/**
 * The contents of this file are subject to the OpenMRS Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://license.openmrs.org
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations
 * under the License.
 *
 * Copyright (C) OpenMRS, LLC.  All Rights Reserved.
 */
package org.eclipse.datatools.connectivity.oda.openmrs.impl;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Properties;

import org.eclipse.datatools.connectivity.oda.IConnection;
import org.eclipse.datatools.connectivity.oda.IDataSetMetaData;
import org.eclipse.datatools.connectivity.oda.IQuery;
import org.eclipse.datatools.connectivity.oda.OdaException;

/**
 * Implementation class of IConnection for an ODA runtime driver.
 */
public class Connection implements IConnection {
    
    private boolean m_isOpen = false;

    private String path, user, pass;

    private HttpURLConnection urlconn;

    private static final String urlend = "moduleServlet/logicws/api/",
            xmlstart = "<?xml version=\"1.0\" encoding=\"utf-8\"?>";

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#open(java.util.Properties)
     */
    public void open(Properties connProperties) throws OdaException {
        // Check for null properties
        if (connProperties == null)
            throw new OdaException("No Connection Properties Provided.");

        // Set global path, username, and password
        path = connProperties.getProperty("PATH");
        user = connProperties.getProperty("USERNAME");
        pass = connProperties.getProperty("PASSWORD");

        // Make sure there is a slash at the end of the path
        if (!path.endsWith("/"))
            path += "/";
        path += urlend;

        // Check for user/pass and URL correctness
        checkProperties();

        // Check that the API is working as expected and is available
        if (!canAccessAPI())
            throw new OdaException(
                    "Expected API functions do not respond correctly.");

        // Mark the connection as open
        m_isOpen = true;
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#setAppContext(java.lang.Object)
     */
    public void setAppContext(Object context) throws OdaException {
        // do nothing; assumes no support for pass-through context
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#close()
     */
    public void close() throws OdaException {
        // Remove pointers to these strings and connections
        path = null;
        user = null;
        pass = null;
        urlconn = null;

        // Mark the connection as closed
        m_isOpen = false;
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#isOpen()
     */
    public boolean isOpen() throws OdaException {
        return m_isOpen;
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#getMetaData(java.lang.String)
     */
    public IDataSetMetaData getMetaData(String dataSetType) throws OdaException {
        // assumes that this driver supports only one type of data set,
        // ignores the specified dataSetType
        return new DataSetMetaData(this);
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#newQuery(java.lang.String)
     */
    public IQuery newQuery(String dataSetType) throws OdaException {
        // assumes that this driver supports only one type of data set,
        // ignores the specified dataSetType
        return new Query(path, user, pass);
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#getMaxQueries()
     */
    public int getMaxQueries() throws OdaException {
        return 0; // no limit
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#commit()
     */
    public void commit() throws OdaException {
        // do nothing; assumes no transaction support needed
    }

    /*
     * @see org.eclipse.datatools.connectivity.oda.IConnection#rollback()
     */
    public void rollback() throws OdaException {
        // do nothing; assumes no transaction support needed
    }

    /**
     * Sets the uRL conn.
     * 
     * @param url the new uRL conn
     * 
     * @throws IOException Signals that an I/O exception has occurred.
     */
    private void setURLConn(URL url) throws IOException {
        urlconn = (HttpURLConnection) url.openConnection();
        urlconn.setRequestProperty("Authorization", "Basic "
                + Base64.encodeBytes((user + ":" + pass).getBytes()));
        urlconn.setRequestMethod("POST");
        urlconn.connect();
    }

    
    /**
     * Should be in format: http(s)://server(:port)(/openmrs)(/)
     * 
     * @throws OdaException the oda exception
     */
    private void checkProperties() throws OdaException {
        try {
            // create URL and Connection
            setURLConn(new URL(path));

            // Test for authentication errors
            if (urlconn.getResponseCode() == 401)
                throw new OdaException(
                        "OpenMRS Server cannot be reached: Incorrect User/Pass.");

            // Test for 404 file not found errors
            if (urlconn.getResponseCode() == 404)
                throw new OdaException(
                        "OpenMRS Server cannot be reached: URL is incorrect");

            // Clean up
            urlconn.disconnect();

        } catch (MalformedURLException e) {
            throw new OdaException(
                    "OpenMRS Server cannot be reached: Malformed URL.");
        } catch (IOException e) {
            throw new OdaException("OpenMRS Server cannot be reached: " + e);
        }
    }

    /**
     * Can access api.
     * 
     * @return true, if successful
     * 
     * @throws OdaException the oda exception
     */
    private boolean canAccessAPI() throws OdaException {
        try {
            InputStream contents;
            BufferedReader in;

            // check access to "getFilters"
            setURLConn(new URL(path + "getFilters"));
            contents = urlconn.getInputStream();
            in = new BufferedReader(new InputStreamReader(contents));
            if (!in.readLine().startsWith(xmlstart + "<filterList>")) {
                urlconn.disconnect();
                return false;
            }

            // check access to "getEntities"
            setURLConn(new URL(path + "getTokenTags"));
            contents = urlconn.getInputStream();
            in = new BufferedReader(new InputStreamReader(contents));
            if (!in.readLine().startsWith(xmlstart + "<tokenTagList>")) {
                urlconn.disconnect();
                return false;
            }

            // check access to "getTokens"
            setURLConn(new URL(path + "getTokens"));
            contents = urlconn.getInputStream();
            in = new BufferedReader(new InputStreamReader(contents));
            if (!in.readLine().startsWith(xmlstart + "<tokenList>")) {
                urlconn.disconnect();
                return false;
            }

            // check access to "getData"
            setURLConn(new URL(path + "getData"));
            contents = urlconn.getInputStream();
            in = new BufferedReader(new InputStreamReader(contents));
            if (!in.readLine().equals(xmlstart + "<dataset />")) {
                urlconn.disconnect();
                return false;
            }
        } catch (IOException e) {

            throw new OdaException(e);

            // return false;
        }

        // Clean up
        urlconn.disconnect();

        // No errors, so return true
        return true;
    }
}