diff --git a/slither/utils/code_generation.py b/slither/utils/code_generation.py
index bb8344d8fb..2157570101 100644
--- a/slither/utils/code_generation.py
+++ b/slither/utils/code_generation.py
@@ -12,16 +12,18 @@
     MappingType,
     ArrayType,
     ElementaryType,
+    TypeAlias,
 )
-from slither.core.declarations import Structure, Enum, Contract
+from slither.core.declarations import Structure, StructureContract, Enum, Contract
 
 if TYPE_CHECKING:
     from slither.core.declarations import FunctionContract, CustomErrorContract
     from slither.core.variables.state_variable import StateVariable
     from slither.core.variables.local_variable import LocalVariable
+    from slither.core.variables.structure_variable import StructureVariable
 
 
-# pylint: disable=too-many-arguments
+# pylint: disable=too-many-arguments,too-many-locals,too-many-branches
 def generate_interface(
     contract: "Contract",
     unroll_structs: bool = True,
@@ -56,12 +58,47 @@ def generate_interface(
         for enum in contract.enums:
             interface += f"    enum {enum.name} {{ {', '.join(enum.values)} }}\n"
     if include_structs:
-        for struct in contract.structures:
+        # Include structures defined in this contract and at the top level
+        structs = contract.structures + contract.compilation_unit.structures_top_level
+        # Function signatures may reference other structures as well
+        # Include structures defined in libraries used for them
+        for _for in contract.using_for.keys():
+            if (
+                isinstance(_for, UserDefinedType)
+                and isinstance(_for.type, StructureContract)
+                and _for.type not in structs
+            ):
+                structs.append(_for.type)
+        # Include any other structures used as function arguments/returns
+        for func in contract.functions_entry_points:
+            for arg in func.parameters + func.returns:
+                _type = arg.type
+                if isinstance(_type, ArrayType):
+                    _type = _type.type
+                while isinstance(_type, MappingType):
+                    _type = _type.type_to
+                if isinstance(_type, UserDefinedType):
+                    _type = _type.type
+                if isinstance(_type, Structure) and _type not in structs:
+                    structs.append(_type)
+        for struct in structs:
             interface += generate_struct_interface_str(struct, indent=4)
+            for elem in struct.elems_ordered:
+                if (
+                    isinstance(elem.type, UserDefinedType)
+                    and isinstance(elem.type.type, StructureContract)
+                    and elem.type.type not in structs
+                ):
+                    structs.append(elem.type.type)
     for var in contract.state_variables_entry_points:
-        interface += f"    function {generate_interface_variable_signature(var, unroll_structs)};\n"
+        # if any(func.name == var.name for func in contract.functions_entry_points):
+        #     # ignore public variables that override a public function
+        #     continue
+        var_sig = generate_interface_variable_signature(var, unroll_structs)
+        if var_sig is not None and var_sig != "":
+            interface += f"    function {var_sig};\n"
     for func in contract.functions_entry_points:
-        if func.is_constructor or func.is_fallback or func.is_receive:
+        if func.is_constructor or func.is_fallback or func.is_receive or not func.is_implemented:
             continue
         interface += (
             f"    function {generate_interface_function_signature(func, unroll_structs)};\n"
@@ -75,6 +112,10 @@ def generate_interface_variable_signature(
 ) -> Optional[str]:
     if var.visibility in ["private", "internal"]:
         return None
+    if isinstance(var.type, UserDefinedType) and isinstance(var.type.type, Structure):
+        for elem in var.type.type.elems_ordered:
+            if isinstance(elem.type, MappingType):
+                return ""
     if unroll_structs:
         params = [
             convert_type_for_solidity_signature_to_string(x).replace("(", "").replace(")", "")
@@ -93,6 +134,11 @@ def generate_interface_variable_signature(
             _type = _type.type_to
         while isinstance(_type, (ArrayType, UserDefinedType)):
             _type = _type.type
+        if isinstance(_type, TypeAlias):
+            _type = _type.type
+        if isinstance(_type, Structure):
+            if any(isinstance(elem.type, MappingType) for elem in _type.elems_ordered):
+                return ""
         ret = str(_type)
         if isinstance(_type, Structure) or (isinstance(_type, Type) and _type.is_dynamic):
             ret += " memory"
@@ -125,6 +171,8 @@ def format_var(var: "LocalVariable", unroll: bool) -> str:
                 .replace("(", "")
                 .replace(")", "")
             )
+        if var.type.is_dynamic:
+            return f"{_handle_dynamic_struct_elem(var.type)} {var.location}"
         if isinstance(var.type, ArrayType) and isinstance(
             var.type.type, (UserDefinedType, ElementaryType)
         ):
@@ -135,12 +183,14 @@ def format_var(var: "LocalVariable", unroll: bool) -> str:
                 + f" {var.location}"
             )
         if isinstance(var.type, UserDefinedType):
-            if isinstance(var.type.type, (Structure, Enum)):
+            if isinstance(var.type.type, Structure):
                 return f"{str(var.type.type)} memory"
+            if isinstance(var.type.type, Enum):
+                return str(var.type.type)
             if isinstance(var.type.type, Contract):
                 return "address"
-        if var.type.is_dynamic:
-            return f"{var.type} {var.location}"
+        if isinstance(var.type, TypeAlias):
+            return str(var.type.type)
         return str(var.type)
 
     name, _, _ = func.signature
@@ -154,6 +204,12 @@ def format_var(var: "LocalVariable", unroll: bool) -> str:
     view = " view" if func.view and not func.pure else ""
     pure = " pure" if func.pure else ""
     payable = " payable" if func.payable else ""
+    # Make sure the function doesn't return a struct with nested mappings
+    for ret in func.returns:
+        if isinstance(ret.type, UserDefinedType) and isinstance(ret.type.type, Structure):
+            for elem in ret.type.type.elems_ordered:
+                if isinstance(elem.type, MappingType):
+                    return ""
     returns = [format_var(ret, unroll_structs) for ret in func.returns]
     parameters = [format_var(param, unroll_structs) for param in func.parameters]
     _interface_signature_str = (
@@ -184,17 +240,49 @@ def generate_struct_interface_str(struct: "Structure", indent: int = 0) -> str:
         spaces += " "
     definition = f"{spaces}struct {struct.name} {{\n"
     for elem in struct.elems_ordered:
-        if isinstance(elem.type, UserDefinedType):
-            if isinstance(elem.type.type, (Structure, Enum)):
+        if elem.type.is_dynamic:
+            definition += f"{spaces}    {_handle_dynamic_struct_elem(elem.type)} {elem.name};\n"
+        elif isinstance(elem.type, UserDefinedType):
+            if isinstance(elem.type.type, Structure):
                 definition += f"{spaces}    {elem.type.type} {elem.name};\n"
-            elif isinstance(elem.type.type, Contract):
-                definition += f"{spaces}    address {elem.name};\n"
+            else:
+                definition += f"{spaces}    {convert_type_for_solidity_signature_to_string(elem.type)} {elem.name};\n"
+        elif isinstance(elem.type, TypeAlias):
+            definition += f"{spaces}    {elem.type.type} {elem.name};\n"
         else:
             definition += f"{spaces}    {elem.type} {elem.name};\n"
     definition += f"{spaces}}}\n"
     return definition
 
 
+def _handle_dynamic_struct_elem(elem_type: Type) -> str:
+    assert elem_type.is_dynamic
+    if isinstance(elem_type, ElementaryType):
+        return f"{elem_type}"
+    if isinstance(elem_type, ArrayType):
+        base_type = elem_type.type
+        if isinstance(base_type, UserDefinedType):
+            if isinstance(base_type.type, Contract):
+                return "address[]"
+            if isinstance(base_type.type, Enum):
+                return convert_type_for_solidity_signature_to_string(elem_type)
+            return f"{base_type.type.name}[]"
+        return f"{base_type}[]"
+    if isinstance(elem_type, MappingType):
+        type_to = elem_type.type_to
+        type_from = elem_type.type_from
+        if isinstance(type_from, UserDefinedType) and isinstance(type_from.type, Contract):
+            type_from = ElementaryType("address")
+        if isinstance(type_to, MappingType):
+            return f"mapping({type_from} => {_handle_dynamic_struct_elem(type_to)})"
+        if isinstance(type_to, UserDefinedType):
+            if isinstance(type_to.type, Contract):
+                return f"mapping({type_from} => address)"
+            return f"mapping({type_from} => {type_to.type.name})"
+        return f"{elem_type}"
+    return ""
+
+
 def generate_custom_error_interface(
     error: "CustomErrorContract", unroll_structs: bool = True
 ) -> str:
diff --git a/tests/unit/utils/test_data/code_generation/CodeGeneration.sol b/tests/unit/utils/test_data/code_generation/CodeGeneration.sol
index 6f1f63c72f..292a4b43f7 100644
--- a/tests/unit/utils/test_data/code_generation/CodeGeneration.sol
+++ b/tests/unit/utils/test_data/code_generation/CodeGeneration.sol
@@ -1,7 +1,10 @@
 pragma solidity ^0.8.4;
+
+import "./IFee.sol";
+
 interface I {
-  enum SomeEnum { ONE, TWO, THREE }
-  error ErrorWithEnum(SomeEnum e);
+    enum SomeEnum { ONE, TWO, THREE }
+    error ErrorWithEnum(SomeEnum e);
 }
 
 contract TestContract is I {
@@ -62,4 +65,10 @@ contract TestContract is I {
     function setOtherI(I _i) public {
         otherI = _i;
     }
+
+    function newFee(uint128 fee) public returns (IFee.Fee memory) {
+        IFee.Fee memory _fee;
+        _fee.fee = fee;
+        return _fee;
+    }
 }
\ No newline at end of file
diff --git a/tests/unit/utils/test_data/code_generation/IFee.sol b/tests/unit/utils/test_data/code_generation/IFee.sol
new file mode 100644
index 0000000000..17560f60ce
--- /dev/null
+++ b/tests/unit/utils/test_data/code_generation/IFee.sol
@@ -0,0 +1,5 @@
+interface IFee {
+    struct Fee {
+        uint128 fee;
+    }
+}
diff --git a/tests/unit/utils/test_data/code_generation/TEST_generated_code.sol b/tests/unit/utils/test_data/code_generation/TEST_generated_code.sol
index 373fba9ca2..5240e10633 100644
--- a/tests/unit/utils/test_data/code_generation/TEST_generated_code.sol
+++ b/tests/unit/utils/test_data/code_generation/TEST_generated_code.sol
@@ -14,6 +14,9 @@ interface ITestContract {
     struct Nested {
         St st;
     }
+    struct Fee {
+        uint128 fee;
+    }
     function stateA() external returns (uint256);
     function owner() external returns (address);
     function structsMap(address,uint256) external returns (uint256);
@@ -26,5 +29,6 @@ interface ITestContract {
     function getSt(uint256) external view returns (uint256);
     function removeSt(uint256) external;
     function setOtherI(address) external;
+    function newFee(uint128) external returns (uint128);
 }
 
diff --git a/tests/unit/utils/test_data/code_generation/TEST_generated_code_not_unrolled.sol b/tests/unit/utils/test_data/code_generation/TEST_generated_code_not_unrolled.sol
index 0cc4dc0404..1154ec4cc4 100644
--- a/tests/unit/utils/test_data/code_generation/TEST_generated_code_not_unrolled.sol
+++ b/tests/unit/utils/test_data/code_generation/TEST_generated_code_not_unrolled.sol
@@ -14,6 +14,9 @@ interface ITestContract {
     struct Nested {
         St st;
     }
+    struct Fee {
+        uint128 fee;
+    }
     function stateA() external returns (uint256);
     function owner() external returns (address);
     function structsMap(address,uint256) external returns (St memory);
@@ -26,5 +29,6 @@ interface ITestContract {
     function getSt(uint256) external view returns (St memory);
     function removeSt(St memory) external;
     function setOtherI(address) external;
+    function newFee(uint128) external returns (Fee memory);
 }