# Copyright 2019 The Bazel Authors. All rights reserved.
#
# Licensed 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.

"""Core rules for building Python projects.

Currently the definitions here are re-exports of the native rules, "blessed" to
work under `--incompatible_load_python_rules_from_bzl`. As the native rules get
migrated to Starlark, their implementations will be moved here.
"""

load("@bazel_tools//tools/python:srcs_version.bzl", _find_requirements = "find_requirements")
load("@bazel_tools//tools/python:toolchain.bzl", _py_runtime_pair = "py_runtime_pair")
load("//python/private:reexports.bzl", "internal_PyInfo", "internal_PyRuntimeInfo")

# Exports of native-defined providers.

PyInfo = internal_PyInfo

PyRuntimeInfo = internal_PyRuntimeInfo

# The implementation of the macros and tagging mechanism follows the example
# set by rules_cc and rules_java.

_MIGRATION_TAG = "__PYTHON_RULES_MIGRATION_DO_NOT_USE_WILL_BREAK__"

def _add_tags(attrs):
    if "tags" in attrs and attrs["tags"] != None:
        attrs["tags"] = attrs["tags"] + [_MIGRATION_TAG]
    else:
        attrs["tags"] = [_MIGRATION_TAG]
    return attrs

def py_library(**attrs):
    """See the Bazel core [py_library](https://docs.bazel.build/versions/master/be/python.html#py_library) documentation.

    Args:
      **attrs: Rule attributes
    """

    # buildifier: disable=native-python
    native.py_library(**_add_tags(attrs))

def py_binary(**attrs):
    """See the Bazel core [py_binary](https://docs.bazel.build/versions/master/be/python.html#py_binary) documentation.

    Args:
      **attrs: Rule attributes
    """

    # buildifier: disable=native-python
    native.py_binary(**_add_tags(attrs))

def py_test(**attrs):
    """See the Bazel core [py_test](https://docs.bazel.build/versions/master/be/python.html#py_test) documentation.

    Args:
      **attrs: Rule attributes
    """

    # buildifier: disable=native-python
    native.py_test(**_add_tags(attrs))

def _py_import_impl(ctx):
    # See https://github.com/bazelbuild/bazel/blob/0.24.0/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPythonSemantics.java#L104 .
    import_paths = [
        "/".join([ctx.workspace_name, x.short_path])
        for x in ctx.files.srcs
    ]

    return [
        DefaultInfo(
            default_runfiles = ctx.runfiles(ctx.files.srcs, collect_default = True),
        ),
        PyInfo(
            transitive_sources = depset(transitive = [
                dep[PyInfo].transitive_sources
                for dep in ctx.attr.deps
            ]),
            imports = depset(direct = import_paths, transitive = [
                dep[PyInfo].imports
                for dep in ctx.attr.deps
            ]),
        ),
    ]

py_import = rule(
    doc = """This rule allows the use of Python packages as dependencies.

    It imports the given `.egg` file(s), which might be checked in source files,
    fetched externally as with `http_file`, or produced as outputs of other rules.

    It may be used like a `py_library`, in the `deps` of other Python rules.

    This is similar to [java_import](https://docs.bazel.build/versions/master/be/java.html#java_import).
    """,
    implementation = _py_import_impl,
    attrs = {
        "deps": attr.label_list(
            doc = "The list of other libraries to be linked in to the " +
                  "binary target.",
            providers = [PyInfo],
        ),
        "srcs": attr.label_list(
            doc = "The list of Python package files provided to Python targets " +
                  "that depend on this target. Note that currently only the .egg " +
                  "format is accepted. For .whl files, try the whl_library rule. " +
                  "We accept contributions to extend py_import to handle .whl.",
            allow_files = [".egg"],
        ),
    },
)

def py_runtime(**attrs):
    """See the Bazel core [py_runtime](https://docs.bazel.build/versions/master/be/python.html#py_runtime) documentation.

    Args:
      **attrs: Rule attributes
    """

    # buildifier: disable=native-python
    native.py_runtime(**_add_tags(attrs))

# Re-exports of Starlark-defined symbols in @bazel_tools//tools/python.

py_runtime_pair = _py_runtime_pair

find_requirements = _find_requirements