Fix leafDataFromValue

Leafrefs were not working correctly, when pointing to a data node not in
the tree. Because of this I had to rework the thing a little bit (I
basically copied the algorithm from cla-sysrepo, where I had the same
issue). I also changed the name. And also added test, both versions of
leafref included.

Funnily enough, it seems that I was already fixing this before, but for
some reason the bug appeared again while using netconf-cli, oh well, now
the tests should cover that hopefully.

Change-Id: I8a102c54bf58a4221610c8a83d26979fb7b4461d
diff --git a/src/libyang_utils.cpp b/src/libyang_utils.cpp
index 274fec1..f1af868 100644
--- a/src/libyang_utils.cpp
+++ b/src/libyang_utils.cpp
@@ -4,60 +4,65 @@
 #include "libyang_utils.hpp"
 #include "utils.hpp"
 
-leaf_data_ leafValueFromValue(const libyang::S_Value& value, LY_DATA_TYPE type)
+leaf_data_ leafValueFromNode(libyang::S_Data_Node_Leaf_List node)
 {
-    using namespace std::string_literals;
-    switch (type) {
-    case LY_TYPE_INT8:
-        return value->int8();
-    case LY_TYPE_INT16:
-        return value->int16();
-    case LY_TYPE_INT32:
-        return value->int32();
-    case LY_TYPE_INT64:
-        return value->int64();
-    case LY_TYPE_UINT8:
-        return value->uint8();
-    case LY_TYPE_UINT16:
-        return value->uint16();
-    case LY_TYPE_UINT32:
-        return value->uint32();
-    case LY_TYPE_UINT64:
-        return value->uint64();
-    case LY_TYPE_BOOL:
-        return value->bln();
-    case LY_TYPE_STRING:
-        return std::string(value->string());
-    case LY_TYPE_ENUM:
-        return enum_{std::string(value->enm()->name())};
-    case LY_TYPE_IDENT:
-        return identityRef_{value->ident()->module()->name(), value->ident()->name()};
-    case LY_TYPE_BINARY:
-        return binary_{value->binary()};
-    case LY_TYPE_EMPTY:
-        return empty_{};
-    case LY_TYPE_BITS:
-    {
-        auto bits = value->bit();
-        std::vector<libyang::S_Type_Bit> filterNull;
-        std::copy_if(bits.begin(), bits.end(), std::back_inserter(filterNull), [] (auto bit) { return bit; });
-        bits_ res;
-        std::transform(filterNull.begin(), filterNull.end(), std::inserter(res.m_bits, res.m_bits.end()), [] (const auto& bit) { return bit->name(); });
-        return bits_{res};
+    std::function<leaf_data_(libyang::S_Data_Node_Leaf_List)> impl = [&impl] (libyang::S_Data_Node_Leaf_List node) -> leaf_data_ {
+        // value_type() is what's ACTUALLY stored inside `node`
+        // Leafrefs sometimes don't hold a reference to another, but they have the actual pointed-to value.
+        switch (node->value_type()) {
+        case LY_TYPE_ENUM:
+            return enum_{node->value()->enm()->name()};
+        case LY_TYPE_UINT8:
+            return node->value()->uint8();
+        case LY_TYPE_UINT16:
+            return node->value()->uint16();
+        case LY_TYPE_UINT32:
+            return node->value()->uint32();
+        case LY_TYPE_UINT64:
+            return node->value()->uint64();
+        case LY_TYPE_INT8:
+            return node->value()->int8();
+        case LY_TYPE_INT16:
+            return node->value()->int16();
+        case LY_TYPE_INT32:
+            return node->value()->int32();
+        case LY_TYPE_INT64:
+            return node->value()->int64();
+        case LY_TYPE_DEC64:
+        {
+            auto v = node->value()->dec64();
+            return v.value * std::pow(10, -v.digits);
+        }
+        case LY_TYPE_BOOL:
+            return node->value()->bln();
+        case LY_TYPE_STRING:
+            return std::string{node->value()->string()};
+        case LY_TYPE_BINARY:
+            return binary_{node->value()->binary()};
+        case LY_TYPE_IDENT:
+            return identityRef_{node->value()->ident()->module()->name(), node->value()->ident()->name()};
+        case LY_TYPE_EMPTY:
+            return empty_{};
+        case LY_TYPE_LEAFREF:
+        {
+            auto refsTo = node->value()->leafref();
+            assert(refsTo);
+            return impl(std::make_shared<libyang::Data_Node_Leaf_List>(node->value()->leafref()));
+        }
+        case LY_TYPE_BITS:
+        {
+            auto bits = node->value()->bit();
+            std::vector<libyang::S_Type_Bit> filterNull;
+            std::copy_if(bits.begin(), bits.end(), std::back_inserter(filterNull), [] (auto bit) { return bit; });
+            bits_ res;
+            std::transform(filterNull.begin(), filterNull.end(), std::inserter(res.m_bits, res.m_bits.end()), [] (const auto& bit) { return bit->name(); });
+            return bits_{res};
+        }
+        default:
+            return std::string{"(can't print)"};
     }
-    case LY_TYPE_DEC64:
-    {
-        auto v = value->dec64();
-        return v.value * std::pow(10, -v.digits);
-    }
-    case LY_TYPE_LEAFREF:
-    {
-        libyang::Data_Node_Leaf_List toPrint{value->leafref()};
-        return leafValueFromValue(toPrint.value(), toPrint.value_type());
-    }
-    default: // TODO: implement all types
-        return "(can't print)"s;
-    }
+    };
+    return impl(node);
 }
 
 namespace {
@@ -80,8 +85,8 @@
             res.emplace_back(stripXPathPrefix(it->path()), special_{SpecialValue::List});
         }
         if (it->schema()->nodetype() == LYS_LEAF || it->schema()->nodetype() == LYS_LEAFLIST) {
-            libyang::Data_Node_Leaf_List leaf(it);
-            auto value = leafValueFromValue(leaf.value(), leaf.value_type());
+            auto leaf = std::make_shared<libyang::Data_Node_Leaf_List>(it);
+            auto value = leafValueFromNode(leaf);
             res.emplace_back(stripXPathPrefix(it->path()), value);
         }
     }
diff --git a/src/libyang_utils.hpp b/src/libyang_utils.hpp
index d8bf4ad..a33e70b 100644
--- a/src/libyang_utils.hpp
+++ b/src/libyang_utils.hpp
@@ -9,5 +9,5 @@
 #include "ast_values.hpp"
 #include "datastore_access.hpp"
 
-leaf_data_ leafValueFromValue(const libyang::S_Value& value, LY_DATA_TYPE type);
+leaf_data_ leafValueFromNode(libyang::S_Data_Node_Leaf_List node);
 void lyNodesToTree(DatastoreAccess::Tree& res, const std::vector<std::shared_ptr<libyang::Data_Node>> items, std::optional<std::string> ignoredXPathPrefix = std::nullopt);
diff --git a/src/netconf_access.cpp b/src/netconf_access.cpp
index 307ccf1..2c64cd4 100644
--- a/src/netconf_access.cpp
+++ b/src/netconf_access.cpp
@@ -232,9 +232,8 @@
 
         // I take the first child here, because the first element (the parent of the child()) will be the list
         for (const auto& keyLeaf : instance->child()->tree_for()) {
-            auto leafData = libyang::Data_Node_Leaf_List{keyLeaf};
-            auto leafSchema = libyang::Schema_Node_Leaf{leafData.schema()};
-            instanceRes.insert({ leafSchema.name(), leafValueFromValue(leafData.value(), leafSchema.type()->base())});
+            auto leafData = std::make_shared<libyang::Data_Node_Leaf_List>(keyLeaf);
+            instanceRes.insert({ leafData->schema()->name(), leafValueFromNode(leafData)});
         }
         res.emplace_back(instanceRes);
     }
diff --git a/src/sysrepo_access.cpp b/src/sysrepo_access.cpp
index 6176f67..cdaff49 100644
--- a/src/sysrepo_access.cpp
+++ b/src/sysrepo_access.cpp
@@ -419,8 +419,8 @@
         ListInstance instanceRes;
         for (const auto& key : keys) {
             auto vec = wantedList->find_path(key->name())->data();
-            auto leaf = libyang::Data_Node_Leaf_List{*(vec.begin())};
-            instanceRes.emplace(key->name(), leafValueFromValue(leaf.value(), leaf.leaf_type()->base()));
+            auto leaf = std::make_shared<libyang::Data_Node_Leaf_List>(*(vec.begin()));
+            instanceRes.emplace(key->name(), leafValueFromNode(leaf));
         }
         res.emplace_back(instanceRes);
     }
diff --git a/src/yang_access.cpp b/src/yang_access.cpp
index 8171c89..a460150 100644
--- a/src/yang_access.cpp
+++ b/src/yang_access.cpp
@@ -284,8 +284,8 @@
             if (child->schema()->nodetype() == LYS_LEAF) {
                 libyang::Schema_Node_Leaf leafSchema(child->schema());
                 if (leafSchema.is_key()) {
-                    libyang::Data_Node_Leaf_List leafData(child);
-                    instance.insert({leafSchema.name(), leafValueFromValue(leafData.value(), leafSchema.type()->base())});
+                    auto leafData = std::make_shared<libyang::Data_Node_Leaf_List>(child);
+                    instance.insert({leafSchema.name(), leafValueFromNode(leafData)});
                 }
             }
         }