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package ch.qos.logback.classic.pattern;

import java.util.List;

import org.slf4j.event.KeyValuePair;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.CoreConstants;

/**
 * Convert the contents of {@link KeyValuePair} list to a String.
 * 
 * Assuming the list contains the list {k1, v1}, {k2, v2}, the String output
 * will be "k1=v1 k2=v2", without the quotes.
 *
 * 
 * @since 1.3.0
 * @author Ceki Gülcü
 *
 */
public class KeyValuePairConverter extends ClassicConverter {

    static final String DOUBLE_OPTION_STR = "DOUBLE";
    static final String SINGLE_OPTION_STR = "SINGLE";
    static final String NONE_OPTION_STR = "NONE";

    enum ValueQuoteSpecification {
        NONE, SINGLE, DOUBLE;

        Character asChar() {
            switch (this) {
            case NONE:
                return null;
            case DOUBLE:
                return '"';
            case SINGLE:
                return '\'';
            default:
                throw new IllegalStateException();
            }
        }
    }

    ValueQuoteSpecification valueQuoteSpec = ValueQuoteSpecification.DOUBLE;

    public void start() {
        String optStr = getFirstOption();
        valueQuoteSpec = optionStrToSpec(optStr);
        super.start();
    }

    private ValueQuoteSpecification optionStrToSpec(String optStr) {
        if (optStr == null)
            return ValueQuoteSpecification.DOUBLE;
        if (DOUBLE_OPTION_STR.equalsIgnoreCase(optStr))
            return ValueQuoteSpecification.DOUBLE;
        if (SINGLE_OPTION_STR.equalsIgnoreCase(optStr))
            return ValueQuoteSpecification.SINGLE;
        if (NONE_OPTION_STR.equalsIgnoreCase(optStr))
            return ValueQuoteSpecification.NONE;
        return ValueQuoteSpecification.DOUBLE;
    }

    @Override
    public String convert(ILoggingEvent event) {

        List kvpList = event.getKeyValuePairs();
        if (kvpList == null || kvpList.isEmpty()) {
            return CoreConstants.EMPTY_STRING;
        }

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < kvpList.size(); i++) {
            KeyValuePair kvp = kvpList.get(i);
            if (i != 0)
                sb.append(' ');
            sb.append(String.valueOf(kvp.key));
            sb.append('=');
            Character quoteChar = valueQuoteSpec.asChar();
            if (quoteChar != null)
                sb.append(quoteChar);
            sb.append(String.valueOf(kvp.value));
            if (quoteChar != null)
                sb.append(quoteChar);
        }

        return sb.toString();
    }

}