import javax.net.ssl.HttpsURLConnection;
import java.io.*;
import java.net.HttpCookie;
import java.net.URL;
import java.util.List;

/**
 * An example client which is able to authenticate with the LIMS application server and issue basic requests to the
 * non-public API
 */
public class LIMSClient {
    /**
     * The value to set for the Cookie header on all requests. This value is populated by authenticating the client.
     */
    private String cookie;

    public static void main(String[] args) throws Exception {
        LIMSClient client = new LIMSClient();
        client.authenticate();

        String reindexResponse = client.startElasticsearchReindex();
        System.out.println(reindexResponse);

        String statusResponse = client.getElasticsearchStatus();
        System.out.println(statusResponse);
    }

    /**
     * Initializes a session with the LIMS application server
     */
    public void authenticate() throws Exception {
        URL url = new URL("https://example.claritylims.com/clarity/j_spring_security_check");
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setInstanceFollowRedirects(false);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        byte[] params = "j_username=admin&j_password=password".getBytes("UTF-8");
        connection.setRequestProperty("Content-Length", String.valueOf(params.length));
        connection.getOutputStream().write(params);

        if (connection.getResponseCode() != 302) {
            System.err.println("Unable to authenticate");
            System.exit(-1);
        }

        cookie = extractCookie(connection.getHeaderField("Set-Cookie"));
        connection.disconnect();
    }

    /**
     * Obtains the current status of Elasticsearch indexing.
     * @return The status JSON response as plain text.
     */
    public String getElasticsearchStatus() throws Exception {
        URL url = new URL("https://example.claritylims.com/clarity/api/search-index/status");
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        connection.setRequestProperty("Cookie", cookie);

        /*
         * The X-Requested-With and Origin headers must be set to satisfy CSRF protections
         */
        connection.setRequestProperty("X-Requested-With", "XMLHttpRequest");
        connection.setRequestProperty("Origin", "https://example.claritylims.com");

        String response = readInputStreamToString(connection.getInputStream());
        connection.disconnect();
        return response;
    }

    /**
     * Initializes a full rebuild of the Elasticsearch index
     * @return The reindex JSON response as plain text.
     */
    public String startElasticsearchReindex() throws Exception {
        URL url = new URL("https://example.claritylims.com/clarity/api/search-index/reindex");
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Cookie", cookie);

        /*
         * The X-Requested-With and Origin headers must be set to satisfy CSRF protections
         */
        connection.setRequestProperty("X-Requested-With", "XMLHttpRequest");
        connection.setRequestProperty("Origin", "https://example.claritylims.com");

        String response = readInputStreamToString(connection.getInputStream());
        connection.disconnect();
        return response;
    }

    /**
     * Extracts the Cookie request header from a Set-Cookie response header. The Cookie header is needed to perform
     * authenticated requests.
     * @param setCookieHeader The Set-Cookie response header from an authentication request.
     * @return The Cookie header value to use for authenticated requests.
     */
    private String extractCookie(String setCookieHeader) {
        List<HttpCookie> cookies = HttpCookie.parse(setCookieHeader);
        for (HttpCookie cookie : cookies) {
            if (cookie.getName().equals("JSESSIONID")) {
                return cookie.toString();
            }
        }

        return null;
    }

    /**
     * Helper method to read an input stream into a string.
     */
    private String readInputStreamToString(InputStream in) throws Exception {
        Reader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));

        int intValueOfChar;
        StringBuilder builder = new StringBuilder();
        while ((intValueOfChar = reader.read()) != -1) {
            builder.append((char) intValueOfChar);
        }
        reader.close();

        return builder.toString();
    }
}