package com.github.jreddit.request.util;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class KeyValueFormatter {

    private static final Logger LOGGER = LoggerFactory.getLogger(KeyValueFormatter.class);
    
    private KeyValueFormatter() {
        // Left empty to prevent instantiation of this utility class
    }
    
    /**
     * Format a mapping of key-value pairs to a string, separating key from value using an
     * equals (=) sign, and separating pairs using an ampersand (&) sign.
     * 
     * @param keyValueParameters Mapping of key-value pairs
     * @param encodeUTF8 Whether or not the values should be encoded in UTF-8
     * 
     * @return Formatted string of key-value pairs (e.g. "a=1&b=something")
     */
    public static String format(Map<String, String> keyValueParameters, boolean encodeUTF8) {
        
        // Key set
        Set<String> keys = keyValueParameters.keySet();
        
        // Iterate over keys
        String paramsString = "";
        boolean start = true;
        for (String key : keys) {
            
            // Add separation ampersand
            if (!start) {
                paramsString = paramsString.concat("&");
            } else {
                start = false;
            }
            
            // Retrieve value
            String value = keyValueParameters.get(key);
            
            // Encode key
            if (encodeUTF8) {
                try {
                    value = URLEncoder.encode(value, "UTF-8");
                } catch (UnsupportedEncodingException e) {
                    LOGGER.warn("Unsupported Encoding Exception thrown when encoding value", e);
                }
            }
            
            // Add key-value pair
            paramsString = paramsString.concat(key + "=" + value);

        }
        
        // Return final parameter string
        return paramsString;
        
    }
    
    /**
     * Format a comma separated list of the given list.
     * 
     * @param list List of strings
     * 
     * @return Comma-separated list string (e.g. "a,b,c,d")
     */
    public static String formatCommaSeparatedList(List<String> list) {
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < list.size(); i++) {
            if (i != 0) {
                builder.append(",");
            }
            builder.append(list.get(i));
        }
        return builder.toString();
    }
    
}