#!/usr/bin/env python3

import os
import re
import yaml
import tempfile
import subprocess

from email.utils import parsedate_to_datetime
from debian.changelog import Changelog


BASE_DIR = os.path.dirname(__file__)

TEMPLATE = """
---
layout: post
title: diffoscope {version} released
author: {author}
---

The diffoscope maintainers are pleased to announce the release of diffoscope
version `{version}`. This version includes the following changes:

```
{changes}
```

You find out more by [visiting the project homepage](https://diffoscope.org).
"""


def main():
    src = "https://salsa.debian.org/reproducible-builds/diffoscope.git"

    # Prefer a local checkout if it exists
    basepath = os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
    candidates = [
        os.path.join(*basepath, "diffoscope", ".git"),
        os.path.join(*basepath, "diffoscope", "diffoscope", ".git"),
    ]

    for candidate in candidates:
        if os.path.exists(candidate):
            src = candidate
            break

    with tempfile.TemporaryDirectory() as t:
        git_dir = os.path.join(t, "diffoscope")
        subprocess.check_call(("git", "clone", src, git_dir))

        releases = get_releases(git_dir)
        debian_substvars = get_debian_substvars(git_dir)

        data = {
            "latest_release": {
                "date": int(releases[0]["date"].timestamp()),
                "version": releases[0]["version"],
            },
            "contributors": get_contributors(git_dir),
            "description": debian_substvars["diffoscope:Description"],
        }

        with open(os.path.join(BASE_DIR, "_data", "diffoscope.yml"), "w") as f:
            print("# This file is automatically generated\n", file=f)
            yaml.dump(data, stream=f)

        for x in releases:
            date_fmt = x["date"].strftime("%Y-%m-%d")

            target = os.path.join(
                BASE_DIR, "_posts", f"{date_fmt}-diffoscope-{x['version']}-released.md"
            )

            with open(target, "w") as f:
                print(TEMPLATE.format(**x).strip(), file=f)


def get_contributors(git_dir):
    result = set()
    emails = set()

    for x in git(git_dir, "log", "--format=%aN|%aE").splitlines():
        name, email = x.rsplit("|", 1)
        if name != "root" and email not in emails:
            emails.add(email)
            result.add(name)

    return list(sorted(result, key=lambda x: x.lower()))


def get_releases(git_dir):
    result = []
    changelog = Changelog()

    with open(os.path.join(git_dir, "debian", "changelog")) as f:
        changelog.parse_changelog(f)

    for x in changelog:
        if x.distributions == "UNRELEASED":
            continue

        changes = (
            (re.sub(r"^  ", "", "\n".join(x.changes()), flags=re.MULTILINE))
            .lstrip("\n")
            .rstrip("\n")
        )

        result.append(
            {
                "date": parsedate_to_datetime(x.date),
                "author": x.author,
                "changes": changes,
                "version": str(x.version),
            }
        )

    return result


def get_debian_substvars(git_dir):
    val = subprocess.check_output(
        ("bin/diffoscope", "--list-debian-substvars"), cwd=git_dir
    )

    data = {}

    for x in val.decode("utf-8").splitlines():
        key, _, val = x.partition("=")

        data[key] = val.replace("${Newline}", " ")

    return data


def git(git_dir, *args):
    cmd = ("git",) + args

    val = subprocess.check_output(cmd, env={"GIT_DIR": os.path.join(git_dir, ".git")})

    return val.decode("utf-8")


if __name__ == "__main__":
    main()