3 files changed, 197 insertions, 0 deletions
diff --git a/src/aristaproto/compile/__init__.py b/src/aristaproto/compile/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/aristaproto/compile/__init__.py
diff --git a/src/aristaproto/compile/importing.py b/src/aristaproto/compile/importing.py
new file mode 100644
index 0000000..8486ddd
--- /dev/null
+++ b/src/aristaproto/compile/importing.py
@@ -0,0 +1,176 @@
+import os
+import re
+from typing import (
+    Dict,
+    List,
+    Set,
+    Tuple,
+    Type,
+)
+
+from ..casing import safe_snake_case
+from ..lib.google import protobuf as google_protobuf
+from .naming import pythonize_class_name
+
+
+WRAPPER_TYPES: Dict[str, Type] = {
+    ".google.protobuf.DoubleValue": google_protobuf.DoubleValue,
+    ".google.protobuf.FloatValue": google_protobuf.FloatValue,
+    ".google.protobuf.Int32Value": google_protobuf.Int32Value,
+    ".google.protobuf.Int64Value": google_protobuf.Int64Value,
+    ".google.protobuf.UInt32Value": google_protobuf.UInt32Value,
+    ".google.protobuf.UInt64Value": google_protobuf.UInt64Value,
+    ".google.protobuf.BoolValue": google_protobuf.BoolValue,
+    ".google.protobuf.StringValue": google_protobuf.StringValue,
+    ".google.protobuf.BytesValue": google_protobuf.BytesValue,
+}
+
+
+def parse_source_type_name(field_type_name: str) -> Tuple[str, str]:
+    """
+    Split full source type name into package and type name.
+    E.g. 'root.package.Message' -> ('root.package', 'Message')
+         'root.Message.SomeEnum' -> ('root', 'Message.SomeEnum')
+    """
+    package_match = re.match(r"^\.?([^A-Z]+)\.(.+)", field_type_name)
+    if package_match:
+        package = package_match.group(1)
+        name = package_match.group(2)
+    else:
+        package = ""
+        name = field_type_name.lstrip(".")
+    return package, name
+
+
+def get_type_reference(
+    *,
+    package: str,
+    imports: set,
+    source_type: str,
+    unwrap: bool = True,
+    pydantic: bool = False,
+) -> str:
+    """
+    Return a Python type name for a proto type reference. Adds the import if
+    necessary. Unwraps well known type if required.
+    """
+    if unwrap:
+        if source_type in WRAPPER_TYPES:
+            wrapped_type = type(WRAPPER_TYPES[source_type]().value)
+            return f"Optional[{wrapped_type.__name__}]"
+
+        if source_type == ".google.protobuf.Duration":
+            return "timedelta"
+
+        elif source_type == ".google.protobuf.Timestamp":
+            return "datetime"
+
+    source_package, source_type = parse_source_type_name(source_type)
+
+    current_package: List[str] = package.split(".") if package else []
+    py_package: List[str] = source_package.split(".") if source_package else []
+    py_type: str = pythonize_class_name(source_type)
+
+    compiling_google_protobuf = current_package == ["google", "protobuf"]
+    importing_google_protobuf = py_package == ["google", "protobuf"]
+    if importing_google_protobuf and not compiling_google_protobuf:
+        py_package = (
+            ["aristaproto", "lib"] + (["pydantic"] if pydantic else []) + py_package
+        )
+
+    if py_package[:1] == ["aristaproto"]:
+        return reference_absolute(imports, py_package, py_type)
+
+    if py_package == current_package:
+        return reference_sibling(py_type)
+
+    if py_package[: len(current_package)] == current_package:
+        return reference_descendent(current_package, imports, py_package, py_type)
+
+    if current_package[: len(py_package)] == py_package:
+        return reference_ancestor(current_package, imports, py_package, py_type)
+
+    return reference_cousin(current_package, imports, py_package, py_type)
+
+
+def reference_absolute(imports: Set[str], py_package: List[str], py_type: str) -> str:
+    """
+    Returns a reference to a python type located in the root, i.e. sys.path.
+    """
+    string_import = ".".join(py_package)
+    string_alias = safe_snake_case(string_import)
+    imports.add(f"import {string_import} as {string_alias}")
+    return f'"{string_alias}.{py_type}"'
+
+
+def reference_sibling(py_type: str) -> str:
+    """
+    Returns a reference to a python type within the same package as the current package.
+    """
+    return f'"{py_type}"'
+
+
+def reference_descendent(
+    current_package: List[str], imports: Set[str], py_package: List[str], py_type: str
+) -> str:
+    """
+    Returns a reference to a python type in a package that is a descendent of the
+    current package, and adds the required import that is aliased to avoid name
+    conflicts.
+    """
+    importing_descendent = py_package[len(current_package) :]
+    string_from = ".".join(importing_descendent[:-1])
+    string_import = importing_descendent[-1]
+    if string_from:
+        string_alias = "_".join(importing_descendent)
+        imports.add(f"from .{string_from} import {string_import} as {string_alias}")
+        return f'"{string_alias}.{py_type}"'
+    else:
+        imports.add(f"from . import {string_import}")
+        return f'"{string_import}.{py_type}"'
+
+
+def reference_ancestor(
+    current_package: List[str], imports: Set[str], py_package: List[str], py_type: str
+) -> str:
+    """
+    Returns a reference to a python type in a package which is an ancestor to the
+    current package, and adds the required import that is aliased (if possible) to avoid
+    name conflicts.
+
+    Adds trailing __ to avoid name mangling (python.org/dev/peps/pep-0008/#id34).
+    """
+    distance_up = len(current_package) - len(py_package)
+    if py_package:
+        string_import = py_package[-1]
+        string_alias = f"_{'_' * distance_up}{string_import}__"
+        string_from = f"..{'.' * distance_up}"
+        imports.add(f"from {string_from} import {string_import} as {string_alias}")
+        return f'"{string_alias}.{py_type}"'
+    else:
+        string_alias = f"{'_' * distance_up}{py_type}__"
+        imports.add(f"from .{'.' * distance_up} import {py_type} as {string_alias}")
+        return f'"{string_alias}"'
+
+
+def reference_cousin(
+    current_package: List[str], imports: Set[str], py_package: List[str], py_type: str
+) -> str:
+    """
+    Returns a reference to a python type in a package that is not descendent, ancestor
+    or sibling, and adds the required import that is aliased to avoid name conflicts.
+    """
+    shared_ancestry = os.path.commonprefix([current_package, py_package])  # type: ignore
+    distance_up = len(current_package) - len(shared_ancestry)
+    string_from = f".{'.' * distance_up}" + ".".join(
+        py_package[len(shared_ancestry) : -1]
+    )
+    string_import = py_package[-1]
+    # Add trailing __ to avoid name mangling (python.org/dev/peps/pep-0008/#id34)
+    string_alias = (
+        f"{'_' * distance_up}"
+        + safe_snake_case(".".join(py_package[len(shared_ancestry) :]))
+        + "__"
+    )
+    imports.add(f"from {string_from} import {string_import} as {string_alias}")
+    return f'"{string_alias}.{py_type}"'
diff --git a/src/aristaproto/compile/naming.py b/src/aristaproto/compile/naming.py
new file mode 100644
index 0000000..0c45dde
--- /dev/null
+++ b/src/aristaproto/compile/naming.py
@@ -0,0 +1,21 @@
+from aristaproto import casing
+
+
+def pythonize_class_name(name: str) -> str:
+    return casing.pascal_case(name)
+
+
+def pythonize_field_name(name: str) -> str:
+    return casing.safe_snake_case(name)
+
+
+def pythonize_method_name(name: str) -> str:
+    return casing.safe_snake_case(name)
+
+
+def pythonize_enum_member_name(name: str, enum_name: str) -> str:
+    enum_name = casing.snake_case(enum_name).upper()
+    find = name.find(enum_name)
+    if find != -1:
+        name = name[find + len(enum_name) :].strip("_")
+    return casing.sanitize_name(name)