using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;

namespace Cosmos.Compiler.XSharp {
  public class Generator {
    public static void Execute(TextReader input, string inputFilename, TextWriter output, string defaultNamespace) {
      var xGenerator = new Generator();
      xGenerator.Name = Path.GetFileNameWithoutExtension(inputFilename);
      xGenerator.Namespace = defaultNamespace;
      xGenerator.Execute(input, output);
    }

    public string Namespace {
      get;
      set;
    }

    public string Name {
      get;
      set;
    }

    private void EnsureHeaderWritten() {
      if (mHeaderWritten) {
        return;
      }
      mHeaderWritten = true;
      EmitHeader();
    }

    private bool mHeaderWritten = false;

    private TextReader mInput;
    private TextWriter mOutput;

    public void Execute(TextReader aInput, TextWriter aOutput) {
      mInput = aInput;
      mOutput = aOutput;

      while (true) {
        string xLine = aInput.ReadLine();
        if (xLine == null) {
          break;
        }

        ProcessLine(xLine);
      }

      EmitFooter();
    }

    private void EmitHeader() {
      mOutput.WriteLine("using System;");
      mOutput.WriteLine("using System.Linq;");
      mOutput.WriteLine("using Cosmos.Assembler;");
      mOutput.WriteLine("using Cosmos.Assembler.x86;");
      mOutput.WriteLine();
      mOutput.WriteLine("namespace {0}", Namespace);
      mOutput.WriteLine("{");
      mOutput.WriteLine("\tpublic class {0}: Cosmos.IL2CPU.Plugs.AssemblerMethod", Name);
      mOutput.WriteLine("\t{");
      mOutput.WriteLine("\t\tpublic override void AssembleNew(object aAssembler, object aMethodInfo)");
      mOutput.WriteLine("\t\t{");
    }

    private void EmitFooter() {
      EnsureHeaderWritten();
      mOutput.WriteLine("\t\t}");
      mOutput.WriteLine("\t}");
      mOutput.WriteLine("}");
    }

    // +-[].=
    protected Regex mRegex = new Regex(@"(\W)");

    protected void ProcessLine(string aLine) {
      aLine = aLine.Trim();
      if (String.IsNullOrEmpty(aLine)) {
        // Skip
      } else if (aLine[0] == '#') {
        ProcessComment(aLine.Substring(1));
      } else if (aLine[0] == '!') {
        ProcessLiteral(aLine.Substring(1));
      } else {
        if (aLine.EndsWith("++")) {
          // TODO
        } else if (aLine.EndsWith("--")) {
          // TODO
        } else {
          var xParts = mRegex.Split(aLine);
          xParts = xParts.Where(q => string.IsNullOrWhiteSpace(q) == false).ToArray();

          if (xParts.Contains("=")) {
            ProcessAssignment(xParts);
          } else {
            throw new Exception("Syntax error: '" + aLine + "'");
          }
        }
      }
    }

    private void ProcessAssignment(string[] aParts) {
      if (aParts.Length != 3) {
        throw new Exception("Wrong Assignment");
      }

      string xLeft = aParts[0];
      string xRight = aParts[2];

      if (IsRegister(xLeft)) {
        uint xValue;
        if (UInt32.TryParse(xRight, out xValue)) {
          mOutput.WriteLine("new Move{{DestinationReg = RegistersEnum.{0}, SourceValue = {1}}};", xLeft, xRight);
          return;
        }
      }

      throw new Exception("Wrong Assignment");
    }

    private void ProcessLiteral(string line) {
      EnsureHeaderWritten();
      mOutput.WriteLine("new LiteralAssemblerCode(\"{0}\");", line);
    }

    private void ProcessComment(string line) {
      EnsureHeaderWritten();
      mOutput.WriteLine("new Comment(\"{0}\");", line);
    }

    private bool IsRegister(string aWord) {
      aWord = aWord.ToLower();
      return
        aWord == "eax" || aWord == "ax" || aWord == "ah" || aWord == "al" ||
        aWord == "ebx" || aWord == "bx" || aWord == "bh" || aWord == "bl" ||
        aWord == "ecx" || aWord == "cx" || aWord == "ch" || aWord == "cl" ||
        aWord == "edx" || aWord == "dx" || aWord == "dh" || aWord == "dl" ||
        aWord == "esp" ||
        aWord == "ebp" ||
        aWord == "esi" ||
        aWord == "edi";
    }
  }
}