package edu.umd.cs.findbugs.detect;

import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Constant;
import org.apache.bcel.classfile.ConstantCP;
import org.apache.bcel.classfile.ConstantClass;
import org.apache.bcel.classfile.ConstantDouble;
import org.apache.bcel.classfile.ConstantFieldref;
import org.apache.bcel.classfile.ConstantLong;
import org.apache.bcel.classfile.ConstantNameAndType;
import org.apache.bcel.classfile.ConstantPool;
import org.apache.bcel.classfile.ConstantUtf8;
import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Detector;
import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.XClass;
import edu.umd.cs.findbugs.ba.ch.Subtypes2;
import edu.umd.cs.findbugs.classfile.CheckedAnalysisException;
import edu.umd.cs.findbugs.classfile.Global;
import edu.umd.cs.findbugs.classfile.IAnalysisCache;
import edu.umd.cs.findbugs.classfile.MissingClassException;
import edu.umd.cs.findbugs.util.ClassName;
import edu.umd.cs.findbugs.visitclass.PreorderVisitor;

public class ResolveAllReferences extends PreorderVisitor implements Detector {

    private BugReporter bugReporter;

    public ResolveAllReferences(BugReporter bugReporter) {
        this.bugReporter = bugReporter;

    }

    Set<String> defined;

    private void compute() {
        if (defined == null) {
            // System.out.println("Computing");
            defined = new HashSet<String>();

            Subtypes2 subtypes2 = AnalysisContext.currentAnalysisContext().getSubtypes2();
            Collection<XClass> allClasses = subtypes2.getXClassCollection();

            IAnalysisCache analysisCache = Global.getAnalysisCache();

            for (XClass c : allClasses) {
                try {
                    JavaClass jclass = analysisCache.getClassAnalysis(JavaClass.class, c.getClassDescriptor());
                    addAllDefinitions(jclass);
                } catch (MissingClassException e) {
                    bugReporter.reportMissingClass(e.getClassDescriptor());
                } catch (CheckedAnalysisException e) {
                    bugReporter.logError("Could not find class " + c.getClassDescriptor().toDottedClassName(), e);
                }
            }
            // System.out.println("Done Computing: " +
            // defined.contains("edu.umd.cs.findbugs.ba.IsNullValueAnalysis.UNKNOWN_VALUES_ARE_NSP : Z"));
        }
    }

    public void visitClassContext(ClassContext classContext) {
        classContext.getJavaClass().accept(this);

    }

    public void report() {
    }

    public void addAllDefinitions(JavaClass obj) {
        String className2 = obj.getClassName();

        defined.add(className2);
        for (Method m : obj.getMethods())
            if (!m.isPrivate()) {
                String name = getMemberName(obj, className2, m.getNameIndex(), m.getSignatureIndex());
                defined.add(name);
            }
        for (Field f : obj.getFields())
            if (!f.isPrivate()) {
                String name = getMemberName(obj, className2, f.getNameIndex(), f.getSignatureIndex());
                defined.add(name);
            }
    }

    private String getClassName(JavaClass c, int classIndex) {
        String name = c.getConstantPool().getConstantString(classIndex, CONSTANT_Class);
        return ClassName.extractClassName(name).replace('/', '.');
    }

    private String getMemberName(JavaClass c, String className, int memberNameIndex, int signatureIndex) {
        return className + "." + ((ConstantUtf8) c.getConstantPool().getConstant(memberNameIndex, CONSTANT_Utf8)).getBytes()
                + " : " + ((ConstantUtf8) c.getConstantPool().getConstant(signatureIndex, CONSTANT_Utf8)).getBytes();
    }

    private String getMemberName(String className, String memberName, String signature) {
        return className.replace('/', '.') + "." + memberName + " : " + signature;
    }

    private boolean find(JavaClass target, String name, String signature) throws ClassNotFoundException {
        if (target == null)
            return false;
        String ref = getMemberName(target.getClassName(), name, signature);
        if (defined.contains(ref))
            return true;
        if (find(target.getSuperClass(), name, signature))
            return true;
        for (JavaClass i : target.getInterfaces())
            if (find(i, name, signature))
                return true;
        return false;
    }

    @Override
    public void visit(JavaClass obj) {
        compute();
        ConstantPool cp = obj.getConstantPool();
        Constant[] constants = cp.getConstantPool();
        checkConstant: for (int i = 0; i < constants.length; i++) {
            Constant co = constants[i];
            if (co instanceof ConstantDouble || co instanceof ConstantLong)
                i++;
            if (co instanceof ConstantClass) {
                String ref = getClassName(obj, i);
                if ((ref.startsWith("java") || ref.startsWith("org.w3c.dom")) && !defined.contains(ref))
                    bugReporter.reportBug(new BugInstance(this, "VR_UNRESOLVABLE_REFERENCE", NORMAL_PRIORITY).addClass(obj)
                            .addString(ref));

            } else if (co instanceof ConstantFieldref) {
                // do nothing until we handle static fields defined in
                // interfaces
            } else if (co instanceof ConstantCP) {
                ConstantCP co2 = (ConstantCP) co;
                String className = getClassName(obj, co2.getClassIndex());

                // System.out.println("checking " + ref);
                if (className.equals(obj.getClassName()) || !defined.contains(className)) {
                    // System.out.println("Skipping check of " + ref);
                    continue checkConstant;
                }
                ConstantNameAndType nt = (ConstantNameAndType) cp.getConstant(co2.getNameAndTypeIndex());
                String name = ((ConstantUtf8) obj.getConstantPool().getConstant(nt.getNameIndex(), CONSTANT_Utf8)).getBytes();
                String signature = ((ConstantUtf8) obj.getConstantPool().getConstant(nt.getSignatureIndex(), CONSTANT_Utf8))
                        .getBytes();

                try {
                    JavaClass target = Repository.lookupClass(className);
                    if (!find(target, name, signature))
                        bugReporter.reportBug(new BugInstance(this, "VR_UNRESOLVABLE_REFERENCE", NORMAL_PRIORITY).addClass(obj)
                                .addString(getMemberName(target.getClassName(), name, signature)));

                } catch (ClassNotFoundException e) {
                    bugReporter.reportMissingClass(e);
                }
            }

        }
    }

}
