/**
 *
 * Copyright 2014 Anno van Vliet 
 *
 * 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 org.jivesoftware.smackx.xdatavalidation.packet;

import org.jivesoftware.smack.packet.ExtensionElement;
import org.jivesoftware.smack.packet.NamedElement;
import org.jivesoftware.smack.util.NumberUtil;
import org.jivesoftware.smack.util.StringUtils;
import org.jivesoftware.smack.util.XmlStringBuilder;

import org.jivesoftware.smackx.xdata.FormField;
import org.jivesoftware.smackx.xdata.packet.DataForm;
import org.jivesoftware.smackx.xdatavalidation.ValidationConsistencyException;

/**
 * DataValidation Extension according to XEP-0122: Data Forms Validation. This specification defines a
 * backwards-compatible extension to the XMPP Data Forms protocol that enables applications to specify additional
 * validation guidelines related to a {@link FormField} in a {@link DataForm}, such as validation of standard XML
 * datatypes, application-specific datatypes, value ranges, and regular expressions.
 *
 * @author Anno van Vliet
 */
public abstract class ValidateElement implements ExtensionElement {

    public static final String DATATYPE_XS_STRING = "xs:string";
    public static final String ELEMENT = "validate";
    public static final String NAMESPACE = "http://jabber.org/protocol/xdata-validate";

    private final String datatype;

    private ListRange listRange;

    /**
     * The 'datatype' attribute specifies the datatype. This attribute is OPTIONAL, and when not specified, defaults to
     * "xs:string".
     * 
     * @param datatype the data type of any value contained within the {@link FormField} element.
     */
    private ValidateElement(String datatype) {
        this.datatype = StringUtils.isNotEmpty(datatype) ? datatype : null;
    }

    /**
     * Specifies the data type of any value contained within the {@link FormField} element. It MUST meet one of the
     * following conditions:
     * <ul>
     * <li>Start with "xs:", and be one of the "built-in" datatypes defined in XML Schema Part 2 <a
     * href="http://www.xmpp.org/extensions/xep-0122.html#nt-idp1476016">[2]</a></li>
     * <li>Start with a prefix registered with the XMPP Registrar <a
     * href="http://www.xmpp.org/extensions/xep-0122.html#nt-idp1478544">[3]</a></li>
     * <li>Start with "x:", and specify a user-defined datatype <a
     * href="http://www.xmpp.org/extensions/xep-0122.html#nt-idp1477360">[4]</a></li>
     * </ul>
     * 
     * @return the datatype
     */
    public String getDatatype() {
        return datatype != null ? datatype : DATATYPE_XS_STRING;
    }

    @Override
    public String getElementName() {
        return ELEMENT;
    }

    @Override
    public String getNamespace() {
        return NAMESPACE;
    }

    @Override
    public XmlStringBuilder toXML() {
        XmlStringBuilder buf = new XmlStringBuilder(this);
        buf.optAttribute("datatype", datatype);
        buf.rightAngleBracket();
        appendXML(buf);
        buf.optAppend(getListRange());
        buf.closeElement(this);
        return buf;
    }

    /**
     * @param buf
     */
    protected abstract void appendXML(XmlStringBuilder buf);

    /**
     * Set list range.
     * @param listRange the listRange to set
     */
    public void setListRange(ListRange listRange) {
        this.listRange = listRange;
    }

    /**
     * Get list range.
     * @return the listRange
     */
    public ListRange getListRange() {
        return listRange;
    }

    /**
     * Check if this element is consistent according to the business rules in XEP=0122.
     * 
     * @param formField
     */
    public abstract void checkConsistency(FormField formField);

    /**
     * Validation only against the datatype itself. Indicates that the value(s) should simply match the field type and
     * datatype constraints.
     * 
     * @see ValidateElement
     */
    public static class BasicValidateElement extends ValidateElement {

        public static final String METHOD = "basic";

        /**
         * Basic validate element constructor.
         * @param dataType
         * @see #getDatatype()
         */
        public BasicValidateElement(String dataType) {
            super(dataType);
        }

        @Override
        protected void appendXML(XmlStringBuilder buf) {
            buf.emptyElement(METHOD);
        }

        @Override
        public void checkConsistency(FormField formField) {
            checkListRangeConsistency(formField);
            if (formField.getType() != null) {
                switch (formField.getType()) {
                case hidden:
                case jid_multi:
                case jid_single:
                    throw new ValidationConsistencyException(String.format(
                                    "Field type '%1$s' is not consistent with validation method '%2$s'.",
                                    formField.getType(), BasicValidateElement.METHOD));
                default:
                    break;
                }
            }
        }

    }

    /**
     * For "list-single" or "list-multi", indicates that the user may enter a custom value (matching the datatype
     * constraints) or choose from the predefined values.
     * 
     * @see ValidateElement
     */
    public static class OpenValidateElement extends ValidateElement {

        public static final String METHOD = "open";

        /**
         * Open validate element constructor.
         * @param dataType
         * @see #getDatatype()
         */
        public OpenValidateElement(String dataType) {
            super(dataType);
        }

        @Override
        protected void appendXML(XmlStringBuilder buf) {
            buf.emptyElement(METHOD);
        }

        @Override
        public void checkConsistency(FormField formField) {
            checkListRangeConsistency(formField);
            if (formField.getType() != null) {
                switch (formField.getType()) {
                case hidden:
                    throw new ValidationConsistencyException(String.format(
                                    "Field type '%1$s' is not consistent with validation method '%2$s'.",
                                    formField.getType(), OpenValidateElement.METHOD));
                default:
                    break;
                }
            }
        }

    }

    /**
     * Indicate that the value should fall within a certain range.
     * 
     * @see ValidateElement
     */
    public static class RangeValidateElement extends ValidateElement {

        public static final String METHOD = "range";
        private final String min;
        private final String max;

        /**
         * Range validate element constructor.
         * @param dataType
         * @param min the minimum allowable value. This attribute is OPTIONAL. The value depends on the datatype in use.
         * @param max the maximum allowable value. This attribute is OPTIONAL. The value depends on the datatype in use.
         * @see #getDatatype()
         * 
         */
        public RangeValidateElement(String dataType, String min, String max) {
            super(dataType);
            this.min = min;
            this.max = max;
        }

        @Override
        protected void appendXML(XmlStringBuilder buf) {
            buf.halfOpenElement(METHOD);
            buf.optAttribute("min", getMin());
            buf.optAttribute("max", getMax());
            buf.closeEmptyElement();
        }

        /**
         * The 'min' attribute specifies the minimum allowable value.
         * 
         * @return the minimum allowable value. This attribute is OPTIONAL. The value depends on the datatype in use.
         */
        public String getMin() {
            return min;
        }

        /**
         * The 'max' attribute specifies the maximum allowable value.
         * 
         * @return the maximum allowable value. This attribute is OPTIONAL. The value depends on the datatype in use.
         */
        public String getMax() {
            return max;
        }

        @Override
        public void checkConsistency(FormField formField) {
            checkNonMultiConsistency(formField, METHOD);
            if (getDatatype().equals(ValidateElement.DATATYPE_XS_STRING)) {
                throw new ValidationConsistencyException(String.format(
                                "Field data type '%1$s' is not consistent with validation method '%2$s'.",
                                getDatatype(), RangeValidateElement.METHOD));
            }
        }

    }

    /**
     * Indicates that the value should be restricted to a regular expression. The regular expression must be that
     * defined for <a href="http://www.xmpp.org/extensions/xep-0122.html#nt-idp1501344"> POSIX extended regular
     * expressions </a> including support for <a
     * href="http://www.xmpp.org/extensions/xep-0122.html#nt-idp1502496">Unicode</a>.
     * 
     * @see ValidateElement
     */
    public static class RegexValidateElement extends ValidateElement {

        public static final String METHOD = "regex";
        private final String regex;

        /**
         * Regex validate element.
         * @param dataType
         * @param regex
         * @see #getDatatype()
         */
        public RegexValidateElement(String dataType, String regex) {
            super(dataType);
            this.regex = regex;
        }

        /**
         * the expression is that defined for POSIX extended regular expressions, including support for Unicode.
         * 
         * @return the regex
         */
        public String getRegex() {
            return regex;
        }

        @Override
        protected void appendXML(XmlStringBuilder buf) {
            buf.element("regex", getRegex());
        }

        @Override
        public void checkConsistency(FormField formField) {
            checkNonMultiConsistency(formField, METHOD);
        }

    }

    /**
     * This element indicates for "list-multi", that a minimum and maximum number of options should be selected and/or
     * entered.
     */
    public static class ListRange implements NamedElement {

        public static final String ELEMENT = "list-range";
        private final Long min;
        private final Long max;

        /**
         * The 'max' attribute specifies the maximum allowable number of selected/entered values. The 'min' attribute
         * specifies the minimum allowable number of selected/entered values. Both attributes are optional, but at
         * least one must bet set, and the value must be within the range of a unsigned 32-bit integer.
         * 
         * @param min
         * @param max
         */
        public ListRange(Long min, Long max) {
            if (min != null) {
                NumberUtil.checkIfInUInt32Range(min);
            }
            if (max != null) {
                NumberUtil.checkIfInUInt32Range(max);
            }
            if (max == null && min == null) {
                throw new IllegalArgumentException("Either min or max must be given");
            }
            this.min = min;
            this.max = max;
        }

        @Override
        public XmlStringBuilder toXML() {
            XmlStringBuilder buf = new XmlStringBuilder(this);
            buf.optLongAttribute("min", getMin());
            buf.optLongAttribute("max", getMax());
            buf.closeEmptyElement();
            return buf;
        }

        @Override
        public String getElementName() {
            return ELEMENT;
        }

        /**
         * The minimum allowable number of selected/entered values.
         * 
         * @return a positive integer, can be null
         */
        public Long getMin() {
            return min;
        }

        /**
         * The maximum allowable number of selected/entered values.
         * 
         * @return a positive integer, can be null
         */
        public Long getMax() {
            return max;
        }

    }

    /**
     * The &gt;list-range/&lt; element SHOULD be included only when the &lt;field/&gt; is of type "list-multi" and SHOULD be ignored
     * otherwise.
     * 
     * @param formField
     */
    protected void checkListRangeConsistency(FormField formField) {
        ListRange listRange = getListRange();
        if (listRange == null) {
            return;
        }

        Long max = listRange.getMax();
        Long min = listRange.getMin();
        if ((max != null || min != null) && formField.getType() != FormField.Type.list_multi) {
            throw new ValidationConsistencyException(
                            "Field type is not of type 'list-multi' while a 'list-range' is defined.");
        }
    }

    /**
     * @param formField
     * @param method
     */
    protected void checkNonMultiConsistency(FormField formField, String method) {
        checkListRangeConsistency(formField);
        if (formField.getType() != null) {
            switch (formField.getType()) {
            case hidden:
            case jid_multi:
            case list_multi:
            case text_multi:
                throw new ValidationConsistencyException(String.format(
                                "Field type '%1$s' is not consistent with validation method '%2$s'.",
                                formField.getType(), method));
            default:
                break;
            }
        }
    }
}