module clixon-xml-changelog {
    yang-version 1.1;
    namespace "http://clicon.org/xml-changelog";
    prefix ml;

    import ietf-yang-library {
        prefix yanglib;
    }
    import ietf-yang-types {
        prefix yang;
    }

    organization    "Clixon";
    contact
        "Olof Hagsand <olof@hagsand.se>";
    description
        "This is experimental XML changelog module with several influences:
       1) draft-wang-netmod-module-revision-management-01, by:
         Qin Wu               <mailto:bill.wu@huawei.com>
         Zitao Wang           <mailto:wangzitao@huawei.com>
       2) XProc https://www.w3.org/TR/xproc/#xpath-context";

    revision 2019-03-21 {
        description
            "Initial Clixon derived version";
    }

    typedef operation_type {
        description
            "From: https://en.wikipedia.org/wiki/XML_pipeline:
              Rename - renames elements or attributes without modifying the content
              Replace - replaces elements or attributes
              Insert - adds a new data element to the output stream at a specified point
              Delete - removes an element or attribute (also known as pruning the input tree)
              Wrap - wraps elements with additional elements
              Reorder - changes the order of elements
             More inspiration in XProc: https://www.w3.org/TR/xproc/#ex2";
        type enumeration{
            enum rename {
                description
                "Rename the 'where' node, ie XML label
                 Synopsis: rename(where:targets, when:bool, tag:string)";
            }
            enum replace {
                description
                "Replace the target data node modification is given by the leaf
                 transform which is a string with %s where the original value
                 is inserted.
                 Synopsis: replace(where:targets, when:bool, new:xml)";
            }
            enum insert {
                description
                "Create new data nodes and insert under an existing node.
                 Synopsis: insert(where:parents, when:bool, new:xml)";
            }
            enum delete {
                description
                "Delete the target node.
                 Synopsis: delete(where:parents, when:bool)";
            }
            enum move {
                description
                "Move the target node(Added).
                 Synopsis: move(where:parents, when:bool, dst:node)";
            }
        }
    }
    container changelogs {
        config false;
        list changelog {
            key "namespace revision";
            leaf namespace {
                type string;
                description
                    "The YANG namespace identifying a module or submodule.
               XML needs to be identified by namespace, translation to
               module name may not always be possible.";
            }
            leaf revision {
                type yanglib:revision-identifier;
                description
                    "The YANG module or submodule revision date. 
           This is the actual date of the changlelog items. 
           Note however if the terminate flag is set, this is a virtual
           revision just in place to terminate the XML, such as removing or
           moving items,.";
            }
            leaf revfrom {
                type yanglib:revision-identifier;
                description
                    "Optional revision from date. This changelog is effective in the
           range [from,to]. If from is not given the changelog is open-ended.
           Several changelogs may be applied if the upgrade spans multiple
           ranges: [from0,to0],..[fromN,toN]";
            }
            list step {
                description
                    "List for module revision change log";
                key "name";
                leaf name {
                    type string;
                    description
                        "Unique step name";
                }
                leaf op {
                    type operation_type;
                    mandatory true;
                    description
                        "This leaf indicate the change operation, such as create, move, delete, modify, etc.";
                }
                leaf where {
                    type yang:xpath1.0;
                    mandatory true;
                    description
                        "Identifies the target data node for update.
                         for move, modify or delete the target-node points to 
                         the data node of the old version.
                         For create, it is the parent where it should be
                         inserted.";
                }
                leaf when {
                    type yang:xpath1.0;
                    description
                        "Boolean XPATH. Execute this step if this xpath exists
                         and evaluates to true";
                }
                leaf tag {
                    description
                        "For rename, a string XPath definining the new tag.";
                    type yang:xpath1.0;
                }
                leaf dst {
                    description
                    "For move, a destination XPath definining the parent where
                     to insert.";
                    type yang:xpath1.0;
                }
                anydata new {
                    description
                    "If op is replace or insert, new XML for the new node.";
                }
            }
        }
    }
}