/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

package org.apache.jena.fuseki.servlets;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import org.apache.jena.atlas.io.IndentedWriter;
import org.apache.jena.atlas.json.JSON;
import org.apache.jena.atlas.json.JsonValue;
import org.apache.jena.fuseki.system.UploadDetails;
import org.apache.jena.fuseki.system.UploadDetails.PreState;
import org.apache.jena.riot.RiotParseException;
import org.apache.jena.riot.WebContent;
import org.apache.jena.riot.web.HttpNames;
import org.apache.jena.web.HttpSC;
import org.apache.jena.web.HttpSC.Code;

public class ServletOps {

    public static void responseSendError(HttpServletResponse response, int statusCode, String message) {
        try {
            response.sendError(statusCode, message);
        } catch (IOException ex) {
            errorOccurred(ex);
        } catch (IllegalStateException ex) {}
    }

    public static void responseSendError(HttpServletResponse response, int statusCode) {
        try {
            response.sendError(statusCode);
        } catch (IOException ex) {
            errorOccurred(ex);
        }
    }

    public static void successNoContent(HttpAction action) {
        success(action, HttpSC.NO_CONTENT_204);
    }

    public static void success(HttpAction action) {
        success(action, HttpSC.OK_200);
    }

    public static void successCreated(HttpAction action) {
        success(action, HttpSC.CREATED_201);
    }

    // When 404 is no big deal e.g. HEAD
    public static void successNotFound(HttpAction action) {
        success(action, HttpSC.NOT_FOUND_404);
    }

    //
    public static void success(HttpAction action, int httpStatusCode) {
        action.response.setStatus(httpStatusCode);
    }

    public static void successPage(HttpAction action, String message) {
        try {
            action.response.setContentType("text/html");
            action.response.setStatus(HttpSC.OK_200);
            PrintWriter out = action.response.getWriter();
            out.println("<html>");
            out.println("<head>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Success</h1>");
            if ( message != null ) {
                out.println("<p>");
                out.println(message);
                out.println("</p>");
            }
            out.println("</body>");
            out.println("</html>");
            out.flush();
        } catch (IOException ex) {
            errorOccurred(ex);
        }
    }

    public static void warning(HttpAction action, String string) {
        action.log.warn(string);
    }

    public static void warning(HttpAction action, String string, Throwable thorwable) {
        action.log.warn(string, thorwable);
    }

    public static void errorParseError(RiotParseException ex) {
        error(HttpSC.BAD_REQUEST_400, "Parse Error: "+ex.getMessage());
    }

    public static void errorBadRequest(String string) {
        error(HttpSC.BAD_REQUEST_400, string);
    }

    public static void errorNotFound() {    
        errorNotFound(Code.NOT_FOUND.getMessage());
    }

    public static void errorNotFound(String string) {
        error(HttpSC.NOT_FOUND_404, string);
    }

    public static void errorNotImplemented(String msg) {
        error(HttpSC.NOT_IMPLEMENTED_501, msg);
    }

    public static void errorMethodNotAllowed(String method) {
        errorMethodNotAllowed(method, "HTTP method not allowed: " + method);
    }

    public static void errorMethodNotAllowed(String method, String msg) {
        error(HttpSC.METHOD_NOT_ALLOWED_405, msg);
    }

    public static void errorForbidden() {
        error(HttpSC.FORBIDDEN_403, "Forbidden");
    }

    public static void errorForbidden(String msg) {
        if ( msg != null )
            error(HttpSC.FORBIDDEN_403, msg);
        else
            errorForbidden();
    }

    public static void error(int statusCode) {
        throw new ActionErrorException(null, null, statusCode);
    }

    public static void error(int statusCode, String string) {
        throw new ActionErrorException(null, string, statusCode);
    }

    public static void errorOccurred(String message) {
        errorOccurred(message, null);
    }

    public static void errorOccurred(Throwable ex) {
        errorOccurred(null, ex);
    }

    public static void errorOccurred(String message, Throwable ex) {
        throw new ActionErrorException(ex, message, HttpSC.INTERNAL_SERVER_ERROR_500);
    }

    public static String formatForLog(String string) {
        if ( string == null )
            return "<null>";
        string = string.replace('\n', ' ');
        string = string.replace('\r', ' ');
        return string;
    }

    public static void setNoCache(HttpAction action) {
        setNoCache(action.response);
    }

    public static void setNoCache(HttpServletResponse response) {
        response.setHeader(HttpNames.hCacheControl, "must-revalidate,no-cache,no-store");
        response.setHeader(HttpNames.hPragma, "no-cache");
    }

    /** Send a JSON value as a 200 response.  Null object means no response body and no content-type headers. */
    public static void sendJsonReponse(HttpAction action, JsonValue v) {
        if ( v == null ) {
            ServletOps.success(action);
            //ServletOps.successNoContent(action);
            return;
        }

        ServletOps.success(action);
        sendJson(action, v);
    }

    /** Send a JSON value as a 200 response.  Null object means no response body and no content-type headers. */
    public static void sendJson(HttpAction action, JsonValue v) {
        if ( v == null )
            return;

        try {
            HttpServletResponse response = action.response;
            ServletOutputStream out = response.getOutputStream();
            response.setContentType(WebContent.contentTypeJSON);
            response.setCharacterEncoding(WebContent.charsetUTF8);

            IndentedWriter iOut = new IndentedWriter(out);
            JSON.write(iOut, v);
            // Make sure we end with a newline.
            iOut.ensureStartOfLine();
            iOut.flush();
            out.flush();
        } catch (IOException ex) { ServletOps.errorOccurred(ex); }
    }

    /** response to a upload operation of some kind. */
    public static void uploadResponse(HttpAction action, UploadDetails details) {
        if ( details.getExistedBefore().equals(PreState.ABSENT) )
            ServletOps.successCreated(action);
        else
            ServletOps.success(action); // successNoContent if empty body.
        JsonValue v = details.detailsJson();
        ServletOps.sendJson(action, v);
    }
}