"""Repository rule for Python autoconfiguration.

`python_configure` depends on the following environment variables:

  * `PYTHON_BIN_PATH`: location of python binary.
  * `PYTHON_LIB_PATH`: Location of python libraries.
"""

load(
    "//third_party/remote_config:common.bzl",
    "BAZEL_SH",
    "PYTHON_BIN_PATH",
    "PYTHON_LIB_PATH",
    "TF_PYTHON_CONFIG_REPO",
    "auto_config_fail",
    "config_repo_label",
    "execute",
    "get_bash_bin",
    "get_host_environ",
    "get_python_bin",
    "is_windows",
    "raw_exec",
    "read_dir",
)

def _genrule(src_dir, genrule_name, command, outs):
    """Returns a string with a genrule.

    Genrule executes the given command and produces the given outputs.
    """
    return (
        "genrule(\n" +
        '    name = "' +
        genrule_name + '",\n' +
        "    outs = [\n" +
        outs +
        "\n    ],\n" +
        '    cmd = """\n' +
        command +
        '\n   """,\n' +
        ")\n"
    )

def _norm_path(path):
    """Returns a path with '/' and remove the trailing slash."""
    path = path.replace("\\", "/")
    if path[-1] == "/":
        path = path[:-1]
    return path

def _symlink_genrule_for_dir(
        repository_ctx,
        src_dir,
        dest_dir,
        genrule_name,
        src_files = [],
        dest_files = []):
    """Returns a genrule to symlink(or copy if on Windows) a set of files.

    If src_dir is passed, files will be read from the given directory; otherwise
    we assume files are in src_files and dest_files
    """
    if src_dir != None:
        src_dir = _norm_path(src_dir)
        dest_dir = _norm_path(dest_dir)
        files = "\n".join(read_dir(repository_ctx, src_dir))

        # Create a list with the src_dir stripped to use for outputs.
        dest_files = files.replace(src_dir, "").splitlines()
        src_files = files.splitlines()
    command = []
    outs = []
    for i in range(len(dest_files)):
        if dest_files[i] != "":
            # If we have only one file to link we do not want to use the dest_dir, as
            # $(@D) will include the full path to the file.
            dest = "$(@D)/" + dest_dir + dest_files[i] if len(dest_files) != 1 else "$(@D)/" + dest_files[i]

            # Copy the headers to create a sandboxable setup.
            cmd = "cp -f"
            command.append(cmd + ' "%s" "%s"' % (src_files[i], dest))
            outs.append('        "' + dest_dir + dest_files[i] + '",')
    genrule = _genrule(
        src_dir,
        genrule_name,
        " && ".join(command),
        "\n".join(outs),
    )
    return genrule

def _get_python_lib(repository_ctx, python_bin):
    """Gets the python lib path."""
    python_lib = get_host_environ(repository_ctx, PYTHON_LIB_PATH)
    if python_lib != None:
        return python_lib

    # The interesting program to execute.
    print_lib = [
        "from __future__ import print_function",
        "import site",
        "import os",
        "python_paths = []",
        "if os.getenv('PYTHONPATH') is not None:",
        "  python_paths = os.getenv('PYTHONPATH').split(':')",
        "try:",
        "  library_paths = site.getsitepackages()",
        "except AttributeError:",
        "  from distutils.sysconfig import get_python_lib",
        "  library_paths = [get_python_lib()]",
        "all_paths = set(python_paths + library_paths)",
        "paths = []",
        "for path in all_paths:",
        "  if os.path.isdir(path):",
        "    paths.append(path)",
        "if len(paths) >=1:",
        "  print(paths[0])",
    ]

    # The below script writes the above program to a file
    # and executes it. This is to work around the limitation
    # of not being able to upload files as part of execute.
    cmd = "from os import linesep;"
    cmd += "f = open('script.py', 'w');"
    for line in print_lib:
        cmd += "f.write(\"%s\" + linesep);" % line
    cmd += "f.close();"
    cmd += "from os import system;"
    cmd += "system(\"%s script.py\");" % python_bin

    result = execute(repository_ctx, [python_bin, "-c", cmd])
    return result.stdout.strip()

def _check_python_lib(repository_ctx, python_lib):
    """Checks the python lib path."""
    cmd = 'test -d "%s" -a -x "%s"' % (python_lib, python_lib)
    result = raw_exec(repository_ctx, [get_bash_bin(repository_ctx), "-c", cmd])
    if result.return_code == 1:
        auto_config_fail("Invalid python library path: %s" % python_lib)

def _check_python_bin(repository_ctx, python_bin):
    """Checks the python bin path."""
    cmd = '[[ -x "%s" ]] && [[ ! -d "%s" ]]' % (python_bin, python_bin)
    result = raw_exec(repository_ctx, [get_bash_bin(repository_ctx), "-c", cmd])
    if result.return_code == 1:
        auto_config_fail("--define %s='%s' is not executable. Is it the python binary?" % (
            PYTHON_BIN_PATH,
            python_bin,
        ))

def _get_python_include(repository_ctx, python_bin):
    """Gets the python include path."""
    result = execute(
        repository_ctx,
        [
            python_bin,
            "-c",
            "from __future__ import print_function;" +
            "from distutils import sysconfig;" +
            "print(sysconfig.get_python_inc())",
        ],
        error_msg = "Problem getting python include path.",
        error_details = ("Is the Python binary path set up right? " +
                         "(See ./configure or " + PYTHON_BIN_PATH + ".) " +
                         "Is distutils installed?"),
    )
    return result.stdout.splitlines()[0]

def _get_python_import_lib_name(repository_ctx, python_bin):
    """Get Python import library name (pythonXY.lib) on Windows."""
    result = execute(
        repository_ctx,
        [
            python_bin,
            "-c",
            "import sys;" +
            'print("python" + str(sys.version_info[0]) + ' +
            '      str(sys.version_info[1]) + ".lib")',
        ],
        error_msg = "Problem getting python import library.",
        error_details = ("Is the Python binary path set up right? " +
                         "(See ./configure or " + PYTHON_BIN_PATH + ".) "),
    )
    return result.stdout.splitlines()[0]

def _get_numpy_include(repository_ctx, python_bin):
    """Gets the numpy include path."""
    return execute(
        repository_ctx,
        [
            python_bin,
            "-c",
            "from __future__ import print_function;" +
            "import numpy;" +
            " print(numpy.get_include());",
        ],
        error_msg = "Problem getting numpy include path.",
        error_details = "Is numpy installed?",
    ).stdout.splitlines()[0]

def _create_local_python_repository(repository_ctx):
    """Creates the repository containing files set up to build with Python."""

    # Resolve all labels before doing any real work. Resolving causes the
    # function to be restarted with all previous state being lost. This
    # can easily lead to a O(n^2) runtime in the number of labels.
    build_tpl = repository_ctx.path(Label("//third_party/py:BUILD.tpl"))

    python_bin = get_python_bin(repository_ctx)
    _check_python_bin(repository_ctx, python_bin)
    python_lib = _get_python_lib(repository_ctx, python_bin)
    _check_python_lib(repository_ctx, python_lib)
    python_include = _get_python_include(repository_ctx, python_bin)
    numpy_include = _get_numpy_include(repository_ctx, python_bin) + "/numpy"
    python_include_rule = _symlink_genrule_for_dir(
        repository_ctx,
        python_include,
        "python_include",
        "python_include",
    )
    python_import_lib_genrule = ""

    # To build Python C/C++ extension on Windows, we need to link to python import library pythonXY.lib
    # See https://docs.python.org/3/extending/windows.html
    if is_windows(repository_ctx):
        python_include = _norm_path(python_include)
        python_import_lib_name = _get_python_import_lib_name(repository_ctx, python_bin)
        python_import_lib_src = python_include.rsplit("/", 1)[0] + "/libs/" + python_import_lib_name
        python_import_lib_genrule = _symlink_genrule_for_dir(
            repository_ctx,
            None,
            "",
            "python_import_lib",
            [python_import_lib_src],
            [python_import_lib_name],
        )
    numpy_include_rule = _symlink_genrule_for_dir(
        repository_ctx,
        numpy_include,
        "numpy_include/numpy",
        "numpy_include",
    )

    platform_constraint = ""
    if repository_ctx.attr.platform_constraint:
        platform_constraint = "\"%s\"" % repository_ctx.attr.platform_constraint
    repository_ctx.template("BUILD", build_tpl, {
        "%{PYTHON_BIN_PATH}": python_bin,
        "%{PYTHON_INCLUDE_GENRULE}": python_include_rule,
        "%{PYTHON_IMPORT_LIB_GENRULE}": python_import_lib_genrule,
        "%{NUMPY_INCLUDE_GENRULE}": numpy_include_rule,
        "%{PLATFORM_CONSTRAINT}": platform_constraint,
    })

def _create_remote_python_repository(repository_ctx, remote_config_repo):
    """Creates pointers to a remotely configured repo set up to build with Python.
    """
    repository_ctx.template("BUILD", config_repo_label(remote_config_repo, ":BUILD"), {})

def _python_autoconf_impl(repository_ctx):
    """Implementation of the python_autoconf repository rule."""
    if get_host_environ(repository_ctx, TF_PYTHON_CONFIG_REPO) != None:
        _create_remote_python_repository(
            repository_ctx,
            get_host_environ(repository_ctx, TF_PYTHON_CONFIG_REPO),
        )
    else:
        _create_local_python_repository(repository_ctx)

_ENVIRONS = [
    BAZEL_SH,
    PYTHON_BIN_PATH,
    PYTHON_LIB_PATH,
]

local_python_configure = repository_rule(
    implementation = _create_local_python_repository,
    environ = _ENVIRONS,
    attrs = {
        "environ": attr.string_dict(),
        "platform_constraint": attr.string(),
    },
)

remote_python_configure = repository_rule(
    implementation = _create_local_python_repository,
    environ = _ENVIRONS,
    remotable = True,
    attrs = {
        "environ": attr.string_dict(),
        "platform_constraint": attr.string(),
    },
)

python_configure = repository_rule(
    implementation = _python_autoconf_impl,
    environ = _ENVIRONS + [TF_PYTHON_CONFIG_REPO],
    attrs = {
        "platform_constraint": attr.string(),
    },
)
"""Detects and configures the local Python.

Add the following to your WORKSPACE FILE:

```python
python_configure(name = "local_config_python")
```

Args:
  name: A unique name for this workspace rule.
"""