git-url-rewrite

#!/bin/bash
export PS4="+\D{%Y/%m/%d %T} \${BASH_SOURCE/\$HOME/\~}@\${LINENO}(\${FUNCNAME[0]}): "

me=`basename $0`

usage () {
    # Call as: usage [EXITCODE] [USAGE MESSAGE]
    exit_code=1
    if [[ "$1" == [0-9] ]]; then
        exit_code="$1"
        shift
    fi
    if [ -n "$1" ]; then
        echo "$*" >&2
        echo
    fi

    cat <<EOF >&2
Usage:
  $me [<file-option>]           Lists all rewrite rules.
  $me [<file-option>] ABBREV    Lists rewrite rule(s) for ABBREV
  $me [<file-option>] [-p] ABBREV FULL
                                Sets rewrite rule for ABBREV to FULL
                                  -p uses pushInsteadOf, not insteadOf.
                                  If FULL is empty string, clears the rule.

<file-option> is as for git-config, i.e. --system, --global, --local,
--file <filename>.  Defaults to --global.
EOF
    exit "$exit_code"
}

get_rewrites () {
    git config $config --list | \
        perl -lne '
            if (m!^url\.(.+)\.(push)?insteadOf=(.+)$!i) {
                $abbrev  = sprintf "%-15s", $3;
                $full = $1;
                $abbrev =~ s/ {0,5}$/ PUSH/ if $2;
                print("$abbrev -> $full");
            }' | \
        sort
}

get_rewrites_by_abbrev () {
    abbrev="$1"

    git config $config --list | \
        perl -lne '
            if (m!^url\.(.+)\.(push)?insteadOf='"${abbrev//!/\!}"'$!i) {
                print(($2 ? "PUSH " : "") . $1);
            }'
}

get_rewrite_by_URL () {
    URL="$1"

    git config $config url.$URL.$insteadOf
}

get_and_clear_rewrite () {
    abbrev="$1"
    full="$2"

    git config $config --list | \
        perl -lne '
            if (m!^(url\.(.+)\.'"$insteadOf"')='"${abbrev//!/\!}"'$!i) {
                print $2;
                next if $2 eq "'"$full"'";
                system qw(git config '"$config"' --unset), $1;
            }'
}

set_rewrite () {
    [ -z "$1" ] && usage "Abbreviation cannot be empty."
    abbrev="$1"
    full="$2"

    if [ -n "$full" ]; then
        existing_abbrev=$( get_rewrite_by_URL "$full" )
        if [ "$abbrev" = "$existing_abbrev" ]; then
            : Nothing to change
            return 0
        fi
        if [ -n "$existing_abbrev" ]; then
            echo "$existing_abbrev already points to \"$full\"; git won't"\
                 "allow pointing something else to it" >&2
            exit 1
        fi
    fi

    existing_full=$( get_and_clear_rewrite "$abbrev" "$full" )

    if [ -z "$full" ]; then
        git config $config --unset "url.$full.$insteadOf"
        echo "Cleared ${push:+push }URL rewrite of $abbrev (was $existing_full)"
        return
    fi

    git config $config "url.$full.$insteadOf" "$abbrev"

    if [ -z "$existing_full" ]; then
        echo "Set ${push:+push }URL rewrite of $abbrev -> $full"
    elif [ "$full" != "$existing_full" ]; then
        echo "Changed ${push:+push }URL rewrite of $abbrev -> $full (was $existing_full)"
    fi
}

parse_opts () {
    config=

    while [ $# != 0 ]; do
        case "$1" in
            -h|--help)
                usage 0
                ;;
            --system|--global|--local)
                config="$1"
                shift
                break
                ;;
            -f|--file)
                config="--file $2"
                shift 2
                break
                ;;
            *)
                break
                ;;
        esac
    done

    if [ -z "$config" ]; then
        #if ! git rev-parse --git-dir 2>/dev/null; then
        config=--global
        #fi
    fi

    insteadOf='insteadOf'
    if [ "$1" == '-p' ]; then
        push=y
        insteadOf='pushInsteadOf'
        shift
        if [ $# != 2 ]; then
            usage "-p only valid when setting"
        fi
    fi

    ARGV=( "$@" )
}

main () {
    parse_opts "$@"

    set -- "${ARGV[@]}"

    if [ $# = 0 ]; then
        get_rewrites
    elif [ $# = 1 ]; then
        get_rewrites_by_abbrev "$1"
    elif [ $# = 2 ]; then
        set_rewrite "$@"
    else
        usage 1
    fi
}

main "$@"