#!/usr/bin/env python3
# Copied from https://github.com/rerun-io/rerun_template

"""
Summarizes recent PRs based on their GitHub labels.

The result can be copy-pasted into CHANGELOG.md,
though it often needs some manual editing too.
"""

from __future__ import annotations

import argparse
import multiprocessing
import os
import re
import sys
from dataclasses import dataclass
from typing import Any, Optional

import requests
from git import Repo  # pip install GitPython
from tqdm import tqdm

OWNER = "rerun-io"
REPO = "new_repo_name"
INCLUDE_LABELS = False  # It adds quite a bit of visual noise
OFFICIAL_RERUN_DEVS = [
    "abey79",
    "emilk",
    "jleibs",
    "jprochazk",
    "nikolausWest",
    "teh-cmc",
    "Wumpf",
]


@dataclass
class PrInfo:
    gh_user_name: str
    pr_title: str
    labels: list[str]


@dataclass
class CommitInfo:
    hexsha: str
    title: str
    pr_number: Optional[int]


def get_github_token() -> str:
    token = os.environ.get("GH_ACCESS_TOKEN", "")
    if token != "":
        return token

    home_dir = os.path.expanduser("~")
    token_file = os.path.join(home_dir, ".githubtoken")

    try:
        with open(token_file, encoding="utf8") as f:
            token = f.read().strip()
        return token
    except Exception:
        pass

    print("ERROR: expected a GitHub token in the environment variable GH_ACCESS_TOKEN or in ~/.githubtoken")
    sys.exit(1)


# Slow
def fetch_pr_info_from_commit_info(commit_info: CommitInfo) -> Optional[PrInfo]:
    if commit_info.pr_number is None:
        return None
    else:
        return fetch_pr_info(commit_info.pr_number)


# Slow
def fetch_pr_info(pr_number: int) -> Optional[PrInfo]:
    url = f"https://api.github.com/repos/{OWNER}/{REPO}/pulls/{pr_number}"
    gh_access_token = get_github_token()
    headers = {"Authorization": f"Token {gh_access_token}"}
    response = requests.get(url, headers=headers)
    json = response.json()

    # Check if the request was successful (status code 200)
    if response.status_code == 200:
        labels = [label["name"] for label in json["labels"]]
        gh_user_name = json["user"]["login"]
        return PrInfo(gh_user_name=gh_user_name, pr_title=json["title"], labels=labels)
    else:
        print(f"ERROR {url}: {response.status_code} - {json['message']}")
        return None


def get_commit_info(commit: Any) -> CommitInfo:
    match = re.match(r"(.*) \(#(\d+)\)", commit.summary)
    if match:
        title = str(match.group(1))
        pr_number = int(match.group(2))
        return CommitInfo(hexsha=commit.hexsha, title=title, pr_number=pr_number)
    else:
        return CommitInfo(hexsha=commit.hexsha, title=commit.summary, pr_number=None)


def remove_prefix(text: str, prefix: str) -> str:
    if text.startswith(prefix):
        return text[len(prefix) :]
    return text  # or whatever


def print_section(crate: str, items: list[str]) -> None:
    if 0 < len(items):
        print(f"#### {crate}")
        for line in items:
            print(f"* {line}")
    print()


def main() -> None:
    parser = argparse.ArgumentParser(description="Generate a changelog.")
    parser.add_argument("--commit-range", help="e.g. 0.1.0..HEAD", required=True)
    args = parser.parse_args()

    repo = Repo(".")
    commits = list(repo.iter_commits(args.commit_range))
    commits.reverse()  # Most recent last
    commit_infos = list(map(get_commit_info, commits))

    pool = multiprocessing.Pool()
    pr_infos = list(
        tqdm(
            pool.imap(fetch_pr_info_from_commit_info, commit_infos),
            total=len(commit_infos),
            desc="Fetch PR info commits",
        )
    )

    prs = []
    unsorted_commits = []

    for commit_info, pr_info in zip(commit_infos, pr_infos):
        hexsha = commit_info.hexsha
        title = commit_info.title
        title = title.rstrip(".").strip()  # Some PR end with an unnecessary period
        pr_number = commit_info.pr_number

        if pr_number is None:
            # Someone committed straight to main:
            summary = f"{title} [{hexsha[:7]}](https://github.com/{OWNER}/{REPO}/commit/{hexsha})"
            unsorted_commits.append(summary)
        else:
            # We prefer the PR title if available
            title = pr_info.pr_title if pr_info else title
            labels = pr_info.labels if pr_info else []

            if "exclude from changelog" in labels:
                continue
            if "typo" in labels:
                # We get so many typo PRs. Let's not flood the changelog with them.
                continue

            summary = f"{title} [#{pr_number}](https://github.com/{OWNER}/{REPO}/pull/{pr_number})"

            if INCLUDE_LABELS and 0 < len(labels):
                summary += f" ({', '.join(labels)})"

            if pr_info is not None:
                gh_user_name = pr_info.gh_user_name
                if gh_user_name not in OFFICIAL_RERUN_DEVS:
                    summary += f" (thanks [@{gh_user_name}](https://github.com/{gh_user_name})!)"

            prs.append(summary)

    # Clean up:
    for i in range(len(prs)):
        line = prs[i]
        line = line[0].upper() + line[1:]  # Upper-case first letter
        prs[i] = line

    print()
    print(f"Full diff at https://github.com/rerun-io/{REPO}/compare/{args.commit_range}")
    print()
    print_section("PRs", prs)
    print_section("Unsorted commits", unsorted_commits)


if __name__ == "__main__":
    main()