/*
 * Copyright (C) 2010 Teleal GmbH, Switzerland
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.teleal.cling.model.types;

import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;

/**
 * The type of a state variable value, able to convert to/from string representation.
 *
 * @param <V> The Java type of the value handled by this datatype.
 * @author Christian Bauer
 */
public interface Datatype<V> {

    /**
     * Mapping from Java type to UPnP built-in type.
     * <p>
     * This map is used for service binding, when we have to figure out
     * the type of a UPnP state variable by reflecting on a method or field of
     * a service class. From a known Java type we default to a UPnP built-in type.
     * </p>
     */
    public static enum Default {

        BOOLEAN(Boolean.class, Builtin.BOOLEAN),
        BOOLEAN_PRIMITIVE(Boolean.TYPE, Builtin.BOOLEAN),
        SHORT(Short.class, Builtin.I2),
        SHORT_PRIMITIVE(Short.TYPE, Builtin.BOOLEAN),
        INTEGER(Integer.class, Builtin.I4),
        INTEGER_PRIMITIVE(Integer.TYPE, Builtin.I4),
        UNSIGNED_INTEGER_ONE_BYTE(UnsignedIntegerOneByte.class, Builtin.UI1),
        UNSIGNED_INTEGER_TWO_BYTES(UnsignedIntegerTwoBytes.class, Builtin.UI2),
        UNSIGNED_INTEGER_FOUR_BYTES(UnsignedIntegerFourBytes.class, Builtin.UI4),
        FLOAT(Float.class, Builtin.R4),
        FLOAT_PRIMITIVE(Float.TYPE, Builtin.R4),
        DOUBLE(Double.class, Builtin.FLOAT),
        DOUBLE_PRIMTIIVE(Double.TYPE, Builtin.FLOAT),
        CHAR(Character.class, Builtin.CHAR),
        CHAR_PRIMITIVE(Character.TYPE, Builtin.CHAR),
        STRING(String.class, Builtin.STRING),
        CALENDAR(Calendar.class, Builtin.DATETIME),
        BYTES(Byte[].class, Builtin.BIN_BASE64),
        URI(java.net.URI.class, Builtin.URI);

        private Class javaType;
        private Builtin builtinType;

        Default(Class javaType, Builtin builtinType) {
            this.javaType = javaType;
            this.builtinType = builtinType;
        }

        public Class getJavaType() {
            return javaType;
        }

        public Builtin getBuiltinType() {
            return builtinType;
        }

        public static Default getByJavaType(Class javaType) {
            for (Default d : Default.values()) {
                if (d.getJavaType().equals(javaType)) {
                    return d;
                }
            }
            return null;
        }
    }

    /**
     * Mapping from UPnP built-in standardized type to actual subtype of {@link Datatype}.
     */
    public static enum Builtin {

        UI1("ui1", new UnsignedIntegerOneByteDatatype()),
        UI2("ui2", new UnsignedIntegerTwoBytesDatatype()),
        UI4("ui4", new UnsignedIntegerFourBytesDatatype()),
        I1("i1", new IntegerDatatype(1)),
        I2("i2", new IntegerDatatype(2)),
        I4("i4", new IntegerDatatype(4)),
        INT("int", new IntegerDatatype(4)),
        R4("r4", new FloatDatatype()),
        R8("r8", new DoubleDatatype()),
        NUMBER("number", new DoubleDatatype()),
        FIXED144("fixed.14.4", new DoubleDatatype()),
        FLOAT("float", new DoubleDatatype()), // TODO: Is that Double or Float?
        CHAR("char", new CharacterDatatype()),
        STRING("string", new StringDatatype()),
        DATE("date", new DateTimeDatatype(
                new String[]{"yyyy-MM-dd"},
                "yyyy-MM-dd"
        )),
        DATETIME("dateTime", new DateTimeDatatype(
                new String[]{"yyyy-MM-dd", "yyyy-MM-dd'T'HH:mm:ss"},
                "yyyy-MM-dd'T'HH:mm:ss"
        )),
        DATETIME_TZ("dateTime.tz", new DateTimeDatatype(
                new String[]{"yyyy-MM-dd", "yyyy-MM-dd'T'HH:mm:ss", "yyyy-MM-dd'T'HH:mm:ssZ"},
                "yyyy-MM-dd'T'HH:mm:ssZ"
        )),
        TIME("time", new DateTimeDatatype(
                new String[]{"HH:mm:ss"},
                "HH:mm:ss"
        )),
        TIME_TZ("time.tz", new DateTimeDatatype(
                new String[]{"HH:mm:ssZ", "HH:mm:ss"},
                "HH:mm:ssZ"
        )),
        BOOLEAN("boolean", new BooleanDatatype()),
        BIN_BASE64("bin.base64", new Base64Datatype()),
        BIN_HEX("bin.hex", new BinHexDatatype()),
        URI("uri", new URIDatatype()),
        UUID("uuid", new StringDatatype());

        private static Map<String, Builtin> byName = new HashMap<String, Builtin>() {{
            for (Builtin b : Builtin.values()) {
                // Lowercase it!
                put(b.getDescriptorName().toLowerCase(), b);
            }
        }};

        private String descriptorName;
        private Datatype datatype;

        <VT> Builtin(String descriptorName, AbstractDatatype<VT> datatype) {
            datatype.setBuiltin(this); // Protected, we actually want this to be immutable
            this.descriptorName = descriptorName;
            this.datatype = datatype;
        }

        public String getDescriptorName() {
            return descriptorName;
        }

        public Datatype getDatatype() {
            return datatype;
        }

        public static Builtin getByDescriptorName(String descriptorName) {
            // The UPnP spec clearly says "must be one of these values", so I'm assuming
            // they are case sensitive. But we want to work with broken devices, which of
            // course produce mixed upper/lowercase values.
            if (descriptorName == null) return null;
            return byName.get(descriptorName.toLowerCase());
        }

        public static boolean isNumeric(Builtin builtin) {
            return builtin != null &&
                    (builtin.equals(UI1) ||
                            builtin.equals(UI2) ||
                            builtin.equals(UI4) ||
                            builtin.equals(I1) ||
                            builtin.equals(I2) ||
                            builtin.equals(I4));
        }
    }

    /**
     * @return The built-in UPnP standardized type this datatype is mapped to or
     *         <code>null</code> if this is a custom datatype.
     */
    public Builtin getBuiltin();

    /**
     * @param value The value to validate or <code>null</code>.
     * @return Returns <code>true</code> if the value was <code>null</code>, validation result otherwise.
     */
    public boolean isValid(V value);

    /**
     * Transforms a value supported by this datatype into a string representation.
     * <p>
     * This method calls {@link #isValid(Object)} before converting the value, it throws
     * an exception if validation fails.
     * </p>
     *
     * @param value The value to transform.
     * @return The transformed value as a string, or an empty string when the value is null, never returns <code>null</code>.
     * @throws InvalidValueException
     */
    public String getString(V value) throws InvalidValueException;

    /**
     * Transforms a string representation into a value of the supported type.
     *
     * @param s The string representation of a value.
     * @return The converted value or <code>null</code> if the string was <code>null</code> or empty.
     * @throws InvalidValueException If the string couldn't be parsed.
     */
    public V valueOf(String s) throws InvalidValueException;

    /**
     * @return Metadata about this datatype, a nice string for display that describes
     *         this datatype (e.g. concrete class name).
     */
    public String getDisplayString();


}
