<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

    <xs:element name="ruleSetDefinition">
        <xs:annotation>
            <xs:documentation>Container of rules. This container should have a globally unique name</xs:documentation>
        </xs:annotation>
        <xs:complexType>
            <xs:sequence>
                <!--Identifiers for selecting the source and target resource. Later it can be used to just select types and provide the actual resources at application time -->
                <xs:element name="sourceModel">
                    <xs:complexType>
                        <xs:attribute name="name" type="xs:string"></xs:attribute>
                    </xs:complexType>
                </xs:element>
                <xs:element name="targetModel">
                    <xs:complexType>
                        <xs:attribute name="name" type="xs:string"></xs:attribute>
                    </xs:complexType>
                </xs:element>
                <!--A rule set must have at least one rule -->
                <xs:element name="param" type="paramDefType" maxOccurs="unbounded" minOccurs="0"></xs:element>
                <xs:element maxOccurs="unbounded" name="rule" type="rule" />
            </xs:sequence>
            <xs:attribute name="name" type="xs:string" use="required" />
            <xs:attribute fixed="1.0" name="version" type="xs:string" />
            <!--Mandatory attributes for rule set-->
            <xs:attribute name="description" type="xs:string" use="optional"></xs:attribute>
        </xs:complexType>
    </xs:element>

    <xs:complexType name="rule">
        <xs:annotation>
            <xs:documentation>A rule in a ruleset. A rule is uniquely identified by its name within a rule set</xs:documentation>
        </xs:annotation>
        <xs:sequence>
            <xs:element name="sourceFilter" type="sourceElementSelectorType"/>
            <xs:element name="targetFilter" type="targetElementSelectorType"/>
            <xs:element name="link" type="linkType"/>
        </xs:sequence>
        <xs:attribute name="name" type="xs:string" use="required"/>
        <xs:attribute name="direction" type="directionType"/>
        <!--A rule must have source, target, link in the sequence-->
    </xs:complexType>

    <xs:simpleType name="directionType">
        <xs:restriction base="xs:string">
            <xs:enumeration value="SourceToTarget"/>
            <xs:enumeration value="TargetToSource"/>
            <xs:enumeration value="Auto"/>
        </xs:restriction>
    </xs:simpleType>

    <xs:complexType name="sourceElementSelectorType">
        <xs:choice>
            <xs:element name="element" type="elementFilterType"/>
            <xs:element name="endPoint" type="endPointType"/>
        </xs:choice>
    </xs:complexType>

    <xs:complexType name="targetElementSelectorType">
        <xs:choice>
            <xs:element name="element" type="elementFilterType"/>
        </xs:choice>
    </xs:complexType>

    <!-- Right now we are not creating simple types that can define a pattern for specifying identifiers (like class name, feature name, type etc). If we have leisure time later :) we can do that -->

    <xs:complexType name="elementFilterType">
        <xs:choice>
            <xs:element maxOccurs="unbounded" minOccurs="0" name="element" type="elementFilterType"/>
        </xs:choice>
        <xs:attribute name="class" type="xs:string"/>
        <xs:attribute name="type" type="xs:string"/>
        <xs:attribute name="condition" type="xs:string"/>
    </xs:complexType>

    <xs:complexType name="endPointType">
        <xs:attribute name="class" type="xs:string"/>
        <xs:attribute name="type" type="xs:string"/>
        <xs:attribute name="connection" type="xs:string"/>
        <xs:attribute name="package" type="xs:string"/>
    </xs:complexType>

    <xs:complexType name="linkType">
        <xs:attribute name="condition" type="xs:string" use="required"/>
    </xs:complexType>
    
    <xs:complexType name="paramDefType">
        <xs:attribute name="name" type="xs:string"></xs:attribute>
        <xs:attribute name="description" type="xs:string"></xs:attribute>
        <xs:attribute name="defaultValue" type="xs:string"></xs:attribute>
        <xs:attribute name="type" default="string">
            <xs:simpleType>
                <xs:restriction base="xs:string">
                    <xs:enumeration value="connection"></xs:enumeration>
                    <xs:enumeration value="package"></xs:enumeration>
                    <xs:enumeration value="string"></xs:enumeration>
                </xs:restriction>
            </xs:simpleType>
        </xs:attribute>
    </xs:complexType>

</xs:schema>