package com.googlecode.gwt.test.internal.resources;

import com.googlecode.gwt.test.internal.AfterTestCallback;
import com.googlecode.gwt.test.internal.AfterTestCallbackManager;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Utility class to parse text files.<strong>For internal use only.</strong>
 *
 * @author Gael Lazzari
 */
class TextResourceReader implements AfterTestCallback {

    private static final TextResourceReader INSTANCE = new TextResourceReader();

    public static TextResourceReader get() {
        return INSTANCE;
    }

    private final Map<URL, String> cache;

    private TextResourceReader() {
        cache = new HashMap<URL, String>();
        AfterTestCallbackManager.get().registerCallback(this);
    }

    public void afterTest() throws Throwable {
        cache.clear();
    }

    public String readFiles(List<URL> urls) throws UnsupportedEncodingException, IOException {

        StringBuilder sb = new StringBuilder();

        for (URL url : urls) {
            sb.append(readFile(url));
        }

        return sb.toString();
    }

    private String readFile(URL url) throws UnsupportedEncodingException, IOException {

        if (!cache.containsKey(url)) {
            StringBuilder sb = new StringBuilder();

            BufferedReader reader = null;

            try {
                reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));

                String line;
                while ((line = reader.readLine()) != null) {
                    sb.append(line).append("\r\n");
                }

                if (sb.length() > 0) {
                    sb.delete(sb.length() - "\r\n".length(), sb.length());
                }
                cache.put(url, sb.toString());
            } finally {
                if (reader != null) {
                    reader.close();
                }
            }
        }

        return cache.get(url);

    }

}