/*
Copyright (c) 2008, Centre for Educational Technology, Tallinn University
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package ee.tlu.htk.waramu.servlets;

import ee.tlu.htk.waramu.annotations.Transformers;
import ee.tlu.htk.waramu.base.BaseType;
import ee.tlu.htk.waramu.db.DataLoaderLocal;
import ee.tlu.htk.waramu.server.Catalogs;
import ee.tlu.htk.waramu.server.DBLocal;
import ee.tlu.htk.waramu.utils.GenerateId;
import ee.tlu.htk.waramu.utils.UTCTime;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.ejb.EJB;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Content restrctions: type must have field created.
 * @author vahur
 */
public class OAIHandler extends HttpServlet {

    @EJB
    private DataLoaderLocal dataLoaderBean;
    @EJB
    private DBLocal dBBean;
    private static final String oai_prefix = "oai:ait.opetaja.ee:";
    private static final Integer maxListSize = 50;
    private static final String[] verbs = new String[]{
        "Identify",
        "GetRecord",
        "ListMetadataFormats",
        "ListRecords",
        "ListSets",
        "ListIdentifiers"
    };
    private HashMap resumptions = new HashMap();
    private HashMap resumptionOptions = new HashMap();

    /** 
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/xml;charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.println("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");

        String reqVerb = request.getParameter("verb");
        String verb = "";

        if (reqVerb == null) {
            out.println("verb is empty");
            out.close();
            return;
        }

        boolean isValidVerb = false;
        for (String v : verbs) {
            if (reqVerb.equals(v)) {
                isValidVerb = true;
                verb = v;
                break;
            }
        }

        out.println("<OAI-PMH xmlns=\"http://www.openarchives.org/OAI/2.0/\" " +
                "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" " +
                "xsi:schemaLocation=\"http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd\">");

        out.println("<responseDate>" + new UTCTime(new Date()) + "</responseDate>");

        if (isValidVerb) {
            if (verb.equals("Identify")) {
                Identify(out, request);
            }
            if (verb.equals("GetRecord")) {
                GetRecord(out, request);
            }
            if (verb.equals("ListMetadataFormats")) {
                ListMetadataFormats(out, request);
            }
            if (verb.equals("ListRecords")) {
                ListRecords(out, request);
            }
            if (verb.equals("ListSets")) {
                ListSets(out, request);
            }
            if (verb.equals("ListIdentifiers")) {
                ListIdentifiers(out, request);
            }
        } else {
            out.println("<error code=\"notValidVerb\">Not valid verb</error>");
        }

        out.println("</OAI-PMH>");

        out.close();
    }

    // done
    public void ListSets(PrintWriter out, HttpServletRequest request) {
        /*
         * badArgument
         * badResumptionToken
         * noSetHierarchy
         */
        out.println("<request verb=\"ListSets\">" + request.getRequestURL() + "</request>");
        out.println("<ListSets>");

        List<Catalogs> catList = dBBean.getCatalogs();
        for (Catalogs c : catList) {
            out.println("<set>");
            out.println("<setSpec>" + c.getCid() + "</setSpec>");
            out.println("<setName>" + c.getCatalogName() + "</setName>");
            out.println("</set>");
        }
        out.println("</ListSets>");
    }

    // done, TODO: transformers!
    public void ListRecords(PrintWriter out, HttpServletRequest request) {
        String from = request.getParameter("from");
        String until = request.getParameter("until");
        String mdPrefix = request.getParameter("metadataPrefix"); // *
        String set = request.getParameter("set");
        Integer setint = null;
        String resumptionToken = request.getParameter("resumptionToken");

        /*
         * badArgument
         * badResumptionToken
         * cannotDisseminateFormat
         * noRecordsMatch
         * noSetHierarchy
         */

        if (mdPrefix == null && resumptionToken == null) {
            out.println("<error code=\"badArgument\">Not enough arguments</error>");
            return;
        }

        if (resumptionToken != null && !resumptions.containsKey(resumptionToken)) {
            out.println("<error code=\"badResumptionToken\">Not enough arguments</error>");
            return;
        }

        if (set != null) {
            /* TODO
            Catalog c = catalogFacade.findByName(set);
            if (c == null) {
            out.println("<error code=\"noSetHierarchy\">Invalid set</error>");
            return;
            }
             * */
            setint = new Integer(set);
        }

        if (from != null) {
            from = from.replace("T", " ");
            from = from.replace("Z", "");
        }

        if (until != null) {
            until = until.replace("T", " ");
            until = until.replace("Z", "");
        }

        // get list from resumption if exists;
        List<BaseType> fulllist = null;
        if (resumptionToken == null) {
            // TODO: FIX!
            fulllist = dataLoaderBean.getObjectsBy(setint, from, until);
        } else {
            fulllist = (List<BaseType>) resumptions.get(resumptionToken);
            String[] resOpts = (String[]) resumptionOptions.get(resumptionToken);
            from = resOpts[0];
            until = resOpts[1];
            mdPrefix = resOpts[2];
            set = resOpts[3];
        }

        if (fulllist.size() == 0) {
            out.println("<error code=\"noRecordsMatch\">No records</error>");
            return;
        }

        List<BaseType> mdlist = new ArrayList<BaseType>();
        String resumToken = "";
        if (fulllist.size() > maxListSize) {
            // generate resumption
            if (resumptionToken != null) {
                resumToken = resumptionToken;
            } else {
                resumToken = GenerateId.getUID();
            }
            List<BaseType> tmp = fulllist.subList(0, maxListSize);
            for (BaseType m : tmp) {
                mdlist.add(m);
            }
            for (BaseType m : mdlist) {
                fulllist.remove(m);
            }
            resumptions.put(resumToken, fulllist);
            resumptionOptions.put(resumToken, new String[]{from, until, mdPrefix, set});
        } else {
            if (resumptionToken != null) {
                List<BaseType> tmp = fulllist;
                for (BaseType m : tmp) {
                    mdlist.add(m);
                }
                for (BaseType m : mdlist) {
                    fulllist.remove(m);
                }
            } else {
                mdlist = fulllist;
            }
        }

        out.println("<request verb=\"ListRecords\" metadataPrefix=\"" + mdPrefix + "\">" + request.getRequestURL() + "</request>");
        out.println("<ListRecords>");

        String fullurl = request.getRequestURL().toString();
        String[] parts = fullurl.split("OAIHandler");
        String url = parts[0] + request.getContextPath() + "/";
        url = parts[0];
        for (BaseType obj : mdlist) {

            Object transformer = obj.getTransformer(mdPrefix);
            if (transformer == null) {
                continue;
            }

            Method meth;
            String objres = "";
            try {
                meth = transformer.getClass().getMethod("transform", new Class[]{BaseType.class});
                objres = (String) meth.invoke(transformer, new Object[]{obj});
            } catch (SecurityException ex) {
                ex.printStackTrace();
            } catch (NoSuchMethodException ex) {
                ex.printStackTrace();
            } catch (IllegalArgumentException ex) {
                ex.printStackTrace();
            } catch (IllegalAccessException ex) {
                ex.printStackTrace();
            } catch (InvocationTargetException ex) {
                ex.printStackTrace();
            }

            objres = objres.replace("REPLACE_FULL_PATH_HERE", url);

            out.println("<record>");

            out.println("<header>");
            out.println("<identifier>" + oai_prefix + obj.getInternalId() + "</identifier>");
            String dateval = obj.getValue("created").toString();
            String[] datesplit = dateval.split(" ");
            String timeval = datesplit[1].split("\\.")[0];
            String newDateVal = datesplit[0] + "T" + timeval + "Z";
            out.println("<datestamp>" + newDateVal + "</datestamp>");
            out.println("<setSpec>" + obj.getCatalogId() + "</setSpec>");
            out.println("</header>");

            out.println("<metadata>");
            out.println(objres);
            out.println("</metadata>");

            out.println("</record>");
        }
        if (fulllist != null && fulllist.size() > 0) {
            out.println("<resumptionToken>" + resumToken + "</resumptionToken>");
        }
        out.println("</ListRecords>");
    }

    // done
    public void ListMetadataFormats(PrintWriter out, HttpServletRequest request) {
        String identifier = parseIdentifier(request);
        /*
         * badArgument
         * idDoesNotExist
         * noMetadataFormats
         */

        boolean dc_support = false;
        boolean lom_support = false;

        if (identifier == null) {
            dc_support = true;
            lom_support = true;
        } else {
            BaseType bt = dataLoaderBean.getObjectById(identifier);
            if (bt == null) {
                out.println("<error code=\"idDoesNotExist\">Id not found</error>");
                return;
            }
            Transformers trfs = bt.getClass().getAnnotation(Transformers.class);
            if (trfs != null) {
                Class[] cls = trfs.transformers();
                for (Class tf : cls) {
                    try {
                        Object transf = tf.newInstance();
                        Method m = tf.getMethod("supports", new Class[]{String.class});
                        System.out.println("Method::" + m);
                        if (!dc_support) {
                            dc_support = (Boolean) m.invoke(transf, new Object[]{"oai_dc"});
                        }
                        if (!lom_support) {
                            lom_support = (Boolean) m.invoke(transf, new Object[]{"oai_lom"});
                        }
                    } catch (InstantiationException ex) {
                        Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
                    } catch (IllegalAccessException ex) {
                        Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
                    } catch (NoSuchMethodException ex) {
                        Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
                    } catch (SecurityException ex) {
                        Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
                    } catch (IllegalArgumentException ex) {
                        Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
                    } catch (InvocationTargetException ex) {
                        Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }
            }
        }
        if (!lom_support && !dc_support) {
            out.println("<error code=\"noMetadataFormats\">Id not found</error>");
            return;
        }
        out.println("<request verb=\"ListMetadataFormats\">" +
                request.getRequestURL() +
                "</request>" +
                "<ListMetadataFormats>");
        if (dc_support) {
            out.println("<metadataFormat>" +
                    "<metadataPrefix>oai_dc</metadataPrefix>" +
                    "<schema>http://www.openarchives.org/OAI/2.0/oai_dc.xsd</schema>" +
                    "<metadataNamespace>http://www.openarchives.org/OAI/2.0/oai_dc/" +
                    "</metadataNamespace>" +
                    "</metadataFormat>");
        }
        if (lom_support) {
            out.println("<metadataFormat>" +
                    "<metadataPrefix>oai_lom</metadataPrefix>" +
                    "<schema>http://standards.ieee.org/reading/ieee/downloads/LOM/lomv1.0/xsd/lom.xsd</schema>" +
                    "<metadataNamespace>http://ltsc.ieee.org/xsd/LOM" +
                    "</metadataNamespace>" +
                    "</metadataFormat>");
        }
        out.println("</ListMetadataFormats>");

    }

    // done with TODOs
    public void ListIdentifiers(PrintWriter out, HttpServletRequest request) {
        String from = request.getParameter("from");
        String until = request.getParameter("until");
        String mdPrefix = request.getParameter("metadataPrefix");
        String set = request.getParameter("set");
        Integer setint = null;
        String resumptionToken = request.getParameter("resumptionToken");

        /*
         * badArgument
         * badResumptionToken
         * cannotDisseminateFormat
         * noRecordsMatch
         * noSetHierarchy
         */

        if (mdPrefix == null && resumptionToken == null) {
            out.println("<error code=\"badArgument\">Not enough arguments</error>");
            return;
        }

        if (resumptionToken != null && !resumptions.containsKey(resumptionToken)) {
            out.println("<error code=\"badResumptionToken\">Not enough arguments</error>");
            return;
        }

        //String query = "SELECT * FROM metadata WHERE 1=1 ";

        if (set != null) {
            /*
            Catalog c = catalogFacade.findByName(set);
            if (c == null) {
            out.println("<error code=\"noSetHierarchy\">Invalid set</error>");
            return;
            }
             * */
            setint = new Integer(set);
        }

        if (from != null) {
            from = from.replace("T", " ");
            from = from.replace("Z", "");
        }

        if (until != null) {
            until = until.replace("T", " ");
            until = until.replace("Z", "");
        }

        List<BaseType> fulllist = null;
        if (resumptionToken == null) {
            fulllist = fulllist = dataLoaderBean.getObjectsBy(setint, from, until);
        } else {
            fulllist = (List<BaseType>) resumptions.get(resumptionToken);
            String[] resOpts = (String[]) resumptionOptions.get(resumptionToken);
            from = resOpts[0];
            until = resOpts[1];
            mdPrefix = resOpts[2];
            set = resOpts[3];
        }

        if (fulllist.size() == 0) {
            out.println("<error code=\"noRecordsMatch\">No records</error>");
            return;
        }
        List<BaseType> mdlist = new ArrayList<BaseType>();
        String resumToken = "";
        if (fulllist.size() > maxListSize) {
            // generate resumption
            if (resumptionToken != null) {
                resumToken = resumptionToken;
            } else {
                resumToken = GenerateId.getUID();
            }
            List<BaseType> tmp = fulllist.subList(0, maxListSize);
            for (BaseType m : tmp) {
                mdlist.add(m);
            }
            for (BaseType m : mdlist) {
                fulllist.remove(m);
            }
            resumptions.put(resumToken, fulllist);
            resumptionOptions.put(resumToken, new String[]{from, until, mdPrefix, set});
        } else {
            List<BaseType> tmp = fulllist;
            for (BaseType m : tmp) {
                mdlist.add(m);
            }
            for (BaseType m : mdlist) {
                fulllist.remove(m);
            }
        }


        out.println("<request verb=\"ListIdentifiers\" metadataPrefix=\"" + mdPrefix + "\">" + request.getRequestURL() + "</request>");
        out.println("<ListIdentifiers>");

        for (BaseType m : mdlist) {
            out.println("<header>");
            out.println("<identifier>" + oai_prefix + m.getInternalId() + "</identifier>");
            String dateval = m.getValue("created").toString();
            String[] datesplit = dateval.split(" ");
            String timeval = datesplit[1].split("\\.")[0];
            String newDateVal = datesplit[0] + "T" + timeval + "Z";
            out.println("<datestamp>" + newDateVal + "</datestamp>");
            out.println("<setSpec>" + m.getCatalogId() + "</setSpec>");
            out.println("</header>");
        }

        // resumption token here!
        if (fulllist != null && fulllist.size() > 0) {
            out.println("<resumptionToken>" + resumToken + "</resumptionToken>");
        }
        out.println("</ListIdentifiers>");

    }

    // done with TODOs
    public void GetRecord(PrintWriter out, HttpServletRequest request) {
        String identifier = parseIdentifier(request);
        String mdPrefix = request.getParameter("metadataPrefix");

        /*
         * badArgument
         * cannotDisseminateFormat
         * idDoesNotExist
         */

        if (identifier == null || mdPrefix == null) {
            out.println("<error code=\"badArgument\">Not enough arguments</error>");
            return;
        }

        BaseType obj = dataLoaderBean.getObjectById(identifier);
        if (obj == null) {
            out.println("<error code=\"idDoesNotExist\">Id not found</error>");
            return;
        }

        Object transformer = obj.getTransformer(mdPrefix);
        if (transformer == null) {
            out.println("<error code=\"cannotDisseminateFormat\">Error</error>");
            return;
        }
        String objres = "";

        Method meth;
        try {
            meth = transformer.getClass().getMethod("transform", new Class[]{BaseType.class});
            objres = (String) meth.invoke(transformer, new Object[]{obj});
        } catch (NoSuchMethodException ex) {
            Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
        } catch (SecurityException ex) {
            Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IllegalArgumentException ex) {
            Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
        } catch (InvocationTargetException ex) {
            Logger.getLogger(OAIHandler.class.getName()).log(Level.SEVERE, null, ex);
        }

        String fullurl = request.getRequestURL().toString();
        String[] parts = fullurl.split("OAIHandler");
        String url = parts[0] + request.getContextPath() + "/";
        url = parts[0];
        objres = objres.replace("REPLACE_FULL_PATH_HERE", url);

        out.println("<request verb=\"GetRecord\" identifier=\"" + identifier + "\" metadataPrefix=\"" + mdPrefix + "\">" + request.getRequestURL() + "</request>");
        out.println("<GetRecord>");
        out.println("<record>");
        out.println("<header>");
        out.println("<identifier>" + oai_prefix + obj.getInternalId() + "</identifier>");
        String dateval = obj.getValue("created").toString();
        String[] datesplit = dateval.split(" ");
        String timeval = datesplit[1].split("\\.")[0];
        String newDateVal = datesplit[0] + "T" + timeval + "Z";
        out.println("<datestamp>" + newDateVal + "</datestamp>");
        out.println("<setSpec>" + obj.getCatalogId() + "</setSpec>");
        out.println("</header>");
        out.println("<metadata>");

        // TODO: transformed object here!
        out.println(objres);

        out.println("</metadata>");
        out.println("</record>");
        out.println("</GetRecord>");
    }

    // done
    public void Identify(PrintWriter out, HttpServletRequest request) {
        /*
         * badArgument
         */

        out.println("<request verb=\"Identify\">" + request.getRequestURL() + "</request>");
        out.println("<Identify>");

        // repositoryName
        out.println("<repositoryName>TLÜ Repository</repositoryName>");
        // baseURL
        out.println("<baseURL>" + request.getRequestURL() + "</baseURL>");
        // protocolVersion
        out.println("<protocolVersion>2.0</protocolVersion>");
        // earliestDatestamp
        out.println("<earliestDatestamp>1990-02-01T12:00:00Z</earliestDatestamp>");
        // deletedRecord
        out.println("<deletedRecord>no</deletedRecord>");
        // granularity
        out.println("<granularity>YYYY-MM-DDThh:mm:ssZ</granularity>");
        // adminEmail
        out.println("<adminEmail>vahur@tlu.ee</adminEmail>");

        out.println("<description>" +
                "<oai-identifier xmlns=\"http://www.openarchives.org/OAI/2.0/oai-identifier\" " +
                "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://www.openarchives.org/OAI/2.0/oai-identifier http://www.openarchives.org/OAI/2.0/oai-identifier.xsd\">" +
                "<scheme>oai</scheme>" +
                "<repositoryIdentifier>ait.opetaja.ee</repositoryIdentifier>" +
                "<delimiter>:</delimiter>" +
                "<sampleIdentifier>oai:ait.opetaja.ee:1513</sampleIdentifier>" +
                "</oai-identifier>" +
                "</description>");

        out.println("</Identify>");
    }

    public String parseIdentifier(HttpServletRequest request) {
        String identifier = request.getParameter("identifier");
        if (identifier == null) {
            return null;
        }
        identifier = identifier.replace(oai_prefix, "");
        return identifier;
    }
    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** 
     * Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Returns a short description of the servlet.
     */
    @Override
    public String getServletInfo() {
        return "Waramu OAI target.";
    }// </editor-fold>
}