#!/usr/bin/env python3
# Copyright 2019 The IREE Authors
#
# Licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

# pylint: disable=missing-docstring
"""Updates LLVM-dependent submodules based on the current LLVM commit.

Updates the third_party/tensorflow and third_party/mlir-hlo submodules to
commits that match the LLVM commit in the third_party/llvm-project submodule.
We have special conditions around these submodules since they are synced as part
of the integration of LLVM into Google's source repository. See
https://github.com/google/iree/blob/main/docs/developers/developing_iree/repository_management.md#the-special-relationship-with-llvm-and-tensorflow.

Typical usage:
  Syntax: ./scripts/git/update_to_llvm_syncpoint.py

  By default, this will update TensorFlow and MLIR-HLO to the most recent commit
  that has a matching LLVM commit.
"""

import argparse
import re
import os
import sys

import submodule_versions
import utils

REMOTE_HEAD_COMMIT_OPTION = "REMOTE"
KEEP_COMMIT_OPTION = "KEEP"
INTEGRATE_COMMIT_OPTION = "INTEGRATE"
LATEST_MATCHING_COMMIT_OPTION = "LATEST_MATCH"

COMMIT_OPTIONS = {
    REMOTE_HEAD_COMMIT_OPTION:
        "Update to the HEAD commit on the remote repository default branch",
    KEEP_COMMIT_OPTION:
        "Do not modify the current commit",
    INTEGRATE_COMMIT_OPTION:
        "Update to the commit where the current version of LLVM was first "
        "integrated",
    LATEST_MATCHING_COMMIT_OPTION:
        "Update to the most recent commit with a matching version of LLVM",
}

TF_LLVM_WORKSPACE_FILEPATH = "third_party/llvm/workspace.bzl"
TF_WORKSPACE_LLVM_COMMIT_REGEXP = re.compile(
    r"""\s*LLVM_COMMIT\s*=\s*"(.+)"\s*""", flags=re.MULTILINE)
MLIR_HLO_LLVM_VERSION_FILEPATH = "build_tools/llvm_version.txt"


def parse_arguments():
  parser = argparse.ArgumentParser()
  parser.add_argument("--repo", help="Repository root directory")
  parser.add_argument("--llvm_path",
                      help="Path to the LLVM sources "
                      "(defaults to third_party/llvm-project)",
                      default=None)
  parser.add_argument("--tensorflow_path",
                      help="Path to the tensorflow sources "
                      "(default to third_party/tensorflow)",
                      default=None)
  parser.add_argument("--tensorflow_rev",
                      "--tf_rev",
                      "--tensorflow_commit",
                      "--tf_commit",
                      help=("Update TensorFlow to this rev, or a named option:"
                            f" {COMMIT_OPTIONS}"),
                      default=LATEST_MATCHING_COMMIT_OPTION)
  parser.add_argument("--mlir_hlo_path",
                      help="Path to the tensorflow sources "
                      "(default to third_party/tensorflow)",
                      default=None)
  parser.add_argument("--mlir_hlo_rev",
                      "--mlir_hlo_commit",
                      help=("Update mlir-hlo to this rev, or a named option:"
                            f" {COMMIT_OPTIONS}"),
                      default=LATEST_MATCHING_COMMIT_OPTION)
  parser.add_argument(
      "--validate",
      help="Validate that the selected commits all match the LLVM commit",
      type=utils.str2bool,
      nargs="?",
      default=True,
  )

  args = parser.parse_args()

  # Default repo path.
  if args.repo is None:
    args.repo = utils.find_git_toplevel()

  # Set some defaults.
  if not args.llvm_path:
    args.llvm_path = os.path.join(args.repo, "third_party", "llvm-project")
  if not args.tensorflow_path:
    args.tensorflow_path = os.path.join(args.repo, "third_party", "tensorflow")
  if not args.mlir_hlo_path:
    args.mlir_hlo_path = os.path.join(args.repo, "third_party", "mlir-hlo")

  return args


def main(args):
  print("IREE handy-dandy-LLVM-submodule-updater at your service...")
  print(f"  IREE Path: {args.repo}")
  print(f"  LLVM Path: {args.llvm_path}")
  print(f"  TensorFlow Path: {args.tensorflow_path}")
  print(f"  MLIR-HLO Path: {args.tensorflow_path}")

  current_llvm_commit = parse_rev(args.llvm_path, "HEAD")
  current_tf_commit = parse_rev(args.tensorflow_path, "HEAD")
  current_mlir_hlo_commit = parse_rev(args.mlir_hlo_path, "HEAD")
  print("Current Commits:")
  print(f"  llvm = {current_llvm_commit}")
  print(f"  tensorflow = {current_tf_commit}")
  print(f"  mlir-hlo = {current_mlir_hlo_commit}")

  # Update TensorFlow
  new_tf_commit = find_new_commit_from_version_file(args.tensorflow_path,
                                                    TF_LLVM_WORKSPACE_FILEPATH,
                                                    current_llvm_commit,
                                                    args.tensorflow_rev)
  print("\n*** Updating TensorFlow to", new_tf_commit, "***")
  utils.execute(["git", "checkout", new_tf_commit], cwd=args.tensorflow_path)
  stage_path(args.repo, args.tensorflow_path)

  validate_tf_commit(current_llvm_commit,
                     args.tensorflow_path,
                     exit_on_failure=args.validate)

  # Update MLIR-HLO
  new_mlir_hlo_commit = find_new_commit_from_version_file(
      args.mlir_hlo_path, MLIR_HLO_LLVM_VERSION_FILEPATH, current_llvm_commit,
      args.mlir_hlo_rev)
  print("\n*** Updating MLIR-HLO to", new_mlir_hlo_commit, "***")
  utils.execute(["git", "checkout", new_mlir_hlo_commit],
                cwd=args.mlir_hlo_path)
  stage_path(args.repo, args.mlir_hlo_path)

  validate_mlir_hlo_commit(current_llvm_commit,
                           args.mlir_hlo_path,
                           exit_on_failure=args.validate)

  # Export SUBMODULE_VERSIONS.txt.
  print()  # Add line break.
  submodule_versions.export_versions(args.repo)


def parse_rev(path, rev):
  return utils.execute(["git", "rev-parse", rev],
                       cwd=path,
                       silent=True,
                       capture_output=True).stdout.strip()


def find_llvm_commit_changes_to_file(repo_path,
                                     filepath,
                                     llvm_commit,
                                     branch="origin/master"):
  """Finds commits where the occurrence of the given LLVM commit hash changes.

  In normal cases, there should be at most two commits that match this:
    1. The commit that first introduced the new hash in the file.
    2. The commit that changed it to a new hash afterwards.
  """
  commits = utils.execute(
      [
          "git",
          "log",
          # Only follow the first parent of a merge commit. We don't want to go
          # off to some random PR.
          "--first-parent",
          # Just print the commit hash
          "--format=%H",
          # Look for commits where the number of occurrences of llvm_commit
          # changed.
          # https://git-scm.com/docs/git-log#Documentation/git-log.txt--Sltstringgt
          "-S",
          llvm_commit,
          # Search along the appropriate branch
          branch,
          # Only look in the specified file where the llvm_commit is recorded
          "--",
          filepath,
      ],
      capture_output=True,
      cwd=repo_path).stdout.split()

  if len(commits) > 2:
    raise RuntimeError(
        f"Expected one or two commits in {repo_path} {branch} {filepath} to "
        f" involve LLVM commit {llvm_commit}, but got {len(commits)}")

  if not commits:
    raise RuntimeError(
        f"{repo_path} {branch} {filepath} does not have any references to LLVM"
        f" commit {llvm_commit}. Maybe  export is behind?")

  return commits


def find_new_commit_from_version_file(repo_path,
                                      version_filepath,
                                      llvm_commit,
                                      rev,
                                      branch="origin/master"):
  utils.execute(["git", "fetch"], cwd=repo_path)

  if rev not in COMMIT_OPTIONS:
    return parse_rev(repo_path, rev)

  if rev == KEEP_COMMIT_OPTION:
    return parse_rev(repo_path, "HEAD")

  if rev == REMOTE_HEAD_COMMIT_OPTION:
    return parse_rev(repo_path, branch)

  commit_options = find_llvm_commit_changes_to_file(repo_path, version_filepath,
                                                    llvm_commit)

  if rev == INTEGRATE_COMMIT_OPTION:
    return commit_options[-1]

  assert rev == LATEST_MATCHING_COMMIT_OPTION
  if len(commit_options) == 1:
    # There hasn't been a subsequent integrate, use remote head.
    return parse_rev(repo_path, branch)

  # Use the commit one before the one that changed away from this LLVM version.
  return parse_rev(repo_path, f"{commit_options[0]}^")


def validate_tf_commit(llvm_commit, tensorflow_path, exit_on_failure=True):
  tf_llvm_commit = find_tensorflow_llvm_commit(tensorflow_path)

  matches = tf_llvm_commit == llvm_commit
  if not matches:
    print("WARNING: LLVM commit in TF  does not match that in IREE"
          f" ({tf_llvm_commit} vs {llvm_commit})")
    if exit_on_failure:
      sys.exit(1)


def find_tensorflow_llvm_commit(tensorflow_path):
  # TensorFlow keeps its commit in workspace.bzl on a line like:
  # LLVM_COMMIT = "..."
  # Yeah. This is how we do it.
  workspace_path = os.path.join(tensorflow_path, TF_LLVM_WORKSPACE_FILEPATH)

  for line in open(workspace_path, "r", encoding="UTF-8"):
    m = re.match(TF_WORKSPACE_LLVM_COMMIT_REGEXP, line)
    if m:
      return m.group(1)

  print(f"ERROR: Could not find LLVM commit in {workspace_path}.")
  print("Please file a bug)")
  print("Expected pattern match for:", TF_WORKSPACE_LLVM_COMMIT_REGEXP.pattern)
  sys.exit(1)


def validate_mlir_hlo_commit(llvm_commit, mlir_hlo_path, exit_on_failure=True):
  mlir_hlo_llvm_commit = find_mlir_hlo_llvm_commit(mlir_hlo_path)

  matches = mlir_hlo_llvm_commit == llvm_commit
  if not matches:
    print("WARNING: LLVM commit in mlir-hlo does not match that in IREE"
          f" ({mlir_hlo_llvm_commit} vs {llvm_commit})")
    if exit_on_failure:
      sys.exit(1)


def find_mlir_hlo_llvm_commit(mlir_hlo_path):
  llvm_version_file_path = os.path.join(mlir_hlo_path,
                                        MLIR_HLO_LLVM_VERSION_FILEPATH)
  with open(llvm_version_file_path, "r", encoding="UTF-8") as f:
    return f.read().strip()


def stage_path(repo_path, to_stage):
  # TODO(laurenzo): Move to utils.py.
  utils.execute(["git", "add", to_stage], cwd=repo_path)


if __name__ == "__main__":
  main(parse_arguments())