#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2020 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Get an upstream patch to LLVM's PATCHES.json."""

import argparse
import dataclasses
from datetime import datetime
import json
import logging
import os
from pathlib import Path
import shlex
import subprocess
import sys
import typing as t

import chroot
import get_llvm_hash
import git
import git_llvm_rev
import patch_utils
import update_chromeos_llvm_hash


__DOC_EPILOGUE = """
Example Usage:
  get_upstream_patch --chroot_path ~/chromiumos --platform chromiumos \
--sha 1234567 --sha 890abdc
"""


class CherrypickError(ValueError):
    """A ValueError that highlights the cherry-pick has been seen before"""


class CherrypickVersionError(ValueError):
    """A ValueError that highlights the cherry-pick is before the start_sha"""


class PatchApplicationError(ValueError):
    """A ValueError indicating that a test patch application was unsuccessful"""


def validate_patch_application(
    llvm_dir: Path, svn_version: int, patches_json_fp: Path, patch_props
):

    start_sha = get_llvm_hash.GetGitHashFrom(llvm_dir, svn_version)
    subprocess.run(["git", "-C", llvm_dir, "checkout", start_sha], check=True)

    predecessor_apply_results = patch_utils.apply_all_from_json(
        svn_version, llvm_dir, patches_json_fp, continue_on_failure=True
    )

    if predecessor_apply_results.failed_patches:
        logging.error("Failed to apply patches from PATCHES.json:")
        for p in predecessor_apply_results.failed_patches:
            logging.error(f"Patch title: {p.title()}")
        raise PatchApplicationError("Failed to apply patch from PATCHES.json")

    patch_entry = patch_utils.PatchEntry.from_dict(
        patches_json_fp.parent, patch_props
    )
    test_apply_result = patch_entry.test_apply(Path(llvm_dir))

    if not test_apply_result:
        logging.error("Could not apply requested patch")
        logging.error(test_apply_result.failure_info())
        raise PatchApplicationError(
            f'Failed to apply patch: {patch_props["metadata"]["title"]}'
        )


def add_patch(
    patches_json_path: str,
    patches_dir: str,
    relative_patches_dir: str,
    start_version: git_llvm_rev.Rev,
    llvm_dir: str,
    rev: t.Union[git_llvm_rev.Rev, str],
    sha: str,
    package: str,
    platforms: t.List[str],
):
    """Gets the start and end intervals in 'json_file'.

    Args:
      patches_json_path: The absolute path to PATCHES.json.
      patches_dir: The aboslute path to the directory patches are in.
      relative_patches_dir: The relative path to PATCHES.json.
      start_version: The base LLVM revision this patch applies to.
      llvm_dir: The path to LLVM checkout.
      rev: An LLVM revision (git_llvm_rev.Rev) for a cherrypicking, or a
      differential revision (str) otherwise.
      sha: The LLVM git sha that corresponds to the patch. For differential
      revisions, the git sha from  the local commit created by 'arc patch'
      is used.
      package: The LLVM project name this patch applies to.
      platforms: List of platforms this patch applies to.

    Raises:
      CherrypickError: A ValueError that highlights the cherry-pick has been
      seen before.
      CherrypickRangeError: A ValueError that's raised when the given patch
      is from before the start_sha.
    """

    is_cherrypick = isinstance(rev, git_llvm_rev.Rev)
    if is_cherrypick:
        file_name = f"{sha}.patch"
    else:
        file_name = f"{rev}.patch"
    rel_patch_path = os.path.join(relative_patches_dir, file_name)

    # Check that we haven't grabbed a patch range that's nonsensical.
    end_vers = rev.number if isinstance(rev, git_llvm_rev.Rev) else None
    if end_vers is not None and end_vers <= start_version.number:
        raise CherrypickVersionError(
            f"`until` version {end_vers} is earlier or equal to"
            f" `from` version {start_version.number} for patch"
            f" {rel_patch_path}"
        )

    with open(patches_json_path, encoding="utf-8") as f:
        patches_json = json.load(f)

    for p in patches_json:
        rel_path = p["rel_patch_path"]
        if rel_path == rel_patch_path:
            raise CherrypickError(
                f"Patch at {rel_path} already exists in PATCHES.json"
            )
        if is_cherrypick:
            if sha in rel_path:
                logging.warning(
                    "Similarly-named patch already exists in PATCHES.json: %r",
                    rel_path,
                )

    with open(os.path.join(patches_dir, file_name), "wb") as f:
        cmd = ["git", "show", sha]
        # Only apply the part of the patch that belongs to this package, expect
        # LLVM. This is because some packages are built with LLVM ebuild on X86 but
        # not on the other architectures. e.g. compiler-rt. Therefore always apply
        # the entire patch to LLVM ebuild as a workaround.
        if package != "llvm":
            cmd.append(package_to_project(package))
        subprocess.check_call(cmd, stdout=f, cwd=llvm_dir)

    commit_subject = subprocess.check_output(
        ["git", "log", "-n1", "--format=%s", sha],
        cwd=llvm_dir,
        encoding="utf-8",
    )
    patch_props = {
        "rel_patch_path": rel_patch_path,
        "metadata": {
            "title": commit_subject.strip(),
            "info": [],
        },
        "platforms": sorted(platforms),
        "version_range": {
            "from": start_version.number,
            "until": end_vers,
        },
    }

    with patch_utils.git_clean_context(Path(llvm_dir)):
        validate_patch_application(
            Path(llvm_dir),
            start_version.number,
            Path(patches_json_path),
            patch_props,
        )

    patches_json.append(patch_props)

    temp_file = patches_json_path + ".tmp"
    with open(temp_file, "w", encoding="utf-8") as f:
        json.dump(
            patches_json, f, indent=4, separators=(",", ": "), sort_keys=True
        )
        f.write("\n")
    os.rename(temp_file, patches_json_path)


def parse_ebuild_for_assignment(ebuild_path: str, var_name: str) -> str:
    # '_pre' filters the LLVM 9.0 ebuild, which we never want to target, from
    # this list.
    candidates = [
        x
        for x in os.listdir(ebuild_path)
        if x.endswith(".ebuild") and "_pre" in x
    ]

    if not candidates:
        raise ValueError("No ebuilds found under %r" % ebuild_path)

    ebuild = os.path.join(ebuild_path, max(candidates))
    with open(ebuild, encoding="utf-8") as f:
        var_name_eq = var_name + "="
        for orig_line in f:
            if not orig_line.startswith(var_name_eq):
                continue

            # We shouldn't see much variety here, so do the simplest thing possible.
            line = orig_line[len(var_name_eq) :]
            # Remove comments
            line = line.split("#")[0]
            # Remove quotes
            line = shlex.split(line)
            if len(line) != 1:
                raise ValueError(
                    "Expected exactly one quoted value in %r" % orig_line
                )
            return line[0].strip()

    raise ValueError("No %s= line found in %r" % (var_name, ebuild))


# Resolves a git ref (or similar) to a LLVM SHA.
def resolve_llvm_ref(llvm_dir: str, sha: str) -> str:
    return subprocess.check_output(
        ["git", "rev-parse", sha],
        encoding="utf-8",
        cwd=llvm_dir,
    ).strip()


# Get the package name of an LLVM project
def project_to_package(project: str) -> str:
    if project == "libunwind":
        return "llvm-libunwind"
    return project


# Get the LLVM project name of a package
def package_to_project(package: str) -> str:
    if package == "llvm-libunwind":
        return "libunwind"
    return package


# Get the LLVM projects change in the specifed sha
def get_package_names(sha: str, llvm_dir: str) -> list:
    paths = subprocess.check_output(
        ["git", "show", "--name-only", "--format=", sha],
        cwd=llvm_dir,
        encoding="utf-8",
    ).splitlines()
    # Some LLVM projects are built by LLVM ebuild on X86, so always apply the
    # patch to LLVM ebuild
    packages = {"llvm"}
    # Detect if there are more packages to apply the patch to
    for path in paths:
        package = project_to_package(path.split("/")[0])
        if package in ("compiler-rt", "libcxx", "libcxxabi", "llvm-libunwind"):
            packages.add(package)
    packages = list(sorted(packages))
    return packages


def create_patch_for_packages(
    packages: t.List[str],
    symlinks: t.List[str],
    start_rev: git_llvm_rev.Rev,
    rev: t.Union[git_llvm_rev.Rev, str],
    sha: str,
    llvm_dir: str,
    platforms: t.List[str],
):
    """Create a patch and add its metadata for each package"""
    for package, symlink in zip(packages, symlinks):
        symlink_dir = os.path.dirname(symlink)
        patches_json_path = os.path.join(symlink_dir, "files/PATCHES.json")
        relative_patches_dir = "cherry" if package == "llvm" else ""
        patches_dir = os.path.join(symlink_dir, "files", relative_patches_dir)
        logging.info("Getting %s (%s) into %s", rev, sha, package)
        add_patch(
            patches_json_path,
            patches_dir,
            relative_patches_dir,
            start_rev,
            llvm_dir,
            rev,
            sha,
            package,
            platforms=platforms,
        )


def make_cl(
    symlinks_to_uprev: t.List[str],
    llvm_symlink_dir: str,
    branch: str,
    commit_messages: t.List[str],
    reviewers: t.Optional[t.List[str]],
    cc: t.Optional[t.List[str]],
):
    symlinks_to_uprev = sorted(set(symlinks_to_uprev))
    for symlink in symlinks_to_uprev:
        update_chromeos_llvm_hash.UprevEbuildSymlink(symlink)
        subprocess.check_output(
            ["git", "add", "--all"], cwd=os.path.dirname(symlink)
        )
    git.UploadChanges(llvm_symlink_dir, branch, commit_messages, reviewers, cc)
    git.DeleteBranch(llvm_symlink_dir, branch)


def resolve_symbolic_sha(start_sha: str, llvm_symlink_dir: str) -> str:
    if start_sha == "llvm":
        return parse_ebuild_for_assignment(llvm_symlink_dir, "LLVM_HASH")

    if start_sha == "llvm-next":
        return parse_ebuild_for_assignment(llvm_symlink_dir, "LLVM_NEXT_HASH")

    return start_sha


def find_patches_and_make_cl(
    chroot_path: str,
    patches: t.List[str],
    start_rev: git_llvm_rev.Rev,
    llvm_config: git_llvm_rev.LLVMConfig,
    llvm_symlink_dir: str,
    create_cl: bool,
    skip_dependencies: bool,
    reviewers: t.Optional[t.List[str]],
    cc: t.Optional[t.List[str]],
    platforms: t.List[str],
):

    converted_patches = [
        _convert_patch(llvm_config, skip_dependencies, p) for p in patches
    ]
    potential_duplicates = _get_duplicate_shas(converted_patches)
    if potential_duplicates:
        err_msg = "\n".join(
            f"{a.patch} == {b.patch}" for a, b in potential_duplicates
        )
        raise RuntimeError(f"Found Duplicate SHAs:\n{err_msg}")

    # CL Related variables, only used if `create_cl`
    symlinks_to_uprev = []
    commit_messages = [
        "llvm: get patches from upstream\n",
    ]
    branch = f'get-upstream-{datetime.now().strftime("%Y%m%d%H%M%S%f")}'

    if create_cl:
        git.CreateBranch(llvm_symlink_dir, branch)

    for parsed_patch in converted_patches:
        # Find out the llvm projects changed in this commit
        packages = get_package_names(parsed_patch.sha, llvm_config.dir)
        # Find out the ebuild symlinks of the corresponding ChromeOS packages
        symlinks = chroot.GetChrootEbuildPaths(
            chroot_path,
            [
                "sys-devel/llvm" if package == "llvm" else "sys-libs/" + package
                for package in packages
            ],
        )
        symlinks = chroot.ConvertChrootPathsToAbsolutePaths(
            chroot_path, symlinks
        )
        # Create a local patch for all the affected llvm projects
        create_patch_for_packages(
            packages,
            symlinks,
            start_rev,
            parsed_patch.rev,
            parsed_patch.sha,
            llvm_config.dir,
            platforms=platforms,
        )
        if create_cl:
            symlinks_to_uprev.extend(symlinks)

            commit_messages.extend(
                [
                    parsed_patch.git_msg(),
                    subprocess.check_output(
                        ["git", "log", "-n1", "--oneline", parsed_patch.sha],
                        cwd=llvm_config.dir,
                        encoding="utf-8",
                    ),
                ]
            )

        if parsed_patch.is_differential:
            subprocess.check_output(
                ["git", "reset", "--hard", "HEAD^"], cwd=llvm_config.dir
            )

    if create_cl:
        make_cl(
            symlinks_to_uprev,
            llvm_symlink_dir,
            branch,
            commit_messages,
            reviewers,
            cc,
        )


@dataclasses.dataclass(frozen=True)
class ParsedPatch:
    """Class to keep track of bundled patch info."""

    patch: str
    sha: str
    is_differential: bool
    rev: t.Union[git_llvm_rev.Rev, str]

    def git_msg(self) -> str:
        if self.is_differential:
            return f"\n\nreviews.llvm.org/{self.patch}\n"
        return f"\n\nreviews.llvm.org/rG{self.sha}\n"


def _convert_patch(
    llvm_config: git_llvm_rev.LLVMConfig, skip_dependencies: bool, patch: str
) -> ParsedPatch:
    """Extract git revision info from a patch.

    Args:
      llvm_config: LLVM configuration object.
      skip_dependencies: Pass --skip-dependecies for to `arc`
      patch: A single patch referent string.

    Returns:
      A [ParsedPatch] object.
    """

    # git hash should only have lower-case letters
    is_differential = patch.startswith("D")
    if is_differential:
        subprocess.check_output(
            [
                "arc",
                "patch",
                "--nobranch",
                "--skip-dependencies" if skip_dependencies else "--revision",
                patch,
            ],
            cwd=llvm_config.dir,
        )
        sha = resolve_llvm_ref(llvm_config.dir, "HEAD")
        rev = patch
    else:
        sha = resolve_llvm_ref(llvm_config.dir, patch)
        rev = git_llvm_rev.translate_sha_to_rev(llvm_config, sha)
    return ParsedPatch(
        patch=patch, sha=sha, rev=rev, is_differential=is_differential
    )


def _get_duplicate_shas(
    patches: t.List[ParsedPatch],
) -> t.List[t.Tuple[ParsedPatch, ParsedPatch]]:
    """Return a list of Patches which have duplicate SHA's"""
    return [
        (left, right)
        for i, left in enumerate(patches)
        for right in patches[i + 1 :]
        if left.sha == right.sha
    ]


def get_from_upstream(
    chroot_path: str,
    create_cl: bool,
    start_sha: str,
    patches: t.List[str],
    platforms: t.List[str],
    skip_dependencies: bool = False,
    reviewers: t.List[str] = None,
    cc: t.List[str] = None,
):
    llvm_symlink = chroot.ConvertChrootPathsToAbsolutePaths(
        chroot_path,
        chroot.GetChrootEbuildPaths(chroot_path, ["sys-devel/llvm"]),
    )[0]
    llvm_symlink_dir = os.path.dirname(llvm_symlink)

    git_status = subprocess.check_output(
        ["git", "status", "-s"], cwd=llvm_symlink_dir, encoding="utf-8"
    )

    if git_status:
        error_path = os.path.dirname(os.path.dirname(llvm_symlink_dir))
        raise ValueError(f"Uncommited changes detected in {error_path}")

    start_sha = resolve_symbolic_sha(start_sha, llvm_symlink_dir)
    logging.info("Base llvm hash == %s", start_sha)

    llvm_config = git_llvm_rev.LLVMConfig(
        remote="origin", dir=get_llvm_hash.GetAndUpdateLLVMProjectInLLVMTools()
    )
    start_sha = resolve_llvm_ref(llvm_config.dir, start_sha)

    find_patches_and_make_cl(
        chroot_path=chroot_path,
        patches=patches,
        platforms=platforms,
        start_rev=git_llvm_rev.translate_sha_to_rev(llvm_config, start_sha),
        llvm_config=llvm_config,
        llvm_symlink_dir=llvm_symlink_dir,
        create_cl=create_cl,
        skip_dependencies=skip_dependencies,
        reviewers=reviewers,
        cc=cc,
    )
    logging.info("Complete.")


def main():
    chroot.VerifyOutsideChroot()
    logging.basicConfig(
        format="%(asctime)s: %(levelname)s: %(filename)s:%(lineno)d: %(message)s",
        level=logging.INFO,
    )

    parser = argparse.ArgumentParser(
        description=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=__DOC_EPILOGUE,
    )
    parser.add_argument(
        "--chroot_path",
        default=os.path.join(os.path.expanduser("~"), "chromiumos"),
        help="the path to the chroot (default: %(default)s)",
    )
    parser.add_argument(
        "--start_sha",
        default="llvm-next",
        help="LLVM SHA that the patch should start applying at. You can specify "
        '"llvm" or "llvm-next", as well. Defaults to %(default)s.',
    )
    parser.add_argument(
        "--sha",
        action="append",
        default=[],
        help="The LLVM git SHA to cherry-pick.",
    )
    parser.add_argument(
        "--differential",
        action="append",
        default=[],
        help="The LLVM differential revision to apply. Example: D1234."
        " Cannot be used for changes already merged upstream; use --sha"
        " instead for those.",
    )
    parser.add_argument(
        "--platform",
        action="append",
        required=True,
        help="Apply this patch to the give platform. Common options include "
        '"chromiumos" and "android". Can be specified multiple times to '
        "apply to multiple platforms",
    )
    parser.add_argument(
        "--create_cl",
        action="store_true",
        help="Automatically create a CL if specified",
    )
    parser.add_argument(
        "--skip_dependencies",
        action="store_true",
        help="Skips a LLVM differential revision's dependencies. Only valid "
        "when --differential appears exactly once.",
    )
    args = parser.parse_args()

    if not (args.sha or args.differential):
        parser.error("--sha or --differential required")

    if args.skip_dependencies and len(args.differential) != 1:
        parser.error(
            "--skip_dependencies is only valid when there's exactly one "
            "supplied differential"
        )

    get_from_upstream(
        chroot_path=args.chroot_path,
        create_cl=args.create_cl,
        start_sha=args.start_sha,
        patches=args.sha + args.differential,
        skip_dependencies=args.skip_dependencies,
        platforms=args.platform,
    )


if __name__ == "__main__":
    sys.exit(main())