git-pr

#!/usr/bin/env bash

set -euo pipefail

checknargs() {
    if (( $1 != $2 )); then
        usage
        exit 1
    fi
}

checkout() {
    checknargs $# 1
    git fetch -fu "${2:-origin}" "refs/pull/$1/head:pr/$1"
    git checkout "pr/$1"
}

fetch() {
    checknargs $# 1
    git fetch -fu "${2:-origin}" "refs/pull/$1/head:pr/$1"
}

merge() {
    checknargs $# 1
    git fetch -fu "${2:-origin}" "refs/pull/$1/head:pr/$1"
    git merge "pr/$1" --no-ff --edit -m "Merge pull request #$1"
}

clean() {
    checknargs $# 0
    for ref in $(git for-each-ref refs/heads/pr/* --format="%(refname)"); do
        branch=${ref#refs/heads/}
        git branch -D "$branch"
    done
}

usage() {
    echo "git pr <subcommand> [number] [remote]"
    echo
    echo "subcommands"
    echo "  checkout   Fetch a PR by number and switch to the new branch"
    echo "  fetch      Fetch a PR by number"
    echo "  merge      Merge a PR by number"
    echo "  clean      Delete all local PR branches"
}

if (( $# == 0 )); then
    usage
    exit 1
fi

cmd="$1"
shift
args=("${@}")

case "${cmd}" in
    checkout)
        checkout "${args[@]}"
        ;;
    fetch)
        fetch "${args[@]}"
        ;;
    merge)
        merge "${args[@]}"
        ;;
    clean)
        clean "${args[@]}"
        ;;
    *)
        echo "Unknown command ${cmd}"
        usage
        exit 1
esac