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package com.ximsfei.stark.gradle.asm.monitor;

import com.android.SdkConstants;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.ximsfei.stark.gradle.StarkConstants;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.SerialVersionUIDAdder;
import org.objectweb.asm.tree.AnnotationNode;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.FieldNode;
import org.objectweb.asm.tree.MethodNode;

import java.io.File;
import java.io.IOException;
import java.util.List;

public class MonitorVisitor extends ClassVisitor {
    public static final String RUNTIME_PACKAGE = StarkConstants.STARK_CORE_RUNTIME_PACKAGE;
    public static final Type CHANGE_TYPE = Type.getObjectType(RUNTIME_PACKAGE + "/StarkChange");
    public static final Type TARGET_API_TYPE = Type.getObjectType("android/annotation/TargetApi");
    protected static final Type STARK_RELOAD_EXCEPTION = Type.getObjectType(RUNTIME_PACKAGE + "/StarkReloadException");
    protected static final Type RUNTIME_TYPE = Type.getObjectType(RUNTIME_PACKAGE + "/StarkRuntime");
    public static final String ABSTRACT_PATCH_LOADER_IMPL = RUNTIME_PACKAGE + "/AbstractPatchLoaderImpl";
    public static final String STARK_PATCH_LOADER_IMPL = RUNTIME_PACKAGE + "/StarkPatchLoaderImpl";

    protected String visitedClassName;
    protected String visitedSuperName;
    @NonNull
    protected final AsmClassNode classAndInterfaceNode;

    /**
     * Enumeration describing a method of field access rights.
     */
    protected enum AccessRight {
        PRIVATE, PACKAGE_PRIVATE, PROTECTED, PUBLIC;

        @NonNull
        static AccessRight fromNodeAccess(int nodeAccess) {
            if ((nodeAccess & Opcodes.ACC_PRIVATE) != 0) return PRIVATE;
            if ((nodeAccess & Opcodes.ACC_PROTECTED) != 0) return PROTECTED;
            if ((nodeAccess & Opcodes.ACC_PUBLIC) != 0) return PUBLIC;
            return PACKAGE_PRIVATE;
        }
    }

    MonitorVisitor(
            @NonNull AsmClassNode classAndInterfaceNode, @NonNull ClassVisitor classVisitor) {
        super(Opcodes.ASM5, classVisitor);
        this.classAndInterfaceNode = classAndInterfaceNode;
    }

    @NonNull
    protected static String getRuntimeTypeName(@NonNull Type type) {
        return "L" + type.getInternalName() + ";";
    }

    @Nullable
    AccessRight getFieldAccessRightByName(@NonNull String fieldName) {
        FieldNode fieldNode = getFieldByNameInClass(fieldName, classAndInterfaceNode);
        return fieldNode != null ? AccessRight.fromNodeAccess(fieldNode.access) : null;
    }

    @Nullable
    protected static FieldNode getFieldByNameInClass(
            @NonNull String fieldName, @NonNull AsmClassNode classAndInterfaceNode) {
        return classAndInterfaceNode.onHierarchy(
                classNode -> getFieldByNameInClass(fieldName, classNode));
    }

    @Nullable
    protected static FieldNode getFieldByNameInClass(
            @NonNull String fieldName, @NonNull ClassNode classNode) {
        //noinspection unchecked ASM api.
        List<FieldNode> fields = classNode.fields;
        for (FieldNode field : fields) {
            if (field.name.equals(fieldName)) {
                return field;
            }
        }
        return null;
    }

    @Nullable
    protected AccessRight getMethodAccessRightByName(String methodName, String desc) {
        MethodNode methodNode = getMethodByNameInClass(methodName, desc, classAndInterfaceNode);
        return methodNode != null ? AccessRight.fromNodeAccess(methodNode.access) : null;
    }

    @Nullable
    protected static MethodNode getMethodByNameInClass(
            String methodName, String desc, AsmClassNode classAndInterfaceNode) {
        return classAndInterfaceNode.onAll(
                classNode -> getMethodByNameInClass(methodName, desc, classNode));
    }

    @Nullable
    protected static MethodNode getMethodByNameInClass(String methodName, String desc, ClassNode classNode) {
        //noinspection unchecked ASM API
        List<MethodNode> methods = classNode.methods;
        for (MethodNode method : methods) {
            if (method.name.equals(methodName) && method.desc.equals(desc)) {
                return method;
            }
        }
        return null;
    }

    /**
     * Simple Builder interface for common methods between all byte code visitors.
     */
    interface VisitorBuilder {
        @NonNull
        MonitorVisitor build(@NonNull AsmClassNode classNode, @NonNull ClassVisitor classVisitor);

        @NonNull
        String getMangledRelativeClassFilePath(@NonNull String originalClassFilePath);
    }

    /**
     * Defines when a method access flags are compatible with InstantRun technology.
     * <p>
     * - If the method is a bridge method, we do not enable it for instantReload.
     * it is most likely only calling a twin method (same name, same parameters).
     * - if the method is abstract or native, we don't add a redirection.
     *
     * @param access the method access flags
     * @return true if the method should be InstantRun enabled, false otherwise.
     */
    protected static boolean isAccessCompatibleWithStark(int access) {
        return (access & (Opcodes.ACC_ABSTRACT | Opcodes.ACC_BRIDGE | Opcodes.ACC_NATIVE)) == 0;
    }

    public static byte[] instrumentClass(String name, byte[] classBytes,
                                         @NonNull ClassLoader baseClassLoader,
                                         @NonNull VisitorBuilder builder) throws IOException {
        // if the class is not eligible for IR, return the non instrumented version or null if
        // the override class is requested.
//        Files.createParentDirs(outputFile);
        if (!isClassEligibleForStark(name)) {
            return null;
        }
        ClassReader classReader = new ClassReader(classBytes);
        // override the getCommonSuperClass to use the thread context class loader instead of
        // the system classloader. This is useful as ASM needs to load classes from the project
        // which the system classloader does not have visibility upon.
        // TODO: investigate if there is not a simpler way than overriding.
        ClassWriter classWriter = new ClassWriter(classReader, ClassWriter.COMPUTE_FRAMES) {
            @Override
            protected String getCommonSuperClass(final String type1, final String type2) {
                Class<?> c, d;
                ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
                try {
                    c = Class.forName(type1.replace('/', '.'), false, classLoader);
                    d = Class.forName(type2.replace('/', '.'), false, classLoader);
                } catch (ClassNotFoundException e) {
                    // This may happen if we're processing class files which reference APIs not
                    // available on the target device. In this case return a dummy value, since this
                    // is ignored during dx compilation.
                    return "instant/run/NoCommonSuperClass";
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                if (c.isAssignableFrom(d)) {
                    return type1;
                }
                if (d.isAssignableFrom(c)) {
                    return type2;
                }
                if (c.isInterface() || d.isInterface()) {
                    return "java/lang/Object";
                } else {
                    do {
                        c = c.getSuperclass();
                    } while (!c.isAssignableFrom(d));
                    return c.getName().replace('.', '/');
                }
            }
        };

        ClassNode classNode = AsmUtils.readClass(classReader);

        // when dealing with interface, we just copy the inputFile over without any changes unless
        // this is a package private interface.
        AccessRight accessRight = AccessRight.fromNodeAccess(classNode.access);
        // no need to visit interfaces that do not have default methods.
        if ((classNode.access & Opcodes.ACC_INTERFACE) != 0 && !hasDefaultMethods(classNode)) {
            if (accessRight == AccessRight.PACKAGE_PRIVATE) {
                classNode.access = classNode.access | Opcodes.ACC_PUBLIC;
                classNode.accept(classWriter);
//                Files.write(classWriter.toByteArray(), outputFile);
                return classWriter.toByteArray();
            }
            return null;
        }

        AsmUtils.ClassLoaderBasedClassReader directoryClassReader =
                new AsmUtils.ClassLoaderBasedClassReader(baseClassLoader);

        SuperClassRedirection.redirect(classNode);

        // if we are targeting a more recent version than the current device, disable instant run
        // for that class.
        AsmClassNode parentedClassNode =
                isClassTargetingNewerPlatform(14,
                        TARGET_API_TYPE,
                        directoryClassReader,
                        classNode)
                        ? null
                        : AsmUtils.loadClass(directoryClassReader, classNode, 14);

        // if we could not determine the parent hierarchy, disable instant run.
        if (parentedClassNode == null) {// || isPackageInstantRunDisabled(inputFile)) {
            return null;
        }

        MonitorVisitor visitor = builder.build(parentedClassNode, classWriter);
        classNode.accept(new SerialVersionUIDAdder(visitor));
//        Files.write(classWriter.toByteArray(), outputFile);
        return classWriter.toByteArray();
    }

    static boolean isClassTargetingNewerPlatform(
            int targetApiLevel,
            @NonNull Type targetApiAnnotationType,
            @NonNull AsmUtils.ClassNodeProvider locator,
            @NonNull ClassNode classNode)
            throws IOException {

        List<AnnotationNode> invisibleAnnotations =
                AsmUtils.getInvisibleAnnotationsOnClassOrOuterClasses(locator, classNode);
        for (AnnotationNode classAnnotation : invisibleAnnotations) {
            if (classAnnotation.desc.equals(targetApiAnnotationType.getDescriptor())) {
                int valueIndex = 0;
                List values = classAnnotation.values;
                while (valueIndex < values.size()) {
                    String name = (String) values.get(valueIndex);
                    if (name.equals("value")) {
                        Object value = values.get(valueIndex + 1);
                        return Integer.class.cast(value) > targetApiLevel;
                    }
                    valueIndex = valueIndex + 2;
                }
            }
        }
        return false;
    }

    static boolean hasDefaultMethods(@NonNull ClassNode classNode) {
        if ((classNode.access & Opcodes.ACC_INTERFACE) == 0) {
            return false;
        }
        // interfaces before V1_8 cannot have default methods.
        return classNode.version >= Opcodes.V1_8
                && ((List<MethodNode>) classNode.methods)
                .stream()
                .anyMatch(methodNode -> (methodNode.access & Opcodes.ACC_ABSTRACT) == 0);
    }

    static boolean isClassEligibleForStark(@NonNull File inputFile) {
        if (inputFile.getPath().endsWith(SdkConstants.DOT_CLASS)) {
            return isClassEligibleForStark(inputFile.getName());
        } else {
            return false;
        }
    }

    static boolean isClassEligibleForStark(@NonNull String name) {
        if (name.endsWith(SdkConstants.DOT_CLASS)) {
            return !name.equals("R" + SdkConstants.DOT_CLASS) && !name.startsWith("R$");
        } else {
            return false;
        }
    }
}