/**
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE and NOTICE files at the root of the source
 * tree and available online at
 *
 * http://www.dspace.org/license/
 */
package org.dspace.identifier;

import org.apache.log4j.Logger;
import org.dspace.authorize.AuthorizeException;
import org.dspace.content.*;
import org.dspace.content.service.ItemService;
import org.dspace.core.ConfigurationManager;
import org.dspace.core.Constants;
import org.dspace.core.Context;
import org.dspace.core.LogManager;
import org.dspace.handle.service.HandleService;
import org.dspace.services.factory.DSpaceServicesFactory;
import org.dspace.versioning.*;
import org.dspace.versioning.service.VersionHistoryService;
import org.dspace.versioning.service.VersioningService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.sql.SQLException;
import java.util.Date;
import java.util.List;
import org.apache.commons.lang.StringUtils;

/**
 *
 *
 * @author Fabio Bolognesi (fabio at atmire dot com)
 * @author Mark Diggory (markd at atmire dot com)
 * @author Ben Bosman (ben at atmire dot com)
 */
@Component
public class VersionedHandleIdentifierProviderWithCanonicalHandles extends IdentifierProvider {
    /** log4j category */
    private static Logger log = Logger.getLogger(VersionedHandleIdentifierProviderWithCanonicalHandles.class);

    /** Prefix registered to no one */
    static final String EXAMPLE_PREFIX = "123456789";

    private static final char DOT = '.';

    @Autowired(required = true)
    private VersioningService versionService;

    @Autowired(required = true)
    private VersionHistoryService versionHistoryService;

    @Autowired(required = true)
    private HandleService handleService;

    @Autowired(required = true)
    private ItemService itemService;

    @Override
    public boolean supports(Class<? extends Identifier> identifier)
    {
        return Handle.class.isAssignableFrom(identifier);
    }

    @Override
    public boolean supports(String identifier)
    {
    	String prefix = handleService.getPrefix();
        String canonicalPrefix = DSpaceServicesFactory.getInstance().getConfigurationService().getProperty("handle.canonical.prefix");
        if (identifier == null)
        {
            return false;
        }
        // return true if handle has valid starting pattern
        if (identifier.startsWith(prefix + "/")
                || identifier.startsWith(canonicalPrefix)
                || identifier.startsWith("hdl:")
                || identifier.startsWith("info:hdl")
                || identifier.matches("^https?://hdl\\.handle\\.net/.*")
                || identifier.matches("^https?://.+/handle/.*"))
        {
            return true;
        }

        //Check additional prefixes supported in the config file
        String[] additionalPrefixes = DSpaceServicesFactory.getInstance().getConfigurationService().getArrayProperty("handle.additional.prefixes");
        for(String additionalPrefix: additionalPrefixes) {
            if (identifier.startsWith(additionalPrefix + "/")) {
                return true;
            }
        }

        // otherwise, assume invalid handle
        return false;
    }

    @Override
    public String register(Context context, DSpaceObject dso)
    {
        String id = mint(context, dso);

        // move canonical to point the latest version
        if(dso != null && dso.getType() == Constants.ITEM)
        {
            Item item = (Item)dso;
            VersionHistory history = null;
            try {
                history = versionHistoryService.findByItem(context, (Item) dso);
            } catch (SQLException ex) {
                throw new RuntimeException("A problem with the database connection occured.", ex);
            }
            if(history!=null)
            {
                String canonical = getCanonical(context, item);
                
                // Modify Canonical: 12345/100 will point to the new item
                try {
                    handleService.modifyHandleDSpaceObject(context, canonical, item);
                } catch (SQLException ex) {
                    throw new RuntimeException("A problem with the database connection occured.", ex);
                }
                
                Version version;
                Version previous;
                boolean previousIsFirstVersion = false;
                String previousItemHandle = null;
                try {
                    version = versionService.getVersion(context, item);
                    previous = versionHistoryService.getPrevious(context, history, version);
                    if (previous != null)
                    {
                        previousIsFirstVersion = versionHistoryService.isFirstVersion(context, history, previous);
                        previousItemHandle = handleService.findHandle(context, previous.getItem());
                    }
                } catch (SQLException ex) {
                    throw new RuntimeException("A problem with the database connection occured.", ex);
                }

                // we have to ensure the previous item still has a handle
                // check if we have a previous item
                if (previous != null)
                {
                    try {
                        // If we have a reviewer he/she might not have the
                        // rights to edit the metadata of thes previous item.
                        // Temporarly grant them:
                        context.turnOffAuthorisationSystem();

                        // Check if our previous item hasn't got a handle anymore.
                        // This only occurs when a switch has been made from 
                        // the default handle identifier provider to the 
                        // versioned one. In this case no "versioned handle" is
                        // reserved so we need to create one.
                        if (previousItemHandle == null)
                        {
                            if (previousIsFirstVersion)
                            {
                                previousItemHandle = getCanonical(id) + DOT + previous.getVersionNumber();
                                handleService.createHandle(context, previous.getItem(), previousItemHandle);
                            } else {
                                previousItemHandle = makeIdentifierBasedOnHistory(context, previous.getItem(), history);
                            }
                        }
                        // remove the canonical handle from the previous item's metadata
                        modifyHandleMetadata(context, previous.getItem(), previousItemHandle);
                    } catch (SQLException ex) {
                        throw new RuntimeException("A problem with the database connection occured.", ex);
                    } catch (AuthorizeException ex) {
                        // cannot occure, as the authorization system is turned of
                        throw new IllegalStateException("Caught an "
                                + "AuthorizeException while the "
                                + "authorization system was turned off!", ex);
                    } finally {
                        context.restoreAuthSystemState();
                    }
                }
            }
            try {
                // remove all handles from metadata and add the canonical one.
                modifyHandleMetadata(context, item, getCanonical(id));
            } catch (SQLException ex) {
                throw new RuntimeException("A problem with the database connection occured.", ex);
            } catch (AuthorizeException ex) {
                throw new RuntimeException("The current user is not authorized to change this item.", ex);
            }
        }

        return id;
    }

    @Override
    public void register(Context context, DSpaceObject dso, String identifier)
    {
        try
        {

            Item item = (Item) dso;

            // if for this identifier is already present a record in the Handle table and the corresponding item
            // has an history someone is trying to restore the latest version for the item. When
            // trying to restore the latest version the identifier in input doesn't have the for 1234/123.latestVersion
            // it is the canonical 1234/123
            VersionHistory itemHistory = getHistory(context, identifier);
            if(!identifier.matches(".*/.*\\.\\d+") && itemHistory!=null){

                int newVersionNumber = versionHistoryService.getLatestVersion(context, itemHistory).getVersionNumber()+1;
                String canonical = identifier;
                identifier = identifier.concat(".").concat("" + newVersionNumber);
                restoreItAsVersion(context, dso, identifier, item, canonical, itemHistory);
            }
            // if identifier == 1234.5/100.4 reinstate the version 4 in the version table if absent
            else if(identifier.matches(".*/.*\\.\\d+"))
            {
                // if it is a version of an item is needed to put back the record
                // in the versionitem table
                String canonical = getCanonical(identifier);
                DSpaceObject canonicalItem = this.resolve(context, canonical);
                if(canonicalItem==null){
                    restoreItAsCanonical(context, dso, identifier, item, canonical);
                }
                else{
                    VersionHistory history = versionHistoryService.findByItem(context, (Item) canonicalItem);
                    if(history==null){
                        restoreItAsCanonical(context, dso, identifier, item, canonical);
                    }
                    else
                    {
                        restoreItAsVersion(context, dso, identifier, item, canonical, history);

                    }
                }
            }
            else
            {
                //A regular handle
                createNewIdentifier(context, dso, identifier);
                if(dso instanceof Item)
                {
                    modifyHandleMetadata(context, item, getCanonical(identifier));
                }
            }
        }catch (Exception e){
            log.error(LogManager.getHeader(context, "Error while attempting to create handle", "Item id: " + dso.getID()), e);
            throw new RuntimeException("Error while attempting to create identifier for Item id: " + dso.getID(), e);
        }
    }

    protected VersionHistory getHistory(Context context, String identifier) throws SQLException {
        DSpaceObject item = this.resolve(context, identifier);
        if(item!=null){
            VersionHistory history = versionHistoryService.findByItem(context, (Item) item);
            return history;
        }
        return null;
    }

    protected void restoreItAsVersion(Context context, DSpaceObject dso, String identifier, Item item, String canonical, VersionHistory history)
            throws SQLException, IOException, AuthorizeException
    {
        createNewIdentifier(context, dso, identifier);
        modifyHandleMetadata(context, item, getCanonical(identifier));

        int versionNumber = Integer.parseInt(identifier.substring(identifier.lastIndexOf(".") + 1));
        versionService.createNewVersion(context, history, item, "Restoring from AIP Service", new Date(), versionNumber);
        Version latest = versionHistoryService.getLatestVersion(context, history);


        // if restoring the lastest version: needed to move the canonical
        if(latest.getVersionNumber() < versionNumber){
            handleService.modifyHandleDSpaceObject(context, canonical, dso);
        }
    }

    protected void restoreItAsCanonical(Context context, DSpaceObject dso, String identifier, Item item, String canonical) throws SQLException, IOException, AuthorizeException
    {
        createNewIdentifier(context, dso, identifier);
        modifyHandleMetadata(context, item, getCanonical(identifier));

        int versionNumber = Integer.parseInt(identifier.substring(identifier.lastIndexOf(".")+1));
        VersionHistory history=versionHistoryService.create(context);
        versionService.createNewVersion(context, history, item, "Restoring from AIP Service", new Date(), versionNumber);

        handleService.modifyHandleDSpaceObject(context, canonical, dso);

    }


    @Override
    public void reserve(Context context, DSpaceObject dso, String identifier)
    {
        try{
            handleService.createHandle(context, dso, identifier);
        }catch(Exception e){
            log.error(LogManager.getHeader(context, "Error while attempting to create handle", "Item id: " + dso.getID()), e);
            throw new RuntimeException("Error while attempting to create identifier for Item id: " + dso.getID());
        }
    }


    /**
     * Creates a new handle in the database.
     *
     * @param context DSpace context
     * @param dso The DSpaceObject to create a handle for
     * @return The newly created handle
     */
    @Override
    public String mint(Context context, DSpaceObject dso)
    {
        if(dso.getHandle() != null)
        {
            return dso.getHandle();
        }

        try{
            String handleId = null;
            VersionHistory history = null;
            if(dso instanceof Item)
            {
                history = versionHistoryService.findByItem(context, (Item) dso);
            }

            if(history!=null)
            {
                handleId = makeIdentifierBasedOnHistory(context, dso, history);
            }else{
                handleId = createNewIdentifier(context, dso, null);
            }
            return handleId;
        }catch (Exception e){
            log.error(LogManager.getHeader(context, "Error while attempting to create handle", "Item id: " + dso.getID()), e);
            throw new RuntimeException("Error while attempting to create identifier for Item id: " + dso.getID());
        }
    }

    @Override
    public DSpaceObject resolve(Context context, String identifier, String... attributes)
    {
        // We can do nothing with this, return null
        try{
            return handleService.resolveToObject(context, identifier);
        }catch (Exception e){
            log.error(LogManager.getHeader(context, "Error while resolving handle to item", "handle: " + identifier), e);
        }
        return null;
    }

    @Override
    public String lookup(Context context, DSpaceObject dso) throws IdentifierNotFoundException, IdentifierNotResolvableException {

        try
        {
            return handleService.findHandle(context, dso);
        }catch(SQLException sqe){
            throw new IdentifierNotResolvableException(sqe.getMessage(),sqe);
        }
    }

    @Override
    public void delete(Context context, DSpaceObject dso, String identifier) throws IdentifierException {
        delete(context, dso);
    }

    @Override
    public void delete(Context context, DSpaceObject dso) throws IdentifierException {

        try {
            if (dso instanceof Item)
            {
                Item item = (Item) dso;

                // If it is the most current version occurs to move the canonical to the previous version
                VersionHistory history = versionHistoryService.findByItem(context, item);
                if(history!=null && versionHistoryService.getLatestVersion(context, history).getItem().equals(item)
                        && versionService.getVersionsByHistory(context, history).size() > 1)
                {
                    Item previous;
                    try {
                        previous = versionHistoryService.getPrevious(context, history, versionHistoryService.getLatestVersion(context, history)).getItem();
                    } catch (SQLException ex) {
                        throw new RuntimeException("A problem with our database connection occured.", ex);
                    }

                    // Modify Canonical: 12345/100 will point to the new item
                    String canonical = getCanonical(context, previous);
                    handleService.modifyHandleDSpaceObject(context, canonical, previous);
                }
            }
        } catch (Exception e) {
            log.error(LogManager.getHeader(context, "Error while attempting to register doi", "Item id: " + dso.getID()), e);
            throw new IdentifierException("Error while moving doi identifier", e);
        }


    }

    public static String retrieveHandleOutOfUrl(String url)
    {
        // We can do nothing with this, return null
        if (!url.contains("/")) return null;

        String[] splitUrl = url.split("/");

        return splitUrl[splitUrl.length - 2] + "/" + splitUrl[splitUrl.length - 1];
    }

    /**
     * Get the configured Handle prefix string, or a default
     * @return configured prefix or "123456789"
     */
    public static String getPrefix()
    {
        String prefix = ConfigurationManager.getProperty("handle.prefix");
        if (null == prefix)
        {
            prefix = EXAMPLE_PREFIX; // XXX no good way to exit cleanly
            log.error("handle.prefix is not configured; using " + prefix);
        }
        return prefix;
    }

    protected String createNewIdentifier(Context context, DSpaceObject dso, String handleId) throws SQLException {
        if(handleId == null)
        {
            return handleService.createHandle(context, dso);
        }else{
            return handleService.createHandle(context,  dso, handleId);
        }
    }

    protected String makeIdentifierBasedOnHistory(Context context, DSpaceObject dso, VersionHistory history)
            throws AuthorizeException, SQLException
    {
        Item item = (Item)dso;

        // FIRST time a VERSION is created 2 identifiers will be minted  and the canonical will be updated to point to the newer URL:
        //  - id.1-->old URL
        //  - id.2-->new URL
        Version version = versionService.getVersion(context, item);
        Version previous;
        try {
            previous = versionHistoryService.getPrevious(context, history, version);
        } catch (SQLException ex) {
            throw new RuntimeException("A problem with our database connection occured.");
        }
        String canonical = getCanonical(context, previous.getItem());

        if (versionHistoryService.isFirstVersion(context, history, previous))
        {
            // add a new Identifier for previous item: 12345/100.1
            String identifierPreviousItem=canonical + DOT + previous.getVersionNumber();
            //Make sure that this hasn't happened already
            if(handleService.resolveToObject(context, identifierPreviousItem) == null)
            {
                handleService.createHandle(context, previous.getItem(), identifierPreviousItem, true);
            }
        }

        // add a new Identifier for this item: 12345/100.x
        String idNew = canonical + DOT + version.getVersionNumber();
        //Make sure we don't have an old handle hanging around (if our previous version was deleted in the workspace)
        if(handleService.resolveToObject(context, idNew) == null)
        {
            handleService.createHandle(context, dso, idNew);
        }else{
            handleService.modifyHandleDSpaceObject(context, idNew, dso);
        }

        return idNew;
    }


    protected String getCanonical(Context context, Item item) {
        String canonical = item.getHandle();
        if( canonical.matches(".*/.*\\.\\d+") && canonical.lastIndexOf(DOT)!=-1)
        {
            canonical =  canonical.substring(0, canonical.lastIndexOf(DOT));
        }

        return canonical;
    }

    protected String getCanonical(String identifier)
    {
        String canonical = identifier;
        if( canonical.matches(".*/.*\\.\\d+") && canonical.lastIndexOf(DOT)!=-1)
        {
            canonical =  canonical.substring(0, canonical.lastIndexOf(DOT));
        }

        return canonical;
    }

    /**
     * Remove all handles from an item's metadata and add the supplied handle instead.
     * @param context
     * @param item
     * @param handle
     * @throws SQLException if database error
     * @throws AuthorizeException if authorization error
     */
    protected void modifyHandleMetadata(Context context, Item item, String handle)
            throws SQLException, AuthorizeException
    {
        // we want to exchange the old handle against the new one. To do so, we 
        // load all identifiers, clear the metadata field, re add all 
        // identifiers which are not from type handle and add the new handle.
        String handleref = handleService.getCanonicalForm(handle);
        List<MetadataValue> identifiers = itemService.getMetadata(item, MetadataSchema.DC_SCHEMA, "identifier", "uri", Item.ANY);
        itemService.clearMetadata(context, item, MetadataSchema.DC_SCHEMA, "identifier", "uri", Item.ANY);
        for (MetadataValue identifier : identifiers)
        {
            if (this.supports(identifier.getValue()))
            {
                // ignore handles
                continue;
            }
            itemService.addMetadata(context, 
                    item,
                    identifier.getMetadataField(),
                    identifier.getLanguage(),
                    identifier.getValue(),
                    identifier.getAuthority(),
                    identifier.getConfidence());
        }
        if (!StringUtils.isEmpty(handleref))
        {
            itemService.addMetadata(context, item, MetadataSchema.DC_SCHEMA, "identifier", "uri", null, handleref);
        }
        itemService.update(context, item);
    }
}