////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2022 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.api;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;

import com.puppycrawl.tools.checkstyle.grammar.CommentListener;
import com.puppycrawl.tools.checkstyle.utils.CommonUtil;

/**
 * Represents the contents of a file.
 *
 */
public final class FileContents implements CommentListener {

    /**
     * The pattern to match a single line comment containing only the comment
     * itself -- no code.
     */
    private static final String MATCH_SINGLELINE_COMMENT_PAT = "^\\s*//.*$";
    /** Compiled regexp to match a single-line comment line. */
    private static final Pattern MATCH_SINGLELINE_COMMENT = Pattern
            .compile(MATCH_SINGLELINE_COMMENT_PAT);

    /** The text. */
    private final FileText text;

    /**
     * Map of the Javadoc comments indexed on the last line of the comment.
     * The hack is it assumes that there is only one Javadoc comment per line.
     */
    private final Map<Integer, TextBlock> javadocComments = new HashMap<>();
    /** Map of the C++ comments indexed on the first line of the comment. */
    private final Map<Integer, TextBlock> cppComments = new HashMap<>();

    /**
     * Map of the C comments indexed on the first line of the comment to a list
     * of comments on that line.
     */
    private final Map<Integer, List<TextBlock>> clangComments = new HashMap<>();

    /**
     * Creates a new {@code FileContents} instance.
     *
     * @param text the contents of the file
     */
    public FileContents(FileText text) {
        this.text = new FileText(text);
    }

    /**
     * Get the full text of the file.
     *
     * @return an object containing the full text of the file
     */
    public FileText getText() {
        return new FileText(text);
    }

    /**
     * Gets the lines in the file.
     *
     * @return the lines in the file
     */
    public String[] getLines() {
        return text.toLinesArray();
    }

    /**
     * Get the line from text of the file.
     *
     * @param index index of the line
     * @return line from text of the file
     */
    public String getLine(int index) {
        return text.get(index);
    }

    /**
     * Gets the name of the file.
     *
     * @return the name of the file
     */
    public String getFileName() {
        return text.getFile().toString();
    }

    @Override
    public void reportSingleLineComment(String type, int startLineNo,
            int startColNo) {
        reportSingleLineComment(startLineNo, startColNo);
    }

    /**
     * Report the location of a single line comment.
     *
     * @param startLineNo the starting line number
     * @param startColNo the starting column number
     **/
    public void reportSingleLineComment(int startLineNo, int startColNo) {
        final String line = line(startLineNo - 1);
        final String[] txt = {line.substring(startColNo)};
        final Comment comment = new Comment(txt, startColNo, startLineNo,
                line.length() - 1);
        cppComments.put(startLineNo, comment);
    }

    @Override
    public void reportBlockComment(String type, int startLineNo,
            int startColNo, int endLineNo, int endColNo) {
        reportBlockComment(startLineNo, startColNo, endLineNo, endColNo);
    }

    /**
     * Report the location of a block comment.
     *
     * @param startLineNo the starting line number
     * @param startColNo the starting column number
     * @param endLineNo the ending line number
     * @param endColNo the ending column number
     **/
    public void reportBlockComment(int startLineNo, int startColNo,
            int endLineNo, int endColNo) {
        final String[] cComment = extractBlockComment(startLineNo, startColNo,
                endLineNo, endColNo);
        final Comment comment = new Comment(cComment, startColNo, endLineNo,
                endColNo);

        // save the comment
        final List<TextBlock> entries = clangComments.computeIfAbsent(startLineNo,
                empty -> new ArrayList<>());

        entries.add(comment);

        // Remember if possible Javadoc comment
        final String firstLine = line(startLineNo - 1);
        if (firstLine.contains("/**") && !firstLine.contains("/**/")) {
            javadocComments.put(endLineNo - 1, comment);
        }
    }

    /**
     * Returns the specified block comment as a String array.
     *
     * @param startLineNo the starting line number
     * @param startColNo the starting column number
     * @param endLineNo the ending line number
     * @param endColNo the ending column number
     * @return block comment as an array
     **/
    private String[] extractBlockComment(int startLineNo, int startColNo,
            int endLineNo, int endColNo) {
        final String[] returnValue;
        if (startLineNo == endLineNo) {
            returnValue = new String[1];
            returnValue[0] = line(startLineNo - 1).substring(startColNo,
                    endColNo + 1);
        }
        else {
            returnValue = new String[endLineNo - startLineNo + 1];
            returnValue[0] = line(startLineNo - 1).substring(startColNo);
            for (int i = startLineNo; i < endLineNo; i++) {
                returnValue[i - startLineNo + 1] = line(i);
            }
            returnValue[returnValue.length - 1] = line(endLineNo - 1).substring(0,
                    endColNo + 1);
        }
        return returnValue;
    }

    /**
     * Get a single line.
     * For internal use only, as getText().get(lineNo) is just as
     * suitable for external use and avoids method duplication.
     *
     * @param lineNo the number of the line to get
     * @return the corresponding line, without terminator
     * @throws IndexOutOfBoundsException if lineNo is invalid
     */
    private String line(int lineNo) {
        return text.get(lineNo);
    }

    /**
     * Returns the Javadoc comment before the specified line.
     * A return value of {@code null} means there is no such comment.
     *
     * @param lineNoBefore the line number to check before
     * @return the Javadoc comment, or {@code null} if none
     **/
    public TextBlock getJavadocBefore(int lineNoBefore) {
        // Lines start at 1 to the callers perspective, so need to take off 2
        int lineNo = lineNoBefore - 2;

        // skip blank lines
        while (lineNo > 0 && (lineIsBlank(lineNo) || lineIsComment(lineNo))) {
            lineNo--;
        }

        return javadocComments.get(lineNo);
    }

    /**
     * Checks if the specified line is blank.
     *
     * @param lineNo the line number to check
     * @return if the specified line consists only of tabs and spaces.
     **/
    public boolean lineIsBlank(int lineNo) {
        return CommonUtil.isBlank(line(lineNo));
    }

    /**
     * Checks if the specified line is a single-line comment without code.
     *
     * @param lineNo  the line number to check
     * @return if the specified line consists of only a single line comment
     *         without code.
     **/
    public boolean lineIsComment(int lineNo) {
        return MATCH_SINGLELINE_COMMENT.matcher(line(lineNo)).matches();
    }

    /**
     * Checks if the specified position intersects with a comment.
     *
     * @param startLineNo the starting line number
     * @param startColNo the starting column number
     * @param endLineNo the ending line number
     * @param endColNo the ending column number
     * @return true if the positions intersects with a comment.
     **/
    public boolean hasIntersectionWithComment(int startLineNo,
            int startColNo, int endLineNo, int endColNo) {
        return hasIntersectionWithBlockComment(startLineNo, startColNo, endLineNo, endColNo)
                || hasIntersectionWithSingleLineComment(startLineNo, startColNo, endLineNo,
                        endColNo);
    }

    /**
     * Checks if the specified position intersects with a block comment.
     *
     * @param startLineNo the starting line number
     * @param startColNo the starting column number
     * @param endLineNo the ending line number
     * @param endColNo the ending column number
     * @return true if the positions intersects with a block comment.
     */
    private boolean hasIntersectionWithBlockComment(int startLineNo, int startColNo,
            int endLineNo, int endColNo) {
        // Check C comments (all comments should be checked)
        final Collection<List<TextBlock>> values = clangComments.values();
        return values.stream()
            .flatMap(List::stream)
            .anyMatch(comment -> comment.intersects(startLineNo, startColNo, endLineNo, endColNo));
    }

    /**
     * Checks if the specified position intersects with a single line comment.
     *
     * @param startLineNo the starting line number
     * @param startColNo the starting column number
     * @param endLineNo the ending line number
     * @param endColNo the ending column number
     * @return true if the positions intersects with a single line comment.
     */
    private boolean hasIntersectionWithSingleLineComment(int startLineNo, int startColNo,
            int endLineNo, int endColNo) {
        boolean hasIntersection = false;
        // Check CPP comments (line searching is possible)
        for (int lineNumber = startLineNo; lineNumber <= endLineNo;
             lineNumber++) {
            final TextBlock comment = cppComments.get(lineNumber);
            if (comment != null && comment.intersects(startLineNo, startColNo,
                    endLineNo, endColNo)) {
                hasIntersection = true;
                break;
            }
        }
        return hasIntersection;
    }

    /**
     * Returns a map of all the single line comments. The key is a line number,
     * the value is the comment {@link TextBlock} at the line.
     *
     * @return the Map of comments
     */
    public Map<Integer, TextBlock> getSingleLineComments() {
        return Collections.unmodifiableMap(cppComments);
    }

    /**
     * Returns a map of all block comments. The key is the line number, the
     * value is a {@link List} of block comment {@link TextBlock}s
     * that start at that line.
     *
     * @return the map of comments
     */
    public Map<Integer, List<TextBlock>> getBlockComments() {
        return Collections.unmodifiableMap(clangComments);
    }

    /**
     * Checks if the current file is a package-info.java file.
     *
     * @return true if the package file.
     */
    public boolean inPackageInfo() {
        return getFileName().endsWith("package-info.java");
    }

}