# Copyright 2017 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.

"""Repository Rules to generate toolchain configs for an RBE-ubuntu16-04 container.

Exposes the rbe_autoconfig macro that does the following:
- Pulls an rbe-ubuntu 16_04 image (using 'docker pull')
- Starts up a container using the rbe-ubuntu 16_04 image mounting the current project
- Installs the current version of Bazel (one currently running) on the container
  (or the one passed in with optional attr).
- Runs a bazel command to build the local_config_cc remote repository inside the container.
- Extracts local_config_cc produced files (inside the container) to the produced
  remote repository.
- Optionally copies the local_config_cc produced files to the project srcs under the
  given output_base directory

Add to your WORKSPACE file the following:

  load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive", "http_file")

  http_archive(
    name = "bazel_toolchains",
    urls = [
      "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/<latest_release>.tar.gz",
      "https://github.com/bazelbuild/bazel-toolchains/archive/<latest_release>.tar.gz",
    ],
    strip_prefix = "bazel-toolchains-<latest_commit>",
    sha256 = "<sha256>",
  )

  load(
    "@bazel_toolchains//repositories:repositories.bzl",
    bazel_toolchains_repositories = "repositories",
  )

  bazel_toolchains_repositories()

  load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")

  rbe_autoconfig(
    name = "rbe_default",
    # Optional. See below.
    output_base = "rbe-configs"
  )

For values of <latest_release> and other placeholders above, please see
the WORKSPACE file in this repo.

This rule depends on the value of the environment variable "RBE_AUTOCONF_ROOT"
when output_base is used.
This env var should be set to point to the absolute path root of your project.
Use the full absolute path to the project root (i.e., no '~', '../', or
other special chars).

There are two modes of using this repo rules:
  1 - When output_base set (recommended; env var "RBE_AUTOCONF_ROOT" is required),
    running the repo rule target will copy the toolchain config files to the
    output_base folder in the project sources.
    After that, you can run an RBE build pointing your crosstool_top flag to the
    produced files. If output_base is set to "rbe-configs" (recommended):

      bazel build ... \
                --crosstool_top=//rbe-configs/bazel_{bazel_version}:toolchain \
                --host_javabase=//rbe-configs/bazel_{bazel_version}/platforms:jdk8 \
                --javabase=//rbe-configs/bazel_{bazel_version}/platforms:jdk8 \
                --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8 \
                --java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8 \
                --extra_execution_platforms=/rbe-configs/bazel_{bazel_version}/platforms:rbe_ubuntu1604 \
                --host_platform=/rbe-configs/bazel_{bazel_version}/platforms:rbe_ubuntu1604 \
                --platforms=/rbe-configs/bazel_{bazel_version}/platforms:rbe_ubuntu1604 \
                --extra_toolchains=/rbe-configs/bazel_{bazel_version}/platforms:cc-toolchain \
                ... <other rbe flags> <build targets>

    We recommend you check in the code in //rbe-configs/bazel_{bazel_version}
    so that users typically do not need to run this repo rule in order to do a
    remote build (i.e., once files are checked in, you do not need to run this
    rule until there is a new version of Bazel you want to support running with).

  2 - When output_base is not set (env var "RBE_AUTOCONF_ROOT" is not required),
    running this rule will create targets in the
    external repository (e.g., rbe_default) which can be used to point your
    flags to:

      bazel build ... \
                --crosstool_top=@rbe_default//rbe_config_cc:toolchain \
                --host_javabase=@rbe_default//platforms:jdk8 \
                --javabase=@rbe_default//platforms:jdk8 \
                --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8 \
                --java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8 \
                --extra_execution_platforms=@rbe_default//platforms:rbe_ubuntu1604 \
                --host_platform=@rbe_default//platforms:rbe_ubuntu1604 \
                --platforms=@rbe_default//platforms:rbe_ubuntu1604 \
                --extra_toolchains=@rbe_default//platforms:cc-toolchain \

    Note running bazel clean --expunge_async, or otherwise modifying attrs or
    env variables used by this rule will trigger it to re-execute. Running this
    repo rule takes some time as it needs to pull a container, run it, and then
    run some commands inside. We recommend you use output_base and check in the produced
    files so you dont need to run this rule with every clean build.

The {bazel_version} above corresponds to the version of bazel installed locally.
Note you can override this version and pass an optional rc# if desired.
Running this rule with a non release version (e.g., built from source) will not work.
If running with bazel built from source you must pass a bazel_version and bazel_rc
to rbe_autoconfig. Also, note the bazel_version bazel_rc must be published in
https://releases.bazel.build/...

Note this is a very not hermetic repository rule that can actually change the
contents of your project sources. While this is generally not recommended by
Bazel, its the only reasonable way to get a rule that can produce valid
toolchains / platforms that need to be made available to Bazel before execution
of any build actions.

Note: this rule expects the following utilities to be installed and available on
the PATH:
  - docker
  - tar
  - bash utilities (e.g., cp, mv, rm, etc)

Known limitations:
  - This rule cannot be executed inside a docker container.
  - This rule can only run in Linux.
"""

load(
    "@bazel_toolchains//rules:version_check.bzl",
    "check_bazel_version",
    "extract_version_number",
    "parse_rc",
)
load(
    "@bazel_toolchains//rules:toolchain_containers.bzl",
    "RBE_UBUNTU16_04_LATEST",
    "public_rbe_ubuntu16_04_sha256s",
)

# External folder is set to be deprecated, lets keep it here for easy
# refactoring
# https://github.com/bazelbuild/bazel/issues/1262
_EXTERNAL_FOLDER_PREFIX = "external/"

_BAZEL_CONFIG_DIR = "/bazel-config"
_CONFIG_REPOS = ["local_config_cc"]
_PLATFORM_DIR = "platforms"
_PROJECT_REPO_DIR = "project_src"
_OUTPUT_DIR = _BAZEL_CONFIG_DIR + "/autoconf_out"
_REPO_DIR = _BAZEL_CONFIG_DIR + "/" + _PROJECT_REPO_DIR
_RBE_AUTOCONF_ROOT = "RBE_AUTOCONF_ROOT"
_RBE_CONFIG_DIR = "rbe_config_cc"

# We use 'l.gcr.io' to not require users to do gcloud login
_RBE_UBUNTU_GCR = "l.gcr.io/google/rbe-ubuntu16-04@"
_VERBOSE = False

def _impl(ctx):
    """Core implementation of _rbe_autoconfig repository rule."""

    # Perform some safety checks
    _validate_host(ctx)
    project_root = ctx.os.environ.get(_RBE_AUTOCONF_ROOT, None)
    use_default_project = False
    if not project_root:
        if ctx.attr.output_base != "":
            fail(("%s env variable must be set for rbe_autoconfig" +
                  " to function properly when output_base is set") % _RBE_AUTOCONF_ROOT)

        # Try to use the default project
        # This is Bazel black magic, we're traversing the directories in the output_base,
        # assuming that the bazel_toolchains external repo will exist in the
        # expected path.
        project_root = ctx.path(".").dirname.get_child("bazel_toolchains").get_child("rules").get_child("cc-sample-project")
        if not project_root.exists:
            fail("Could not find default autoconf project in %s, please make sure " +
                 "the bazel-toolchains repo is properly imported in your workspace")
        project_root = str(project_root)
        use_default_project = True

    name = ctx.attr.name
    outputs_tar = ctx.attr.name + "_out.tar"

    # Pull the image using 'docker pull'
    _pull_image(ctx)
    image_id = _RBE_UBUNTU_GCR + ctx.attr.digest

    bazel_version = None
    bazel_rc_version = None
    if ctx.attr.bazel_version == "local":
        check_bazel_version()
        bazel_version = str(extract_version_number(native.bazel_version))
        rc = parse_rc(native.bazel_version)
        bazel_rc_version = rc if rc != -1 else None
    if ctx.attr.bazel_version != "local":
        bazel_version = ctx.attr.bazel_version
        bazel_rc_version = ctx.attr.bazel_rc_version

    # run the container and extract the autoconf directory
    _run_and_extract(
        ctx,
        bazel_version = bazel_version,
        bazel_rc_version = bazel_rc_version,
        image_id = image_id,
        outputs_tar = outputs_tar,
        project_root = project_root,
        use_default_project = use_default_project,
    )

    # Create a default BUILD file with the platform + toolchain targets that
    # will work with RBE with the produced toolchain
    _create_platform(ctx, bazel_version = bazel_version, name = name)

    # Expand outputs to project dir if user requested it
    _expand_outputs(
        ctx,
        bazel_version = bazel_version,
        project_root = project_root,
    )

# Convenience method to print results of execute (and fail on errors if needed).
# Verbose logging is enabled via a global var in this bzl file.
def _print_exec_results(prefix, exec_result, fail = False, args = None):
    if _VERBOSE and exec_result.return_code != 0:
        print(prefix + "::error::" + exec_result.stderr)
    elif _VERBOSE:
        print(prefix + "::success::" + exec_result.stdout)
    if fail and exec_result.return_code != 0:
        if _VERBOSE and args:
            print("failed to run execute with the following args:" + str(args))
        fail("Failed to run:" + prefix + ":" + exec_result.stderr)

# Perform validations of host environment to be able to run the rule.
def _validate_host(ctx):
    if ctx.os.name.lower() != "linux":
        fail("Not running on linux host, cannot run rbe_autoconfig.")
    if not ctx.which("docker"):
        fail("Cannot run rbe_autoconfig as 'docker' was not found on the path.")
    if ctx.execute(["docker", "ps"]).return_code != 0:
        fail("Cannot run rbe_autoconfig as running 'docker ps' returned a " +
             "non 0 exit code, please check you have permissions to run docker.")
    if not ctx.which("tar"):
        fail("Cannot run rbe_autoconfig as 'tar' was not found on the path.")

# Pulls an image using 'docker pull'.
def _pull_image(ctx):
    print("Pulling image.")
    result = ctx.execute(["docker", "pull", _RBE_UBUNTU_GCR + ctx.attr.digest])
    _print_exec_results("pull image", result, fail = True)
    print("Image pulled.")

# Creates file "container/run_in_container.sh" which can be mounted onto container
# to run the commands to install bazel, run it and create the output tar
def _create_docker_cmd(
        ctx,
        bazel_version,
        bazel_rc_version,
        outputs_tar,
        use_default_project):
    # Command to install Bazel version
    # If a specific Bazel and Bazel RC version is specified, install that version.
    bazel_url = "https://releases.bazel.build/" + bazel_version
    if bazel_rc_version:
        bazel_url += ("/rc" + bazel_rc_version +
                      "/bazel-" + bazel_version + "rc" +
                      bazel_rc_version)
    else:
        bazel_url += "/release/bazel-" + bazel_version
    bazel_url += "-installer-linux-x86_64.sh"
    install_bazel_cmd = ["bazel_url=" + bazel_url]
    install_bazel_cmd += ["mkdir -p /src/bazel"]
    install_bazel_cmd += ["cd /src/bazel/"]
    install_bazel_cmd += ["wget $bazel_url --no-verbose --ca-certificate=/etc/ssl/certs/ca-certificates.crt -O /tmp/bazel-installer.sh"]
    install_bazel_cmd += ["chmod +x /tmp/bazel-installer.sh"]
    install_bazel_cmd += ["/tmp/bazel-installer.sh"]
    install_bazel_cmd += ["rm -f /tmp/bazel-installer.sh"]

    # Command to copy produced toolchain configs to a tar at the root
    # of the container.
    copy_cmd = ["mkdir " + _OUTPUT_DIR]
    for config_repo in _CONFIG_REPOS:
        src_dir = "$(bazel info output_base)/" + _EXTERNAL_FOLDER_PREFIX + config_repo
        copy_cmd.append("cp -dr " + src_dir + " " + _OUTPUT_DIR)
    copy_cmd.append("tar -cf /" + outputs_tar + " -C " + _OUTPUT_DIR + "/ . ")
    output_copy_cmd = " && ".join(copy_cmd)

    # if use_default_project was selected, we need to modify the WORKSPACE and BUILD file
    setup_default_project_cmd = ["cd ."]
    if use_default_project:
        setup_default_project_cmd += ["cd " + _BAZEL_CONFIG_DIR + "/" + _PROJECT_REPO_DIR]
        setup_default_project_cmd += ["mv BUILD.sample BUILD"]
        setup_default_project_cmd += ["touch WORKSPACE"]

    bazel_cmd = "cd " + _BAZEL_CONFIG_DIR + "/" + _PROJECT_REPO_DIR

    # For each config repo we run the target @<config_repo>//...
    bazel_targets = "@" + "//... @".join(_CONFIG_REPOS) + "//..."
    bazel_flags = ""
    if not ctx.attr.incompatible_changes_off:
        bazel_flags += " --all_incompatible_changes"
    bazel_cmd += " && bazel build " + bazel_flags + " " + bazel_targets

    # Command to run to clean up after autoconfiguration.
    # we start with "cd ." to make sure in case of failure everything after the
    # ";" will be executed
    clean_cmd = "cd . ; bazel clean"
    if use_default_project:
        clean_cmd += "; rm WORKSPACE ; mv BUILD BUILD.sample"

    docker_cmd = [
        "#!/bin/bash",
        ctx.attr.setup_cmd,
    ]
    docker_cmd += install_bazel_cmd
    docker_cmd += setup_default_project_cmd
    docker_cmd += [
        bazel_cmd,
        output_copy_cmd,
        clean_cmd,
    ]
    ctx.file("container/run_in_container.sh", "\n".join(docker_cmd), True)

# Runs the container (creates command to run inside container) and extracts the
# toolchain configs.
def _run_and_extract(
        ctx,
        bazel_version,
        bazel_rc_version,
        image_id,
        outputs_tar,
        project_root,
        use_default_project):
    # Create command to run inside docker container
    _create_docker_cmd(
        ctx,
        bazel_version = bazel_version,
        bazel_rc_version = bazel_rc_version,
        outputs_tar = outputs_tar,
        use_default_project = use_default_project,
    )

    # Create the docker run flags to mount the project + install file
    # + set env vars
    docker_run_flags = [""]
    for env in ctx.attr.env:
        docker_run_flags += ["--env", env + "=" + ctx.attr.env[env]]
    mount_read_only_flag = ":ro"
    if use_default_project:
        # If we use the default project, we need to modify the WORKSPACE
        # and BUILD files, so don't mount read-only
        mount_read_only_flag = ""
    target = project_root + ":" + _REPO_DIR + mount_read_only_flag
    docker_run_flags += ["-v", target]
    docker_run_flags += ["-v", str(ctx.path("container")) + ":/container"]

    # Create the template to run
    template = ctx.path(Label("@bazel_toolchains//rules:extract.sh.tpl"))
    ctx.template(
        "run_and_extract.sh",
        template,
        {
            "%{docker_run_flags}": " ".join(docker_run_flags),
            "%{commands}": "/container/run_in_container.sh",
            "%{image_id}": image_id,
            "%{extract_file}": "/" + outputs_tar,
            "%{output}": str(ctx.path(".")) + "/output.tar",
        },
        True,
    )

    # run run_and_extract.sh
    print("Running container")
    result = ctx.execute(["./run_and_extract.sh"])
    _print_exec_results("run_and_extract", result)

    # Expand outputs inside this remote repo
    result = ctx.execute(["tar", "-xf", "output.tar"])
    _print_exec_results("expand_tar", result)
    result = ctx.execute(["mv", "./local_config_cc", ("./%s" % _RBE_CONFIG_DIR)])
    _print_exec_results("expand_tar", result)
    result = ctx.execute(["rm", ("./%s/WORKSPACE" % _RBE_CONFIG_DIR)])
    _print_exec_results("clean WORKSPACE", result)
    result = ctx.execute(["rm", ("./%s/tools" % _RBE_CONFIG_DIR), "-drf"])
    _print_exec_results("clean tools", result)

# Creates a BUILD file with the java and cc toolchain + platform targets
def _create_platform(ctx, bazel_version, name):
    toolchain_target = "@" + name + "//" + _RBE_CONFIG_DIR
    if ctx.attr.output_base != "":
        toolchain_target = "//" + ctx.attr.output_base + "/bazel_" + bazel_version
        if ctx.attr.config_dir != "":
            toolchain_target += ctx.attr.config_dir
    template = ctx.path(Label("@bazel_toolchains//rules:BUILD.platform.tpl"))
    ctx.template(
        "platforms/BUILD",
        template,
        {
            "%{revision}": ctx.attr.revision,
            "%{rbe_ubuntu16_04_sha256}": ctx.attr.digest,
            "%{toolchain}": toolchain_target,
        },
        False,
    )

# Copies all outputs of the autoconfig rule to a directory in the project
# sources
def _expand_outputs(ctx, bazel_version, project_root):
    if ctx.attr.output_base != "":
        print("Copying outputs to project directory")
        dest = project_root + "/" + ctx.attr.output_base + "/bazel_" + bazel_version + "/"
        if ctx.attr.config_dir != "":
            dest += ctx.attr.config_dir + "/"
        platform_dest = dest + _PLATFORM_DIR + "/"

        # Create the directories
        result = ctx.execute(["mkdir", "-p", "platform_dest"])
        _print_exec_results("create output dir", result)

        # Get the files that were created in the _RBE_CONFIG_DIR
        ctx.file("local_config_files.sh", ("echo $(find ./%s -type f | sort -n)" % _RBE_CONFIG_DIR), True)
        result = ctx.execute(["./local_config_files.sh"])
        _print_exec_results("resolve autoconf files", result)
        autoconf_files = result.stdout.splitlines()[0].split(" ")
        args = ["cp"] + autoconf_files + [dest]

        # Copy the files to dest
        result = ctx.execute(args)
        _print_exec_results("copy outputs", result, True, args)

        # Copy the dest/platforms/BUILD file
        result = ctx.execute("cp", str(ctx.path("platforms/BUILD")), platform_dest)

# Private declaration of _rbe_autoconfig repository rule. Do not use this
# rule directly, use rbe_autoconfig macro declared below.
_rbe_autoconfig = repository_rule(
    attrs = {
        "bazel_version": attr.string(
            default = "local",
            doc = ("The version of Bazel to use to generate toolchain configs." +
                   "Use only (major, minor, patch), e.g., '0.20.0'."),
        ),
        "bazel_rc_version": attr.string(
            doc = ("Optional. An rc version to use. Note an installer for the rc " +
                   "must be available in https://releases.bazel.build."),
        ),
        "digest": attr.string(
            mandatory = True,
            doc = ("The digest (sha256 sum) of the rbe-ubuntu16-04 " +
                   "container to pull."),
        ),
        "env": attr.string_dict(
            doc = ("Optional. Dictionary from strings to strings. Additional env " +
                   "variables that will be set when running the Bazel command to " +
                   "generate the toolchain configs."),
        ),
        "incompatible_changes_off": attr.bool(
            default = True,
            doc = ("If set to False the flag --all_incompatible_changes will " +
                   "be used when generating the toolchain configs."),
        ),
        "output_base": attr.string(
            default = "",
            doc = ("Optional. The directory (under the project root) where the " +
                   "produced toolchain configs will be copied to."),
        ),
        "config_dir": attr.string(
            default = "",
            doc = ("Optional. Use only if output_base is defined. If you want to " +
                   "create multiple toolchain configs (for the same version of Bazel) " +
                   "you can use this attr to indicate a type of config (e.g., default, " +
                   "msan). The configs will be generated in a sub-directory when this attr  " +
                   "is used."),
        ),
        "setup_cmd": attr.string(
            default = "cd .",
            doc = ("Optional. Pass an additional command that will be executed " +
                   "(inside the container) before running bazel to generate the " +
                   "toolchain configs"),
        ),
        "revision": attr.string(
            mandatory = True,
            doc = ("The revision of the rbe-ubuntu16-04 container"),
        ),
    },
    environ = [
        _RBE_AUTOCONF_ROOT,
    ],
    implementation = _impl,
)

load("@bazel_toolchains//rules:environments.bzl", "clang_env")

def rbe_autoconfig(
        name,
        bazel_version = None,
        bazel_rc = None,
        output_base = "",
        config_dir = "",
        revision = "latest",
        env = clang_env()):
    """ Creates a repository with toolchain configs generated for an rbe-ubuntu container.

    This macro wraps (and simplifies) invocation of _rbe_autoconfig rule.
    Use this macro in your WORKSPACE.

    Args:
      bazel_version: The version of Bazel to use to generate toolchain configs.
          `Use only (major, minor, patch), e.g., '0.20.0'. Default is "local"
          which means the same version of Bazel that is currently running will
          be used.
      bazel_rc: The rc (for the given version of Bazel) to use. Must be published
          in https://releases.bazel.build
      output_base: Optional. The directory (under the project root) where the
          produced toolchain configs will be copied to.
      config_dir: Optional. Subdirectory where configs will be copied to.
          Use only if output_base is defined.
      revision: a revision of an rbe-ubuntu16-04 container.
          See gcr.io/cloud-marketplace/google/rbe-ubuntu16-04
      env: dict. Additional env variables that will be set when running the
          Bazel command to generate the toolchain configs.
    """
    if output_base == "" and config_dir != "":
        fail("config_dir can only be used when output_base is set.")
    if revision == "latest":
        revision = RBE_UBUNTU16_04_LATEST
    if bazel_rc and not bazel_version:
        fail("bazel_rc can only be used with bazel_version.")
    digest = public_rbe_ubuntu16_04_sha256s().get(revision, None)
    if not digest:
        fail(("Could not find a valid digest for revision %s, " +
              "please make sure it is declared in " +
              "@bazel_toolchains//rules:toolchain_containers.bzl" % revision))
    _rbe_autoconfig(
        name = name,
        bazel_version = bazel_version,
        bazel_rc = bazel_rc,
        config_dir = config_dir,
        digest = digest,
        env = env,
        output_base = output_base,
        revision = revision,
    )