package com.ibm.wala.dalvik.analysis.typeInference;

import com.ibm.wala.analysis.typeInference.TypeAbstraction;
import com.ibm.wala.analysis.typeInference.TypeInference;
import com.ibm.wala.analysis.typeInference.TypeVariable;
import com.ibm.wala.fixpoint.AbstractOperator;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.SSAPhiInstruction;
import com.ibm.wala.ssa.SymbolTable;

public class DalvikTypeInference extends TypeInference {
  @Override
  protected TypeVariable[] makeStmtRHS(int size) {
    return new DalvikTypeVariable[size];
  }

  private static AbstractOperator<TypeVariable> dalvikPhiOp = new DalvikPhiOperator();

  protected DalvikTypeInference(IR ir, boolean doPrimitives) {
    super(ir, doPrimitives);
  }

  @Override
  protected void initialize() {
    init(ir, this.new DalvikTypeVarFactory(), this.new TypeOperatorFactory());
  }

  public static DalvikTypeInference make(IR ir, boolean doPrimitives) {
    return new DalvikTypeInference(ir, doPrimitives);
  }

  public class DalvikTypeVarFactory extends TypeInference.TypeVarFactory {

    @Override
    public TypeVariable makeVariable(int valueNumber) {
      SymbolTable st = ir.getSymbolTable();
      if (st.isIntegerConstant(valueNumber) && st.isZero(valueNumber)) {
        return new DalvikTypeVariable(language.getPrimitive(language.getConstantType(0)), true);
      } else {
        if (doPrimitives) {
          if (st.isConstant(valueNumber)) {
            if (st.isBooleanConstant(valueNumber)) {
              return new DalvikTypeVariable(
                  language.getPrimitive(language.getConstantType(Boolean.TRUE)));
            }
          }
        }
        return new DalvikTypeVariable(TypeAbstraction.TOP);
      }
    }
  }

  protected class TypeOperatorFactory extends TypeInference.TypeOperatorFactory {

    @Override
    public void visitPhi(SSAPhiInstruction instruction) {
      assert dalvikPhiOp != null;
      this.result = dalvikPhiOp;
    }
  }

  private static final class DalvikPhiOperator extends AbstractOperator<TypeVariable> {
    private DalvikPhiOperator() {}

    @Override
    public byte evaluate(TypeVariable _lhs, TypeVariable[] _rhs) {
      /*
       * TODO: Find a better solution than downcasting. Downcasting is really ugly, although I can
       * be sure here that it succeeds because I control what type the parameters have. There must
       * be a cleaner solution which does not cause tons of changes in WALA's code, but I don't see
       * it yet...
       */
      assert _lhs instanceof DalvikTypeVariable;
      assert _rhs instanceof DalvikTypeVariable[];
      DalvikTypeVariable lhs = (DalvikTypeVariable) _lhs;
      DalvikTypeVariable[] rhs = (DalvikTypeVariable[]) _rhs;
      TypeAbstraction lhsType = lhs.getType();
      TypeAbstraction meet = TypeAbstraction.TOP;
      boolean ignoreZero = containsNonPrimitiveAndZero(rhs);
      for (DalvikTypeVariable rh : rhs) {
        if (rh != null && rh.getType() != null && !(ignoreZero && rh.isIntZeroConstant())) {
          meet = meet.meet(rh.getType());
        }
      }
      if (lhsType.equals(meet)) {
        return NOT_CHANGED;
      } else {
        lhs.setType(meet);
        return CHANGED;
      }
    }

    private static boolean containsNonPrimitiveAndZero(DalvikTypeVariable[] types) {
      boolean containsNonPrimitive = false;
      boolean containsZero = false;
      for (DalvikTypeVariable type : types) {
        if (type != null) {
          if (type.getType() != null
              && type.getType().getTypeReference() != null
              && !type.getType().getTypeReference().isPrimitiveType()) {
            containsNonPrimitive = true;
          }
          if (type.isIntZeroConstant()) {
            containsZero = true;
          }
        }
      }
      return containsNonPrimitive && containsZero;
    }

    @Override
    public String toString() {
      return "phi meet (dalvik)";
    }

    @Override
    public int hashCode() {
      return 2297;
    }

    @Override
    public boolean equals(Object o) {
      return (o instanceof DalvikPhiOperator);
    }
  }
}
