package com.nimbusds.oauth2.sdk.token;


import java.util.Map;

import net.jcip.annotations.Immutable;

import net.minidev.json.JSONObject;

import org.apache.commons.lang3.StringUtils;

import com.nimbusds.oauth2.sdk.ParseException;
import com.nimbusds.oauth2.sdk.Scope;
import com.nimbusds.oauth2.sdk.http.HTTPRequest;
import com.nimbusds.oauth2.sdk.util.JSONObjectUtils;


/**
 * Bearer access token.
 *
 * <p>Example bearer access token serialised to JSON:
 *
 * <pre>
 * {
 *   "access_token" : "2YotnFZFEjr1zCsicMWpAA",
 *   "token_type"   : "bearer",
 *   "expires_in"   : 3600,
 *   "scope"        : "read write"
 * }
 * </pre>
 *
 * <p>The above example token serialised to a HTTP Authorization header:
 *
 * <pre>
 * Authorization: Bearer 2YotnFZFEjr1zCsicMWpAA
 * </pre>
 *
 * <p>Related specifications:
 *
 * <ul>
 *     <li>OAuth 2.0 (RFC 6749), sections 1.4 and 5.1.
 *     <li>OAuth 2.0 Bearer Token Usage (RFC 6750).
 * </ul>
 */
@Immutable
public final class BearerAccessToken extends AccessToken {

        
        /**
         * Creates a new minimal bearer access token with a randomly generated 
         * 256-bit (32-byte) value, Base64URL-encoded. The optional lifetime 
         * and scope are left undefined.
         */
        public BearerAccessToken() {
        
                this(32);
        }       


        /**
         * Creates a new minimal bearer access token with a randomly generated 
         * value of the specified byte length, Base64URL-encoded. The optional 
         * lifetime and scope are left undefined.
         *
         * @param byteLength The byte length of the value to generate. Must be
         *                   greater than one.
         */
        public BearerAccessToken(final int byteLength) {
        
                this(byteLength, 0l, null);
        }


        /**
         * Creates a new bearer access token with a randomly generated 256-bit 
         * (32-byte) value, Base64URL-encoded.
         *
         * @param lifetime The lifetime in seconds, 0 if not specified.
         * @param scope    The scope, {@code null} if not specified.
         */
        public BearerAccessToken(final long lifetime, final Scope scope) {
        
                this(32, lifetime, scope);
        }


        /**
         * Creates a new bearer access token with a randomly generated value of 
         * the specified byte length, Base64URL-encoded.
         *
         * @param byteLength The byte length of the value to generate. Must be
         *                   greater than one.
         * @param lifetime   The lifetime in seconds, 0 if not specified.
         * @param scope      The scope, {@code null} if not specified.
         */
        public BearerAccessToken(final int byteLength, final long lifetime, final Scope scope) {
        
                super(AccessTokenType.BEARER, byteLength, lifetime, scope);
        }
        
        
        /**
         * Creates a new minimal bearer access token with the specified value.
         * The optional lifetime and scope are left undefined.
         *
         * @param value The access token value. Must not be {@code null} or
         *              empty string.
         */
        public BearerAccessToken(final String value) {
        
                this(value, 0l, null);
        }
        
        
        /**
         * Creates a new bearer access token with the specified value and 
         * optional lifetime and scope.
         *
         * @param value    The access token value. Must not be {@code null} or
         *                 empty string.
         * @param lifetime The lifetime in seconds, 0 if not specified.
         * @param scope    The scope, {@code null} if not specified.
         */
        public BearerAccessToken(final String value, final long lifetime, final Scope scope) {
        
                super(AccessTokenType.BEARER, value, lifetime, scope);
        }
        
        
        /**
         * Returns the HTTP Authorization header value for this bearer access 
         * token.
         *
         * <p>Example:
         *
         * <pre>
         * Authorization: Bearer eyJhbGciOiJIUzI1NiJ9
         * </pre>
         *
         * @return The HTTP Authorization header.
         */
        @Override
        public String toAuthorizationHeader(){
        
                return "Bearer " + getValue();
        }
        
        
        @Override
        public boolean equals(final Object object) {
        
                return object instanceof BearerAccessToken &&
                       this.toString().equals(object.toString());
        }


        /**
         * Parses a bearer access token from a JSON object access token 
         * response.
         *
         * @param jsonObject The JSON object to parse. Must not be 
         *                   {@code null}.
         *
         * @return The bearer access token.
         *
         * @throws ParseException If the JSON object couldn't be parsed to a
         *                        bearer access token.
         */
        public static BearerAccessToken parse(final JSONObject jsonObject)
                throws ParseException {

                // Parse and verify type
                AccessTokenType tokenType = new AccessTokenType(JSONObjectUtils.getString(jsonObject, "token_type"));
                
                if (! tokenType.equals(AccessTokenType.BEARER))
                        throw new ParseException("Token type must be \"Bearer\"");
                

                // Parse value
                String accessTokenValue = JSONObjectUtils.getString(jsonObject, "access_token");
                

                // Parse lifetime
                long lifetime = 0;
                
                if (jsonObject.containsKey("expires_in")) {

                        // Lifetime can be a JSON number or string

                        if (jsonObject.get("expires_in") instanceof Number) {

                                lifetime = JSONObjectUtils.getLong(jsonObject, "expires_in");
                        }
                        else {
                                String lifetimeStr = JSONObjectUtils.getString(jsonObject, "expires_in");

                                try {
                                        lifetime = new Long(lifetimeStr);

                                } catch (NumberFormatException e) {

                                        throw new ParseException("Invalid \"expires_in\" parameter, must be integer");
                                }
                        }
                }


                // Parse scope
                Scope scope = null;

                if (jsonObject.containsKey("scope"))
                        scope = Scope.parse(JSONObjectUtils.getString(jsonObject, "scope"));


                return new BearerAccessToken(accessTokenValue, lifetime, scope);
        }
        
        
        /**
         * Parses an HTTP Authorization header for a bearer access token.
         *
         * @param header The HTTP Authorization header value to parse. May be
         *               {@code null} if the header is missing, in which case
         *               an exception will be thrown.
         *
         * @return The bearer access token.
         *
         * @throws ParseException If the HTTP Authorization header value 
         *                        couldn't be parsed to a bearer access token.
         */
        public static BearerAccessToken parse(final String header)
                throws ParseException {

                if (StringUtils.isBlank(header))
                        throw new ParseException("Missing HTTP Authorization header", BearerTokenError.MISSING_TOKEN);
        
                String[] parts = header.split("\\s", 2);
        
                if (parts.length != 2)
                        throw new ParseException("Invalid HTTP Authorization header value", BearerTokenError.INVALID_REQUEST);
                
                if (! parts[0].equals("Bearer"))
                        throw new ParseException("Token type must be \"Bearer\"", BearerTokenError.INVALID_REQUEST);
                
                try {
                        return new BearerAccessToken(parts[1]);
                        
                } catch (IllegalArgumentException e) {
                
                        throw new ParseException(e.getMessage(), BearerTokenError.INVALID_REQUEST);
                }
        }
        
        
        /**
         * Parses an HTTP request for a bearer access token.
         * 
         * @param request The HTTP request to parse. Must not be {@code null}.
         * 
         * @return The bearer access token.
         * 
         * @throws ParseException If a bearer access token wasn't found in the
         *                        HTTP request.
         */
        public static BearerAccessToken parse(final HTTPRequest request)
                throws ParseException {

                // See http://tools.ietf.org/html/rfc6750#section-2

                String authzHeader = request.getAuthorization();

                if (authzHeader != null) {

                        return parse(authzHeader);
                }

                // Try alternative token locations, form and query string are
                // parameters are not differentiated here

                Map<String,String> params = request.getQueryParameters();

                String accessTokenValue = params.get("access_token");

                if (StringUtils.isBlank(accessTokenValue))
                        throw new ParseException("Missing access token value", BearerTokenError.MISSING_TOKEN);
                        
                return new BearerAccessToken(accessTokenValue);
        }
}