# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

"""
Extract docstrings from pyarrow runtime and insert them into stub files.

Usage (from python/ directory with pyarrow built):
    python scripts/update_stub_docstrings.py pyarrow-stubs
"""

import argparse
import importlib
import inspect
import sys
from pathlib import Path
from textwrap import indent

import libcst
from libcst import matchers as m


def _resolve_object(module, path):
    """Resolve an object by dotted path from a module."""
    if not path:
        return module, None, module.__name__

    parts = path.split(".")
    parent = None
    obj = module

    for part in parts:
        parent = obj
        try:
            obj = getattr(obj, part)
        except AttributeError:
            try:
                obj = vars(parent).get(part)
                if obj is not None:
                    continue
            except TypeError:
                pass
            return None, None, None

    return obj, parent, getattr(obj, "__name__", parts[-1])


def _get_docstring(name, module, indentation):
    """Extract and format a docstring for insertion into a stub file."""
    obj, parent, obj_name = _resolve_object(module, name)
    if obj is None:
        print(f"{name} not found in {module.__name__}")
        return None

    docstring = inspect.getdoc(obj)
    if not docstring:
        return None

    # Remove signature prefix
    parent_name = getattr(parent, "__name__", None) if parent else None
    if docstring.startswith(obj_name) or (
        parent_name and docstring.startswith(f"{parent_name}.{obj_name}")
    ):
        docstring = "\n".join(docstring.splitlines()[2:])

    # Skip empty docstrings
    if not docstring.strip():
        return None

    prefix = "    " * indentation
    return '"""\n' + indent(docstring + '\n"""', prefix)


class DocstringInserter(libcst.CSTTransformer):
    """CST transformer that inserts docstrings into stub file nodes."""

    def __init__(self, module, namespace):
        self.module = module
        self.base_namespace = namespace
        self.stack = []
        self.indentation = 0

    def _full_name(self):
        name = ".".join(self.stack)
        return f"{self.base_namespace}.{name}" if self.base_namespace else name

    def leave_Module(self, original_node, updated_node):
        new_body = []
        clone_matcher = m.SimpleStatementLine(
            body=[m.Assign(value=m.Call(func=m.Name(value="_clone_signature"))),
                  m.ZeroOrMore()]
        )
        for stmt in updated_node.body:
            new_body.append(stmt)
            if m.matches(stmt, clone_matcher):
                name = stmt.body[0].targets[0].target.value
                if self.base_namespace:
                    name = f"{self.base_namespace}.{name}"
                docstring = _get_docstring(name, self.module, 0)
                if docstring:
                    new_body.append(libcst.SimpleStatementLine(
                        body=[libcst.Expr(value=libcst.SimpleString(docstring))]))
        return updated_node.with_changes(body=new_body)

    def visit_ClassDef(self, node):
        self.stack.append(node.name.value)
        self.indentation += 1

    def leave_ClassDef(self, original_node, updated_node):
        name = self._full_name()
        docstring = _get_docstring(name, self.module, self.indentation)

        if docstring:
            ellipsis_class = m.ClassDef(body=m.IndentedBlock(body=[
                m.SimpleStatementLine(body=[
                    m.Expr(m.Ellipsis()), m.ZeroOrMore()]), m.ZeroOrMore()]))
            func_class = m.ClassDef(body=m.IndentedBlock(
                body=[m.FunctionDef(), m.ZeroOrMore()]))

            if m.matches(updated_node, ellipsis_class):
                updated_node = updated_node.deep_replace(
                    updated_node.body.body[0].body[0].value,
                    libcst.SimpleString(value=docstring))
            elif m.matches(updated_node, func_class):
                docstring_stmt = libcst.SimpleStatementLine(
                    body=[libcst.Expr(value=libcst.SimpleString(value=docstring))])
                updated_node = updated_node.with_changes(
                    body=updated_node.body.with_changes(
                        body=[docstring_stmt] + list(updated_node.body.body)))

        self.stack.pop()
        self.indentation -= 1
        return updated_node

    def visit_FunctionDef(self, node):
        self.stack.append(node.name.value)
        self.indentation += 1

    def leave_FunctionDef(self, original_node, updated_node):
        name = self._full_name()
        ellipsis_func = m.FunctionDef(
            body=m.SimpleStatementSuite(body=[m.Expr(m.Ellipsis())]))

        if m.matches(original_node, ellipsis_func):
            docstring = _get_docstring(name, self.module, self.indentation)
            if docstring:
                docstring_stmt = libcst.SimpleStatementLine(
                    body=[libcst.Expr(value=libcst.SimpleString(value=docstring))])
                updated_node = updated_node.with_changes(
                    body=libcst.IndentedBlock(body=[docstring_stmt]))

        self.stack.pop()
        self.indentation -= 1
        return updated_node


LIB_MODULES = {"array", "builder", "compat", "config", "device", "error", "io",
               "_ipc", "memory", "pandas_shim", "scalar", "table", "tensor", "_types"}


def add_docstrings_to_stubs(stubs_dir):
    """Update all stub files in stubs_dir with docstrings from pyarrow runtime."""
    stubs_dir = Path(stubs_dir)
    print(f"Updating stub docstrings in: {stubs_dir}")

    pyarrow = importlib.import_module("pyarrow")

    for stub_file in stubs_dir.rglob('*.pyi'):
        if stub_file.name == "_stubs_typing.pyi":
            continue

        module_name = stub_file.stem
        if module_name in LIB_MODULES:
            namespace = "lib"
        elif stub_file.parent.name in ("parquet", "interchange"):
            namespace = f"{stub_file.parent.name}.{module_name}"
        elif module_name == "__init__":
            namespace = ""
        else:
            namespace = module_name

        print(f"  {stub_file.name} -> {namespace or '(root)'}")
        tree = libcst.parse_module(stub_file.read_text())
        modified = tree.visit(DocstringInserter(pyarrow, namespace))
        stub_file.write_text(modified.code)


def add_docstrings_from_build(stubs_dir, build_lib):
    """
    Entry point for setup.py: update docstrings using pyarrow from build directory.

    During the build process, pyarrow is not installed in the system Python.
    We need to temporarily add the build directory to sys.path so we can
    import pyarrow and extract docstrings from it.
    """
    stubs_dir, build_lib = Path(stubs_dir), Path(build_lib)

    sys.path.insert(0, str(build_lib))
    try:
        add_docstrings_to_stubs(stubs_dir)
    finally:
        sys.path.pop(0)


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("stubs_dir", type=Path, help="Path to pyarrow-stubs folder")
    args = parser.parse_args()

    # Add the directory containing this script's parent (python/) to sys.path
    # so pyarrow can be imported when running from the python/ directory
    script_dir = Path(__file__).resolve().parent
    python_dir = script_dir.parent
    sys.path.insert(0, str(python_dir))
    add_docstrings_to_stubs(args.stubs_dir.resolve())