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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2013-2014 sagyf Yang. The Four Group.
 */

package goja.core.kits.io;

import com.google.common.collect.Lists;

import goja.core.StringPool;
import goja.core.kits.lang.CharKit;

import org.apache.commons.lang3.StringUtils;

import java.util.List;

/**
 *  . 
 *
 * @author sagyf yang
 * @version 1.0 2014-01-31 17:57
 * @since JDK 1.6
 */
public abstract class CsvKit {

    protected static final char   FIELD_SEPARATOR = ',';
    protected static final char   FIELD_QUOTE     = '"';
    protected static final String DOUBLE_QUOTE    = "\"\"";
    protected static final String SPECIAL_CHARS   = StringPool.CRLF;

    /**
     * Parse fields as csv string,
     */
    public static String toCsvString(Object... elements) {
        StringBuilder line = new StringBuilder();
        int last = elements.length - 1;
        for (int i = 0; i < elements.length; i++) {
            if (elements[i] == null) {
                if (i != last) {
                    line.append(FIELD_SEPARATOR);
                }
                continue;
            }
            String field = elements[i].toString();

            // check for special cases
            int ndx = field.indexOf(FIELD_SEPARATOR);
            if (ndx == -1) {
                ndx = field.indexOf(FIELD_QUOTE);
            }
            if (ndx == -1) {
                if (field.startsWith(StringPool.SPACE) || field.endsWith(StringPool.SPACE)) {
                    ndx = 1;
                }
            }
            if (ndx == -1) {
                ndx = CharKit.indexOfChars(field, SPECIAL_CHARS);
            }

            // add field
            if (ndx != -1) {
                line.append(FIELD_QUOTE);
            }
            field = StringUtils.replace(field, StringPool.QUOTE, DOUBLE_QUOTE);
            line.append(field);
            if (ndx != -1) {
                line.append(FIELD_QUOTE);
            }

            // last
            if (i != last) {
                line.append(FIELD_SEPARATOR);
            }
        }
        return line.toString();
    }

    /**
     * Converts CSV line to string array.
     */
    public static String[] toStringArray(String line) {
        List row = Lists.newArrayList();

        boolean inQuotedField = false;
        int fieldStart = 0;

        final int len = line.length();
        for (int i = 0; i < len; i++) {
            char c = line.charAt(i);
            if (c == FIELD_SEPARATOR) {
                if (!inQuotedField) {    // ignore we are quoting
                    addField(row, line, fieldStart, i, inQuotedField);
                    fieldStart = i + 1;
                }
            } else if (c == FIELD_QUOTE) {
                if (inQuotedField) {
                    if (i + 1 == len
                            || line.charAt(i + 1)
                            == FIELD_SEPARATOR) {    // we are already quoting - peek to see if this is the end of the field
                        addField(row, line, fieldStart, i, inQuotedField);
                        fieldStart = i + 2;
                        i++; // and skip the comma
                        inQuotedField = false;
                    }
                } else if (fieldStart == i) {
                    inQuotedField = true;    // this is a beginning of a quote
                    fieldStart++;            // move field start
                }
            }
        }
        // add last field - but only if string was not empty
        if (len > 0 && fieldStart <= len) {
            addField(row, line, fieldStart, len, inQuotedField);
        }
        return row.toArray(new String[row.size()]);
    }

    private static void addField(List row, String line, int startIndex, int endIndex,
                                 boolean inQuoted) {
        String field = line.substring(startIndex, endIndex);
        if (inQuoted) {
            field = StringUtils.replace(field, DOUBLE_QUOTE, StringPool.QUOTE);
        }
        row.add(field);
    }
}