/*
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the "License").  You may not use this file except
 * in compliance with the License.
 * 
 * You can obtain a copy of the license at
 * http://www.opensource.org/licenses/cddl1.php
 * See the License for the specific language governing
 * permissions and limitations under the License.
 */

/*
 * MediaType.java
 *
 * Created on March 22, 2007, 2:35 PM
 *
 */

package javax.ws.rs.core;

import java.util.Collections;
import java.util.Comparator;
import java.util.Map;
import java.util.TreeMap;
import javax.ws.rs.ext.RuntimeDelegate;
import javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate;

/**
 * An abstraction for a media type. Instances are immutable.
 * @see <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7">HTTP/1.1 section 3.7</a>
 */
public class MediaType {
    
    private String type;
    private String subtype;
    private Map<String, String> parameters;

    /**
     * Empty immutable map used for all instances without parameters
     */
    private static final Map<String, String> emptyMap = Collections.emptyMap();
    
    private static final HeaderDelegate<MediaType> delegate = 
            RuntimeDelegate.getInstance().createHeaderDelegate(MediaType.class);

    /** The value of a type or subtype wildcard: "*" */
    public static final String MEDIA_TYPE_WILDCARD = "*";
    
    // Common media type constants
    /** "*&#47;*" */
    public final static String WILDCARD = "*/*";
    /** "*&#47;*" */
    public final static MediaType WILDCARD_TYPE = new MediaType();
    
    /** "application/xml" */
    public final static String APPLICATION_XML = "application/xml";
    /** "application/xml" */
    public final static MediaType APPLICATION_XML_TYPE = new MediaType("application","xml");
    
    /** "application/atom+xml" */
    public final static String APPLICATION_ATOM_XML = "application/atom+xml";
    /** "application/atom+xml" */
    public final static MediaType APPLICATION_ATOM_XML_TYPE = new MediaType("application","atom+xml");
    
    /** "application/xhtml+xml" */
    public final static String APPLICATION_XHTML_XML = "application/xhtml+xml";
    /** "application/xhtml+xml" */
    public final static MediaType APPLICATION_XHTML_XML_TYPE = new MediaType("application","xhtml+xml");
    
    /** "application/svg+xml" */
    public final static String APPLICATION_SVG_XML = "application/svg+xml";
    /** "application/svg+xml" */
    public final static MediaType APPLICATION_SVG_XML_TYPE = new MediaType("application","svg+xml");
    
    /** "application/json" */
    public final static String APPLICATION_JSON = "application/json";
    /** "application/json" */
    public final static MediaType APPLICATION_JSON_TYPE = new MediaType("application","json");

    /** "application/x-www-form-urlencoded" */
    public final static String APPLICATION_FORM_URLENCODED = "application/x-www-form-urlencoded";
    /** "application/x-www-form-urlencoded" */
    public final static MediaType APPLICATION_FORM_URLENCODED_TYPE = new MediaType("application","x-www-form-urlencoded");

    /** "multipart/form-data" */
    public final static String MULTIPART_FORM_DATA = "multipart/form-data";
    /** "multipart/form-data" */
    public final static MediaType MULTIPART_FORM_DATA_TYPE = new MediaType("multipart","form-data");

    /** "application/octet-stream" */
    public final static String APPLICATION_OCTET_STREAM = "application/octet-stream";
    /** "application/octet-stream" */
    public final static MediaType APPLICATION_OCTET_STREAM_TYPE = new MediaType("application","octet-stream");

    /** "text/plain" */
    public final static String TEXT_PLAIN = "text/plain";
    /** "text/plain" */
    public final static MediaType TEXT_PLAIN_TYPE = new MediaType("text","plain");

    /** "text/xml" */
    public final static String TEXT_XML = "text/xml";
    /** "text/xml" */
    public final static MediaType TEXT_XML_TYPE = new MediaType("text","xml");

    /** "text/html" */
    public final static String TEXT_HTML = "text/html";
    /** "text/html" */
    public final static MediaType TEXT_HTML_TYPE = new MediaType("text","html");

    /**
     * Creates a new instance of MediaType by parsing the supplied string.
     * @param type the media type string
     * @return the newly created MediaType
     * @throws IllegalArgumentException if the supplied string cannot be parsed
     * or is null
     */
    public static MediaType valueOf(String type) throws IllegalArgumentException {
        return delegate.fromString(type);
    }

    /**
     * Creates a new instance of MediaType with the supplied type, subtype and
     * parameters. 
     * @param type the primary type, null is equivalent to 
     * {@link #MEDIA_TYPE_WILDCARD}.
     * @param subtype the subtype, null is equivalent to 
     * {@link #MEDIA_TYPE_WILDCARD}.
     * @param parameters a map of media type parameters, null is the same as an
     * empty map.
     */
    public MediaType(String type, String subtype, Map<String, String> parameters) {
        this.type = type==null ? MEDIA_TYPE_WILDCARD : type;
        this.subtype = subtype==null ? MEDIA_TYPE_WILDCARD : subtype;
        if (parameters==null) {
            this.parameters = emptyMap;
        } else {
            Map<String, String> map = new TreeMap<String, String>(new Comparator<String>() {
                public int compare(String o1, String o2) {
                    return o1.compareToIgnoreCase(o2);
                }        
            });
            for (Map.Entry<String, String> e: parameters.entrySet()) {
                map.put(e.getKey().toLowerCase(), e.getValue());
            }
            this.parameters = Collections.unmodifiableMap(map);
        }
    }
    
    /**
     * Creates a new instance of MediaType with the supplied type and subtype.
     * @param type the primary type, null is equivalent to 
     * {@link #MEDIA_TYPE_WILDCARD}
     * @param subtype the subtype, null is equivalent to 
     * {@link #MEDIA_TYPE_WILDCARD}
     */
    public MediaType(String type, String subtype) {
        this(type,subtype,emptyMap);
    }

    /**
     * Creates a new instance of MediaType, both type and subtype are wildcards.
     * Consider using the constant {@link #WILDCARD_TYPE} instead.
     */
    public MediaType() {
        this(MEDIA_TYPE_WILDCARD, MEDIA_TYPE_WILDCARD);
    }

    /**
     * Getter for primary type.
     * @return value of primary type.
     */
    public String getType() {
        return this.type;
    }
    
    /**
     * Checks if the primary type is a wildcard.
     * @return true if the primary type is a wildcard
     */
    public boolean isWildcardType() {
        return this.getType().equals(MEDIA_TYPE_WILDCARD);
    }
    
    /**
     * Getter for subtype.
     * @return value of subtype.
     */
    public String getSubtype() {
        return this.subtype;
    }

    /**
     * Checks if the subtype is a wildcard
     * @return true if the subtype is a wildcard  
     */
    public boolean isWildcardSubtype() {
        return this.getSubtype().equals(MEDIA_TYPE_WILDCARD);
    }
    
    /**
     * Getter for a read-only parameter map. Keys are case-insensitive.
     * @return an immutable map of parameters.
     */
    public Map<String, String> getParameters() {
        return parameters;
    }
    
    /**
     * Check if this media type is compatible with another media type. E.g.
     * image/* is compatible with image/jpeg, image/png, etc. Media type
     * parameters are ignored. The function is commutative.
     * @return true if the types are compatible, false otherwise.
     * @param other the media type to compare with
     */
    public boolean isCompatible(MediaType other) {
        if (other == null)
            return false;
        if (type.equals(MEDIA_TYPE_WILDCARD) || other.type.equals(MEDIA_TYPE_WILDCARD))
            return true;
        else if (type.equalsIgnoreCase(other.type) && (subtype.equals(MEDIA_TYPE_WILDCARD) || other.subtype.equals(MEDIA_TYPE_WILDCARD)))
            return true;
        else
            return this.type.equalsIgnoreCase(other.type)
                && this.subtype.equalsIgnoreCase(other.subtype);
    }
    
    /**
     * Compares obj to this media type to see if they are the same by comparing
     * type, subtype and parameters. Note that the case-sensitivity of parameter
     * values is dependent on the semantics of the parameter name, see
     * {@link <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7">HTTP/1.1</a>}.
     * This method assumes that values are case-sensitive.
     * @param obj the object to compare to
     * @return true if the two media types are the same, false otherwise.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == null)
            return false;
        if (!(obj instanceof MediaType))
            return false;
        MediaType other = (MediaType)obj;
        return (this.type.equalsIgnoreCase(other.type)
                && this.subtype.equalsIgnoreCase(other.subtype)
                && this.parameters.equals(other.parameters));
    }
    
    /**
     * Generate a hashcode from the type, subtype and parameters.
     * @return a hashcode
     */
    @Override
    public int hashCode() {
        return (this.type.toLowerCase()+this.subtype.toLowerCase()).hashCode()+this.parameters.hashCode();
    }
    
    /**
     * Convert the media type to a string suitable for use as the value of a
     * corresponding HTTP header.
     * @return a stringified media type
     */
    @Override
    public String toString() {
        return delegate.toString(this);
    }
}