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/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.tools.lint.checks;

import static com.android.tools.lint.client.api.JavaParser.ResolvedClass;
import static com.android.tools.lint.client.api.JavaParser.ResolvedMethod;
import static com.android.tools.lint.client.api.JavaParser.ResolvedNode;

import com.android.SdkConstants;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Detector;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.JavaContext;
import com.android.tools.lint.detector.api.Location;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.Speed;

import java.lang.reflect.Modifier;
import java.util.Collections;
import java.util.List;

import lombok.ast.AstVisitor;
import lombok.ast.ClassDeclaration;
import lombok.ast.ConstructorDeclaration;
import lombok.ast.ForwardingAstVisitor;
import lombok.ast.Node;
import lombok.ast.NormalTypeBody;
import lombok.ast.TypeMember;

/**
 * Looks for custom views that do not define the view constructors needed by UI builders
 */
public class ViewConstructorDetector extends Detector implements Detector.JavaScanner {
    /** The main issue discovered by this detector */
    public static final Issue ISSUE = Issue.create(
            "ViewConstructor", //$NON-NLS-1$
            "Missing View constructors for XML inflation",
            "Checks that custom views define the expected constructors",

            "Some layout tools (such as the Android layout editor for Studio & Eclipse) needs to " +
            "find a constructor with one of the following signatures:\n" +
            "* `View(Context context)`\n" +
            "* `View(Context context, AttributeSet attrs)`\n" +
            "* `View(Context context, AttributeSet attrs, int defStyle)`\n" +
            "\n" +
            "If your custom view needs to perform initialization which does not apply when " +
            "used in a layout editor, you can surround the given code with a check to " +
            "see if `View#isInEditMode()` is false, since that method will return `false` " +
            "at runtime but true within a user interface editor.",

            Category.USABILITY,
            3,
            Severity.WARNING,
            new Implementation(
                    ViewConstructorDetector.class,
                    Scope.JAVA_FILE_SCOPE));

    /** Constructs a new {@link ViewConstructorDetector} check */
    public ViewConstructorDetector() {
    }

    @NonNull
    @Override
    public Speed getSpeed() {
        return Speed.FAST;
    }

    // ---- Implements JavaScanner ----

    @Nullable
    @Override
    public List> getApplicableNodeTypes() {
        return Collections.>singletonList(ClassDeclaration.class);
    }

    @Nullable
    @Override
    public AstVisitor createJavaVisitor(@NonNull final JavaContext context) {
        return new ViewConstructorVisitor(context);
    }

    private static boolean isXmlConstructor(ResolvedMethod method) {
        // Accept
        //   android.content.Context
        //   android.content.Context,android.util.AttributeSet
        //   android.content.Context,android.util.AttributeSet,int
        int argumentCount = method.getArgumentCount();
        if (argumentCount == 0 || argumentCount > 3) {
            return false;
        }
        if (!method.getArgumentType(0).matchesName("android.content.Context")) {
            return false;
        }
        if (argumentCount == 1) {
            return true;
        }
        if (!method.getArgumentType(1).matchesName("android.util.AttributeSet")) {
            return false;
        }
        //noinspection SimplifiableIfStatement
        if (argumentCount == 2) {
            return true;
        }
        return method.getArgumentType(2).matchesName("int");
    }

    private static class ViewConstructorVisitor extends ForwardingAstVisitor {

        private final JavaContext mContext;

        public ViewConstructorVisitor(JavaContext context) {
            mContext = context;
        }

        @Override
        public boolean visitClassDeclaration(ClassDeclaration node) {
            // Only applies to concrete classes
            int flags = node.astModifiers().getEffectiveModifierFlags();
            // Ignore abstract classes
            if ((flags & Modifier.ABSTRACT) != 0) {
                return true;
            }

            if (node.getParent() instanceof NormalTypeBody
                    && ((flags & Modifier.STATIC) == 0)) {
                // Ignore inner classes that aren't static: we can't create these
                // anyway since we'd need the outer instance
                return true;
            }

            ResolvedNode resolved = mContext.resolve(node);
            if (!(resolved instanceof ResolvedClass)) {
                return true;
            }

            ResolvedClass cls = (ResolvedClass) resolved;
            if (!cls.isSubclassOf(SdkConstants.CLASS_VIEW, false)) {
                return true;
            }

            boolean found = false;
            for (ResolvedMethod constructor : cls.getConstructors()) {
                if (isXmlConstructor(constructor)) {
                    found = true;
                    break;
                }
            }

            if (!found) {
                String message = String.format(
                        "Custom view %1$s is missing constructor used by tools: "
                                + "(Context) or (Context,AttributeSet) "
                                + "or (Context,AttributeSet,int)",
                        node.astName().astValue()
                );
                Location location = mContext.getLocation(node.astName());
                mContext.report(ISSUE, node, location,
                        message, null /*data*/);
            }

            return true;
        }
    }
}