package ca.uhn.fhir.rest.api.server;

import ca.uhn.fhir.context.FhirContext;
import ca.uhn.fhir.interceptor.api.HookParams;
import ca.uhn.fhir.interceptor.api.IInterceptorBroadcaster;
import ca.uhn.fhir.interceptor.api.Pointcut;
import ca.uhn.fhir.rest.api.Constants;
import ca.uhn.fhir.rest.api.RequestTypeEnum;
import ca.uhn.fhir.rest.api.RestOperationTypeEnum;
import ca.uhn.fhir.rest.server.IRestfulServerDefaults;
import ca.uhn.fhir.rest.server.interceptor.IServerInterceptor;
import ca.uhn.fhir.util.StopWatch;
import ca.uhn.fhir.util.UrlUtil;
import org.apache.commons.lang3.Validate;
import org.hl7.fhir.instance.model.api.IBaseResource;
import org.hl7.fhir.instance.model.api.IIdType;

import javax.annotation.Nonnull;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.*;
import java.util.stream.Collectors;

import static org.apache.commons.lang3.StringUtils.isBlank;

/*
 * #%L
 * HAPI FHIR - Server Framework
 * %%
 * Copyright (C) 2014 - 2019 University Health Network
 * %%
 * 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.
 * #L%
 */

public abstract class RequestDetails {

        private final StopWatch myRequestStopwatch = new StopWatch();
        private IInterceptorBroadcaster myInterceptorBroadcaster;
        private String myTenantId;
        private String myCompartmentName;
        private String myCompleteUrl;
        private String myFhirServerBase;
        private IIdType myId;
        private String myOperation;
        private Map<String, String[]> myParameters;
        private byte[] myRequestContents;
        private DeferredOperationCallback myDeferredInterceptorBroadcaster;
        private String myRequestPath;
        private RequestTypeEnum myRequestType;
        private String myResourceName;
        private boolean myRespondGzip;
        private IRestfulResponse myResponse;
        private RestOperationTypeEnum myRestOperationType;
        private String mySecondaryOperation;
        private boolean mySubRequest;
        private Map<String, List<String>> myUnqualifiedToQualifiedNames;
        private Map<Object, Object> myUserData;
        private IBaseResource myResource;
        private String myRequestId;
        private String myFixedConditionalUrl;

        /**
         * Constructor
         */
        public RequestDetails(IInterceptorBroadcaster theInterceptorBroadcaster) {
                myInterceptorBroadcaster = theInterceptorBroadcaster;
        }

        public String getFixedConditionalUrl() {
                return myFixedConditionalUrl;
        }

        public void setFixedConditionalUrl(String theFixedConditionalUrl) {
                myFixedConditionalUrl = theFixedConditionalUrl;
        }

        public String getRequestId() {
                return myRequestId;
        }

        public void setRequestId(String theRequestId) {
                myRequestId = theRequestId;
        }

        public StopWatch getRequestStopwatch() {
                return myRequestStopwatch;
        }

        /**
         * Returns the request resource (as provided in the request body) if it has been parsed.
         * Note that this value is only set fairly late in the processing pipeline, so it
         * may not always be set, even for operations that take a resource as input.
         *
         * @since 4.0.0
         */
        public IBaseResource getResource() {
                return myResource;
        }

        /**
         * Sets the request resource (as provided in the request body) if it has been parsed.
         * Note that this value is only set fairly late in the processing pipeline, so it
         * may not always be set, even for operations that take a resource as input.
         *
         * @since 4.0.0
         */
        public void setResource(IBaseResource theResource) {
                myResource = theResource;
        }

        public void addParameter(String theName, String[] theValues) {
                getParameters();
                myParameters.put(theName, theValues);
        }

        protected abstract byte[] getByteStreamRequestContents();

        /**
         * Return the charset as defined by the header contenttype. Return null if it is not set.
         */
        public abstract Charset getCharset();

        public String getCompartmentName() {
                return myCompartmentName;
        }

        public void setCompartmentName(String theCompartmentName) {
                myCompartmentName = theCompartmentName;
        }

        public String getCompleteUrl() {
                return myCompleteUrl;
        }

        public void setCompleteUrl(String theCompleteUrl) {
                myCompleteUrl = theCompleteUrl;
        }

        /**
         * Returns the <b>conditional URL</b> if this request has one, or <code>null</code> otherwise. For an
         * update or delete method, this is the part of the URL after the <code>?</code>. For a create, this
         * is the value of the <code>If-None-Exist</code> header.
         *
         * @param theOperationType The operation type to find the conditional URL for
         * @return Returns the <b>conditional URL</b> if this request has one, or <code>null</code> otherwise
         */
        public String getConditionalUrl(RestOperationTypeEnum theOperationType) {
                if (myFixedConditionalUrl != null) {
                        return myFixedConditionalUrl;
                }
                switch (theOperationType) {
                        case CREATE:
                                String retVal = this.getHeader(Constants.HEADER_IF_NONE_EXIST);
                                if (isBlank(retVal)) {
                                        return null;
                                }
                                if (retVal.startsWith(this.getFhirServerBase())) {
                                        retVal = retVal.substring(this.getFhirServerBase().length());
                                }
                                return retVal;
                        case DELETE:
                        case UPDATE:
                        case PATCH:
                                if (this.getId() != null && this.getId().hasIdPart()) {
                                        return null;
                                }

                                int questionMarkIndex = this.getCompleteUrl().indexOf('?');
                                if (questionMarkIndex == -1) {
                                        return null;
                                }

                                return this.getResourceName() + this.getCompleteUrl().substring(questionMarkIndex);
                        default:
                                return null;
                }
        }

        /**
         * Returns the HAPI FHIR Context associated with this request
         */
        public abstract FhirContext getFhirContext();

        /**
         * The fhir server base url, independant of the query being executed
         *
         * @return the fhir server base url
         */
        public String getFhirServerBase() {
                return myFhirServerBase;
        }

        public void setFhirServerBase(String theFhirServerBase) {
                myFhirServerBase = theFhirServerBase;
        }

        public abstract String getHeader(String name);

        public abstract List<String> getHeaders(String name);

        public IIdType getId() {
                return myId;
        }

        public void setId(IIdType theId) {
                myId = theId;
        }

        /**
         * Returns the attribute map for this request. Attributes are a place for user-supplied
         * objects of any type to be attached to an individual request. They can be used to pass information
         * between interceptor methods.
         */
        public abstract Object getAttribute(String theAttributeName);

        /**
         * Returns the attribute map for this request. Attributes are a place for user-supplied
         * objects of any type to be attached to an individual request. They can be used to pass information
         * between interceptor methods.
         */
        public abstract void setAttribute(String theAttributeName, Object theAttributeValue);

        /**
         * Retrieves the body of the request as binary data. Either this method or {@link #getReader} may be called to read
         * the body, not both.
         *
         * @return a {@link InputStream} object containing the body of the request
         * @throws IllegalStateException if the {@link #getReader} method has already been called for this request
         * @throws IOException           if an input or output exception occurred
         */
        public abstract InputStream getInputStream() throws IOException;

        public String getOperation() {
                return myOperation;
        }

        public void setOperation(String theOperation) {
                myOperation = theOperation;
        }

        public Map<String, String[]> getParameters() {
                if (myParameters == null) {
                        myParameters = new HashMap<>();
                }
                return Collections.unmodifiableMap(myParameters);
        }

        public void setParameters(Map<String, String[]> theParams) {
                myParameters = theParams;
                myUnqualifiedToQualifiedNames = null;

                // Sanitize keys if necessary to prevent injection attacks
                boolean needsSanitization = false;
                for (String nextKey : theParams.keySet()) {
                        if (UrlUtil.isNeedsSanitization(nextKey)) {
                                needsSanitization = true;
                                break;
                        }
                }
                if (needsSanitization) {
                        myParameters = myParameters
                                .entrySet()
                                .stream()
                                .collect(Collectors.toMap(t -> UrlUtil.sanitizeUrlPart((String) ((Map.Entry) t).getKey()), t -> (String[]) ((Map.Entry) t).getValue()));
                }
        }

        /**
         * Retrieves the body of the request as character data using a <code>BufferedReader</code>. The reader translates the
         * character data according to the character encoding used on the body. Either this method or {@link #getInputStream}
         * may be called to read the body, not both.
         *
         * @return a <code>Reader</code> containing the body of the request
         * @throws UnsupportedEncodingException if the character set encoding used is not supported and the text cannot be decoded
         * @throws IllegalStateException        if {@link #getInputStream} method has been called on this request
         * @throws IOException                  if an input or output exception occurred
         * @see javax.servlet.http.HttpServletRequest#getInputStream
         */
        public abstract Reader getReader() throws IOException;

        /**
         * Returns an invoker that can be called from user code to advise the server interceptors
         * of any nested operations being invoked within operations. This invoker acts as a proxy for
         * all interceptors
         */
        public IInterceptorBroadcaster getInterceptorBroadcaster() {
                if (myDeferredInterceptorBroadcaster != null) {
                        return myDeferredInterceptorBroadcaster;
                }
                return myInterceptorBroadcaster;
        }

        /**
         * The part of the request URL that comes after the server base.
         * <p>
         * Will not contain a leading '/'
         * </p>
         */
        public String getRequestPath() {
                return myRequestPath;
        }

        public void setRequestPath(String theRequestPath) {
                assert theRequestPath.length() == 0 || theRequestPath.charAt(0) != '/';
                myRequestPath = theRequestPath;
        }

        public RequestTypeEnum getRequestType() {
                return myRequestType;
        }

        public void setRequestType(RequestTypeEnum theRequestType) {
                myRequestType = theRequestType;
        }

        public String getResourceName() {
                return myResourceName;
        }

        public void setResourceName(String theResourceName) {
                myResourceName = theResourceName;
        }

        public IRestfulResponse getResponse() {
                return myResponse;
        }

        public void setResponse(IRestfulResponse theResponse) {
                this.myResponse = theResponse;
        }

        public RestOperationTypeEnum getRestOperationType() {
                return myRestOperationType;
        }

        public void setRestOperationType(RestOperationTypeEnum theRestOperationType) {
                myRestOperationType = theRestOperationType;
        }

        public String getSecondaryOperation() {
                return mySecondaryOperation;
        }

        public void setSecondaryOperation(String theSecondaryOperation) {
                mySecondaryOperation = theSecondaryOperation;
        }

        public abstract IRestfulServerDefaults getServer();

        /**
         * Returns the server base URL (with no trailing '/') for a given request
         */
        public abstract String getServerBaseForRequest();

        public String getTenantId() {
                return myTenantId;
        }

        public void setTenantId(String theTenantId) {
                myTenantId = theTenantId;
        }

        public Map<String, List<String>> getUnqualifiedToQualifiedNames() {
                if (myUnqualifiedToQualifiedNames == null) {
                        for (String next : myParameters.keySet()) {
                                for (int i = 0; i < next.length(); i++) {
                                        char nextChar = next.charAt(i);
                                        if (nextChar == ':' || nextChar == '.') {
                                                if (myUnqualifiedToQualifiedNames == null) {
                                                        myUnqualifiedToQualifiedNames = new HashMap<>();
                                                }
                                                String unqualified = next.substring(0, i);
                                                List<String> list = myUnqualifiedToQualifiedNames.get(unqualified);
                                                if (list == null) {
                                                        list = new ArrayList<>(4);
                                                        myUnqualifiedToQualifiedNames.put(unqualified, list);
                                                }
                                                list.add(next);
                                                break;
                                        }
                                }
                        }
                }

                if (myUnqualifiedToQualifiedNames == null) {
                        myUnqualifiedToQualifiedNames = Collections.emptyMap();
                }

                return myUnqualifiedToQualifiedNames;
        }

        /**
         * Returns a map which can be used to hold any user specific data to pass it from one
         * part of the request handling chain to another. Data in this map can use any key, although
         * user code should try to use keys which are specific enough to avoid conflicts.
         * <p>
         * A new map is created for each individual request that is handled by the server,
         * so this map can be used (for example) to pass authorization details from an interceptor
         * to the resource providers, or from an interceptor's {@link IServerInterceptor#incomingRequestPreHandled(RestOperationTypeEnum, ca.uhn.fhir.rest.server.interceptor.IServerInterceptor.ActionRequestDetails)}
         * method to the {@link IServerInterceptor#outgoingResponse(RequestDetails, org.hl7.fhir.instance.model.api.IBaseResource, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)}
         * method.
         * </p>
         */
        public Map<Object, Object> getUserData() {
                if (myUserData == null) {
                        myUserData = new HashMap<>();
                }
                return myUserData;
        }

        public boolean isRespondGzip() {
                return myRespondGzip;
        }

        public void setRespondGzip(boolean theRespondGzip) {
                myRespondGzip = theRespondGzip;
        }

        /**
         * Is this request a sub-request (i.e. a request within a batch or transaction)? This
         * flag is used internally by hapi-fhir-jpaserver-base, but not used in the plain server
         * library. You may use it in your client code as a hint when implementing transaction logic in the plain
         * server.
         * <p>
         * Defaults to {@literal false}
         * </p>
         */
        public boolean isSubRequest() {
                return mySubRequest;
        }

        /**
         * Is this request a sub-request (i.e. a request within a batch or transaction)? This
         * flag is used internally by hapi-fhir-jpaserver-base, but not used in the plain server
         * library. You may use it in your client code as a hint when implementing transaction logic in the plain
         * server.
         * <p>
         * Defaults to {@literal false}
         * </p>
         */
        public void setSubRequest(boolean theSubRequest) {
                mySubRequest = theSubRequest;
        }

        public final byte[] loadRequestContents() {
                if (myRequestContents == null) {
                        myRequestContents = getByteStreamRequestContents();
                }
                return myRequestContents;
        }

        public void removeParameter(String theName) {
                Validate.notNull(theName, "theName must not be null");
                getParameters();
                myParameters.remove(theName);
        }

        /**
         * This method may be used to modify the contents of the incoming
         * request by hardcoding a value which will be used instead of the
         * value received by the client.
         * <p>
         * This method is useful for modifying the request body prior
         * to parsing within interceptors. It generally only has an
         * impact when called in the {@link IServerInterceptor#incomingRequestPostProcessed(RequestDetails, HttpServletRequest, HttpServletResponse)}
         * method
         * </p>
         */
        public void setRequestContents(byte[] theRequestContents) {
                myRequestContents = theRequestContents;
        }

        /**
         * Sets the {@link #getInterceptorBroadcaster()} () interceptor broadcaster} handler in
         * deferred mode, meaning that any notifications will be queued up for delivery, but
         * won't be delivered until {@link #stopDeferredRequestOperationCallbackAndRunDeferredItems()}
         * is called.
         */
        public void startDeferredOperationCallback() {
                myDeferredInterceptorBroadcaster = new DeferredOperationCallback(myInterceptorBroadcaster);
        }

        /**
         * @see #startDeferredOperationCallback()
         */
        public void stopDeferredRequestOperationCallbackAndRunDeferredItems() {
                DeferredOperationCallback deferredCallback = myDeferredInterceptorBroadcaster;
                deferredCallback.playDeferredActions();
                myInterceptorBroadcaster = deferredCallback.getWrap();
                myDeferredInterceptorBroadcaster = null;
        }


        private class DeferredOperationCallback implements IInterceptorBroadcaster {

                private final IInterceptorBroadcaster myWrap;
                private final List<Runnable> myDeferredTasks = new ArrayList<>();

                private DeferredOperationCallback(@Nonnull IInterceptorBroadcaster theWrap) {
                        Validate.notNull(theWrap);
                        myWrap = theWrap;
                }


                void playDeferredActions() {
                        myDeferredTasks.forEach(Runnable::run);
                }

                IInterceptorBroadcaster getWrap() {
                        return myWrap;
                }

                @Override
                public boolean callHooks(Pointcut thePointcut, HookParams theParams) {
                        myDeferredTasks.add(() -> myWrap.callHooks(thePointcut, theParams));
                        return true;
                }

                @Override
                public Object callHooksAndReturnObject(Pointcut thePointcut, HookParams theParams) {
                        myDeferredTasks.add(() -> myWrap.callHooksAndReturnObject(thePointcut, theParams));
                        return null;
                }

                @Override
                public boolean hasHooks(Pointcut thePointcut) {
                        return myWrap.hasHooks(thePointcut);
                }

        }


}