/******************************************************************************
 * Copyright (c) 2002 - 2014 IBM Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *****************************************************************************/

package com.ibm.wala.cast.js.ipa.summaries;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import com.ibm.wala.cast.js.ipa.callgraph.JSCallGraphUtil;
import com.ibm.wala.cast.js.loader.JavaScriptLoader;
import com.ibm.wala.cast.js.ssa.JSInstructionFactory;
import com.ibm.wala.cast.js.types.JavaScriptMethods;
import com.ibm.wala.cast.js.types.JavaScriptTypes;
import com.ibm.wala.cast.loader.DynamicCallSiteReference;
import com.ibm.wala.cast.types.AstMethodReference;
import com.ibm.wala.classLoader.CallSiteReference;
import com.ibm.wala.classLoader.IClass;
import com.ibm.wala.classLoader.IMethod;
import com.ibm.wala.classLoader.Module;
import com.ibm.wala.classLoader.ModuleEntry;
import com.ibm.wala.classLoader.NewSiteReference;
import com.ibm.wala.classLoader.SourceModule;
import com.ibm.wala.ipa.cha.IClassHierarchy;
import com.ibm.wala.ipa.summaries.MethodSummary;
import com.ibm.wala.shrikeBT.IConditionalBranchInstruction.Operator;
import com.ibm.wala.ssa.ConstantValue;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.SSAAbstractInvokeInstruction;
import com.ibm.wala.ssa.SymbolTable;
import com.ibm.wala.types.MethodReference;
import com.ibm.wala.types.TypeName;
import com.ibm.wala.types.TypeReference;
import com.ibm.wala.util.collections.HashMapFactory;
import com.ibm.wala.util.collections.NonNullSingletonIterator;
import com.ibm.wala.util.collections.Pair;

public class JavaScriptConstructorFunctions {

  private final Map<Object, IMethod> constructors = HashMapFactory.make();

  private final IClassHierarchy cha;

  public JavaScriptConstructorFunctions(IClassHierarchy cha) {
    this.cha = cha;
  }

  public static class JavaScriptConstructor extends JavaScriptSummarizedFunction {
    private final String toStringExtra;
    private final IClass constructorForType;
    
    private JavaScriptConstructor(MethodReference ref, MethodSummary summary, IClass declaringClass, IClass constructorForType, String toStringExtra) {
      super(ref, summary, declaringClass);
      this.toStringExtra = toStringExtra;
      this.constructorForType = constructorForType;
    }

    private JavaScriptConstructor(MethodReference ref, MethodSummary summary, IClass declaringClass, IClass constructorForType) {
      this(ref, summary, declaringClass, constructorForType, "");
    }

    @Override
    public String toString() {
      return "<ctor for " + getReference().getDeclaringClass() + toStringExtra + ">";
    }
    
    public IClass constructedType() {
      return constructorForType;
    }
  }

  private IMethod record(Object key, IMethod m) {
    constructors.put(key, m);
    return m;
  }

  private static IMethod makeNullaryValueConstructor(IClass cls, Object value) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
    MethodReference ref = JavaScriptMethods.makeCtorReference(cls.getReference());
    JavaScriptSummary S = new JavaScriptSummary(ref, 1);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 4, 1, "prototype"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.NewInstruction(S.getNumberOfStatements(), 5, NewSiteReference.make(S.getNextProgramCounter(), cls.getReference())));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), 5, 4));
    //S.addStatement(insts.PutInstruction(5, 4, "__proto__"));
    S.getNextProgramCounter();
    
    S.addConstant(Integer.valueOf(8), new ConstantValue(value));
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 5, 8, "$value"));
    if (value instanceof String) {
      S.addConstant(9, new ConstantValue(0));
      S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 5, 9, "length"));
    }
    S.getNextProgramCounter();
    
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 5, false));
    S.getNextProgramCounter();
    
    //S.addConstant(9, new ConstantValue("__proto__"));
    
    return new JavaScriptConstructor(ref, S, cls, cls);
  }

  private static IMethod makeUnaryValueConstructor(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
   MethodReference ref = JavaScriptMethods.makeCtorReference(cls.getReference());
    JavaScriptSummary S = new JavaScriptSummary(ref, 2);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 5, 1, "prototype"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.NewInstruction(S.getNumberOfStatements(), 6, NewSiteReference.make(S.getNextProgramCounter(), cls.getReference())));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), 6, 5));
    //S.addStatement(insts.PutInstruction(6, 5, "__proto__"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 6, 2, "$value"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 6, false));
    S.getNextProgramCounter();
 
    //S.addConstant(7, new ConstantValue("__proto__"));

    return new JavaScriptConstructor(ref, S, cls, cls);
  }

  private IMethod makeValueConstructor(IClass cls, int nargs, Object value) {
    if (nargs == 0 || nargs == 1) {

      Object key = Pair.make(cls, Integer.valueOf(nargs));
      if (constructors.containsKey(key))
        return constructors.get(key);

      else
        return record(key, (nargs == 0) ? makeNullaryValueConstructor(cls, value) : makeUnaryValueConstructor(cls));
    } else {
        // not a legal call, likely due to dataflow imprecision
        return null;
    }
  }

  /**
   * create a method for constructing an Object with no arguments passed
   */
  private IMethod makeNullaryObjectConstructor(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
    MethodReference ref = JavaScriptMethods.makeCtorReference(JavaScriptTypes.Object);
    JavaScriptSummary S = new JavaScriptSummary(ref, 1);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 4, 1, "prototype"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.NewInstruction(S.getNumberOfStatements(), 5, NewSiteReference.make(S.getNextProgramCounter(), JavaScriptTypes.Object)));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), 5, 4));
    //S.addStatement(insts.PutInstruction(5, 4, "__proto__"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 5, false));
    S.getNextProgramCounter();
    
    //S.addConstant(6, new ConstantValue("__proto__"));

    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.Object));
  }

  private IMethod makeUnaryObjectConstructor(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
    MethodReference ref = JavaScriptMethods.makeCtorReference(JavaScriptTypes.Object);
    JavaScriptSummary S = new JavaScriptSummary(ref, 2);

    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 2, false));
    S.getNextProgramCounter();
    
    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.Object));
  }

  private IMethod makeObjectConstructor(IClass cls, int nargs) {
    if (nargs == 0 || nargs == 1) {

      Object key = Pair.make(cls, Integer.valueOf(nargs));
      if (constructors.containsKey(key))
        return constructors.get(key);

      else
        return record(key, (nargs == 0) ? makeNullaryObjectConstructor(cls) : makeUnaryObjectConstructor(cls));
    
    } else {
      // not a legal call, likely the result of analysis imprecision
      return null;
    }
  }
  
  private IMethod makeObjectCall(IClass cls, int nargs) {
    assert nargs == 0;

    Object key = Pair.make(cls, Integer.valueOf(nargs));
    if (constructors.containsKey(key))
      return constructors.get(key);

    else
      return record(key, makeNullaryObjectConstructor(cls));
  }

  private IMethod makeArrayLengthConstructor(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
   MethodReference ref = JavaScriptMethods.makeCtorReference(JavaScriptTypes.Array);
    JavaScriptSummary S = new JavaScriptSummary(ref, 2);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 5, 1, "prototype"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.NewInstruction(S.getNumberOfStatements(), 6, NewSiteReference.make(S.getNextProgramCounter(), JavaScriptTypes.Array)));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), 6, 5));
    //S.addStatement(insts.PutInstruction(6, 5, "__proto__"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 6, 2, "length"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 6, false));
    S.getNextProgramCounter();
  
    //S.addConstant(7, new ConstantValue("__proto__"));

    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.Array));
  }

  private IMethod makeArrayContentsConstructor(IClass cls, int nargs) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
    MethodReference ref = JavaScriptMethods.makeCtorReference(JavaScriptTypes.Array);
    JavaScriptSummary S = new JavaScriptSummary(ref, nargs + 1);

    S.addConstant(Integer.valueOf(nargs + 3), new ConstantValue("prototype"));
    S.addStatement(insts.PropertyRead(S.getNumberOfStatements(), nargs + 4, 1, nargs + 3));
    S.getNextProgramCounter();
    
    S.addStatement(
        insts.NewInstruction(S.getNumberOfStatements(), nargs + 5, NewSiteReference.make(S.getNextProgramCounter(),
            JavaScriptTypes.Array)));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), nargs + 5, nargs + 4));
    //S.addStatement(insts.PutInstruction(nargs + 5, nargs + 4, "__proto__"));
    S.getNextProgramCounter();
    
    S.addConstant(Integer.valueOf(nargs + 7), new ConstantValue(nargs));
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), nargs + 5, nargs + 7, "length"));
    S.getNextProgramCounter();
    
    int vn = nargs + 9;
    for (int i = 0; i < nargs; i++, vn += 2) {
      S.addConstant(Integer.valueOf(vn), new ConstantValue(i));
      S.addStatement(insts.PropertyWrite(S.getNumberOfStatements(), nargs + 5, vn, i + 1));
      S.getNextProgramCounter();
      }

    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 5, false));
    S.getNextProgramCounter();
    
    //S.addConstant(vn, new ConstantValue("__proto__"));

    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.Array));
  }

  private IMethod makeArrayConstructor(IClass cls, int nargs) {
    Object key = Pair.make(cls, Integer.valueOf(nargs));
    if (constructors.containsKey(key))
      return constructors.get(key);

    else
      return record(key, (nargs == 1) ? makeArrayLengthConstructor(cls) : makeArrayContentsConstructor(cls, nargs));
  }

  private IMethod makeNullaryStringCall(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
    MethodReference ref = AstMethodReference.fnReference(JavaScriptTypes.String);
    JavaScriptSummary S = new JavaScriptSummary(ref, 1);

    S.addConstant(Integer.valueOf(2), new ConstantValue(""));

    S.addConstant(Integer.valueOf(3), new ConstantValue(0));
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 2, 3, "length"));
    S.getNextProgramCounter();

    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 2, false));
    S.getNextProgramCounter();
    
    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.String));
  }

  private IMethod makeUnaryStringCall(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
   MethodReference ref = AstMethodReference.fnReference(JavaScriptTypes.String);
    JavaScriptSummary S = new JavaScriptSummary(ref, 2);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 4, 2, "toString"));
    S.getNextProgramCounter();
    
    CallSiteReference cs = new DynamicCallSiteReference(JavaScriptTypes.CodeBody, S.getNextProgramCounter());
    S.addStatement(insts.Invoke(S.getNumberOfStatements(), 4, 5, new int[] { 2 }, 6, cs));

    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 5, false));
    S.getNextProgramCounter();
    
    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.String));
  }

  private IMethod makeStringCall(IClass cls, int nargs) {
    assert nargs == 0 || nargs == 1;

    Object key = Pair.make(cls, Integer.valueOf(nargs));
    if (constructors.containsKey(key))
      return constructors.get(key);

    else
      return record(key, (nargs == 0) ? makeNullaryStringCall(cls) : makeUnaryStringCall(cls));
  }

  private IMethod makeNullaryNumberCall(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
    MethodReference ref = AstMethodReference.fnReference(JavaScriptTypes.Number);
    JavaScriptSummary S = new JavaScriptSummary(ref, 1);

    S.addConstant(Integer.valueOf(2), new ConstantValue(0.0));
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 2, false));
    S.getNextProgramCounter();
    
    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.Number));
  }

  private IMethod makeUnaryNumberCall(IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
   MethodReference ref = AstMethodReference.fnReference(JavaScriptTypes.Number);
    JavaScriptSummary S = new JavaScriptSummary(ref, 2);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 4, 2, "toNumber"));
    S.getNextProgramCounter();
    
    CallSiteReference cs = new DynamicCallSiteReference(JavaScriptTypes.CodeBody, S.getNextProgramCounter());
    S.addStatement(insts.Invoke(S.getNumberOfStatements(), 4, 5, new int[] { 2 }, 6, cs));

    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 5, false));
    S.getNextProgramCounter();
    
    return new JavaScriptConstructor(ref, S, cls, cha.lookupClass(JavaScriptTypes.Number));
  }

  private IMethod makeNumberCall(IClass cls, int nargs) {
    assert nargs == 0 || nargs == 1;

    Object key = Pair.make(cls, Integer.valueOf(nargs));
    if (constructors.containsKey(key))
      return constructors.get(key);

    else
      return record(key, (nargs == 0) ? makeNullaryNumberCall(cls) : makeUnaryNumberCall(cls));
  }

  private IMethod makeFunctionConstructor(IClass receiver, IClass cls) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
   Pair<IClass, IClass> tableKey = Pair.make(receiver, cls);
    if (constructors.containsKey(tableKey))
      return constructors.get(tableKey);

    MethodReference ref = JavaScriptMethods.makeCtorReference(receiver.getReference());
    JavaScriptSummary S = new JavaScriptSummary(ref, 1);

    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), 4, 1, "prototype"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.NewInstruction(S.getNumberOfStatements(), 5, NewSiteReference.make(S.getNextProgramCounter(), cls.getReference())));

    S.addStatement(insts.NewInstruction(S.getNumberOfStatements(), 7, NewSiteReference.make(S.getNextProgramCounter(), JavaScriptTypes.Object)));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), 5, 4));
    //S.addStatement(insts.PutInstruction(5, 4, "__proto__"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 5, 7, "prototype"));
    S.getNextProgramCounter();
    
    S.addStatement(insts.PutInstruction(S.getNumberOfStatements(), 7, 5, "constructor"));
    S.getNextProgramCounter();
    
    // TODO we need to set v7.__proto__ to Object.prototype
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), 5, false));
    S.getNextProgramCounter();
    
    //S.addConstant(8, new ConstantValue("__proto__"));

    if (receiver != cls)
      return record(tableKey, new JavaScriptConstructor(ref, S, receiver, cls, "(" + cls.getReference().getName() + ")"));
    else
      return record(tableKey, new JavaScriptConstructor(ref, S, receiver, cls));
  }

  private int ctorCount = 0;

  private IMethod makeFunctionConstructor(IR callerIR, SSAAbstractInvokeInstruction callStmt, IClass cls, int nargs) {
    SymbolTable ST = callerIR.getSymbolTable();

    if (nargs == 0) {
      return makeFunctionConstructor(cls, cls);
    } else if (nargs == 1) {
      if (ST.isStringConstant(callStmt.getUse(1))) {
        TypeReference ref = TypeReference.findOrCreate(JavaScriptTypes.jsLoader, TypeName.string2TypeName(ST
            .getStringValue(callStmt.getUse(1))));

        IClass cls2 = cha.lookupClass(ref);
        if (cls2 != null) {
          return makeFunctionConstructor(cls, cls2);
        }
      }

      return makeFunctionConstructor(cls, cls);
    } else {
      assert nargs > 1;
      JavaScriptLoader cl = (JavaScriptLoader) cha.getLoader(JavaScriptTypes.jsLoader);

      for (int i = 1; i < callStmt.getNumberOfUses(); i++)
        if (!ST.isStringConstant(callStmt.getUse(i)))
          return makeFunctionConstructor(cls, cls);

      final StringBuffer fun = new StringBuffer("function _fromctor (");
      for (int j = 1; j < callStmt.getNumberOfUses() - 1; j++) {
        if (j != 1)
          fun.append(",");
        fun.append(ST.getStringValue(callStmt.getUse(j)));
      }

      fun.append(") {");
      fun.append(ST.getStringValue(callStmt.getUse(callStmt.getNumberOfUses() - 1)));
      fun.append("}");

      try {
        final String fileName = "ctor$" + ++ctorCount;
        ModuleEntry ME = new SourceModule() {

          @Override
          public String getName() {
            return fileName;
          }

          @Override
          public boolean isClassFile() {
            return false;
          }

          @Override
          public boolean isSourceFile() {
            return true;
          }

          @Override
          public InputStream getInputStream() {
            return new InputStream() {
              private int i = 0;
              @Override
              public int read() throws IOException {
                if (i >= fun.length()) {
                  return -1;
                } else {
                  return fun.codePointAt(i++);
                }
              }
              
            };
          }

          @Override
          public boolean isModuleFile() {
            return false;
          }

          @Override
          public Module asModule() {
            return null;
          }

          @Override
          public String getClassName() {
            return fileName;
          }

          @Override
          public Module getContainer() {
             return null;
          }

          @Override
          public Iterator<? extends ModuleEntry> getEntries() {
            return new NonNullSingletonIterator<ModuleEntry>(this);
          }

          @Override
          public Reader getInputReader() {
             return new StringReader(fun.toString());
          }

          @Override
          public URL getURL() {
            try {
              return new URL("file://" + fileName);
            } catch (MalformedURLException e) {
              assert false;
              return null;
            }
          }
          
        };
         
        Set<String> fnNames = JSCallGraphUtil.loadAdditionalFile(cha, cl, ME);
        IClass fcls = null;
        for(String nm : fnNames) {
          if (nm.endsWith("_fromctor")) {
            fcls = cl.lookupClass(nm, cha);
          }
        }

        assert fcls != null : "cannot find class for " + fileName;
        
        return makeFunctionConstructor(cls, fcls);

      } catch (IOException e) {

      }

      return makeFunctionConstructor(cls, cls);
    }
  }

 
  private IMethod makeFunctionObjectConstructor(IClass cls, int nargs) {
    JSInstructionFactory insts = (JSInstructionFactory)cls.getClassLoader().getInstructionFactory();
   Object key = Pair.make(cls, Integer.valueOf(nargs));
    if (constructors.containsKey(key))
      return constructors.get(key);
    
    MethodReference ref = JavaScriptMethods.makeCtorReference(cls.getReference());
    JavaScriptSummary S = new JavaScriptSummary(ref, nargs + 1);
    S.addStatement(insts.GetInstruction(S.getNumberOfStatements(), nargs + 4, 1, "prototype"));
    S.getNextProgramCounter();
      
    S.addStatement(
        insts.NewInstruction(S.getNumberOfStatements(), nargs + 5, 
                                     NewSiteReference.make(S.getNextProgramCounter(),
                                     JavaScriptTypes.Object)));

    S.addStatement(insts.SetPrototype(S.getNumberOfStatements(), nargs + 5, nargs + 4));
    S.getNextProgramCounter();
    
    CallSiteReference cs = new DynamicCallSiteReference(JavaScriptTypes.CodeBody, S.getNextProgramCounter());
    int[] args = new int[nargs + 1];
    args[0] = nargs + 5;
    for (int i = 0; i < nargs; i++)
      args[i + 1] = i + 2;
    S.addStatement(insts.Invoke(S.getNumberOfStatements(), 1, nargs + 7, args, nargs + 8, cs));
    int pc = S.getNextProgramCounter();

    S.addConstant(nargs + 9, null);
    S.addStatement(insts.ConditionalBranchInstruction(S.getNumberOfStatements(), Operator.EQ, JavaScriptTypes.Root, nargs + 7, nargs + 9, pc+2));
    S.getNextProgramCounter();
    
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), nargs + 7, false));
    S.getNextProgramCounter();
    
    S.addStatement(insts.ReturnInstruction(S.getNumberOfStatements(), nargs + 5, false));
    S.getNextProgramCounter();
    
    return record(key, new JavaScriptConstructor(ref, S, cls, cls));
  }

  public IMethod findOrCreateConstructorMethod(IR callerIR, SSAAbstractInvokeInstruction callStmt, IClass receiver, int nargs) {
    if (receiver.getReference().equals(JavaScriptTypes.Object))
      return makeObjectConstructor(receiver, nargs);
    else if (receiver.getReference().equals(JavaScriptTypes.Array))
      return makeArrayConstructor(receiver, nargs);
    else if (receiver.getReference().equals(JavaScriptTypes.StringObject))
      return makeValueConstructor(receiver, nargs, "");
    else if (receiver.getReference().equals(JavaScriptTypes.BooleanObject)) {
      assert nargs == 1;
      return makeValueConstructor(receiver, nargs, null);
    } else if (receiver.getReference().equals(JavaScriptTypes.NumberObject))
      return makeValueConstructor(receiver, nargs, Integer.valueOf(0));
    else if (receiver.getReference().equals(JavaScriptTypes.Function))
      return makeFunctionConstructor(callerIR, callStmt, receiver, nargs);
    else if (cha.isSubclassOf(receiver, cha.lookupClass(JavaScriptTypes.CodeBody)))
      return makeFunctionObjectConstructor(receiver, nargs);

    else {
      return null;
    }
  }

  public IMethod findOrCreateCallMethod(IR callerIR, SSAAbstractInvokeInstruction callStmt, IClass receiver, int nargs) {
    if (receiver.getReference().equals(JavaScriptTypes.Object))
      return makeObjectCall(receiver, nargs);
    else if (receiver.getReference().equals(JavaScriptTypes.Array))
      return makeArrayConstructor(receiver, nargs);
    else if (receiver.getReference().equals(JavaScriptTypes.StringObject))
      return makeStringCall(receiver, nargs);
    else if (receiver.getReference().equals(JavaScriptTypes.NumberObject))
      return makeNumberCall(receiver, nargs);
    else if (receiver.getReference().equals(JavaScriptTypes.Function))
      return makeFunctionConstructor(callerIR, callStmt, receiver, nargs);
    else {
      return null;
    }
  }

}