UrlsController/src/main/java/eu/openaire/urls_controller/controllers/StatsController.java

package eu.openaire.urls_controller.controllers;


import eu.openaire.urls_controller.configuration.ImpalaConnector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * This controller returns statistics for the database.
 */
@RestController
@RequestMapping("/stats")
public class StatsController {

    private static final Logger logger = LoggerFactory.getLogger(StatsController.class);

    @Autowired
    private JdbcTemplate jdbcTemplate;

    /**
     * This endpoint returns the total number of payloads existing in the database, independently of the way they were aggregated.
     * This includes the payloads created by other pieces of software, before the PDF-Aggregation-Service was created.
     * */
    @GetMapping("getNumberOfAllPayloads")
    public ResponseEntity<?> getNumberOfAllPayloads() {
        logger.info("Received a \"getNumberOfAllPayloads\" request.");
        final String getPayloadsNumberQuery = "select count(id) from " + ImpalaConnector.databaseName + ".payload";
        return getNumberOfPayloads(getPayloadsNumberQuery, "");
    }


    /**
     * This endpoint returns the number of payloads aggregated by the PDF-Aggregated-Service itself.
     * It excludes the payloads aggregated by other methods, by applying a Date-filter for the records created in 2021 or later.
     * */
    @GetMapping("getNumberOfPayloadsAggregatedByService")
    public ResponseEntity<?> getNumberOfPayloadsAggregatedByService() {
        logger.info("Received a \"getNumberOfPayloadsAggregatedByService\" request.");
        String getPayloadsAggregatedQuery = "select count(id) from " + ImpalaConnector.databaseName + ".payload where `date` >= cast(cast('2021-01-01' as timestamp) as bigint)";
        return getNumberOfPayloads(getPayloadsAggregatedQuery, "retrieved by the PDF Aggregation Service");
    }


    /**
     * This endpoint returns the number of records inspected by the PDF-Aggregation-Service.
     * */
    @GetMapping("getNumberOfRecordsInspected")
    public ResponseEntity<?> getNumberOfRecordsInspected()
    {
        // Note that until all the records are inspected, the "attempt" table contains all the inspected records PLUS very few duplicates (id-url) which come from the publications-database.
        // After all the records are inspected, it contains duplicate records of more and more id-urls, as time goes one, since for every eligible record the Service re-attempts to get the full-text.
        // So in order to get the number of inspected records, we want the distinct number, which at some point it will remain stable, even though the Service will try again and again some records.
        // Before all the records are inspected, this endpoint will report all the inspected records MINUS the duplicate records which come straight from the "publication" table.

        logger.info("Received a \"getNumberOfRecordsInspected\" request.");

        final String getInspectedRecordsNumberQuery = "select count(dist.id) from (select distinct id, original_url from " + ImpalaConnector.databaseName + ".attempt) as dist";
        try {
            Object result = jdbcTemplate.queryForObject(getInspectedRecordsNumberQuery, Integer.class);
            if ( result != null ) {
                int numOfInspectedRecords = (int) result;
                logger.info("Number of inspected records from the database \"" + ImpalaConnector.databaseName + "\" is " + numOfInspectedRecords);
                return new ResponseEntity<>(numOfInspectedRecords, HttpStatus.OK);
            } else
                return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("The inspected records' number could not be retrieved from the database \"" + ImpalaConnector.databaseName + "\" using the getInspectedRecordsNumberQuery: " + getInspectedRecordsNumberQuery);
        } catch (EmptyResultDataAccessException erdae) {
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("The inspected records' number could not be retrieved from the database \"" + ImpalaConnector.databaseName + "\" using the getInspectedRecordsNumberQuery: " + getInspectedRecordsNumberQuery);
        } catch (Exception e) {
            String errorMsg = "Problem when executing \"getInspectedRecordsNumberQuery\": " + getInspectedRecordsNumberQuery;
            logger.error(errorMsg, e);
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(errorMsg);
            // We may get a "Class Cast Exception", in case the Impala returns a non-integer value.
        }
    }


    private ResponseEntity<?> getNumberOfPayloads(String getPayloadsNumberQuery, String extraMsg) {
        try {
            Object result = jdbcTemplate.queryForObject(getPayloadsNumberQuery, Integer.class);
            if ( result != null ) {
                int numOfPayloads = (int) result;
                logger.info("Number of payloads " + extraMsg + " in the database \"" + ImpalaConnector.databaseName + "\" is " + numOfPayloads);
                return new ResponseEntity<>(numOfPayloads, HttpStatus.OK);
            } else
                return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("The payloads' number could not be retrieved from the database \"" + ImpalaConnector.databaseName + "\" using the getPayloadsNumberQuery: " + getPayloadsNumberQuery);
        } catch (EmptyResultDataAccessException erdae) {
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("The payloads' number could not be retrieved from the database \"" + ImpalaConnector.databaseName + "\" using the getPayloadsNumberQuery: " + getPayloadsNumberQuery);
        } catch (Exception e) {
            String errorMsg = "Problem when executing \"getPayloadsNumberQuery\": " + getPayloadsNumberQuery;
            logger.error(errorMsg, e);
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(errorMsg);
            // We may get a "Class Cast Exception", in case the Impala returns a non-integer value.
        }
    }

}