/*
 * Copyright 2007 Netflix, Inc.
 *
 * 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.
 */

package net.oauth;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author John Kristian
 * @hide
 */
public class OAuth {

    public static final String VERSION_1_0 = "1.0";

    /** The encoding used to represent characters as bytes. */
    public static final String ENCODING = "UTF-8";

    /** The MIME type for a sequence of OAuth parameters. */
    public static final String FORM_ENCODED = "application/x-www-form-urlencoded";

    public static final String OAUTH_CONSUMER_KEY = "oauth_consumer_key";
    public static final String OAUTH_TOKEN = "oauth_token";
    public static final String OAUTH_TOKEN_SECRET = "oauth_token_secret";
    public static final String OAUTH_SIGNATURE_METHOD = "oauth_signature_method";
    public static final String OAUTH_SIGNATURE = "oauth_signature";
    public static final String OAUTH_TIMESTAMP = "oauth_timestamp";
    public static final String OAUTH_NONCE = "oauth_nonce";
    public static final String OAUTH_VERSION = "oauth_version";

    public static final String HMAC_SHA1 = "HMAC-SHA1";
    public static final String RSA_SHA1 = "RSA-SHA1";

    public static class Problems {
        public static final String TOKEN_NOT_AUTHORIZED = "token_not_authorized";
        public static final String INVALID_USED_NONCE = "invalid_used_nonce";
        public static final String SIGNATURE_INVALID = "signature_invalid";
        public static final String INVALID_EXPIRED_TOKEN = "invalid_expired_token";
        public static final String INVALID_CONSUMER_KEY = "invalid_consumer_key";
        public static final String CONSUMER_KEY_REFUSED = "consumer_key_refused";
        public static final String TIMESTAMP_REFUSED = "timestamp_refused";
        public static final String PARAMETER_REJECTED = "parameter_rejected";
        public static final String PARAMETER_ABSENT = "parameter_absent";
        public static final String VERSION_REJECTED = "version_rejected";
        public static final String SIGNATURE_METHOD_REJECTED = "signature_method_rejected";
        
        public static final String OAUTH_PARAMETERS_ABSENT = "oauth_parameters_absent";
        public static final String OAUTH_PARAMETERS_REJECTED = "oauth_parameters_rejected";
        public static final String OAUTH_ACCEPTABLE_TIMESTAMPS = "oauth_acceptable_timestamps";
        public static final String OAUTH_ACCEPTABLE_VERSIONS = "oauth_acceptable_versions";
    }
    
    /** Return true if the given Content-Type header means FORM_ENCODED. */
    public static boolean isFormEncoded(String contentType) {
        if (contentType == null) {
            return false;
        }
        int semi = contentType.indexOf(";");
        if (semi >= 0) {
            contentType = contentType.substring(0, semi);
        }
        return FORM_ENCODED.equalsIgnoreCase(contentType.trim());
    }

    /**
     * Construct a form-urlencoded document containing the given sequence of
     * name/value pairs. Use OAuth percent encoding (not exactly the encoding
     * mandated by HTTP).
     */
    public static String formEncode(Iterable<? extends Map.Entry> parameters)
            throws IOException {
        ByteArrayOutputStream b = new ByteArrayOutputStream();
        formEncode(parameters, b);
        return new String(b.toByteArray());
    }

    /**
     * Write a form-urlencoded document into the given stream, containing the
     * given sequence of name/value pairs.
     */
    public static void formEncode(Iterable<? extends Map.Entry> parameters,
            OutputStream into) throws IOException {
        if (parameters != null) {
            boolean first = true;
            for (Map.Entry parameter : parameters) {
                if (first) {
                    first = false;
                } else {
                    into.write('&');
                }
                into.write(percentEncode(toString(parameter.getKey()))
                        .getBytes());
                into.write('=');
                into.write(percentEncode(toString(parameter.getValue()))
                        .getBytes());
            }
        }
    }

    /** Parse a form-urlencoded document. */
    public static List<Parameter> decodeForm(String form) {
        List<Parameter> list = new ArrayList<Parameter>();
        if (!isEmpty(form)) {
            for (String nvp : form.split("\\&")) {
                int equals = nvp.indexOf('=');
                String name;
                String value;
                if (equals < 0) {
                    name = decodePercent(nvp);
                    value = null;
                } else {
                    name = decodePercent(nvp.substring(0, equals));
                    value = decodePercent(nvp.substring(equals + 1));
                }
                list.add(new Parameter(name, value));
            }
        }
        return list;
    }

    /** Construct a &-separated list of the given values, percentEncoded. */
    public static String percentEncode(Iterable values) {
        StringBuilder p = new StringBuilder();
        for (Object v : values) {
            if (p.length() > 0) {
                p.append("&");
            }
            p.append(OAuth.percentEncode(toString(v)));
        }
        return p.toString();
    }

    public static String percentEncode(String s) {
        if (s == null) {
            return "";
        }
        try {
            return URLEncoder.encode(s, ENCODING)
                    // OAuth encodes some characters differently:
                    .replace("+", "%20").replace("*", "%2A")
                    .replace("%7E", "~");
            // This could be done faster with more hand-crafted code.
        } catch (UnsupportedEncodingException wow) {
            throw new RuntimeException(wow.getMessage(), wow);
        }
    }

    public static String decodePercent(String s) {
        try {
            return URLDecoder.decode(s, ENCODING);
            // This implements http://oauth.pbwiki.com/FlexibleDecoding
        } catch (java.io.UnsupportedEncodingException wow) {
            throw new RuntimeException(wow.getMessage(), wow);
        }
    }

    /**
     * Construct a Map containing a copy of the given parameters. If several
     * parameters have the same name, the Map will contain the first value,
     * only.
     */
    public static Map<String, String> newMap(Iterable<? extends Map.Entry> from) {
        Map<String, String> map = new HashMap<String, String>();
        if (from != null) {
            for (Map.Entry f : from) {
                String key = toString(f.getKey());
                if (!map.containsKey(key)) {
                    map.put(key, toString(f.getValue()));
                }
            }
        }
        return map;
    }

    /** Construct a list of Parameters from name, value, name, value... */
    public static List<Parameter> newList(String... parameters) {
        List<Parameter> list = new ArrayList<Parameter>(parameters.length / 2);
        for (int p = 0; p + 1 < parameters.length; p += 2) {
            list.add(new Parameter(parameters[p], parameters[p + 1]));
        }
        return list;
    }

    /** A name/value pair. */
    public static class Parameter implements Map.Entry<String, String> {

        public Parameter(String key, String value) {
            this.key = key;
            this.value = value;
        }

        private final String key;

        private String value;

        public String getKey() {
            return key;
        }

        public String getValue() {
            return value;
        }

        public String setValue(String value) {
            try {
                return this.value;
            } finally {
                this.value = value;
            }
        }

        @Override
        public String toString() {
            return percentEncode(getKey()) + '=' + percentEncode(getValue());
        }

        @Override
        public int hashCode()
        {
            final int prime = 31;
            int result = 1;
            result = prime * result + ((key == null) ? 0 : key.hashCode());
            result = prime * result + ((value == null) ? 0 : value.hashCode());
            return result;
        }

        @Override
        public boolean equals(Object obj)
        {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            final Parameter that = (Parameter) obj;
            if (key == null) {
                if (that.key != null)
                    return false;
            } else if (!key.equals(that.key))
                return false;
            if (value == null) {
                if (that.value != null)
                    return false;
            } else if (!value.equals(that.value))
                return false;
            return true;
        }
    }

    private static final String toString(Object from) {
        return (from == null) ? null : from.toString();
    }

    /**
     * Construct a URL like the given one, but with the given parameters added
     * to its query string.
     */
    public static String addParameters(String url, String... parameters)
            throws IOException {
        return addParameters(url, newList(parameters));
    }

    public static String addParameters(String url,
            Iterable<? extends Map.Entry<String, String>> parameters)
            throws IOException {
        String form = formEncode(parameters);
        if (form == null || form.length() <= 0) {
            return url;
        } else {
            return url + ((url.indexOf("?") < 0) ? '?' : '&') + form;
        }
    }

    public static boolean isEmpty(String str) {
	return (str == null) || (str.length() == 0);
    }
}