using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using EnvDTE;
using Microsoft.VisualStudio.Shell;
using Scripty.Core;
using Scripty.Core.Output;

namespace Scripty
{
 /// <summary>
 /// This is the generator class. 
 /// When setting the 'Custom Tool' property of a C# or VB project item to "Scripty", 
 /// the GenerateCode function will get called and will return the contents of the generated file 
 /// to the project system
 /// </summary>
 [ComVisible(true)]
 [Guid("1B8589A2-58FF-4413-9EA3-A66A1605F1E4")]
 [CodeGeneratorRegistration(typeof(ScriptyGenerator), "C# Scripty Generator", "{FAE04EC1-301F-11D3-BF4B-00C04F79EFBC}", GeneratesDesignTimeSource = true)]
 [CodeGeneratorRegistration(typeof(ScriptyGenerator), "VB.NET Scripty Generator", "{164B10B9-B200-11D0-8C61-00A0C91E29D5}", GeneratesDesignTimeSource = true)]
 [ProvideObject(typeof(ScriptyGenerator))]
 public class ScriptyGenerator : BaseCodeGeneratorWithSite
 {
#pragma warning disable 0414, 169
 //The name of this generator (use for 'Custom Tool' property of project item)
 // ReSharper disable once InconsistentNaming
 internal static string name = "ScriptyGenerator";
#pragma warning restore 0414, 169

 protected override string GetDefaultExtension()
 {
 return ".log";
 }

 /// <summary>
 /// Function that builds the contents of the generated file based on the contents of the input file.
 /// </summary>
 /// <param name="inputFileContent">Content of the input file</param>
 /// <returns>Generated file as a byte array</returns>
 protected override byte[] GenerateCode(string inputFileContent)
 {
 // Some good examples: https://t4toolbox.svn.codeplex.com/svn/Source/DteProcessor.cs
 // And https://github.com/madskristensen/ExtensibilityTools/blob/master/src/VsixManifest/Generator/ResxFileGenerator.cs

 try
 {
 ProjectItem projectItem = GetProjectItem();
 string inputFilePath = projectItem.Properties.Item("FullPath").Value.ToString();
 Project project = projectItem.ContainingProject;
 Solution solution = projectItem.DTE.Solution;

 // Run the generator and get the results
 ScriptSource source = new ScriptSource(inputFilePath, inputFileContent);
 ScriptEngine engine = new ScriptEngine(project.FullName, solution.FullName, null);
 ScriptResult result = engine.Evaluate(source).Result;

 // Report errors
 if (result.Errors.Count > 0)
 {
 foreach (ScriptError error in result.Errors)
 {
 GeneratorError(4, error.Message, (uint) error.Line, (uint) error.Column);
 }
 return null;
 }
 
 // Add generated files to the project
 foreach (IOutputFileInfo outputFile in result.OutputFiles.Where(x => x.BuildAction != BuildAction.GenerateOnly))
 {
 ProjectItem outputItem = projectItem.ProjectItems.Cast<ProjectItem>()
 .FirstOrDefault(x => x.Properties.Item("FullPath")?.Value?.ToString() == outputFile.FilePath)
 ?? projectItem.ProjectItems.AddFromFile(outputFile.FilePath);
 outputItem.Properties.Item("ItemType").Value = outputFile.BuildAction.ToString();
 }

 // Remove/delete files from the last generation but not in this one
 string logPath = Path.ChangeExtension(inputFilePath, ".log");
 if (File.Exists(logPath))
 {
 string[] logLines = File.ReadAllLines(logPath);
 foreach (string fileToRemove in logLines.Where(x => result.OutputFiles.All(y => y.FilePath != x)))
 {
 solution.FindProjectItem(fileToRemove)?.Delete();
 }
 }

 // Create the log file
 return Encoding.UTF8.GetBytes(string.Join(Environment.NewLine, result.OutputFiles.Select(x => x.FilePath)));
 }
 catch (Exception ex)
 {
 GeneratorError(4, ex.ToString(), 0, 0);
 return null;
 }
 }
 }
}