#!/usr/bin/env python3

"""
Shared GitHub Actions API helpers for getting workflow information.
"""

import os
import re
from typing import Any, Iterable

import requests

GITHUB_API_URL = os.environ.get("GITHUB_API_URL", "https://api.github.com")


def make_github_session(github_token: str) -> requests.Session:
    session = requests.Session()
    session.headers["Authorization"] = f"Bearer {github_token}"
    session.headers["Accept"] = "application/vnd.github+json"
    session.headers["X-GitHub-Api-Version"] = "2022-11-28"
    return session


def get_required_github_env() -> tuple[str, str, str]:
    """Read and validate the GitHub Actions env vars needed for the API."""
    github_repository = os.environ.get("GITHUB_REPOSITORY")
    github_run = os.environ.get("GITHUB_RUN_ID")
    github_token = os.environ.get("GITHUB_TOKEN")

    if not github_repository:
        raise RuntimeError("GITHUB_REPOSITORY is not set")
    if not github_run:
        raise RuntimeError("GITHUB_RUN_ID is not set")
    if not github_token:
        raise RuntimeError("GITHUB_TOKEN is not set")

    return github_repository, github_run, github_token


def get_most_recent_workflow(
    sess: requests.Session, github_repository: str, github_run: str
) -> Any:
    workflow_run = get_current_run(sess, github_repository, github_run)
    past_runs = get_past_runs(sess, workflow_run)
    for run in past_runs:
        return run

    raise RuntimeError("Could not find a previous successful workflow run")


def get_current_run(
    sess: requests.Session, github_repository: str, github_run: str
) -> Any:
    resp = sess.get(
        f"{GITHUB_API_URL}/repos/{github_repository}/actions/runs/{github_run}"
    )
    resp.raise_for_status()
    run = resp.json()
    for key in ("id", "created_at", "workflow_url"):
        if key not in run:
            raise RuntimeError(
                f"GitHub API response for current run is missing '{key}'"
            )

    return run


def get_past_runs(sess: requests.Session, current_run: Any) -> Iterable[Any]:
    """
    Get all successful workflow runs before our current one.
    """
    params = {
        "status": "success",
        "created": f"<={current_run['created_at']}",
        "per_page": 100,
    }
    url = f"{current_run['workflow_url']}/runs"

    while url:
        resp = sess.get(url, params=params)
        resp.raise_for_status()

        runs = resp.json()
        if "workflow_runs" not in runs:
            raise RuntimeError(
                "GitHub API response for past runs is missing 'workflow_runs'"
            )

        for run in runs["workflow_runs"]:
            # First past successful run that isn't our current run.
            if run["id"] == current_run["id"]:
                continue

            yield run

        next_url = resp.links.get("next", {}).get("url")
        if not next_url:
            break

        url = next_url
        params = None


def get_last_publish_sha(
    sess: requests.Session, github_repository: str, github_run: str
) -> str:
    """
    Get the head commit SHA of the most recent successful workflow run.

    Validates that the found run actually has a head commit id and that the
    value looks like a commit SHA before returning it.
    """
    most_recent = get_most_recent_workflow(sess, github_repository, github_run)

    head_commit = most_recent.get("head_commit")
    last_sha = head_commit.get("id") if head_commit else None
    if not last_sha:
        raise RuntimeError(
            f"Workflow run {most_recent.get('id')} has no head_commit id"
        )

    print(f"Last successful publish job was {most_recent.get('id')}: {last_sha}")

    return last_sha