label.py

# Copyright (C) 2023 Maxwell G <maxwell@gtmx.me>
# SPDX-License-Identifier: GPL-3.0-or-later

from __future__ import annotations

import dataclasses
import json
import os
from collections.abc import Collection
from contextlib import suppress
from functools import cached_property
from pathlib import Path
from typing import Any, ClassVar, Union

import github
import github.Auth
import github.Issue
import github.PullRequest
import github.Repository
import typer
from codeowners import CodeOwners, OwnerTuple
from jinja2 import Environment, FileSystemLoader, StrictUndefined, select_autoescape

OWNER = "ansible"
REPO = "ansible-documentation"
LABELS_BY_CODEOWNER: dict[OwnerTuple, list[str]] = {
    ("TEAM", "@ansible/steering-committee"): ["sc_approval"],
}
HERE = Path(__file__).resolve().parent
ROOT = HERE.parent.parent
CODEOWNERS = (ROOT / ".github/CODEOWNERS").read_text("utf-8")
JINJA2_ENV = Environment(
    loader=FileSystemLoader(HERE / "data"),
    autoescape=select_autoescape(),
    trim_blocks=True,
    undefined=StrictUndefined,
)

IssueOrPrCtx = Union["IssueLabelerCtx", "PRLabelerCtx"]
IssueOrPr = Union["github.Issue.Issue", "github.PullRequest.PullRequest"]


# TODO: If we end up needing to log more things with more granularity,
# switch to something like `logging`
def log(ctx: IssueOrPrCtx, *args: object) -> None:
    print(f"{ctx.member.number}:", *args)


def get_repo(
    *, authed: bool = True, owner: str, repo: str
) -> tuple[github.Github, github.Repository.Repository]:
    gclient = github.Github(
        auth=github.Auth.Token(os.environ["GITHUB_TOKEN"]) if authed else None,
    )
    repo_obj = gclient.get_repo(f"{owner}/{repo}")
    return gclient, repo_obj


def get_event_info() -> dict[str, Any]:
    event_json = os.environ.get("event_json")
    if not event_json:
        return {}
    with suppress(json.JSONDecodeError):
        return json.loads(event_json)
    return {}


@dataclasses.dataclass()
class GlobalArgs:
    owner: str
    repo: str


@dataclasses.dataclass()
class LabelerCtx:
    client: github.Github
    repo: github.Repository.Repository
    dry_run: bool
    event_info: dict[str, Any]
    issue: github.Issue.Issue

    TYPE: ClassVar[str]

    @property
    def member(self) -> IssueOrPr:
        raise NotImplementedError

    @property
    def event_member(self) -> dict[str, Any]:
        raise NotImplementedError

    @cached_property
    def previously_labeled(self) -> frozenset[str]:
        labels: set[str] = set()
        events = (
            self.member.get_events()
            if isinstance(self.member, github.Issue.Issue)
            else self.member.get_issue_events()
        )
        for event in events:
            if event.event in ("labeled", "unlabeled"):
                assert event.label
                labels.add(event.label.name)
        return frozenset(labels)


@dataclasses.dataclass()
class IssueLabelerCtx(LabelerCtx):
    issue: github.Issue.Issue

    TYPE = "issue"

    @property
    def member(self) -> IssueOrPr:
        return self.issue

    @property
    def event_member(self) -> dict[str, Any]:
        return self.event_info.get("issue", {})


@dataclasses.dataclass()
class PRLabelerCtx(LabelerCtx):
    pr: github.PullRequest.PullRequest

    TYPE = "pull request"

    @property
    def member(self) -> IssueOrPr:
        return self.pr

    @property
    def event_member(self) -> dict[str, Any]:
        return self.event_info.get("pull_request", {})


def create_comment(ctx: IssueOrPrCtx, body: str) -> None:
    if ctx.dry_run:
        return
    if isinstance(ctx, IssueLabelerCtx):
        ctx.issue.create_comment(body)
    else:
        ctx.pr.create_issue_comment(body)


def get_data_file(name: str, **kwargs: Any) -> str:
    """
    Template a data file
    """
    return JINJA2_ENV.get_template(name).render(**kwargs).rstrip("\n")


def create_boilerplate_comment(ctx: IssueOrPrCtx, name: str, **kwargs) -> None:
    """
    Add a boilerplate comment if it hasn't already been added
    """
    tmpl = get_data_file(name, ctx=ctx, **kwargs)
    tmpl_lines = tmpl.splitlines()
    last = tmpl_lines[-1]
    if not (last.startswith("<!--- boilerplate: ") and last.endswith(" --->")):
        raise ValueError(
            "Last line must of the template"
            " must have an identifying boilerplate comment"
        )
    for comment in ctx.issue.get_comments():
        if comment.body.splitlines()[-1] == last:
            log(ctx, name, "boilerplate was already commented")
            return
    log(ctx, "Templating", name, "boilerplate")
    create_comment(ctx, tmpl)


def handle_codeowner_labels(ctx: PRLabelerCtx) -> None:
    labels = LABELS_BY_CODEOWNER.copy()
    owners = CodeOwners(CODEOWNERS)
    files = ctx.pr.get_files()
    for file in files:
        for owner in owners.of(file.filename):
            if labels_to_add := labels.pop(owner, None):
                add_label_if_new(ctx, labels_to_add)
        if not labels:
            return


def add_label_if_new(ctx: IssueOrPrCtx, labels: Collection[str] | str) -> None:
    """
    Add a label to a PR if it wasn't added in the past
    """
    labels = {labels} if isinstance(labels, str) else labels
    labels = set(labels) - ctx.previously_labeled
    if not labels:
        return
    log(ctx, "Adding labels", *map(repr, labels))
    if not ctx.dry_run:
        ctx.member.add_to_labels(*labels)


def new_contributor_welcome(ctx: IssueOrPrCtx) -> None:
    """
    Welcome a new contributor to the repo with a message and a label
    """
    # This contributor has already been welcomed!
    if "new_contributor" in ctx.previously_labeled:
        return
    author_association = ctx.event_member.get(
        "author_association", ctx.member.raw_data["author_association"]
    )
    log(ctx, "author_association is", author_association)
    if author_association not in {
        "FIRST_TIMER",
        "FIRST_TIME_CONTRIBUTOR",
    }:
        return
    log(ctx, "Welcoming new contributor")
    add_label_if_new(ctx, "new_contributor")
    create_comment(ctx, get_data_file("docs_team_info.md"))


def no_body_nag(ctx: IssueOrPrCtx) -> None:
    """
    Complain if a non-bot user creates a PR or issue without body text
    """
    if ctx.member.user.login.endswith("[bot]") or (ctx.member.body or "").strip():
        return
    create_boilerplate_comment(ctx, "no_body_nag.md")


APP = typer.Typer()


@APP.callback()
def cb(*, click_ctx: typer.Context, owner: str = OWNER, repo: str = REPO):
    """
    Basic triager for ansible/ansible-documentation
    """
    click_ctx.obj = GlobalArgs(owner, repo)


@APP.command(name="pr")
def process_pr(
    *,
    click_ctx: typer.Context,
    pr_number: int,
    dry_run: bool = False,
    authed_dry_run: bool = False,
) -> None:
    global_args = click_ctx.ensure_object(GlobalArgs)

    authed = not dry_run
    if authed_dry_run:
        dry_run = True
        authed = True

    gclient, repo = get_repo(
        authed=authed, owner=global_args.owner, repo=global_args.repo
    )
    pr = repo.get_pull(pr_number)
    ctx = PRLabelerCtx(
        client=gclient,
        repo=repo,
        pr=pr,
        dry_run=dry_run,
        event_info=get_event_info(),
        issue=pr.as_issue(),
    )
    if pr.state != "open":
        log(ctx, "Refusing to process closed ticket")
        return

    handle_codeowner_labels(ctx)
    add_label_if_new(ctx, "needs_triage")
    new_contributor_welcome(ctx)
    no_body_nag(ctx)


@APP.command(name="issue")
def process_issue(
    *,
    click_ctx: typer.Context,
    issue_number: int,
    dry_run: bool = False,
    authed_dry_run: bool = False,
) -> None:
    global_args = click_ctx.ensure_object(GlobalArgs)

    authed = not dry_run
    if authed_dry_run:
        dry_run = True
        authed = True
    gclient, repo = get_repo(
        authed=authed, owner=global_args.owner, repo=global_args.repo
    )
    issue = repo.get_issue(issue_number)
    ctx = IssueLabelerCtx(
        client=gclient,
        repo=repo,
        issue=issue,
        dry_run=dry_run,
        event_info=get_event_info(),
    )
    if issue.state != "open":
        log(ctx, "Refusing to process closed ticket")
        return

    add_label_if_new(ctx, "needs_triage")
    new_contributor_welcome(ctx)
    no_body_nag(ctx)


if __name__ == "__main__":
    APP()