package indexing;

import com.github.javaparser.ast.ImportDeclaration;

import com.github.javaparser.ast.PackageDeclaration;

import com.github.javaparser.ast.visitor.VoidVisitorAdapter;

import indexing.Index;

import java.util.HashMap;

import java.util.Map;

/**

 * Determines all imports we need to consider including:

 * <ul>

 *     <li>java.util.HashMap</li>

 *     <li>java.util.*</li>

 *     <li>java.lang.* (always included)</li>

 *     <li>current.package.* (always included)</li>

 * </ul>

 */

public class ImportVisitor extends VoidVisitorAdapter<Void> {

    /**

     * SimpleName (ex: Object) to Fully Qualified Name (ex: java.lang.Object)

     */

    public final Map<String, String> imports = new HashMap<>();

    private final Index index;

    public ImportVisitor(Index index) {

        this.index = index;

        for (String fullyQualifiedName : index.getClassIndex().keySet()) {

            if (fullyQualifiedName.startsWith("java.lang.")) {

                imports.put(getLastToken(fullyQualifiedName), fullyQualifiedName);

            }

        }

    }

    private boolean isInPackage(

            String fullyQualifiedName,

            String packageName

    ) {

        return fullyQualifiedName.startsWith(packageName)

                && fullyQualifiedName.lastIndexOf('.') <= packageName.length();

    }

    @Override

    public void visit(PackageDeclaration packageDeclaration, Void arg) {

        String packageName = packageDeclaration.getName().asString();

        for (String fullyQualifiedName : index.getClassIndex().keySet()) {

            if (isInPackage(fullyQualifiedName, packageName)) {

                imports.put(getLastToken(fullyQualifiedName), fullyQualifiedName);

            }

        }

        super.visit(packageDeclaration, arg);

    }

    @Override

    public void visit(ImportDeclaration importDeclaration, Void arg) {

        if (!importDeclaration.isAsterisk() && !importDeclaration.isStatic()) {

            String importName = importDeclaration.getNameAsString();

            imports.put(getLastToken(importName), importName);

        } else if (importDeclaration.isAsterisk() && !importDeclaration.isStatic()) {

            String importName = importDeclaration.getNameAsString();

            for (String fullyQualifiedName : index.getClassIndex().keySet()) {

                if (isInPackage(fullyQualifiedName, importName)) {

                    imports.put(getLastToken(fullyQualifiedName), fullyQualifiedName);

                }

            }

        }

        super.visit(importDeclaration, arg);

    }

    private static String getLastToken(String importName) {

        String [] tokens = importName.split("\\.");

        if (tokens.length <= 0) {

            return "";

        }

        return tokens[tokens.length-1];

    }

}