///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2026 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
///////////////////////////////////////////////////////////////////////////////////////////////

package com.puppycrawl.tools.checkstyle.utils;

import java.util.Optional;

import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.Scope;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

/**
 * Contains utility methods for working on scope.
 *
 */
public final class ScopeUtil {

    /** Prevent instantiation. */
    private ScopeUtil() {
    }

    /**
     * Returns the {@code Scope} explicitly specified by the modifier set.
     * Returns {@code null} if there are no modifiers.
     *
     * @param mods root node of a modifier set
     * @return a {@code Scope} value or {@code null}
     */
    public static Optional<Scope> getDeclaredScopeFromMods(DetailAST mods) {
        Optional<Scope> result = Optional.empty();
        for (DetailAST token = mods.getFirstChild(); token != null;
             token = token.getNextSibling()) {
            result = switch (token.getType()) {
                case TokenTypes.LITERAL_PUBLIC -> Optional.of(Scope.PUBLIC);
                case TokenTypes.LITERAL_PROTECTED -> Optional.of(Scope.PROTECTED);
                case TokenTypes.LITERAL_PRIVATE -> Optional.of(Scope.PRIVATE);
                default -> result;
            };
        }
        return result;
    }

    /**
     * Returns the {@code Scope} for a given {@code DetailAST}.
     *
     * @param ast the DetailAST to examine
     * @return a {@code Scope} value
     */
    public static Scope getScope(DetailAST ast) {
        return Optional.ofNullable(ast.findFirstToken(TokenTypes.MODIFIERS))
                .flatMap(ScopeUtil::getDeclaredScopeFromMods)
                .orElseGet(() -> getDefaultScope(ast));
    }

    /**
     * Returns the {@code Scope} specified by the modifier set. If no modifiers are present,
     * the default scope is used.
     *
     * @param mods root node of a modifier set
     * @return a {@code Scope} value
     * @see #getDefaultScope(DetailAST)
     */
    public static Scope getScopeFromMods(DetailAST mods) {
        return getDeclaredScopeFromMods(mods)
                .orElseGet(() -> getDefaultScope(mods));
    }

    /**
     * Returns the default {@code Scope} for a {@code DetailAST}.
     *
     * <p>The following rules are taken into account:</p>
     * <ul>
     *     <li>enum constants are public</li>
     *     <li>enum constructors are private</li>
     *     <li>interface members are public</li>
     *     <li>everything else is package private</li>
     * </ul>
     *
     * @param ast DetailAST to process
     * @return a {@code Scope} value
     */
    private static Scope getDefaultScope(DetailAST ast) {
        final Scope result;
        if (isInEnumBlock(ast)) {
            if (ast.getType() == TokenTypes.ENUM_CONSTANT_DEF) {
                result = Scope.PUBLIC;
            }
            else if (ast.getType() == TokenTypes.CTOR_DEF) {
                result = Scope.PRIVATE;
            }
            else {
                result = Scope.PACKAGE;
            }
        }
        else if (isInInterfaceOrAnnotationBlock(ast)) {
            result = Scope.PUBLIC;
        }
        else {
            result = Scope.PACKAGE;
        }
        return result;
    }

    /**
     * Returns the scope of the surrounding "block".
     *
     * @param node the node to return the scope for
     * @return the Scope of the surrounding block
     */
    public static Optional<Scope> getSurroundingScope(DetailAST node) {
        Optional<Scope> returnValue = Optional.empty();
        DetailAST child = null;
        for (DetailAST token = node;
             token != null;
             child = token, token = token.getParent()) {
            final int type = token.getType();
            if (TokenUtil.isTypeDeclaration(type)) {
                final Scope tokenScope = getScope(token);
                if (returnValue.isEmpty() || returnValue.get().isIn(tokenScope)) {
                    returnValue = Optional.of(tokenScope);
                }
            }
            else if (type == TokenTypes.LITERAL_NEW) {
                returnValue = Optional.of(Scope.ANONINNER);
                // because Scope.ANONINNER is not in any other Scope
                break;
            }
            else if (type == TokenTypes.COMPACT_COMPILATION_UNIT
                        && !TokenUtil.isOfType(child, TokenTypes.IMPORT,
                                TokenTypes.STATIC_IMPORT, TokenTypes.MODULE_IMPORT)
                        && (returnValue.isEmpty() || returnValue.get().isIn(Scope.PACKAGE))) {
                returnValue = Optional.of(Scope.PACKAGE);
            }
        }

        return returnValue;
    }

    /**
     * Returns whether a node is directly contained within a class block.
     *
     * @param node the node to check if directly contained within a class block.
     * @return a {@code boolean} value
     */
    public static boolean isInClassBlock(DetailAST node) {
        return isInBlockOf(node, TokenTypes.CLASS_DEF);
    }

    /**
     * Returns whether a node is directly contained within a record block.
     *
     * @param node the node to check if directly contained within a record block.
     * @return a {@code boolean} value
     */
    public static boolean isInRecordBlock(DetailAST node) {
        return isInBlockOf(node, TokenTypes.RECORD_DEF);
    }

    /**
     * Returns whether a node is directly contained within an interface block.
     *
     * @param node the node to check if directly contained within an interface block.
     * @return a {@code boolean} value
     */
    public static boolean isInInterfaceBlock(DetailAST node) {
        return isInBlockOf(node, TokenTypes.INTERFACE_DEF);
    }

    /**
     * Returns whether a node is directly contained within an annotation block.
     *
     * @param node the node to check if directly contained within an annotation block.
     * @return a {@code boolean} value
     */
    public static boolean isInAnnotationBlock(DetailAST node) {
        return isInBlockOf(node, TokenTypes.ANNOTATION_DEF);
    }

    /**
     * Returns whether a node is directly contained within a specified block.
     *
     * @param node the node to check if directly contained within a specified block.
     * @param tokenType type of token.
     * @return a {@code boolean} value
     */
    public static boolean isInBlockOf(DetailAST node, int tokenType) {
        boolean returnValue = false;

        // Loop up looking for a containing interface block
        for (DetailAST token = node.getParent();
             token != null; token = token.getParent()) {
            if (TokenUtil.isOfType(token, TokenTypes.LITERAL_NEW, tokenType)
                    || TokenUtil.isTypeDeclaration(token.getType())) {
                returnValue = token.getType() == tokenType;
                break;
            }
        }
        return returnValue;
    }

    /**
     * Returns whether a node is directly contained within an interface or annotation block.
     *
     * @param node the node to check if directly contained within an interface or annotation block.
     * @return a {@code boolean} value
     */
    public static boolean isInInterfaceOrAnnotationBlock(DetailAST node) {
        return isInInterfaceBlock(node) || isInAnnotationBlock(node);
    }

    /**
     * Returns whether a node is directly contained within an enum block.
     *
     * @param node the node to check if directly contained within an enum block.
     * @return a {@code boolean} value
     */
    public static boolean isInEnumBlock(DetailAST node) {
        boolean returnValue = false;

        // Loop up looking for a containing interface block
        for (DetailAST token = node.getParent();
             token != null; token = token.getParent()) {
            if (TokenUtil.isOfType(token, TokenTypes.INTERFACE_DEF,
                TokenTypes.ANNOTATION_DEF, TokenTypes.CLASS_DEF,
                TokenTypes.LITERAL_NEW, TokenTypes.ENUM_DEF)) {
                returnValue = token.getType() == TokenTypes.ENUM_DEF;
                break;
            }
        }

        return returnValue;
    }

    /**
     * Returns whether the scope of a node is restricted to a code block.
     * A code block is a method or constructor body, an initializer block, or lambda body.
     *
     * @param node the node to check
     * @return a {@code boolean} value
     */
    public static boolean isInCodeBlock(DetailAST node) {
        boolean returnValue = false;
        final int[] tokenTypes = {
            TokenTypes.METHOD_DEF,
            TokenTypes.CTOR_DEF,
            TokenTypes.INSTANCE_INIT,
            TokenTypes.STATIC_INIT,
            TokenTypes.LAMBDA,
            TokenTypes.COMPACT_CTOR_DEF,
        };

        // Loop up looking for a containing code block
        for (DetailAST token = node.getParent();
             token != null;
             token = token.getParent()) {
            if (TokenUtil.isOfType(token, tokenTypes)) {
                returnValue = true;
                break;
            }
        }

        return returnValue;
    }

    /**
     * Returns whether a node is contained in the outermost type block.
     *
     * @param node the node to check
     * @return a {@code boolean} value
     */
    public static boolean isOuterMostType(DetailAST node) {
        boolean returnValue = true;
        for (DetailAST parent = node.getParent();
             parent != null;
             parent = parent.getParent()) {
            if (TokenUtil.isTypeDeclaration(parent.getType())
                    || parent.getType() == TokenTypes.COMPACT_COMPILATION_UNIT) {
                returnValue = false;
                break;
            }
        }

        return returnValue;
    }

    /**
     * Determines whether a node is a local variable definition.
     * I.e. if it is declared in a code block, a for initializer,
     * or a catch parameter.
     *
     * @param node the node to check.
     * @return whether aAST is a local variable definition.
     */
    public static boolean isLocalVariableDef(DetailAST node) {
        final boolean localVariableDef;
        // variable declaration?
        if (node.getType() == TokenTypes.VARIABLE_DEF) {
            final DetailAST parent = node.getParent();
            localVariableDef = TokenUtil.isOfType(parent, TokenTypes.SLIST,
                                TokenTypes.FOR_INIT, TokenTypes.FOR_EACH_CLAUSE);
        }

        else if (node.getType() == TokenTypes.RESOURCE) {
            localVariableDef = node.getChildCount() > 1;
        }

        // catch parameter?
        else if (node.getType() == TokenTypes.PARAMETER_DEF) {
            final DetailAST parent = node.getParent();
            localVariableDef = parent.getType() == TokenTypes.LITERAL_CATCH;
        }

        else {
            localVariableDef = false;
        }

        return localVariableDef;
    }

    /**
     * Determines whether a node is a class field definition.
     * I.e. if a variable is not declared in a code block, a for initializer,
     * or a catch parameter.
     *
     * @param node the node to check.
     * @return whether a node is a class field definition.
     */
    public static boolean isClassFieldDef(DetailAST node) {
        return node.getType() == TokenTypes.VARIABLE_DEF
                && !isLocalVariableDef(node);
    }

    /**
     * Checks whether ast node is in a specific scope.
     *
     * @param ast the node to check.
     * @param scope a {@code Scope} value.
     * @return true if the ast node is in the scope.
     */
    public static boolean isInScope(DetailAST ast, Scope scope) {
        return getSurroundingScope(ast)
                .map(surroundingScope -> {
                    return surroundingScope == scope;
                })
                .orElse(Boolean.FALSE);
    }

}