commit divergence between branches

git-divergence

#!/bin/bash

set -e

FORMAT='%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset'

(
    function branch() {
        git branch 2>/dev/null | grep -e '^*' | tr -d '\* '
    }

    function ensure_valid_ref() {
        ref=$1
        (
            set +e
            git show-ref $ref > /dev/null
            if ! test $? == 0
            then
                echo "$0: bad ref: $ref"
                exit 1
            fi
        )
    }

    if test "$1" == '-r'
    then
        rev='true'
        shift
    else
        rev='false'
    fi

    if test $# == 2
    then
        LOCAL=$1
        REMOTE=$2

    elif test $# == 1
    then
        LOCAL=`branch`
        REMOTE=$1

    else
        LOCAL=`branch`
        REMOTE=origin/$LOCAL
    fi

    ensure_valid_ref $LOCAL
    ensure_valid_ref $REMOTE

    function show_div() {
        ref1=$1
        ref2=$2
        echo
        git --no-pager log \
            --graph \
            --pretty=format:"$FORMAT" \
            --abbrev-commit \
            --date=relative \
            $ref1..$ref2
        echo
        echo
        echo
    }

    if test $rev == 'true'
    then
        tmp="$LOCAL"
        LOCAL="$REMOTE"
        REMOTE="$tmp"
    fi


    echo
    echo "${LOCAL}   <--->   ${REMOTE}"
    echo
    echo incoming:
    show_div "$LOCAL" "$REMOTE"
    echo outgoing:
    show_div "$REMOTE" "$LOCAL"
)