git-elegant-prune-repository

#!/usr/bin/env bash
set -e

command-purpose() {
    cat <<MESSAGE
Removes useless local branches.
MESSAGE
}

command-synopsis() {
    cat <<MESSAGE
usage: git elegant prune-repository
MESSAGE
}

command-description() {
    cat<<MESSAGE
Identifies useless branches within the current repository and removes them. A
branch is useless if it either has configured an unavailable upstream branch (1)
or does not have new commits comparing to \`master\` branch (2).

1 - Usually, a local branch has this state when an appropriate remote branch was
merged to a remote target branch and was removed. Since these manipulations were
made on server side, the local branch is still present, but useless.

2 - This kind of branches appears when a branch is created for some purposes but
does not have any commits nowadays. So, it is useless.

Approximate commands flow is
\`\`\`bash
==>> git elegant prune-repository
git checkout master
git fetch --all
git rebase
git branch --delete --force task-24
git branch --delete --force 2349
git branch --delete --force task-1
\`\`\`

The command works even if the remotes are unavailable.
MESSAGE
}

--is-there-upstream-for() {
    git rev-parse --abbrev-ref ${1}@{upstream} >/dev/null  2>&1
}

default() {
    git-verbose checkout ${MASTER}
    if --is-there-upstream-for ${MASTER}; then
        git-verbose fetch --all || info-text "As the remotes can't be fetched, the current local version is used."
        git-verbose rebase
    fi
    for branch in $(git for-each-ref --format "%(refname:short)" refs/heads/**); do
        if [[ ${branch} == ${MASTER} ]]; then continue; fi
        if [[ -n $(git config --get branch.${branch}.merge) ]]; then
            if --is-there-upstream-for ${branch}; then
                # the branch has existing upstream; keep it
                continue
            fi
        else
            if [[ ! $(git merge-base ${MASTER} ${branch}) == $(git rev-parse ${branch}) ]]; then
                # the branch has new commits; keep it
                continue
            fi
        fi
        git-verbose branch --delete --force ${branch}
    done
}