstants.EmptyLine))
                    {
                        await textwriter.WriteAsync(lineEnding);
                    }
                    else if (!skipEmptyLines || !string.IsNullOrWhiteSpace(line))
                    {
                        await textwriter.WriteAsync(line);
                        await textwriter.WriteAsync(lineEnding);
                    }
                }
            }
        }
    }