git-aux

#!/bin/bash

set -e

VERSION=0.3

ga_help() {
    echo "usage: $0 [command] <[arguments]>"
    echo
    echo "Commands:"
    echo "   init [dir]      Initialise git aux to use [dir] as the aux directory"
    echo "   add [file(s)]   Add files from the aux directory to the repo"
    echo "   sync            Synchronise changes from the aux directory to the repo"
    echo "   apply           Apply changes from the repo to the aux directory"

    exit
}

die() {
    echo $@ 1>&2
    kill 0
}

last_commit() {
    git show | grep ^commit | cut -d ' ' -f 2
}

current_branch() {
    git branch | grep "^*" | sed -e 's/^\*\s*//'
}

git_root() {
    git rev-parse --show-toplevel
}

aux_dir() {
    git config aux.home || die "Not a git aux repository"
}

update_aux() {
    (for file in $(git ls-files); do 
        if [ "$file" != ".gitaux" -a -e "$file" ]; then
            echo $file:$(stat -c "%a" $file)
        fi
    done) > $(git_root)/.gitaux
    git add $(git_root)/.gitaux
}

repo_files() {
    find $(git_root) -type f -not -path "$(git_root)/.git/*" -not -path "$(git_root)/.gitaux"
}

relative() {
    local file=$1
    local dir=$2

    echo $file | sed -e "s/^$(echo $dir | sed -e 's/\//\\\//g')//"
}

ga_init() {
    git config aux.home >/dev/null && die "This repository is already initialised for use with git-aux: $(aux_dir)"

    if [ -z "$1" -o ! -d "$1" ]; then
        die "You must supply a directory path"
    fi

    git config aux.home $(readlink -f $1)
    update_aux

    echo "Done"
}

add_all() {
    # Add files to repo
    if [ "$1" == "-f" ]; then
        git add -u
    else
        git add -p
    fi

    # Add new files too
    if [ -n "$(git ls-files -o --exclude-standard)" ]; then
        git add $(git ls-files -o --exclude-standard)
    fi
}

ga_add() {
    for file in $@; do
        local file=$(readlink -f $file)
        local rel_path=$(relative $file $(aux_dir))

        if [ -z "$(find "$file" -type f -path "$(aux_dir)*")" ]; then
            die "$file is not in the aux root"
        else
            echo "Adding $file..."
            cp -af "$file" "$(git_root)/$rel_path"
            git add "$(git_root)/$rel_path"
        fi
    done

    update_aux

    echo "Done"
}

ga_sync() {
    for file in $(repo_files); do
        file=$(relative $file $(git_root))

        rm -r $(git_root)/$file
        # Copy or remove file/dir
        if [ -e "$(aux_dir)/$file" ]; then
            cp -af "$(aux_dir)/$file" "$(git_root)/$file"
        fi
    done

    add_all $@

    update_aux

    # Show status
    git status
}

ga_apply() {
    local current_branch=$(current_branch)
    local temp_branch=git-aux-temp-$RANDOM

    local stashed=true

    if [ "$(git stash save -u)" == "No local changes to save" ]; then
        stashed=false
    fi

    # Copy the files home
    for file in $(repo_files); do
        file=$(relative $file $(git_root))
        
        mkdir -p "$(dirname $(aux_dir)/$file)" || {
            # This catches the edge case that we've moved from a file to a directory
            rm -r "$(dirname $(aux_dir)/$file)"
            mkdir -p "$(dirname $(aux_dir)/$file)"
        }
        echo $file...
        cp -af "$(git_root)/$file" "$(aux_dir)/$file"
    done

    # Apply permissions
    for line in $(cat $(git_root)/.gitaux); do
        local path=$(echo $line | sed -e 's/:[0-9]*$//')
        local permissions=$(echo $line | sed -e 's/^.*:\([0-9]*\)$/\1/')

        chmod $permissions $(aux_dir)/$path
    done

    if $stashed; then
        git stash pop
    fi

    echo "Done"
}

ga_diff() {
    echo "Not yet implemented"
}

command=$1
shift || ga_help
args=$@

git branch &>/dev/null || die "Not a git repository"

case $command in
    init) ga_init ${args[0]} ;;
    add) ga_add $args ;;
    sync) ga_sync ;;
    apply)
        read -p "Are you sure you want to apply changes to the aux directory? (y/n) " choice
        if [[ "$choice" =~ ^[Yy] ]]; then
            ga_apply
        else
            echo "Aborted"
        fi
        ;;
    diff) ga_diff ;;
    --version) echo git aux version $VERSION ;;
    *) ga_help ;;
esac