/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
 * Copyright © 2017-2018 Amdocs
 * ================================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============LICENSE_END=========================================================
 */
package org.onap.aai.sa.rest;

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.onap.aai.cl.api.LogFields;
import org.onap.aai.cl.api.LogLine;
import org.onap.aai.cl.api.Logger;
import org.onap.aai.cl.eelf.LoggerFactory;
import org.onap.aai.sa.searchdbabstraction.elasticsearch.dao.DocumentStoreDataEntityImpl;
import org.onap.aai.sa.searchdbabstraction.elasticsearch.dao.DocumentStoreInterface;
import org.onap.aai.sa.searchdbabstraction.entity.AggregationResults;
import org.onap.aai.sa.searchdbabstraction.entity.DocumentOperationResult;
import org.onap.aai.sa.searchdbabstraction.entity.SearchOperationResult;
import org.onap.aai.sa.searchdbabstraction.logging.SearchDbMsgs;
import org.onap.aai.sa.searchdbabstraction.searchapi.SearchStatement;
import org.onap.aai.sa.searchdbabstraction.searchapi.SuggestionStatement;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;

public class DocumentApi {
    private static final String MSG_REQUEST_BODY = "Request Body: ";
    private static final String REQUEST_HEADER_RESOURCE_VERSION = "If-Match";
    private static final String RESPONSE_HEADER_RESOURCE_VERSION = "ETag";
    private static final String REQUEST_HEADER_ALLOW_IMPLICIT_INDEX_CREATION = "X-CreateIndex";

    protected SearchServiceApi searchService = null;

    private Logger logger = LoggerFactory.getInstance().getLogger(DocumentApi.class.getName());
    private Logger auditLogger = LoggerFactory.getInstance().getAuditLogger(DocumentApi.class.getName());

    public DocumentApi(SearchServiceApi searchService) {
        this.searchService = searchService;
    }

    public ResponseEntity<String> processPost(String content, HttpServletRequest request, HttpHeaders headers,
            HttpServletResponse httpResponse, String index, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);
            if (content == null) {
                return handleError(request, content, HttpStatus.BAD_REQUEST);
            }

            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.POST,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);
            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "DocumentApi.processPost", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            DocumentStoreDataEntityImpl document = new DocumentStoreDataEntityImpl();
            document.setContent(content);

            DocumentOperationResult result =
                    documentStore.createDocument(index, document, implicitlyCreateIndex(headers));
            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getDocument());
            } else {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }

            if (httpResponse != null) {
                httpResponse.setHeader(RESPONSE_HEADER_RESOURCE_VERSION, result.getResultVersion());
            }
            ResponseEntity<String> response =
                    ResponseEntity.status(result.getResultCode()).contentType(MediaType.APPLICATION_JSON).body(output);
            logResult(request, HttpStatus.valueOf(response.getStatusCodeValue()));
            logResult(request, HttpStatus.valueOf(response.getStatusCodeValue()));

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;
        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    public ResponseEntity<String> processPut(String content, HttpServletRequest request, HttpHeaders headers,
            HttpServletResponse httpResponse, String index, String id, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);
            if (content == null) {
                return handleError(request, content, HttpStatus.BAD_REQUEST);
            }

            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.PUT,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);
            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "DocumentApi.processPut", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            String resourceVersion = headers.getFirst(REQUEST_HEADER_RESOURCE_VERSION);

            DocumentStoreDataEntityImpl document = new DocumentStoreDataEntityImpl();
            document.setId(id);
            document.setContent(content);
            document.setVersion(resourceVersion);

            DocumentOperationResult result = null;
            if (resourceVersion == null) {
                result = documentStore.createDocument(index, document, implicitlyCreateIndex(headers));
            } else {
                result = documentStore.updateDocument(index, document, implicitlyCreateIndex(headers));
            }

            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getDocument());
            } else {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }
            if (httpResponse != null) {
                httpResponse.setHeader(RESPONSE_HEADER_RESOURCE_VERSION, result.getResultVersion());
            }
            ResponseEntity<String> response =
                    ResponseEntity.status(result.getResultCode()).contentType(MediaType.APPLICATION_JSON).body(output);
            logResult(request, HttpStatus.valueOf(response.getStatusCodeValue()));

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;
        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    public ResponseEntity<String> processDelete(String content, HttpServletRequest request, HttpHeaders headers,
            HttpServletResponse httpResponse, String index, String id, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);
            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.DELETE,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);
            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "DocumentApi.processDelete", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            String resourceVersion = headers.getFirst(REQUEST_HEADER_RESOURCE_VERSION);
            if (resourceVersion == null || resourceVersion.isEmpty()) {
                return handleError(request, "Request header 'If-Match' missing", HttpStatus.BAD_REQUEST);
            }

            DocumentStoreDataEntityImpl document = new DocumentStoreDataEntityImpl();
            document.setId(id);
            document.setVersion(resourceVersion);

            DocumentOperationResult result = documentStore.deleteDocument(index, document);
            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }

            if (httpResponse != null) {
                httpResponse.setHeader(RESPONSE_HEADER_RESOURCE_VERSION, result.getResultVersion());
            }
            ResponseEntity<String> response;
            if (output == null) {
                response = ResponseEntity.status(result.getResultCode()).build();
            } else {
                response = ResponseEntity.status(result.getResultCode()).contentType(MediaType.APPLICATION_JSON)
                        .body(output);
            }

            logResult(request, HttpStatus.valueOf(response.getStatusCodeValue()));

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;
        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    public ResponseEntity<String> processGet(String content, HttpServletRequest request, HttpHeaders headers,
            HttpServletResponse httpResponse, String index, String id, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);
            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.GET,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);
            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "DocumentApi.processGet", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            String resourceVersion = headers.getFirst(REQUEST_HEADER_RESOURCE_VERSION);

            DocumentStoreDataEntityImpl document = new DocumentStoreDataEntityImpl();
            document.setId(id);
            document.setVersion(resourceVersion);

            DocumentOperationResult result = documentStore.getDocument(index, document);
            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getDocument());
            } else {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }
            if (httpResponse != null) {
                httpResponse.setHeader(RESPONSE_HEADER_RESOURCE_VERSION, result.getResultVersion());
            }
            ResponseEntity<String> response =
                    ResponseEntity.status(result.getResultCode()).contentType(MediaType.APPLICATION_JSON).body(output);
            logResult(request, HttpStatus.valueOf(response.getStatusCodeValue()));

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;
        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    public ResponseEntity<String> processSearchWithGet(String content, HttpServletRequest request, HttpHeaders headers,
            String index, String queryText, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);

            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.GET,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);
            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "processSearchWithGet", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            SearchOperationResult result = documentStore.search(index, queryText);
            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getSearchResult());
            } else {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }
            ResponseEntity<String> response =
                    ResponseEntity.status(result.getResultCode()).contentType(MediaType.APPLICATION_JSON).body(output);

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;
        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    public ResponseEntity<String> queryWithGetWithPayload(String content, HttpServletRequest request,
            HttpHeaders headers, String index, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        logger.info(SearchDbMsgs.PROCESS_PAYLOAD_QUERY, "GET",
                (request != null) ? request.getRequestURL().toString() : "");
        if (logger.isDebugEnabled()) {
            logger.debug(MSG_REQUEST_BODY + content);
        }
        return processQuery(index, content, request, headers, documentStore);
    }

    public ResponseEntity<String> processSearchWithPost(String content, HttpServletRequest request, HttpHeaders headers,
            String index, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        logger.info(SearchDbMsgs.PROCESS_PAYLOAD_QUERY, "POST",
                (request != null) ? request.getRequestURL().toString() : "");
        if (logger.isDebugEnabled()) {
            logger.debug(MSG_REQUEST_BODY + content);
        }

        return processQuery(index, content, request, headers, documentStore);
    }


    public ResponseEntity<String> processSuggestQueryWithPost(String content, HttpServletRequest request,
            HttpHeaders headers, String index, DocumentStoreInterface documentStore) {

        // Initialize the MDC Context for logging purposes.
        ApiUtils.initMdcContext(request, headers);

        logger.info(SearchDbMsgs.PROCESS_PAYLOAD_QUERY, "POST",
                (request != null) ? request.getRequestURL().toString() : "");
        if (logger.isDebugEnabled()) {
            logger.debug(MSG_REQUEST_BODY + content);
        }

        return processSuggestQuery(index, content, request, headers, documentStore);
    }

    /**
     * Common handler for query requests. This is called by both the GET with payload and POST with payload variants of
     * the query endpoint.
     *
     * @param index - The index to be queried against.
     * @param content - The payload containing the query structure.
     * @param request - The HTTP request.
     * @param headers - The HTTP headers.
     * @return - A standard HTTP response.
     */
    private ResponseEntity<String> processQuery(String index, String content, HttpServletRequest request,
            HttpHeaders headers, DocumentStoreInterface documentStore) {

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);

            // Make sure that we were supplied a payload before proceeding.
            if (content == null) {
                return handleError(request, content, HttpStatus.BAD_REQUEST);
            }

            // Validate that the request has the appropriate authorization.
            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.POST,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);

            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "processQuery", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            SearchStatement searchStatement;

            try {
                // Marshall the supplied request payload into a search statement
                // object.
                searchStatement = mapper.readValue(content, SearchStatement.class);

            } catch (Exception e) {
                return handleError(request, e.getMessage(), HttpStatus.BAD_REQUEST);
            }

            // Now, submit the search statement, translated into
            // ElasticSearch syntax, to the document store DAO.
            SearchOperationResult result = documentStore.searchWithPayload(index, searchStatement.toElasticSearch());
            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = prepareOutput(mapper, result);
            } else {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }
            ResponseEntity<String> response =
                    ResponseEntity.status(result.getResultCode()).contentType(MediaType.APPLICATION_JSON).body(output);

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;

        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }


    /**
     * Common handler for query requests. This is called by both the GET with payload and POST with payload variants of
     * the query endpoint.
     *
     * @param index - The index to be queried against.
     * @param content - The payload containing the query structure.
     * @param request - The HTTP request.
     * @param headers - The HTTP headers.
     * @return - A standard HTTP response.
     */
    private ResponseEntity<String> processSuggestQuery(String index, String content, HttpServletRequest request,
            HttpHeaders headers, DocumentStoreInterface documentStore) {

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.setSerializationInclusion(Include.NON_EMPTY);

            // Make sure that we were supplied a payload before proceeding.
            if (content == null) {
                return handleError(request, content, HttpStatus.BAD_REQUEST);
            }

            // Validate that the request has the appropriate authorization.
            boolean isValid;
            try {
                isValid = searchService.validateRequest(headers, request, ApiUtils.Action.POST,
                        ApiUtils.SEARCH_AUTH_POLICY_NAME);

            } catch (Exception e) {
                logger.info(SearchDbMsgs.EXCEPTION_DURING_METHOD_CALL, "processQuery", e.getMessage());
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            if (!isValid) {
                return handleError(request, content, HttpStatus.FORBIDDEN);
            }

            SuggestionStatement suggestionStatement;

            try {
                // Marshall the supplied request payload into a search statement
                // object.
                suggestionStatement = mapper.readValue(content, SuggestionStatement.class);

            } catch (Exception e) {
                return handleError(request, e.getMessage(), HttpStatus.BAD_REQUEST);
            }

            // Now, submit the search statement, translated into
            // ElasticSearch syntax, to the document store DAO.
            SearchOperationResult result =
                    documentStore.suggestionQueryWithPayload(index, suggestionStatement.toElasticSearch());
            String output = null;
            if (ApiUtils.isSuccessStatusCode(result.getResultCode())) {
                output = prepareSuggestOutput(mapper, result);
            } else {
                output = result.getError() != null
                        ? mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getError())
                        : result.getFailureCause();
            }
            ResponseEntity<String> response = ResponseEntity.status(result.getResultCode()).body(output);

            // Clear the MDC context so that no other transaction inadvertently
            // uses our transaction id.
            ApiUtils.clearMdcContext();

            return response;

        } catch (Exception e) {
            return handleError(request, e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Checks the supplied HTTP headers to see if we should allow the underlying document store to implicitly create the
     * index referenced in a document PUT or POST if it does not already exist in the data store.
     *
     * @param headers - The HTTP headers to examine.
     *
     * @return - true if the headers indicate that missing indices should be implicitly created, false otherwise.
     */
    private boolean implicitlyCreateIndex(HttpHeaders headers) {
        String implicitIndexCreationHeader = headers.getFirst(REQUEST_HEADER_ALLOW_IMPLICIT_INDEX_CREATION);
        return implicitIndexCreationHeader != null && "true".equals(implicitIndexCreationHeader);
    }

    private String prepareOutput(ObjectMapper mapper, SearchOperationResult result) throws JsonProcessingException {
        StringBuffer output = new StringBuffer();
        output.append("{\r\n\"searchResult\":");
        output.append(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getSearchResult()));
        AggregationResults aggs = result.getAggregationResult();
        if (aggs != null) {
            output.append(",\r\n\"aggregationResult\":");
            output.append(mapper.setSerializationInclusion(Include.NON_NULL).writerWithDefaultPrettyPrinter()
                    .writeValueAsString(aggs));
        }
        output.append("\r\n}");
        return output.toString();
    }

    private String prepareSuggestOutput(ObjectMapper mapper, SearchOperationResult result)
            throws JsonProcessingException {
        StringBuffer output = new StringBuffer();
        output.append("{\r\n\"searchResult\":");
        output.append(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(result.getSuggestResult()));
        AggregationResults aggs = result.getAggregationResult();
        if (aggs != null) {
            output.append(",\r\n\"aggregationResult\":");
            output.append(mapper.setSerializationInclusion(Include.NON_NULL).writerWithDefaultPrettyPrinter()
                    .writeValueAsString(aggs));
        }
        output.append("\r\n}");
        return output.toString();
    }

    private ResponseEntity<String> handleError(HttpServletRequest request, String message, HttpStatus status) {
        logResult(request, status);
        return ResponseEntity.status(status).contentType(MediaType.APPLICATION_JSON).body(message);
    }

    void logResult(HttpServletRequest request, HttpStatus status) {

        logger.info(SearchDbMsgs.PROCESS_REST_REQUEST, (request != null) ? request.getMethod() : "",
                (request != null) ? request.getRequestURL().toString() : "",
                (request != null) ? request.getRemoteHost() : "", Integer.toString(status.value()));

        auditLogger.info(SearchDbMsgs.PROCESS_REST_REQUEST,
                new LogFields().setField(LogLine.DefinedFields.RESPONSE_CODE, status.value())
                        .setField(LogLine.DefinedFields.RESPONSE_DESCRIPTION, status.getReasonPhrase()),
                (request != null) ? request.getMethod() : "",
                (request != null) ? request.getRequestURL().toString() : "",
                (request != null) ? request.getRemoteHost() : "", Integer.toString(status.value()));

        // Clear the MDC context so that no other transaction inadvertently uses our transaction id.
        ApiUtils.clearMdcContext();
    }
}