[tmp/jakarta-migration.git] /

package org.collectionspace.services.listener;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.collectionspace.services.client.workflow.WorkflowClient;
import org.collectionspace.services.common.api.Tools;
import org.collectionspace.services.common.storage.JDBCTools;
import org.collectionspace.services.movement.nuxeo.MovementConstants;
import org.nuxeo.ecm.core.api.ClientException;
import org.nuxeo.ecm.core.api.DocumentModel;
import org.nuxeo.ecm.core.event.Event;
import org.nuxeo.ecm.core.event.EventContext;
import org.nuxeo.ecm.core.event.EventListener;
import org.nuxeo.ecm.core.event.impl.DocumentEventContext;

public class UpdateObjectLocationOnMove implements EventListener {

    // FIXME: We might experiment here with using log4j instead of Apache Commons Logging;
    // am using the latter to follow Ray's pattern for now
    final Log logger = LogFactory.getLog(UpdateObjectLocationOnMove.class);
    private final String DATABASE_RESOURCE_DIRECTORY_NAME = "db";
    // FIXME: Currently hard-coded; get this from JDBC utilities or equivalent
    private final String DATABASE_SYSTEM_NAME = "postgresql";
    private final String STORED_FUNCTION_NAME = "computecurrentlocation";

    // ####################################################################
    // FIXME: Per Rick, what happens if a relation record is updated,
    // that either adds or removes a relation between a Movement
    // record and a CollectionObject record?  Do we need to listen
    // for that event as well and update the CollectionObject record's
    // computedCurrentLocation accordingly?
    //
    // The following code is currently checking only for creates or
    // updates to Movement records.
    // ####################################################################
    @Override
    public void handleEvent(Event event) throws ClientException {

        logger.trace("In handleEvent in UpdateObjectLocationOnMove ...");

        // FIXME: Check for database product type here.
        // If our database type is one for which we don't yet
        // have tested SQL code to perform this operation, return here.

        EventContext eventContext = event.getContext();
        if (eventContext == null) {
            return;
        }
        DocumentEventContext docEventContext = (DocumentEventContext) eventContext;
        DocumentModel docModel = docEventContext.getSourceDocument();
        if (isMovementDocument(docModel) && isActiveDocument(docModel)) {
            logger.debug("A create or update event for an active Movement document was received by UpdateObjectLocationOnMove ...");

            // Test whether a SQL function exists to supply the computed
            // current location of a CollectionObject.
            if (storedFunctionExists(STORED_FUNCTION_NAME)) {
                logger.debug("Stored function " + STORED_FUNCTION_NAME + "exists.");
            } else {
                logger.debug("Stored function " + STORED_FUNCTION_NAME + "does NOT exist.");

                // If the function does not exist in the database, load the
                // SQL command to create that function from a resource
                // available to this class, and run a JDBC command to create
                // that function in the database.
                //
                // For now, assume this function will be created in the
                // 'nuxeo' database.
                //
                // FIXME: Future work to create per-tenant repositories will
                // likely require that our JDBC statements connect to the
                // appropriate tenant-specific database.
                //
                // It doesn't appear we can reliably create this function via
                // 'ant create_nuxeo db' during the build process, because
                // there's a substantial likelihood at that point that
                // tables referred to by the function (e.g. movements_common
                // and collectionobjects_common) will not yet exist.
                // (PostgreSQL will not permit the function to be created if
                // any of its referred-to tables do not exist.)
                String sqlResourcePath =
                        DATABASE_RESOURCE_DIRECTORY_NAME + "/"
                        + DATABASE_SYSTEM_NAME + "/"
                        + STORED_FUNCTION_NAME + ".sql";
                String sql = getStringFromResource(sqlResourcePath);
                if (Tools.isBlank(sql)) {
                    logger.warn("Could not create stored function to update computed current location.");
                    logger.warn("Actions in this event listener will NOT be performed, as a result of a previous error.");
                    return;
                }

                logger.debug("After reading stored function command from resource path.");
                logger.debug("sql=" + sql);

                // FIXME: Execute SQL command here to create stored function.

                // Pseudocode:

                // Get this Movement record's CSID via the document model.

                // Find every CollectionObject record related to this Movement record:
                //
                // Via an NXQL query, get a list of (non-deleted) relation records where:
                // * This movement record's CSID is the subject CSID of the relation.
                // * The object document type is a CollectionObject doctype.

                // Iterate through that list of Relation records and build a list of
                // CollectionObject CSIDs, by extracting the object CSIDs of those records.

                // For each such CollectionObject:

                // Verify that the CollectionObject record is active (use isActiveDocument(), below).

                // Via a JDBC call, invoke the SQL function to supply the last
                // identified location of that CollectionObject, giving it the CSID
                // of the CollectionObject record as an argument.

                // Check that the SQL function's returned value, which is expected
                // to be a reference (refName) to a storage location authority term,
                // is at a minimum:
                // * Non-null
                // * Capable of being successfully parsed by an authority item parser,
                //   returning a non-null parse result.

                // Compare that returned value to the value in the
                // lastIdentifiedLocation field of that CollectionObject

                // If the two values differ, update the CollectionObject record,
                // setting the value of the lastIdentifiedLocation field of that
                // CollectionObject record to the value returned from the SQL function.

            }
        }

    }

    /**
     * Identifies whether a document is a Movement document
     *
     * @param docModel a document model
     * @return true if the document is a Movement document; false if it is not.
     */
    private boolean isMovementDocument(DocumentModel docModel) {
        return documentMatchesType(docModel, MovementConstants.NUXEO_DOCTYPE);
    }

    // FIXME: Generic methods like many of those below might be split off,
    // into an event utilities class, base classes, or otherwise. - ADR 2012-12-05
    //
    // FIXME: Identify whether the equivalent of the documentMatchesType utility
    // method is already implemented and substitute a call to the latter if so.
    // This may well already exist.
    /**
     * Identifies whether a document matches a supplied document type.
     *
     * @param docModel a document model.
     * @param docType a document type string.
     * @return true if the document matches the supplied document type; false if
     * it does not.
     */
    private boolean documentMatchesType(DocumentModel docModel, String docType) {
        if (docModel == null || Tools.isBlank(docType)) {
            return false;
        }
        if (docModel.getType().startsWith(docType)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Identifies whether a document is an active document; that is, if it is
     * not a versioned record; not a proxy (symbolic link to an actual record);
     * and not in the 'deleted' workflow state.
     *
     * (A note relating the latter: Nuxeo appears to send 'documentModified'
     * events even on workflow transitions, such when records are 'soft deleted'
     * by being transitioned to the 'deleted' workflow state.)
     *
     * @param docModel
     * @return true if the document is an active document; false if it is not.
     */
    private boolean isActiveDocument(DocumentModel docModel) {
        if (docModel == null) {
            return false;
        }
        boolean isActiveDocument = false;
        try {
            if (!docModel.isVersion()
                    && !docModel.isProxy()
                    && !docModel.getCurrentLifeCycleState().equals(WorkflowClient.WORKFLOWSTATE_DELETED)) {
                isActiveDocument = true;
            }
        } catch (ClientException ce) {
            logger.warn("Error while identifying whether document is an active document: ", ce);
        }
        return isActiveDocument;
    }

    // FIXME: The following method is specific to PostgreSQL, because of
    // the SQL command executed; it may need to be generalized.
    // Note: It may be necessary in some cases to provide additional
    // parameters beyond a function name (such as a function signature)
    // to uniquely identify a function. So far, however, this need
    // hasn't arisen in our specific use case here.
    /**
     * Identifies whether a stored function exists in a database.
     *
     * @param functionname the name of the function.
     * @return true if the function exists in the database; false if it does
     * not.
     */
    private boolean storedFunctionExists(String functionname) {
        if (Tools.isBlank(functionname)) {
            return false;
        }
        boolean storedFunctionExists = false;
        String sql = "SELECT proname FROM pg_proc WHERE proname='" + functionname + "'";
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            conn = JDBCTools.getConnection(JDBCTools.getDataSource(JDBCTools.NUXEO_REPOSITORY_NAME));
            stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
            if (rs.next()) {
                storedFunctionExists = true;
            }
            rs.close();
            stmt.close();
            conn.close();
        } catch (Exception e) {
            logger.debug("Error when identifying whether stored function " + functionname + "exists :", e);
        } finally {
            try {
                if (rs != null) {
                    rs.close();
                }
                if (stmt != null) {
                    stmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException sqle) {
                logger.debug("SQL Exception closing statement/connection in "
                        + "UpdateObjectLocationOnMove.storedFunctionExists: "
                        + sqle.getLocalizedMessage());
            }
        }
        return storedFunctionExists;
    }

    /**
     * Returns a string representation of the contents of an input stream.
     *
     * @param instream an input stream.
     * @return a string representation of the contents of the input stream.
     * @throws an IOException if an error occurs when reading the input stream.
     */
    private String stringFromInputStream(InputStream instream) throws IOException {
        if (instream == null) {
        }
        BufferedReader bufreader = new BufferedReader(new InputStreamReader(instream));
        StringBuilder sb = new StringBuilder();
        String line = "";
        while (line != null) {
            sb.append(line);
            line = bufreader.readLine();
            sb.append("\n"); // FIXME: Get appropriate EOL separator rather than hard-coding
        }
        return sb.toString();
    }

    /**
     * Returns a string representation of a resource available to the current
     * class.
     *
     * @param resourcePath a path to the resource.
     * @return a string representation of the resource. Returns null if the
     * resource cannot be read, or if it cannot be successfully represented as a
     * string.
     */
    private String getStringFromResource(String resourcePath) {
        String str = "";
        ClassLoader classLoader = getClass().getClassLoader();
        InputStream instream = classLoader.getResourceAsStream(resourcePath);
        if (instream == null) {
            logger.warn("Could not read from resource from path " + resourcePath);
            return null;
        }
        try {
            str = stringFromInputStream(instream);
        } catch (IOException ioe) {
            logger.warn("Could not create string from stream: ", ioe);
            return null;
        }
        return str;
    }
}