/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.maven.tools.plugin.extractor.annotations.converter;

import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Collectors;

import com.thoughtworks.qdox.JavaProjectBuilder;
import com.thoughtworks.qdox.builder.TypeAssembler;
import com.thoughtworks.qdox.library.ClassNameLibrary;
import com.thoughtworks.qdox.model.JavaClass;
import com.thoughtworks.qdox.model.JavaField;
import com.thoughtworks.qdox.model.JavaModule;
import com.thoughtworks.qdox.model.JavaPackage;
import com.thoughtworks.qdox.model.JavaType;
import com.thoughtworks.qdox.parser.structs.TypeDef;
import com.thoughtworks.qdox.type.TypeResolver;
import org.apache.maven.tools.plugin.extractor.annotations.scanner.MojoAnnotatedClass;
import org.apache.maven.tools.plugin.javadoc.FullyQualifiedJavadocReference;
import org.apache.maven.tools.plugin.javadoc.FullyQualifiedJavadocReference.MemberType;
import org.apache.maven.tools.plugin.javadoc.JavadocLinkGenerator;
import org.apache.maven.tools.plugin.javadoc.JavadocReference;

/** {@link ConverterContext} based on QDox's {@link JavaClass} and {@link JavaProjectBuilder}. */
public class JavaClassConverterContext implements ConverterContext {

    final JavaClass mojoClass; // this is the mojo's class

    final JavaClass declaringClass; // this may be a super class of the mojo's class

    final JavaProjectBuilder javaProjectBuilder;

    final Map<String, MojoAnnotatedClass> mojoAnnotatedClasses;

    final JavadocLinkGenerator linkGenerator; // may be null in case nothing was configured

    final int lineNumber;

    final Optional<JavaModule> javaModule;

    final Map<String, Object> attributes;

    public JavaClassConverterContext(
            JavaClass mojoClass,
            JavaProjectBuilder javaProjectBuilder,
            Map<String, MojoAnnotatedClass> mojoAnnotatedClasses,
            JavadocLinkGenerator linkGenerator,
            int lineNumber) {
        this(mojoClass, mojoClass, javaProjectBuilder, mojoAnnotatedClasses, linkGenerator, lineNumber);
    }

    public JavaClassConverterContext(
            JavaClass mojoClass,
            JavaClass declaringClass,
            JavaProjectBuilder javaProjectBuilder,
            Map<String, MojoAnnotatedClass> mojoAnnotatedClasses,
            JavadocLinkGenerator linkGenerator,
            int lineNumber) {
        this.mojoClass = mojoClass;
        this.declaringClass = declaringClass;
        this.javaProjectBuilder = javaProjectBuilder;
        this.mojoAnnotatedClasses = mojoAnnotatedClasses;
        this.linkGenerator = linkGenerator;
        this.lineNumber = lineNumber;
        this.attributes = new HashMap<>();

        javaModule = mojoClass.getJavaClassLibrary().getJavaModules().stream()
                .filter(m -> m.getDescriptor().getExports().stream()
                        .anyMatch(e -> e.getSource().getName().equals(getPackageName())))
                .findFirst();
    }

    @Override
    public Optional<String> getModuleName() {
        // https://github.com/paul-hammant/qdox/issues/113, module name is not exposed
        return javaModule.map(JavaModule::getName);
    }

    @Override
    public String getPackageName() {
        return mojoClass.getPackageName();
    }

    @Override
    public String getLocation() {
        try {
            URL url = declaringClass.getSource().getURL();
            if (url == null) // url is not always available, just emit FQCN in that case
            {
                return declaringClass.getPackageName() + declaringClass.getSimpleName() + ":" + lineNumber;
            }
            return Paths.get("").toUri().relativize(url.toURI()) + ":" + lineNumber;
        } catch (URISyntaxException e) {
            return declaringClass.getSource().getURL() + ":" + lineNumber;
        }
    }

    /**
     * @param reference
     * @return true in case either the current context class or any of its super classes are referenced
     */
    @Override
    public boolean isReferencedBy(FullyQualifiedJavadocReference reference) {
        JavaClass javaClassInHierarchy = this.mojoClass;
        while (javaClassInHierarchy != null) {
            if (isClassReferencedByReference(javaClassInHierarchy, reference)) {
                return true;
            }
            // check implemented interfaces
            for (JavaClass implementedInterfaces : javaClassInHierarchy.getInterfaces()) {
                if (isClassReferencedByReference(implementedInterfaces, reference)) {
                    return true;
                }
            }
            javaClassInHierarchy = javaClassInHierarchy.getSuperJavaClass();
        }
        return false;
    }

    private static boolean isClassReferencedByReference(JavaClass javaClass, FullyQualifiedJavadocReference reference) {
        return javaClass.getPackageName().equals(reference.getPackageName().orElse(""))
                && javaClass.getSimpleName().equals(reference.getClassName().orElse(""));
    }

    @Override
    public boolean canGetUrl() {
        return linkGenerator != null;
    }

    @Override
    public URI getUrl(FullyQualifiedJavadocReference reference) {
        try {
            if (isReferencedBy(reference)
                    && MemberType.FIELD == reference.getMemberType().orElse(null)) {
                // link to current goal's parameters
                return new URI(null, null, reference.getMember().orElse(null)); // just an anchor if same context
            }
            Optional<String> fqClassName = reference.getFullyQualifiedClassName();
            if (fqClassName.isPresent()) {
                MojoAnnotatedClass mojoAnnotatedClass = mojoAnnotatedClasses.get(fqClassName.get());
                if (mojoAnnotatedClass != null
                        && mojoAnnotatedClass.getMojo() != null
                        && (!reference.getLabel().isPresent()
                                || MemberType.FIELD == reference.getMemberType().orElse(null))) {
                    // link to other mojo (only for fields = parameters or without member)
                    return new URI(
                            null,
                            "./" + mojoAnnotatedClass.getMojo().name() + "-mojo.html",
                            reference.getMember().orElse(null));
                }
            }
        } catch (URISyntaxException e) {
            throw new IllegalStateException("Error constructing a valid URL", e); // should not happen
        }
        if (linkGenerator == null) {
            throw new IllegalStateException("No Javadoc Sites given to create URLs to");
        }
        return linkGenerator.createLink(reference);
    }

    @Override
    public FullyQualifiedJavadocReference resolveReference(JavadocReference reference) {
        Optional<FullyQualifiedJavadocReference> resolvedName;
        // is it already fully qualified?
        if (reference.getPackageNameClassName().isPresent()) {
            resolvedName = resolveMember(
                    reference.getPackageNameClassName().get(), reference.getMember(), reference.getLabel());
            if (resolvedName.isPresent()) {
                return resolvedName.get();
            }
        }
        // is it a member only?
        if (reference.getMember().isPresent()
                && !reference.getPackageNameClassName().isPresent()) {
            // search order for not fully qualified names:
            // 1. The current class or interface (only for members)
            resolvedName = resolveMember(declaringClass, reference.getMember(), reference.getLabel());
            if (resolvedName.isPresent()) {
                return resolvedName.get();
            }
            // 2. Any enclosing classes and interfaces searching the closest first (only members)
            for (JavaClass nestedClass : declaringClass.getNestedClasses()) {
                resolvedName = resolveMember(nestedClass, reference.getMember(), reference.getLabel());
                if (resolvedName.isPresent()) {
                    return resolvedName.get();
                }
            }
            // 3. Any superclasses and superinterfaces, searching the closest first. (only members)
            JavaClass superClass = declaringClass.getSuperJavaClass();
            while (superClass != null) {
                resolvedName = resolveMember(superClass, reference.getMember(), reference.getLabel());
                if (resolvedName.isPresent()) {
                    return resolvedName.get();
                }
                superClass = superClass.getSuperJavaClass();
            }
        } else {
            String packageNameClassName = reference.getPackageNameClassName().get();
            // 4. The current package
            resolvedName = resolveMember(
                    declaringClass.getPackageName() + "." + packageNameClassName,
                    reference.getMember(),
                    reference.getLabel());
            if (resolvedName.isPresent()) {
                return resolvedName.get();
            }
            // 5. Any imported packages, classes, and interfaces, searching in the order of the import statement.
            List<String> importNames = new ArrayList<>();
            importNames.add("java.lang.*"); // default import
            importNames.addAll(declaringClass.getSource().getImports());
            for (String importName : importNames) {
                if (importName.endsWith(".*")) {
                    resolvedName = resolveMember(
                            importName.replace("*", packageNameClassName), reference.getMember(), reference.getLabel());
                    if (resolvedName.isPresent()) {
                        return resolvedName.get();
                    }
                } else {
                    if (importName.endsWith(packageNameClassName)) {
                        resolvedName = resolveMember(importName, reference.getMember(), reference.getLabel());
                        if (resolvedName.isPresent()) {
                            return resolvedName.get();
                        }
                    } else {
                        // ends with prefix of reference (nested class name)
                        int firstDotIndex = packageNameClassName.indexOf(".");
                        if (firstDotIndex > 0
                                && importName.endsWith(packageNameClassName.substring(0, firstDotIndex))) {
                            resolvedName = resolveMember(
                                    importName,
                                    packageNameClassName.substring(firstDotIndex + 1),
                                    reference.getMember(),
                                    reference.getLabel());
                            if (resolvedName.isPresent()) {
                                return resolvedName.get();
                            }
                        }
                    }
                }
            }
        }
        throw new IllegalArgumentException("Could not resolve javadoc reference " + reference);
    }

    @Override
    public String getStaticFieldValue(FullyQualifiedJavadocReference reference) {
        String fqcn = reference
                .getFullyQualifiedClassName()
                .orElseThrow(() ->
                        new IllegalArgumentException("Given reference does not specify a fully qualified class name!"));
        String fieldName = reference
                .getMember()
                .orElseThrow(() -> new IllegalArgumentException("Given reference does not specify a member!"));
        JavaClass javaClass = javaProjectBuilder.getClassByName(fqcn);
        JavaField javaField = javaClass.getFieldByName(fieldName);
        if (javaField == null) {
            throw new IllegalArgumentException("Could not find field with name " + fieldName + " in class " + fqcn);
        }
        if (!javaField.isStatic()) {
            throw new IllegalArgumentException("Field with name " + fieldName + " in class " + fqcn + " is not static");
        }
        return javaField.getInitializationExpression();
    }

    @Override
    public URI getInternalJavadocSiteBaseUrl() {
        return linkGenerator.getInternalJavadocSiteBaseUrl();
    }

    private Optional<FullyQualifiedJavadocReference> resolveMember(
            String fullyQualifiedPackageNameClassName, Optional<String> member, Optional<String> label) {
        return resolveMember(fullyQualifiedPackageNameClassName, "", member, label);
    }

    private Optional<FullyQualifiedJavadocReference> resolveMember(
            String fullyQualifiedPackageNameClassName,
            String nestedClassName,
            Optional<String> member,
            Optional<String> label) {
        JavaClass javaClass = javaProjectBuilder.getClassByName(fullyQualifiedPackageNameClassName);
        if (!isClassFound(javaClass)) {
            JavaPackage javaPackage = javaProjectBuilder.getPackageByName(fullyQualifiedPackageNameClassName);
            if (javaPackage == null || !nestedClassName.isEmpty()) {
                // is it a nested class?
                int lastIndexOfDot = fullyQualifiedPackageNameClassName.lastIndexOf('.');
                if (lastIndexOfDot > 0) {
                    String newNestedClassName = nestedClassName;
                    if (!newNestedClassName.isEmpty()) {
                        newNestedClassName += '.';
                    }
                    newNestedClassName += fullyQualifiedPackageNameClassName.substring(lastIndexOfDot + 1);
                    return resolveMember(
                            fullyQualifiedPackageNameClassName.substring(0, lastIndexOfDot),
                            newNestedClassName,
                            member,
                            label);
                }
                return Optional.empty();
            } else {
                // reference to java package never has a member
                return Optional.of(
                        new FullyQualifiedJavadocReference(javaPackage.getName(), label, isExternal(javaPackage)));
            }
        } else {
            if (!nestedClassName.isEmpty()) {
                javaClass = javaClass.getNestedClassByName(nestedClassName);
                if (javaClass == null) {
                    return Optional.empty();
                }
            }

            return resolveMember(javaClass, member, label);
        }
    }

    private boolean isExternal(JavaClass javaClass) {
        return isExternal(javaClass.getPackage());
    }

    private boolean isExternal(JavaPackage javaPackage) {
        return !javaPackage.getJavaClassLibrary().equals(mojoClass.getJavaClassLibrary());
    }

    private Optional<FullyQualifiedJavadocReference> resolveMember(
            JavaClass javaClass, Optional<String> member, Optional<String> label) {
        final Optional<MemberType> memberType;
        Optional<String> resolvedMember = member;
        if (member.isPresent()) {
            // member is either field...
            if (javaClass.getFieldByName(member.get()) == null) {
                // ...is method...
                List<JavaType> parameterTypes = getParameterTypes(member.get());
                String methodName = getMethodName(member.get());
                if (javaClass.getMethodBySignature(methodName, parameterTypes) == null) {
                    // ...or is constructor
                    if ((!methodName.equals(javaClass.getSimpleName()))
                            || (javaClass.getConstructor(parameterTypes) == null)) {
                        return Optional.empty();
                    } else {
                        memberType = Optional.of(MemberType.CONSTRUCTOR);
                    }
                } else {
                    memberType = Optional.of(MemberType.METHOD);
                }
                // reconstruct member with fully qualified names but leaving out the argument names
                StringBuilder memberBuilder = new StringBuilder(methodName);
                memberBuilder.append("(");
                memberBuilder.append(parameterTypes.stream()
                        .map(JavaType::getFullyQualifiedName)
                        .collect(Collectors.joining(",")));
                memberBuilder.append(")");
                resolvedMember = Optional.of(memberBuilder.toString());
            } else {
                memberType = Optional.of(MemberType.FIELD);
            }
        } else {
            memberType = Optional.empty();
        }
        String className = javaClass
                .getCanonicalName()
                .substring(javaClass.getPackageName().length() + 1);
        return Optional.of(new FullyQualifiedJavadocReference(
                javaClass.getPackageName(),
                Optional.of(className),
                resolvedMember,
                memberType,
                label,
                isExternal(javaClass)));
    }

    private static boolean isClassFound(JavaClass javaClass) {
        // this is never null due to using the ClassNameLibrary in the builder
        // but every instance of ClassNameLibrary basically means that the class was not found
        return !(javaClass.getJavaClassLibrary() instanceof ClassNameLibrary);
    }

    // https://github.com/paul-hammant/qdox/issues/104
    private List<JavaType> getParameterTypes(String member) {
        List<JavaType> parameterTypes = new ArrayList<>();
        // TypeResolver.byClassName() always resolves types as non existing inner class
        TypeResolver typeResolver = TypeResolver.byClassName(
                declaringClass.getPackageName(),
                declaringClass.getJavaClassLibrary(),
                declaringClass.getSource().getImports());

        // method parameters are optionally enclosed by parentheses
        int indexOfOpeningParenthesis = member.indexOf('(');
        int indexOfClosingParenthesis = member.indexOf(')');
        final String signatureArguments;
        if (indexOfOpeningParenthesis >= 0
                && indexOfClosingParenthesis > 0
                && indexOfClosingParenthesis > indexOfOpeningParenthesis) {
            signatureArguments = member.substring(indexOfOpeningParenthesis + 1, indexOfClosingParenthesis);
        } else if (indexOfOpeningParenthesis == -1 && indexOfClosingParenthesis >= 0
                || indexOfOpeningParenthesis >= 0 && indexOfOpeningParenthesis == -1) {
            throw new IllegalArgumentException("Found opening without closing parentheses or vice versa in " + member);
        } else {
            // If any method or constructor is entered as a name with no parentheses, such as getValue,
            // and if there is no field with the same name, then the javadoc command still creates a
            // link to the method. If this method is overloaded, then the javadoc command links to the
            // first method its search encounters, which is unspecified
            // (Source: https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javadoc.html#JSWOR654)
            return Collections.emptyList();
        }
        for (String parameter : signatureArguments.split(",")) {
            // strip off argument name, only type is relevant
            String canonicalParameter = parameter.trim();
            int spaceIndex = canonicalParameter.indexOf(' ');
            final String typeName;
            if (spaceIndex > 0) {
                typeName = canonicalParameter.substring(0, spaceIndex).trim();
            } else {
                typeName = canonicalParameter;
            }
            if (!typeName.isEmpty()) {
                String rawTypeName = getRawTypeName(typeName);
                // already check here for unresolvable types due to https://github.com/paul-hammant/qdox/issues/111
                if (typeResolver.resolveType(rawTypeName) == null) {
                    throw new IllegalArgumentException("Found unresolvable method argument type in " + member);
                }
                TypeDef typeDef = new TypeDef(getRawTypeName(typeName));
                int dimensions = getDimensions(typeName);
                JavaType javaType = TypeAssembler.createUnresolved(typeDef, dimensions, typeResolver);

                parameterTypes.add(javaType);
            }
        }
        return parameterTypes;
    }

    private static int getDimensions(String type) {
        return (int) type.chars().filter(ch -> ch == '[').count();
    }

    private static String getRawTypeName(String typeName) {
        // strip dimensions
        int indexOfOpeningBracket = typeName.indexOf('[');
        if (indexOfOpeningBracket >= 0) {
            return typeName.substring(0, indexOfOpeningBracket);
        } else {
            return typeName;
        }
    }

    private static String getMethodName(String member) {
        // name is separated from arguments either by '(' or spans the full member
        int indexOfOpeningParentheses = member.indexOf('(');
        if (indexOfOpeningParentheses == -1) {
            return member;
        } else {
            return member.substring(0, indexOfOpeningParentheses);
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T setAttribute(String name, T value) {
        return (T) attributes.put(name, value);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T getAttribute(String name, Class<T> clazz, T defaultValue) {
        return (T) attributes.getOrDefault(name, defaultValue);
    }
}