module ietf-module-revision {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-module-revision";
  prefix ml;

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

  organization
    "IETF Network Modeling (NETMOD) Working Group";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/netmod/>

     WG List:  <mailto:netmod@ietf.org>

     Author:   Qin Wu
               <mailto:bill.wu@huawei.com>
               Zitao Wang
               <mailto:wangzitao@huawei.com>";
  description
    "This YANG module defines an module log.";

  revision 2018-08-08 {
    description
      "Initial revision.";
    reference "RFC XXXX: Using Metadata with YANG for Module revisions";
  }

  identity operation-type {
    description
      "Abstract base identity for the operation type ";
  }

  identity create {
    base operation-type;
    description
      "Denotes create new data nodes";
  }

  identity delete {
    base operation-type;
    description
      "Denotes delete the target node";
  }

  identity move {
    base operation-type;
    description
      "Denote move the target node.";
  }

  identity modify {
    base operation-type;
    description
      "Denote modify the target data node.";
  }

  identity statement-type {
    description
      "Base identity for statement type";
  }

  identity feature-statement {
    base statement-type;
    description
      "feature statement, if this type be chose, it means that the
       feature or if-feature statement been modified";
  }
  identity identity-statement {
    base statement-type;
    description
      "identity statement, if this type be chose, it means that the
       identity statement been modified, for example, add new identity, etc.";
  }

  identity grouping-statement {
    base statement-type;
    description
      "grouping statement, if this type be chose, it means that the grouping
       statement been modified.";
  }

  identity typedef-statement {
    base statement-type;
    description
      "typedef statement, if this type be chose, it means that the typedef
       statement been modified.";
  }

  identity augment-statement {
    base statement-type;
    description
      "augment statement, if this type be chose, it means that the augment
       statement been modified.";
  }

  identity rpc-statement {
    base statement-type;
    description
      "rpc statement, if this type be chose, it means that the rpc
       statement been modified.";
  }

  identity notification-statement {
    base statement-type;
    description
      "notification statement, if this type be chose, it means that the notification
       statement been modified.";
  }

  extension purpose {
   argument name;
    description
      "The purpose can be used to mark the data nodes change purpose.
       The name argument can be specified in the following recommended mode
       - bug-fix, which can help user to understand the data nodes' changes present bug fix,
       - new-function, which can help user to understand the data nodes' changes present new function,
       - nmda-conform, which can help user to understand the data nodes' changes conform to NMDA,

       and note that the user can argument the purpose name according to their sepcific requirements.";
  }

  grouping data-definition {
    container data-definition {
      leaf target-node {
        type yang:xpath1.0;
        mandatory true;
        description
          "Identifies the target data node for update.
           Notice that, if the update-type equal to move or delete,
           this target-node must point to the data node of old version.
           \t
           For example, suppose the target node is a YANG leaf named a,
           and the previous version is:
           \t
           container foo {
            leaf a { type string; }
            leaf b { type int32; }
           }
           \t
           the new version is:
            container foo {
           leaf b {type int32;}
            }
           \t
           Therefore, the targe-node should be /foo/a.";
      }
      leaf location-point {
        type yang:xpath1.0;
        description
          "Identifies the location point where the updates happened.";
      }
      leaf where {
        when "derived-from-or-self(../../change-operation, 'move')" {
          description
            "This leaf only applies for 'move'
             updates.";
        }
        type enumeration {
          enum "before" {
            description
              "Insert or move a data node before the data resource
               identified by the 'point' parameter.";
          }
          enum "after" {
            description
              "Insert or move a data node after the data resource
               identified by the 'point' parameter.";
          }
          enum "first" {
            description
              "Insert or move a data node so it becomes ordered
                  as the first entry.";
          }
          enum "last" {
            description
              "Insert or move a data node so it becomes ordered
               as the last entry.";
          }
        }
        default "last";
        description
          "Identifies where a data resource will be inserted
              or moved.";
      }
      anydata data-definition {
        when "derived-from-or-self(../../change-operation, 'modify')" {
          description
            "This nodes only be present when
                the 'change-operation' equal to 'modify'.";
        }
        description
          "This nodes used for present the definitions before updated.
           And this nodes only be present when
           the 'change-operation' equal to 'modify'.";
      }
      description
        "Container for data statement";
    }
    description
      "Grouping for data definition";
  }

  grouping other-statement {
    container other-statement {
      leaf statement-name {
        type identityref {
          base statement-type;
        }
        description
          "Statement name, for example, identity, feature, typedef, etc.";
      }
      anydata statement-definition {
        description
          "This nodes used for present new the definitions.";
      }
      list substatements {
        key "statement-name";
        leaf statement-name {
          type identityref {
            base statement-type;
          }
          description
            "Statement name, for example, identity, feature, typedef, etc.";
        }
        anydata substatement-definition {
          description
            "This nodes used for present new the definitions.";
        }
        description
          "List for substatements updates";
      }
      description
        "Container for header statement updates";
    }
    description
      "Grouping for header statement";
  }

  grouping change-log {
    list revision-change-log {
      key "index";
      leaf index {
        type uint32;
        description
          "Index for module change log";
      }
      leaf change-operation {
        type identityref {
          base operation-type;
        }
        mandatory true;
        description
          "This leaf indicate the change operation, such as create, move, delete, modify, etc.";
      }
      choice yang-statements {
        description
          "Choice for various YANG statements that have been impacted.";
        case data-definition-statement {
          uses data-definition;
        }
        case other-statement {
          uses other-statement;
        }
      }
      description
        "List for module revision change log";
    }
    description
      "Grouping for module revision change log";
  }

  container yang-modules {
    config false;
    list module {
      key "name revision";
      leaf name {
        type yang:yang-identifier;
        description
          "The YANG module or submodule name.";
      }
      leaf revision {
        type yanglib:revision-identifier;
        description
          "The YANG module or submodule revision date.  If no revision
           statement is present in the YANG module or submodule, this
           leaf is not instantiated.";
      }
      leaf backward-compatible {
        type boolean;
        description
          "Indicates whether it is a backward compatible version.
           If this parameter is set to true, it means that this version is
           a backwards compatible version";
      }
      uses change-log;
      description
        "List for module updated log";
    }
    description
      "This container present the modules updated log.";
  }
  augment "/yanglib:yang-library/yanglib:module-set/yanglib:module" {
    description
      "Augment the yang library with backward compatibility indication.";
    leaf backward-compatible {
      type boolean;
      description
        "backward compatibility indication.";
    }
  }
  augment "/yanglib:yang-library/yanglib:module-set/yanglib:module/yanglib:submodule" {
    description
      "Augment the yang library with backward compatibility indication.";
    leaf backward-compatible {
      type boolean;
      description
        "backward compatibility indication.";
    }
  }
  rpc module-revision-change {
    description
      "Module Node change query operation.";
    input {
      leaf source-module-name {
        type yang:yang-identifier;
        mandatory true;
        description
          "The Source YANG module or submodule name.";
      }
      leaf source-revision {
        type yanglib:revision-identifier;
        description
          "The Source YANG module revision date.  If no revision
           statement is present in the YANG module or submodule, this
           leaf is not instantiated.";
      }
     leaf target-module-name {
        type yang:yang-identifier;
        mandatory true;
        description
          "The Target YANG module or submodule name.";
      }
      leaf target-revision {
        type yanglib:revision-identifier;
        description
          "The target YANG module revision date.  If no revision
           statement is present in the YANG module or submodule, this
           leaf is not instantiated.";
      }
    }
    output {
      choice status-response{
      leaf wrong-match{
          type empty;
          description
            "This leaf indicates that two modules have nothing in common.";
      }
      list data-nodes {
        key "data-node-name";
        description
          "Each entry represents a data node of a given module that
           have been changed from source revision of
           a module to target revision of the module.";
        leaf data-node-name {
          type string;
          description
            "a data node name of a given module that
             has been changed.";
        }
        leaf is-new-node {
          type boolean;
          description
            "indicate the data node is newly introduced node in the target revision.";
        }
        leaf change-operation {
          type identityref {
            base operation-type;
          }
          description
          "This leaf indicate the change operation,
           such as create, move, delete, modify, etc.";
        }
      }
     }
    }
  }
}