# Copyright 2018 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.

"""Rules for building wheels."""

def _path_inside_wheel(input_file):
    # input_file.short_path is sometimes relative ("../${repository_root}/foobar")
    # which is not a valid path within a zip file. Fix that.
    short_path = input_file.short_path
    if short_path.startswith('..') and len(short_path) >= 3:
        # Path separator. '/' on linux.
        separator = short_path[2]
        # Consume '../' part.
        short_path = short_path[3:]
        # Find position of next '/' and consume everything up to that character.
        pos = short_path.find(separator)
        short_path = short_path[pos+1:]
    return short_path

def _input_file_to_arg(input_file):
    """Converts a File object to string for --input_file argument to wheelmaker"""
    return "%s;%s" % (_path_inside_wheel(input_file), input_file.path)

def _py_package_impl(ctx):
    inputs = depset(
        transitive = [dep[DefaultInfo].data_runfiles.files for dep in ctx.attr.deps] +
                     [dep[DefaultInfo].default_runfiles.files for dep in ctx.attr.deps],
    )

    # TODO: '/' is wrong on windows, but the path separator is not available in skylark.
    # Fix this once ctx.configuration has directory separator information.
    packages = [p.replace(".", "/") for p in ctx.attr.packages]
    if not packages:
        filtered_inputs = inputs
    else:
        filtered_files = []

        # TODO: flattening depset to list gives poor performance,
        for input_file in inputs.to_list():
            wheel_path = _path_inside_wheel(input_file)
            for package in packages:
                if wheel_path.startswith(package):
                    filtered_files.append(input_file)
        filtered_inputs = depset(direct = filtered_files)

    return [DefaultInfo(
        files = filtered_inputs,
    )]

py_package = rule(
    implementation = _py_package_impl,
    doc = """
A rule to select all files in transitive dependencies of deps which
belong to given set of Python packages.

This rule is intended to be used as data dependency to py_wheel rule
""",
    attrs = {
        "deps": attr.label_list(),
        "packages": attr.string_list(
            mandatory = False,
            allow_empty = True,
            doc = """\
List of Python packages to include in the distribution.
Sub-packages are automatically included.
""",
        ),
    },
)

def _py_wheel_impl(ctx):
    outfile = ctx.actions.declare_file("-".join([
        ctx.attr.distribution,
        ctx.attr.version,
        ctx.attr.python_tag,
        ctx.attr.abi,
        ctx.attr.platform,
    ]) + ".whl")

    inputs_to_package = depset(
        direct = ctx.files.deps,
    )

    # Inputs to this rule which are not to be packaged.
    # Currently this is only the description file (if used).
    other_inputs = []

    args = ctx.actions.args()
    args.add("--name", ctx.attr.distribution)
    args.add("--version", ctx.attr.version)
    args.add("--python_tag", ctx.attr.python_tag)
    args.add("--abi", ctx.attr.abi)
    args.add("--platform", ctx.attr.platform)
    args.add("--out", outfile.path)
    args.add_all(ctx.attr.strip_path_prefixes, format_each = "--strip_path_prefix=%s")

    args.add_all(inputs_to_package, format_each = "--input_file=%s", map_each = _input_file_to_arg)

    extra_headers = []
    if ctx.attr.author:
        extra_headers.append("Author: %s" % ctx.attr.author)
    if ctx.attr.author_email:
        extra_headers.append("Author-email: %s" % ctx.attr.author_email)
    if ctx.attr.homepage:
        extra_headers.append("Home-page: %s" % ctx.attr.homepage)
    if ctx.attr.license:
        extra_headers.append("License: %s" % ctx.attr.license)

    for h in extra_headers:
        args.add("--header", h)

    for c in ctx.attr.classifiers:
        args.add("--classifier", c)

    for r in ctx.attr.requires:
        args.add("--requires", r)

    for option, requirements in ctx.attr.extra_requires.items():
        for r in requirements:
            args.add("--extra_requires", r + ";" + option)

    for name, ref in ctx.attr.console_scripts.items():
        args.add("--console_script", name + " = " + ref)

    if ctx.attr.description_file:
        description_file = ctx.file.description_file
        args.add("--description_file", description_file)
        other_inputs.append(description_file)

    ctx.actions.run(
        inputs = depset(direct = other_inputs, transitive = [inputs_to_package]),
        outputs = [outfile],
        arguments = [args],
        executable = ctx.executable._wheelmaker,
        progress_message = "Building wheel",
    )
    return [DefaultInfo(
        files = depset([outfile]),
        data_runfiles = ctx.runfiles(files = [outfile]),
    )]

py_wheel = rule(
    implementation = _py_wheel_impl,
    doc = """
A rule for building Python Wheels.

Wheels are Python distribution format defined in https://www.python.org/dev/peps/pep-0427/.

This rule packages a set of targets into a single wheel.

Currently only pure-python wheels are supported.

Examples:

<code>
# Package just a specific py_libraries, without their dependencies
py_wheel(
    name = "minimal_with_py_library",
    # Package data. We're building "example_minimal_library-0.0.1-py3-none-any.whl"
    distribution = "example_minimal_library",
    python_tag = "py3",
    version = "0.0.1",
    deps = [
        "//experimental/examples/wheel/lib:module_with_data",
        "//experimental/examples/wheel/lib:simple_module",
    ],
)

# Use py_package to collect all transitive dependencies of a target,
# selecting just the files within a specific python package.
py_package(
    name = "example_pkg",
    # Only include these Python packages.
    packages = ["experimental.examples.wheel"],
    deps = [":main"],
)

py_wheel(
    name = "minimal_with_py_package",
    # Package data. We're building "example_minimal_package-0.0.1-py3-none-any.whl"
    distribution = "example_minimal_package",
    python_tag = "py3",
    version = "0.0.1",
    deps = [":example_pkg"],
)
</code>
""",
    attrs = {
        "deps": attr.label_list(
            doc = """\
Targets to be included in the distribution.

The targets to package are usually `py_library` rules or filesets (for packaging data files).

Note it's usually better to package `py_library` targets and use
`console_scripts` attribute to specify entry points than to package
`py_binary` rules. `py_binary` targets would wrap a executable script that
tries to locate `.runfiles` directory which is not packaged in the wheel.
""",
        ),
        # Attributes defining the distribution
        "distribution": attr.string(
            mandatory = True,
            doc = """
Name of the distribution.

This should match the project name onm PyPI. It's also the name that is used
to refer to the package in other packages' dependencies.
""",
        ),
        "version": attr.string(
            mandatory = True,
            doc = "Version number of the package",
        ),
        "python_tag": attr.string(
            default = "py3",
            doc = "Supported Python major version. 'py2' or 'py3'",
            values = ["py2", "py3"],
        ),
        "abi": attr.string(
            default = "none",
            doc = "Python ABI tag. 'none' for pure-Python wheels.",
        ),
        # TODO(pstradomski): Support non-pure wheels
        "platform": attr.string(
            default = "any",
            doc = "Supported platforms. 'any' for pure-Python wheel.",
        ),
        # Other attributes
        "author": attr.string(default = ""),
        "author_email": attr.string(default = ""),
        "homepage": attr.string(default = ""),
        "license": attr.string(default = ""),
        "classifiers": attr.string_list(),
        "description_file": attr.label(allow_single_file = True),
        "strip_path_prefixes": attr.string_list(
            default = [],
            doc = "path prefixes to strip from files added to the generated package",
        ),
        # Requirements
        "requires": attr.string_list(
            doc = "List of requirements for this package",
        ),
        "extra_requires": attr.string_list_dict(
            doc = "List of optional requirements for this package",
        ),
        # Entry points
        "console_scripts": attr.string_dict(
            doc = """\
console_script entry points, e.g. 'experimental.examples.wheel.main:main'.
""",
        ),
        # Implementation details.
        "_wheelmaker": attr.label(
            executable = True,
            cfg = "host",
            default = "//experimental/rules_python:wheelmaker",
        ),
    },
)