make-fst-release

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-

"""
Creates and pushes a new tag for the current FSTs.

Usage:
    make-new-release [(alpha|beta|post) [<positive integer>]]


This will create a new tag and push it to GitHub. This will subsequently kick-off a
workflow that compiles and uploads the FSTs to GitHub.
"""

import sys
from subprocess import check_call, check_output
from datetime import datetime

EX_USAGE = 64  # refer to `man 3 sysexits`
VALID_PRERELEASE_IDENTIFIERS = "alpha", "beta", "post"
ALLOW_TAG_ON_BRANCH = "main"


class UsageError(Exception):
    """
    Raised when something is the user's fault
    """


def main():
    prerelease = get_prerelease_from_args()

    ensure_on_correct_branch()
    ensure_working_directory_clean()

    tag = generate_tag_text(prerelease)
    check_call(["git", "tag", tag])
    check_call(["git", "push", "--tags"])


def get_prerelease_from_args():
    "get a prerelease like alpha.0/beta.1/post.0 from the args"

    if len(sys.argv) <= 1:
        return ""

    prerelease = sys.argv[1]
    if prerelease not in VALID_PRERELEASE_IDENTIFIERS:
        raise UsageError(
            f"“{prerelease}” is invalid; "
            f"choose one from {VALID_PRERELEASE_IDENTIFIERS}"
        )

    if len(sys.argv) <= 2:
        increment = 0
    else:
        try:
            increment = int(sys.argv[2])
            if increment < 0:
                raise ValueError
        except ValueError:
            raise UsageError(f"invalid increment: {sys.argv[2]}")

    return f"{prerelease}.{increment}"


def generate_tag_text(prerelease):
    "generates an appropriate calver (semver) tag"
    today = datetime.now()
    tag = f"fst-v{today.year}.{today.month}.{today.day}"

    if prerelease:
        tag = f"{tag}-{prerelease}"

    return tag


def ensure_on_correct_branch():
    "makes sure we're on an approved git branch"
    git_branch_output = check_output(["git", "branch"], encoding="UTF-8")
    for line in git_branch_output.split("\n"):
        if line.startswith("*"):
            _star, _space, current_branch = line.partition(" ")
            break
    else:
        raise ValueError("Could not make sense of git branch output: {git_branch_output!r}")

    if current_branch != ALLOW_TAG_ON_BRANCH:
        raise UsageError(
            f"can only tag on branch “{ALLOW_TAG_ON_BRANCH}”; "
            f"(currently on branch “{current_branch}”)"
        )


def ensure_working_directory_clean():
    "makes sure there are no modified/added/renamed/copied files in the git working tree"
    status = check_output(["git", "status", "--porcelain", "--untracked-files=no"], encoding="UTF-8")
    working_directory_clean = True
    for line in status.rstrip("\n").split("\n"):
        line = line.strip()
        if not line or line.startswith("?"):
            continue
        working_directory_clean = False

    if not working_directory_clean:
        raise UsageError(
            "refusing to tag with a dirty working directory; "
            "please commit all changes or stash changes to make the tree clean"
        )


if __name__ == '__main__':
    try:
        main()
    except UsageError as error:
        print(f"{sys.argv[0]}: {str(error)}")
        sys.exit(EX_USAGE)