package altk.comm.engine;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Vector;
import java.util.zip.ZipInputStream;

import javax.servlet.http.HttpServletRequest;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import altk.comm.engine.exception.BroadcastError;
import altk.comm.engine.exception.BroadcastException;
import altk.comm.engine.exception.BroadcastMsgException;
import altk.comm.engine.exception.EngineException;
import altk.comm.engine.exception.InternalErrorException;
import altk.comm.engine.exception.NonExistentException;
import altk.comm.engine.exception.PlatformError;
import altk.comm.engine.exception.PlatformException;

/**
 * Abstract class extending Broadcast by providing an implementation of the decode
 * method to parse HTTP POST input into XML DOM, and extracting the required class
 * attributes broadcast_id, launch_record_id, expire_time, postback and recipientList.
 * @author Yuk-Ming
 *
 */
public abstract class XMLDOMBroadcast extends Broadcast
{
    protected XPath xpathEngine;
    protected DocumentBuilder builder;
    protected Element broadcastNode;

    /**
     * 
     * @param broadcastType
     * @param activityRecordIdParamName - if null, default is used
     * @param jobReportRootNodeName - job report root node name
     */
    protected XMLDOMBroadcast(String broadcastType, String activityRecordIdParamName,
            String jobReportRootNodeName)
    {
        super(broadcastType, activityRecordIdParamName, jobReportRootNodeName);
    }
    
    /** 
     * Sets up XMLDoc and parses broadcast_id, expire_time, postBackUrl and recipientList.
     * Derived class cannot override this method, which is final.
     * @throws EngineException 
     */
    @Override
    protected final void decode(HttpServletRequest request, boolean notInService) throws EngineException
    {
        try
        {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            builder = factory.newDocumentBuilder();
            xpathEngine = XPathFactory.newInstance().newXPath();
        }
        catch (Exception e)
        {
            CommonLogger.alarm.error(e.getMessage());
            throw new PlatformException(PlatformError.RUNTIME_ERROR, e.getMessage());
        }        
        
        
        // parse request into multiple BroadcastSMS pass then to Dispatcher
        Document xmlDoc;
        try
        {
            InputStream inb;
            String contentType = request.getContentType();
            if (contentType != null && contentType.split("/")[1].equalsIgnoreCase("zip"))
            {
                ZipInputStream zip = new ZipInputStream(request.getInputStream());
                zip.getNextEntry();
                inb = zip;
            }
            else
            {
                inb = request.getInputStream();
            }
            int contentLength = request.getContentLength();
            CommonLogger.activity.info("Receiving " + contentLength + " bytes of data");
            byte[] content = new byte[contentLength];
            int offset = 0;
            int length = contentLength;
            int read;
            while (length > 0)
            {
                read = inb.read(content, offset, length);
                if (read < 0) break;
                offset += read;
                length -= read;
            }
            CommonLogger.activity.info("Received: " + new String(content, "UTF-8"));                
            xmlDoc = builder.parse(new ByteArrayInputStream(content), "UTF-8");
        }
        catch (SAXException e)
        {
            throw new BroadcastException(BroadcastError.BAD_REQUEST_DATA, e.getMessage());
        }
        catch (IOException e)
        {
            throw new BroadcastException(BroadcastError.READ_REQUEST_ERROR, "Problem in reading request");
        }

        //String xpath = "//" + broadcastName; // get all first level elements
        NodeList broadcastNodes = null;
        broadcastNodes = xmlDoc.getElementsByTagName(broadcastType);
        if (broadcastNodes.getLength() == 0)
        {
            throw new BroadcastException(BroadcastError.BAD_REQUEST_DATA, "No <" + broadcastType + "> tag");
        }
        
        if (notInService) return;
        
        // Only one broadcast node is processed.  The rest are silently ignored.
        broadcastNode = (Element)broadcastNodes.item(0);
        if (!broadcastType.equals(broadcastNode.getNodeName()))
        {
            throw new BroadcastMsgException("Broadcast node name does not match " + broadcastType);
        }
        
        // broadcast_id
        String broadcastId = broadcastNode.getAttribute("broadcast_id");
        if (broadcastId.length() == 0)
        {
            throw new BroadcastMsgException("Missing broadcast_id");
        }
        setBroadcastId(broadcastId);
        
        // expireTime
        long now = System.currentTimeMillis();
        try
        {
            long expireTime = getLongValue("expire_time", broadcastNode);
            // defaults to 20 minutes
            myLogger.debug("expire_time decoded to be " + expireTime);
            if (expireTime == 0) expireTime = now + 20 * 60 * 1000;
            myLogger.debug("expire time adjusted to be " + expireTime);
            setExpireTime(expireTime);
            
            setLaunchRecordId(broadcastNode.getAttribute("launch_record_id"));
        }
        catch (Exception e)
        {
            throw new BroadcastMsgException("Missing or bad expire_time");
        }
        
        // Postback
        postBackURL = getStringValue("async_status_post_back", broadcastNode);
        if (postBackURL != null && (postBackURL=postBackURL.trim()).length() == 0) postBackURL = null;
        if (postBackURL == null)
        {
            CommonLogger.alarm.warn("Missing asyn_status_post_back in POST data");
        }
        
        NodeList recipientNodes = null;
        String xpath = "recipient_list/recipient";
        try
        {
            recipientNodes = (NodeList) xpathEngine.evaluate(xpath,
                        broadcastNode, XPathConstants.NODESET);
        }
        catch (XPathExpressionException e)
        {
            throw new InternalErrorException("Bad xpath 'recipient_list/recipient", e);
        }
        Element recipientNode;
        String contact_id;
        String activity_record_id;
        xpath = "email";
        for (int i = 0; i < recipientNodes.getLength(); i++)
        {
            recipientNode = (Element)recipientNodes.item(i);
            contact_id = recipientNode.getAttribute("contact_id");
            if (contact_id == null || (contact_id=contact_id.trim()).length() == 0)
            {
                myLogger.warn("Missing or empty contact_id for a recipient in broadcast " + getBroadcastId());
                continue;
            }
            activity_record_id = recipientNode.getAttribute(activityRecordIdParamName);
            if (activity_record_id == null || (activity_record_id = activity_record_id.trim()).length() == 0)
            {
                throw new BroadcastMsgException("Missing or empty " + getActivityRecordIdName() + " attribute for a recipient in broadcast " + getBroadcastId());
            }
            
            Map<String, String> attributes = new HashMap<String, String>();
            NodeList children = recipientNode.getChildNodes();
            for (int j = 0; j < children.getLength(); j++)
            {
                Node child = children.item(j);
                if (child.getNodeType() != Node.ELEMENT_NODE) continue;
                attributes.put(child.getNodeName(), child.getTextContent());
            }
            recipientList.add(new Recipient(contact_id, activity_record_id, attributes));
        }
    }

    /**
     * Gets String value of child with given name.
     * @param childNodeName
     * @param element
     * @return null if no such child exists.
     * @throws IllegalArgumentException when element is null
     */
    protected String getStringValue(String childNodeName, Element element)
    throws IllegalArgumentException
    {
        if (element == null)
        {
            throw new IllegalArgumentException("Element cannot be null");
        }
        NodeList children = element.getChildNodes();
        for (int i = 0; i < children.getLength(); i++)
        {
            Node child = children.item(i);
            if (child.getNodeType() == Node.ELEMENT_NODE &&
                    child.getNodeName().equals(childNodeName))
            {
                return child.getTextContent();
            }
        }
        return null;
    }
    
    /**
     * 
     * @param childNodeName
     * @param element
     * @return
     * @throws IllegalArgumentException when element is null
     */
    protected String getNonNullStringValue(String childNodeName, Element element)
    throws IllegalArgumentException
    {
        String value = getStringValue(childNodeName, element);
        return value==null?"":value;
    }

    /**
     * 
     * @param childNodeName
     * @param element
     * @return
     * @throws IllegalArgumentException when element is null
     */
    public boolean getBooleanValue(String childNodeName, Element element)
    throws IllegalArgumentException
    {
        String str = getStringValue(childNodeName, element);
        if (str == null) return false;
        return Boolean.parseBoolean(str.trim());
    }
    
    /**
     * 
     * @param childNodeName
     * @param element
     * @return
     * @throws NonExistentException
     * @throws NumberFormatException
     * @throws IllegalArgumentException when element is null
     */
    protected int getIntValue(String childNodeName, Element element)
    throws NonExistentException, NumberFormatException, IllegalArgumentException
    {
        if (element == null)
        {
            throw new IllegalArgumentException("Element cannot be null, when invoking getIntValue method");
        }
        try
        {
            String str = getStringValue(childNodeName, element);
            if (str == null)
            {
                throw new NonExistentException("No child \"" + childNodeName + "\" exists for element \"" + xml2Str(element) + "\"");
            }
            return Integer.parseInt(str);
        }
        catch (NumberFormatException e)
        {
            throw new NumberFormatException("Value of child \"" + childNodeName + "\" not integer for element \"" + xml2Str(element) + "\"");
        }
    }

    /**
     * 
     * @param childNodeName
     * @param element
     * @return
     * @throws NonExistentException
     * @throws NumberFormatException
     * @throws IllegalArgumentException when element is null
     */
    protected Long getLongValue(String childNodeName, Element element)
    throws NonExistentException, NumberFormatException, IllegalArgumentException
    {
        if (element == null)
        {
            throw new IllegalArgumentException("Element cannot be null, when invoking getIntValue method");
        }
        try
        {
            String str = getStringValue(childNodeName, element);
            if (str == null)
            {
                throw new NonExistentException("No child \"" + childNodeName + "\" exists for element \"" + xml2Str(element) + "\"");
            }
            return Long.parseLong(str);
        }
        catch (NumberFormatException e)
        {
            throw new NumberFormatException("Value of child \"" + childNodeName + "\" not integer for element \"" + xml2Str(element) + "\"");
        }
    }

    protected NodeList getNodeList(String xpath, Element element)
    {
        try
        {
            NodeList nodes = (NodeList) xpathEngine.evaluate(xpath, element, XPathConstants.NODESET);
            return nodes;
        }
        catch (XPathExpressionException e)
        {
            throw new InternalErrorException("Improper xpath \"" + xpath + "\"", e);
        }  
    }
    
    protected Node getNode(String xpath, Element element)
    {
        try
        {
            Node node = (Node) xpathEngine.evaluate(xpath, element, XPathConstants.NODE);
            return node;
        }
        catch (XPathExpressionException e)
        {
            throw new InternalErrorException("Improper xpath \"" + xpath + "\"", e);
        }  
    }
    
    static public void appendXML(Element topElement, StringBuffer buf)
    {
        // starting tag
        buf.append('<');
        String elementName = topElement.getNodeName();
        buf.append(elementName);
        
        // handle attributes first
        NamedNodeMap attributes = topElement.getAttributes();
        for (int i = 0; i < attributes.getLength(); i++)
        {
            Node attr = attributes.item(i);
            buf.append(' ');
            buf.append(attr.getNodeName());
            buf.append("=\"");
            buf.append(attr.getNodeValue());
            buf.append("\"");
        }
        buf.append('>');
        
        // handling text
        Vector<Node> childElements = new Vector<Node>();
        NodeList children = topElement.getChildNodes();
        for (int i = 0; i < children.getLength(); i++)
        {
            Node node = children.item(i);
            switch (node.getNodeType())
            {
                case Node.ELEMENT_NODE:
                    // defer handling
                    childElements.add(node);
                    break;
                case Node.TEXT_NODE:
                    buf.append(node.getNodeValue());
                    break;
                default:  
            }
        }
        // handling children elements
        for (Node child : childElements)
        {
            appendXML((Element)child, buf);
        }
        // ending tag
        buf.append("</"); buf.append(elementName); buf.append('>');
    }
    
    public String xml2Str(Element element)
    {
        StringBuffer buf = new StringBuffer();
        appendXML(element, buf);
        return buf.toString();
    }

    /**
     * Derived class may override this method to redefine the name of activity_record_id,
     * e.g. email_record_id, sms_record_id, etc.
     * @return name of activity_record_9d.
     */
    protected String getActivityRecordIdName()
    {
        return "activity_record_id";
    }

}