using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;

namespace Cosmos.IL2CPU.ILOpCodes {
  public class OpBranch : ILOpCode {
    public readonly int Value;

    public OpBranch(Code aOpCode, int aPos, int aNextPos, int aValue, System.Reflection.ExceptionHandlingClause aCurrentExceptionHandler)
      : base(aOpCode, aPos, aNextPos, aCurrentExceptionHandler) {
      Value = aValue;
    }

    public override int GetNumberOfStackPops()
    {
      switch (OpCode)
      {
        case Code.Leave:
        case Code.Br:
          return 0;
        case Code.Brtrue:
          return 1;
        case Code.Brfalse:
          return 1;
        case Code.Beq:
        case Code.Ble:
        case Code.Ble_Un:
        case Code.Bne_Un:
        case Code.Bge:
        case Code.Bge_Un:
        case Code.Bgt:
        case Code.Bgt_Un:
        case Code.Blt:
        case Code.Blt_Un:
          return 2;
        default:
          throw new NotImplementedException("OpCode '" + OpCode + "' not implemented!");
      }
    }

    public override int GetNumberOfStackPushes()
    {
      switch (OpCode)
      {
        case Code.Leave:
        case Code.Br:
          return 0;
        case Code.Brtrue:
          return 0;
        case Code.Brfalse:
          return 0;
        case Code.Beq:
        case Code.Ble:
        case Code.Ble_Un:
        case Code.Bne_Un:
        case Code.Bge:
        case Code.Bge_Un:
        case Code.Bgt:
        case Code.Bgt_Un:
        case Code.Blt:
        case Code.Blt_Un:
          return 0;
        default:
          throw new NotImplementedException("OpCode '" + OpCode + "' not implemented!");
      }
    }

    protected override void DoInitStackAnalysis(MethodBase aMethod)
    {
      base.DoInitStackAnalysis(aMethod);

      switch (OpCode)
      {
        default:
          break;
      }
    }

    protected override void DoInterpretStackTypes(ref bool aSituationChanged)
    {
      base.DoInterpretStackTypes(ref aSituationChanged);

      switch (OpCode)
      {
        case Code.Brtrue:
        case Code.Brfalse:
          // check pop types according to ECMA 335
          var xPopType = StackPopTypes[0];
          if (xPopType == null)
          {
            return;
          }

          if (xPopType == typeof (IntPtr))
          {
            return;
          }
          if (xPopType.IsClass)
          {
            return;
          }

          // ECMA apparently sees a boolean on the stack as a native int. We push as boolean, so acccept that as well
          if (xPopType == typeof (bool))
          {
            return;
          }
          
          throw new Exception("Invalid type in PopTypes! (Type = '" + xPopType.AssemblyQualifiedName + "')");
        default:
          throw new NotImplementedException("Checks for opcode " + OpCode + " not implemented!");
      }
    }
  }
}