#!/usr/bin/env python3

"""
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.
"""

import multiprocessing
import re
import sys
from dataclasses import dataclass
from typing import Any, List, Optional

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

OWNER = "emilk"
REPO = "egui"
COMMIT_RANGE = "latest..HEAD"
INCLUDE_LABELS = False  # It adds quite a bit of visual noise
OFFICIAL_DEVS = [
    "emilk",
]


@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:
    import os

    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, "r") 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:
        return CommitInfo(hexsha=commit.hexsha, title=str(match.group(1)), pr_number=int(match.group(2)))
    else:
        return CommitInfo(hexsha=commit.hexsha, title=commit.summary, pr_number=None)


def remove_prefix(text, prefix):
    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:
            line = remove_prefix(line, f"{crate}: ")
            line = remove_prefix(line, f"[{crate}] ")
            print(f"* {line}")
    print()


def main() -> None:
    repo = Repo(".")
    commits = list(repo.iter_commits(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",
        )
    )

    ignore_labels = ["CI", "dependencies"]

    crate_names = [
        "ecolor",
        "eframe",
        "egui_extras",
        "egui_plot",
        "egui_glow",
        "egui-wgpu",
        "egui-winit",
        "egui",
        "epaint",
    ]
    sections = {}
    unsorted_prs = []
    unsorted_commits = []

    for commit_info, pr_info in zip(commit_infos, pr_infos):
        hexsha = commit_info.hexsha
        title = commit_info.title
        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:
            title = pr_info.pr_title if pr_info else title  # We prefer the PR title if available
            labels = pr_info.labels if pr_info else []

            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_DEVS:
                    summary += f" (thanks [@{gh_user_name}](https://github.com/{gh_user_name})!)"

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

            added = False

            for crate in crate_names:
                if crate in labels:
                    sections.setdefault(crate, []).append(summary)
                    added = True

            if not added:
                if not any(label in labels for label in ignore_labels):
                    unsorted_prs.append(summary)

    print()
    for crate in crate_names:
        if crate in sections:
            summary = sections[crate]
            print_section(crate, summary)
    print_section("Unsorted PRs", unsorted_prs)
    print_section("Unsorted commits", unsorted_commits)


if __name__ == "__main__":
    main()