/* Copyright (c) restSQL Project Contributors. Licensed under MIT. */
package org.restsql.core.impl.serial;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.json.simple.parser.ContentHandler;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import org.restsql.core.ColumnMetaData;
import org.restsql.core.Factory;
import org.restsql.core.HttpRequestAttributes;
import org.restsql.core.InvalidRequestException;
import org.restsql.core.RequestValue;
import org.restsql.core.Request;
import org.restsql.core.RequestDeserializer;
import org.restsql.core.RequestLogger;
import org.restsql.core.SqlResource;
import org.restsql.core.SqlResourceException;
import org.restsql.core.RequestValue.Operator;
import org.restsql.core.Request.Type;
import org.restsql.core.WriteResponse;
/**
* Processes requests represented in a JSON string. It expects a top-level array of objects, as in:
*
* <pre>
* { "actors": [
* { "id": "1000", "first_name": "_Jack", "surname": "Daniels" },
* { "id": "1001", "first_name": "_Jack", "surname": "Smith" }
* ]
* }
* </pre>
*
* With hierarchical resources, these top-level objects could either be parents or children. They are children when the
* request URI points to one parent, using its primary key(s), as in <code>res/HierOneToMany/100</code>. The body
* contains JSON like:
*
* <pre>
* { "movies": [
* { "year": "2011", "title": "ESCAPE FROM TOMORROW", "film_id": "5000" },
* { "year": "2012", "title": "BLOOD PURPLE", "film_id": "5001" }
* ]
* }
* </pre>
*
* If the URI is generic, as in <code>res/HierOneToMany</code>, the top-level objects will be parents, and may contain
* an array of child objects, for example:
*
* <pre>
* { "languages": [
* { "language_id": "100", "langName": "New Esperanto",
* "movies": [
* { "year": "2011", "title": "ESCAPE FROM TOMORROW", "film_id": "5000" },
* { "year": "2012", "title": "BLOOD PURPLE", "film_id": "5001" }
* ]
* },
* { "language_id": "101", "langName": "New Greek",
* "movies": [
* { "year": "2012", "title": "THE DARKENING", "film_id": "5002" },
* { "year": "2012", "title": "THE LIGHTENING", "film_id": "5003" }
* ]
* }
* ]
* }
* </pre>
*
* Each top-level object is sent off as one request to the SQL resource. If there are two-levels, then the second level
* array is parsed in full, and then included in the request with the parent attributes. Note that the framework will
* only operate on children if they are included, not parents and children simultaneously.
*
* @author Mark Sawers
*/
public class JsonRequestDeserializer implements RequestDeserializer {
@Override
public WriteResponse execWrite(HttpRequestAttributes httpAttributes, Type requestType,
List<RequestValue> resIds, SqlResource sqlResource, String requestBody,
RequestLogger requestLogger) throws SqlResourceException {
final Handler handler = new Handler(httpAttributes, requestType, resIds, sqlResource, requestLogger);
try {
final JSONParser parser = new JSONParser();
parser.parse(requestBody, handler);
} catch (final ParseException exception) {
throw new InvalidRequestException("Error parsing request body: " + exception.toString());
}
final SqlResourceException handlerException = handler.getHandlerException();
if (handlerException != null) {
throw handlerException;
}
return handler.getWriteResponse();
}
@Override
public String getSupportedMediaType() {
return "application/json";
}
class Handler implements ContentHandler {
private static final int DEFAULT_CHILDREN_SIZE = 10;
private final int childColumnCount;
private String childrenKey, currentKey;
private List<List<RequestValue>> childrenParams;
private SqlResourceException handlerException;
private final HttpRequestAttributes httpAttributes;
private List<RequestValue> params;
private List<RequestValue> parentAttributes;
private final int parentColumnCount;
private final List<RequestValue> parentRequestResIds;
private ParserState parserState = ParserState.Initial;
private final RequestLogger requestLogger;
private final Request.Type requestType;
private List<RequestValue> resIds;
private final SqlResource sqlResource;
private WriteResponse response;
Handler(final HttpRequestAttributes httpAttributes, final Request.Type requestType,
final List<RequestValue> parentRequestResIds, final SqlResource sqlResource,
final RequestLogger requestLogger) {
this.httpAttributes = httpAttributes;
this.requestType = requestType;
this.parentRequestResIds = parentRequestResIds;
this.sqlResource = sqlResource;
this.requestLogger = requestLogger;
parentColumnCount = sqlResource.getMetaData().getParentReadColumns().size();
if (sqlResource.getMetaData().isHierarchical()) {
childColumnCount = sqlResource.getMetaData().getChildReadColumns().size();
childrenKey = sqlResource.getMetaData().getChild().getTableAlias() + "s";
} else {
childColumnCount = 0;
}
}
@Override
public boolean endArray() throws ParseException, IOException {
switch (parserState) {
case EndLevel1Object:
parserState = ParserState.EndLevel1Array;
break;
case EndLevel2Object:
parserState = ParserState.EndLevel2Array;
break;
default:
throw new ParseException(ParseException.ERROR_UNEXPECTED_EXCEPTION,
"reached endArray() in unexpected parser state: " + parserState);
}
if (parentRequestResIds != null && parserState == ParserState.EndLevel1Array) {
resIds = parentRequestResIds;
executeRequest();
}
return true;
}
/** No-op. */
@Override
public void endJSON() throws ParseException, IOException {
}
/**
* Executes request if parentRequestIds are null and at level 1, otherwise continues to collect level 2 objects.
* If parentRequestIds are not null, this is an operation on children at level 1. The request is executed in
* endArray().
*/
@Override
@SuppressWarnings("fallthrough")
public boolean endObject() throws ParseException, IOException {
switch (parserState) {
case EndLevel2Array:
case AtLevel1Object:
parserState = ParserState.EndLevel1Object;
break;
case AtLevel2Object:
parserState = ParserState.EndLevel2Object;
break;
case EndLevel1Array:
break; // we're done
default:
throw new ParseException(ParseException.ERROR_UNEXPECTED_EXCEPTION,
"reached endObject() in unexpected parser state: " + parserState);
}
// Execute request if at end of level 1 object
if (parentRequestResIds == null && parserState == ParserState.EndLevel1Object) {
if (childrenParams != null) {
// Apply operation to the children
// Parent is only for giving context to child inserts and updates
extractResIdsParamsFromParentAttributes(false); // extract only resIds
} else {
// Apply operation to the parent
if (requestType == Type.UPDATE) {
extractResIdsParamsFromParentAttributes(true); // extract resIds and params
} else { // Type.INSERT or Type.DELETE
resIds = null;
params = parentAttributes;
}
}
executeRequest();
if (childrenParams != null) {
// Clear children for the next parent
childrenParams = null;
}
}
// else ignore
return true;
}
/** No-op. */
@Override
public boolean endObjectEntry() throws ParseException, IOException {
return true;
}
public SqlResourceException getHandlerException() {
return handlerException;
}
public WriteResponse getWriteResponse() {
return response;
}
/** Sets string, number or boolean value to current parameter. */
@Override
public boolean primitive(final Object value) throws ParseException, IOException {
RequestValue pair;
if (value != null) {
pair = new RequestValue(currentKey, value.toString(), Operator.Equals);
} else {
pair = new RequestValue(currentKey, null, Operator.Equals);
}
params.add(pair);
return true;
}
@Override
public boolean startArray() throws ParseException, IOException {
switch (parserState) {
case AtLevel1Name:
parserState = ParserState.AtLevel1Array;
break;
case AtLevel2Name:
parserState = ParserState.AtLevel2Array;
break;
default:
throw new ParseException(ParseException.ERROR_UNEXPECTED_EXCEPTION,
"reached startArray() in unexpected parser state: " + parserState);
}
return true;
}
/** No-op. */
@Override
public void startJSON() throws ParseException, IOException {
}
/**
* Reset currentKey and params. If at parent, set params to parentAttributes. child add the params to the
* childrenParams list.
*/
@Override
@SuppressWarnings("fallthrough")
public boolean startObject() throws ParseException, IOException {
switch (parserState) {
case Initial:
parserState = ParserState.AtLevel1Name;
break;
case EndLevel1Object:
case AtLevel1Array:
parserState = ParserState.AtLevel1Object;
break;
case EndLevel2Object:
case AtLevel2Array:
parserState = ParserState.AtLevel2Object;
break;
default:
throw new ParseException(ParseException.ERROR_UNEXPECTED_EXCEPTION,
"reached startObject() in unexpected parser state: " + parserState);
}
currentKey = null;
if (parserState == ParserState.AtLevel1Object && parentRequestResIds == null) {
params = new ArrayList<RequestValue>(parentColumnCount);
parentAttributes = params;
} else if (parserState == ParserState.AtLevel1Object || parserState == ParserState.AtLevel2Object) {
if (childrenParams == null) {
childrenParams = new ArrayList<List<RequestValue>>(DEFAULT_CHILDREN_SIZE);
}
params = new ArrayList<RequestValue>(childColumnCount);
childrenParams.add(params);
}
return true;
}
/** New object found. Set the current key. */
@Override
public boolean startObjectEntry(final String key) throws ParseException, IOException {
currentKey = key;
if (parserState == ParserState.AtLevel1Object && sqlResource.getMetaData().isHierarchical()
&& key.equals(childrenKey)) {
parserState = ParserState.AtLevel2Name;
}
return true;
}
// Private util methods
private void executeRequest() {
try {
final Request request = Factory.getRequest(httpAttributes, requestType,
sqlResource.getName(), resIds, params, childrenParams, requestLogger);
WriteResponse localResponse = sqlResource.write(request);
if (response == null) {
response = localResponse;
} else {
response.addWriteResponse(localResponse);
}
} catch (final SqlResourceException exception) {
handlerException = exception;
}
}
private void extractResIdsParamsFromParentAttributes(final boolean extractParams) {
resIds = new ArrayList<RequestValue>(sqlResource.getMetaData().getParent().getPrimaryKeys()
.size());
if (extractParams) {
params = new ArrayList<RequestValue>(parentAttributes.size() - resIds.size());
}
for (final RequestValue attrib : parentAttributes) {
for (final ColumnMetaData column : sqlResource.getMetaData().getParent().getPrimaryKeys()) {
if (column.getColumnLabel().equals(attrib.getName())) {
resIds.add(attrib);
} else if (extractParams) {
params.add(attrib);
}
}
}
}
}
static enum ParserState {
AtLevel1Array, AtLevel2Array, AtLevel1Name, AtLevel2Name, AtLevel1Object, AtLevel2Object,
EndLevel2Object, EndLevel2Array, EndLevel1Object, EndLevel1Array, Initial;
}
}