package com.nimbusds.oauth2.sdk;


import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import net.jcip.annotations.Immutable;

import org.apache.commons.lang3.StringUtils;

import net.minidev.json.JSONObject;

import com.nimbusds.oauth2.sdk.http.CommonContentTypes;
import com.nimbusds.oauth2.sdk.http.HTTPResponse;
import com.nimbusds.oauth2.sdk.util.JSONObjectUtils;


/**
 * OAuth 2.0 Token error response.
 *
 * <p>Standard token errors:
 *
 * <ul>
 *     <li>{@link OAuth2Error#INVALID_REQUEST}
 *     <li>{@link OAuth2Error#INVALID_CLIENT}
 *     <li>{@link OAuth2Error#INVALID_GRANT}
 *     <li>{@link OAuth2Error#UNAUTHORIZED_CLIENT}
 *     <li>{@link OAuth2Error#UNSUPPORTED_GRANT_TYPE}
 *     <li>{@link OAuth2Error#INVALID_SCOPE}
 * </ul>
 *
 * <p>Example HTTP response:
 *
 * <pre>
 * HTTP/1.1 400 Bad Request
 * Content-Type: application/json
 * Cache-Control: no-store
 * Pragma: no-cache
 * 
 * {
 *  "error": "invalid_request"
 * }
 * </pre>
 *
 * <p>Related specifications:
 *
 * <ul>
 *     <li>OAuth 2.0 (RFC 6749), section 5.2.
 * </ul>
 */
@Immutable
public class TokenErrorResponse 
        extends TokenResponse
        implements ErrorResponse {


        /**
         * The standard OAuth 2.0 errors for an Access Token error response.
         */
        private static final Set<ErrorObject> stdErrors = new HashSet<>();
        
        
        static {
                stdErrors.add(OAuth2Error.INVALID_REQUEST);
                stdErrors.add(OAuth2Error.INVALID_CLIENT);
                stdErrors.add(OAuth2Error.INVALID_GRANT);
                stdErrors.add(OAuth2Error.UNAUTHORIZED_CLIENT);
                stdErrors.add(OAuth2Error.UNSUPPORTED_GRANT_TYPE);
                stdErrors.add(OAuth2Error.INVALID_SCOPE);
        }
        
        
        /**
         * Gets the standard OAuth 2.0 errors for an Access Token error 
         * response.
         *
         * @return The standard errors, as a read-only set.
         */
        public static Set<ErrorObject> getStandardErrors() {
        
                return Collections.unmodifiableSet(stdErrors);
        }
        
        
        /**
         * The error.
         */
        private final ErrorObject error;


        /**
         * Creates a new OAuth 2.0 Access Token error response. No OAuth 2.0 
         * error is specified.
         */
        protected TokenErrorResponse() {

                error = null;
        }
        
        
        /**
         * Creates a new OAuth 2.0 Access Token error response.
         *
         * @param error The error. Should match one of the 
         *              {@link #getStandardErrors standard errors} for a token 
         *              error response. Must not be {@code null}.
         */
        public TokenErrorResponse(final ErrorObject error) {
        
                if (error == null)
                        throw new IllegalArgumentException("The error must not be null");
                        
                this.error = error;
        }
        

        @Override
        public ErrorObject getErrorObject() {
        
                return error;
        }
        
        
        /**
         * Returns the JSON object for this token error response.
         *
         * @return The JSON object for this token error response.
         */
        public JSONObject toJSONObject() {
        
                JSONObject o = new JSONObject();

                // No error?
                if (error == null)
                        return o;

                o.put("error", error.getCode());

                if (error.getDescription() != null)
                        o.put("error_description", error.getDescription());
                
                if (error.getURI() != null)
                        o.put("error_uri", error.getURI().toString());
                
                return o;
        }
        
        
        @Override
        public HTTPResponse toHTTPResponse() {

                int statusCode = (error != null && error.getHTTPStatusCode() > 0) ?
                        error.getHTTPStatusCode() : HTTPResponse.SC_BAD_REQUEST;

                HTTPResponse httpResponse = new HTTPResponse(statusCode);

                if (error == null)
                        return httpResponse;
                
                httpResponse.setContentType(CommonContentTypes.APPLICATION_JSON);
                httpResponse.setCacheControl("no-store");
                httpResponse.setPragma("no-cache");
                
                httpResponse.setContent(toJSONObject().toString());
                
                return httpResponse;
        }


        /**
         * Parses an OAuth 2.0 Token Error response from the specified JSON
         * object.
         *
         * @param jsonObject The JSON object to parse. Its status code must not
         *                   be 200 (OK). Must not be {@code null}.
         *
         * @throws ParseException If the JSON object couldn't be parsed to an 
         *                        OAuth 2.0 Token Error response.
         */
        public static TokenErrorResponse parse(final JSONObject jsonObject)
                throws ParseException {

                // No error code?
                if (! jsonObject.containsKey("error"))
                        return new TokenErrorResponse();
                
                ErrorObject error;
                
                try {
                        // Parse code
                        String code = JSONObjectUtils.getString(jsonObject, "error");

                        // Parse description
                        String description = null;

                        if (jsonObject.containsKey("error_description"))
                                description = JSONObjectUtils.getString(jsonObject, "error_description");

                        // Parse URI
                        URI uri = null;

                        if (jsonObject.containsKey("error_uri"))
                                uri = new URI(JSONObjectUtils.getString(jsonObject, "error_uri"));


                        error = new ErrorObject(code, description, HTTPResponse.SC_BAD_REQUEST, uri);
                        
                } catch (ParseException e) {
                
                        throw new ParseException("Missing or invalid token error response parameter: " + e.getMessage(), e);
                        
                } catch (URISyntaxException e) {
                
                        throw new ParseException("Invalid error URI: " + e.getMessage(), e);
                }
                
                return new TokenErrorResponse(error);
        }
        
        
        /**
         * Parses an OAuth 2.0 Token Error response from the specified HTTP
         * response.
         *
         * @param httpResponse The HTTP response to parse. Its status code must
         *                     not be 200 (OK). Must not be {@code null}.
         *
         * @throws ParseException If the HTTP response couldn't be parsed to an 
         *                        OAuth 2.0 Token Error response.
         */
        public static TokenErrorResponse parse(final HTTPResponse httpResponse)
                throws ParseException {
                
                httpResponse.ensureStatusCodeNotOK();

                if (StringUtils.isNotEmpty(httpResponse.getContent()) &&
                    CommonContentTypes.APPLICATION_JSON.match(httpResponse.getContentType())) {

                        JSONObject jsonObject = httpResponse.getContentAsJSONObject();

                        return parse(jsonObject);
                }

                return new TokenErrorResponse();
        }
}