/**
 Copyright 2005 Bytecode Pty Ltd.

 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 org.gitools.utils.csv;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;

/**
 * A very simple CSV reader released under a commercial-friendly license.
 *
 * @author Glen Smith
 * @noinspection ALL
 */
public class CSVReader implements Closeable {

    private final BufferedReader br;

    private boolean hasNext = true;

    private final CSVParser parser;

    private final int skipLines;

    private final char commentchar;

    private boolean linesSkiped;

    private int lineNumber;

    /**
     * The default line to start reading.
     */
    private static final int DEFAULT_SKIP_LINES = 0;

    /*
    * The default comment character. All lines that start with this
    * character will be skipped.
    *
    */
    private static final char DEFAULT_COMMENT_CHARACTER = '#';

    /**
     * Constructs CSVReader using a comma for the separator.
     *
     * @param reader the reader to an underlying CSV source.
     */
    public CSVReader(Reader reader) {
        this(reader, CSVParser.DEFAULT_SEPARATOR, CSVParser.DEFAULT_QUOTE_CHARACTER, CSVParser.DEFAULT_ESCAPE_CHARACTER);
    }

    /**
     * Constructs CSVReader with supplied separator.
     *
     * @param reader    the reader to an underlying CSV source.
     * @param separator the delimiter to use for separating entries.
     */
    public CSVReader(Reader reader, char separator) {
        this(reader, separator, CSVParser.DEFAULT_QUOTE_CHARACTER, CSVParser.DEFAULT_ESCAPE_CHARACTER);
    }

    /**
     * Constructs CSVReader with supplied separator and quote char.
     *
     * @param reader    the reader to an underlying CSV source.
     * @param separator the delimiter to use for separating entries
     * @param quotechar the character to use for quoted elements
     */
    public CSVReader(Reader reader, char separator, char quotechar) {
        this(reader, separator, quotechar, CSVParser.DEFAULT_ESCAPE_CHARACTER, DEFAULT_SKIP_LINES, CSVParser.DEFAULT_STRICT_QUOTES);
    }

    /**
     * Constructs CSVReader with supplied separator, quote char and quote handling
     * behavior.
     *
     * @param reader       the reader to an underlying CSV source.
     * @param separator    the delimiter to use for separating entries
     * @param quotechar    the character to use for quoted elements
     * @param strictQuotes sets if characters outside the quotes are ignored
     */
    public CSVReader(Reader reader, char separator, char quotechar, boolean strictQuotes) {
        this(reader, separator, quotechar, CSVParser.DEFAULT_ESCAPE_CHARACTER, DEFAULT_SKIP_LINES, strictQuotes);
    }

    /**
     * Constructs CSVReader with supplied separator and quote char.
     *
     * @param reader    the reader to an underlying CSV source.
     * @param separator the delimiter to use for separating entries
     * @param quotechar the character to use for quoted elements
     * @param escape    the character to use for escaping a separator or quote
     */

    private CSVReader(Reader reader, char separator, char quotechar, char escape) {
        this(reader, separator, quotechar, escape, DEFAULT_SKIP_LINES, CSVParser.DEFAULT_STRICT_QUOTES);
    }

    /**
     * Constructs CSVReader with supplied separator and quote char.
     *
     * @param reader    the reader to an underlying CSV source.
     * @param separator the delimiter to use for separating entries
     * @param quotechar the character to use for quoted elements
     * @param line      the line number to skip for start reading
     */
    public CSVReader(Reader reader, char separator, char quotechar, int line) {
        this(reader, separator, quotechar, CSVParser.DEFAULT_ESCAPE_CHARACTER, line, CSVParser.DEFAULT_STRICT_QUOTES);
    }

    /**
     * Constructs CSVReader with supplied separator and quote char.
     *
     * @param reader    the reader to an underlying CSV source.
     * @param separator the delimiter to use for separating entries
     * @param quotechar the character to use for quoted elements
     * @param escape    the character to use for escaping a separator or quote
     * @param line      the line number to skip for start reading
     */
    public CSVReader(Reader reader, char separator, char quotechar, char escape, int line) {
        this(reader, separator, quotechar, escape, line, CSVParser.DEFAULT_STRICT_QUOTES);
    }

    /**
     * Constructs CSVReader with supplied separator and quote char.
     *
     * @param reader       the reader to an underlying CSV source.
     * @param separator    the delimiter to use for separating entries
     * @param quotechar    the character to use for quoted elements
     * @param escape       the character to use for escaping a separator or quote
     * @param line         the line number to skip for start reading
     * @param strictQuotes sets if characters outside the quotes are ignored
     */
    private CSVReader(Reader reader, char separator, char quotechar, char escape, int line, boolean strictQuotes) {
        this(reader, separator, quotechar, escape, DEFAULT_COMMENT_CHARACTER, line, strictQuotes, CSVParser.DEFAULT_IGNORE_LEADING_WHITESPACE);
    }

    /**
     * Constructs CSVReader with supplied separator and quote char.
     *
     * @param reader                  the reader to an underlying CSV source.
     * @param separator               the delimiter to use for separating entries
     * @param quotechar               the character to use for quoted elements
     * @param escape                  the character to use for escaping a separator or quote
     * @param commentchar             the comment char, all lines that start with this char will be skipped.
     * @param line                    the line number to skip for start reading
     * @param strictQuotes            sets if characters outside the quotes are ignored
     * @param ignoreLeadingWhiteSpace it true, parser should ignore white space before a quote in a field
     */
    public CSVReader(Reader reader, char separator, char quotechar, char escape, char commentchar, int line, boolean strictQuotes, boolean ignoreLeadingWhiteSpace) {
        this.br = new BufferedReader(reader);
        this.parser = new CSVParser(separator, quotechar, escape, strictQuotes, ignoreLeadingWhiteSpace);
        this.skipLines = line;
        this.commentchar = commentchar;
        this.lineNumber = 0;
    }

    /**
     * Reads the entire file into a List with each element being a String[] of
     * tokens.
     *
     * @return a List of String[], with each String[] representing a line of the
     *         file.
     * @throws IOException if bad things happen during the read
     */
    @NotNull
    public List<String[]> readAll() throws IOException {

        List<String[]> allElements = new ArrayList<String[]>();
        while (hasNext) {
            String[] nextLineAsTokens = readNext();
            if (nextLineAsTokens != null) {
                allElements.add(nextLineAsTokens);
            }
        }
        return allElements;

    }

    /**
     * Reads the next line from the buffer and converts to a string array.
     *
     * @return a string array with each comma-separated element as a separate
     *         entry.
     * @throws IOException if bad things happen during the read
     */
    @Nullable
    public String[] readNext() throws IOException {

        String[] result = null;
        do {
            String nextLine = getNextLine();
            if (!hasNext) {
                return result; // should throw if still pending?
            }
            String[] r = parser.parseLineMulti(nextLine);
            if (r.length > 0) {
                if (result == null) {
                    result = r;
                } else {
                    String[] t = new String[result.length + r.length];
                    System.arraycopy(result, 0, t, 0, result.length);
                    System.arraycopy(r, 0, t, result.length, r.length);
                    result = t;
                }
            }
        } while (parser.isPending());
        return result;
    }

    /**
     * Reads the next line from the file.
     *
     * @return the next line from the file without trailing newline
     * @throws IOException if bad things happen during the read
     */
    @Nullable
    private String getNextLine() throws IOException {
        if (!this.linesSkiped) {
            for (int i = 0; i < skipLines; i++) {
                br.readLine();
                lineNumber++;
            }
            this.linesSkiped = true;
        }
        String nextLine = br.readLine();
        lineNumber++;

        // Skip comments & empty lines
        while (nextLine != null && (nextLine.isEmpty() || nextLine.charAt(0) == commentchar)) {
            nextLine = br.readLine();
            lineNumber++;
        }

        if (nextLine == null) {
            hasNext = false;
        }
        return hasNext ? nextLine : null;
    }

    /**
     * Closes the underlying reader.
     *
     * @throws IOException if the close fails
     */
    public void close() throws IOException {
        br.close();
    }

    public int getLineNumber() {
        return lineNumber;
    }



}
