#!/usr/bin/env python3
#
# ====- code-format-helper, runs code formatters from the ci --*- python -*--==#
#
# Part of the LLVM Project, 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
#
# ==-------------------------------------------------------------------------==#

import argparse
import os
import subprocess
import sys
from functools import cached_property

import github
from github import IssueComment, PullRequest


class FormatHelper:
    COMMENT_TAG = "<!--LLVM CODE FORMAT COMMENT: {fmt}-->"
    name: str
    friendly_name: str

    @property
    def comment_tag(self) -> str:
        return self.COMMENT_TAG.replace("fmt", self.name)

    @property
    def instructions(self) -> str:
        raise NotImplementedError()

    def format_run(
        self, changed_files: list[str], args: argparse.Namespace
    ) -> str | None:
        raise NotImplementedError()

    def pr_comment_text_for_diff(self, diff: str) -> str:
        return f"""
:warning: {self.friendly_name}, {self.name} found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
{self.instructions}
``````````

</details>

<details>
<summary>
View the diff from {self.name} here.
</summary>

``````````diff
{diff}
``````````

</details>
"""

    def find_comment(
        self, pr: PullRequest.PullRequest
    ) -> IssueComment.IssueComment | None:
        for comment in pr.as_issue().get_comments():
            if self.comment_tag in comment.body:
                return comment
        return None

    def update_pr(
        self, comment_text: str, args: argparse.Namespace, create_new: bool
    ) -> None:
        repo = github.Github(args.token).get_repo(args.repo)
        pr = repo.get_issue(args.issue_number).as_pull_request()

        comment_text = self.comment_tag + "\n\n" + comment_text

        existing_comment = self.find_comment(pr)
        if existing_comment:
            existing_comment.edit(comment_text)
        elif create_new:
            pr.as_issue().create_comment(comment_text)

    def run(self, changed_files: list[str], args: argparse.Namespace) -> bool:
        diff = self.format_run(changed_files, args)
        if diff is None:
            comment_text = f"""
:white_check_mark: With the latest revision this PR passed the {self.friendly_name}.
"""
            self.update_pr(comment_text, args, create_new=False)
            return True
        elif len(diff) > 0:
            comment_text = self.pr_comment_text_for_diff(diff)
            self.update_pr(comment_text, args, create_new=True)
            return False
        else:
            # The formatter failed but didn't output a diff (e.g. some sort of
            # infrastructure failure).
            comment_text = f"""
:warning: The {self.friendly_name} failed without printing a diff. Check the logs for stderr output. :warning:
"""
            self.update_pr(comment_text, args, create_new=False)
            return False


class ClangFormatHelper(FormatHelper):
    name = "clang-format"
    friendly_name = "C/C++ code formatter"

    @property
    def instructions(self) -> str:
        return " ".join(self.cf_cmd)

    def should_include_extensionless_file(self, path: str) -> bool:
        return path.startswith("libcxx/include")

    def filter_changed_files(self, changed_files: list[str]) -> list[str]:
        filtered_files = []
        for path in changed_files:
            _, ext = os.path.splitext(path)
            if ext in (".cpp", ".c", ".h", ".hpp", ".hxx", ".cxx", ".inc", ".cppm"):
                filtered_files.append(path)
            elif ext == "" and self.should_include_extensionless_file(path):
                filtered_files.append(path)
        return filtered_files

    def format_run(
        self, changed_files: list[str], args: argparse.Namespace
    ) -> str | None:
        cpp_files = self.filter_changed_files(changed_files)
        if not cpp_files:
            return None
        cf_cmd = [
            "git-clang-format",
            "--diff",
            args.start_rev,
            args.end_rev,
            "--",
        ] + cpp_files
        print(f"Running: {' '.join(cf_cmd)}")
        self.cf_cmd = cf_cmd
        proc = subprocess.run(cf_cmd, capture_output=True)
        sys.stdout.write(proc.stderr.decode("utf-8"))

        if proc.returncode != 0:
            # formatting needed, or the command otherwise failed
            print(f"error: {self.name} exited with code {proc.returncode}")
            # Print the diff in the log so that it is viewable there
            print(proc.stdout.decode("utf-8"))
            return proc.stdout.decode("utf-8")
        else:
            sys.stdout.write(proc.stdout.decode("utf-8"))
            return None


class DarkerFormatHelper(FormatHelper):
    name = "darker"
    friendly_name = "Python code formatter"

    @property
    def instructions(self) -> str:
        return " ".join(self.darker_cmd)

    def filter_changed_files(self, changed_files: list[str]) -> list[str]:
        filtered_files = []
        for path in changed_files:
            name, ext = os.path.splitext(path)
            if ext == ".py":
                filtered_files.append(path)

        return filtered_files

    def format_run(
        self, changed_files: list[str], args: argparse.Namespace
    ) -> str | None:
        py_files = self.filter_changed_files(changed_files)
        if not py_files:
            return None
        darker_cmd = [
            "darker",
            "--check",
            "--diff",
            "-r",
            f"{args.start_rev}..{args.end_rev}",
        ] + py_files
        print(f"Running: {' '.join(darker_cmd)}")
        self.darker_cmd = darker_cmd
        proc = subprocess.run(darker_cmd, capture_output=True)
        sys.stdout.write(proc.stderr.decode("utf-8"))

        if proc.returncode != 0:
            # formatting needed, or the command otherwise failed
            print(f"error: {self.name} exited with code {proc.returncode}")
            # Print the diff in the log so that it is viewable there
            print(proc.stdout.decode("utf-8"))
            return proc.stdout.decode("utf-8")
        else:
            sys.stdout.write(proc.stdout.decode("utf-8"))
            return None


ALL_FORMATTERS = (DarkerFormatHelper(), ClangFormatHelper())

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--token", type=str, required=True, help="GitHub authentiation token"
    )
    parser.add_argument(
        "--repo",
        type=str,
        default=os.getenv("GITHUB_REPOSITORY", "llvm/llvm-project"),
        help="The GitHub repository that we are working with in the form of <owner>/<repo> (e.g. llvm/llvm-project)",
    )
    parser.add_argument("--issue-number", type=int, required=True)
    parser.add_argument(
        "--start-rev",
        type=str,
        required=True,
        help="Compute changes from this revision.",
    )
    parser.add_argument(
        "--end-rev", type=str, required=True, help="Compute changes to this revision"
    )
    parser.add_argument(
        "--changed-files",
        type=str,
        help="Comma separated list of files that has been changed",
    )

    args = parser.parse_args()

    changed_files = []
    if args.changed_files:
        changed_files = args.changed_files.split(",")

    failed_formatters = []
    for fmt in ALL_FORMATTERS:
        if not fmt.run(changed_files, args):
            failed_formatters.append(fmt.name)

    if len(failed_formatters) > 0:
        print(f"error: some formatters failed: {' '.join(failed_formatters)}")
        sys.exit(1)