#!/bin/bash
list_branches() {
    git for-each-ref refs/heads --format="%(refname:short)"
}
list_tracked() {
    git ls-tree HEAD | grep blob | awk '{print $4}';
    git ls-tree HEAD | grep tree | awk '{print $4"/"}';
}
list_untracked() {
    git ls-files --exclude-standard --other --directory --no-empty-directory
}
list_modified() {
    git ls-files --modified
}
list_staged() {
    git diff --name-only --relative --cached
}
_get_complete()
{
# Available variables:
# COMP_LINE COMP_POINT COMP_KEY COMP_TYPE COMP_WORDS COMP_CWORD
# $1 : name of command whose arguments are being completed
# $2 : the word being completed
# $3 : the word preceding the word being completed
case ${COMP_CWORD} in
1)
    commands="branch commit diff fetch ignore reset rmbranch review stage status unstage"
    COMPREPLY=( $(compgen -W "${commands}" "$2") )
;;
2)
    compopt -o nospace
    case "$3" in
        # <branch>
        branch | rmbranch | fetch)
            COMPREPLY=( $(compgen -W "$(list_branches)" "$2") )
        ;;
        # <modified path>
        stage)
            COMPREPLY=( $(compgen -W "$(list_modified)" "$2") )
        ;;
        # <tracked path>
        unstage)
            COMPREPLY=( $(compgen -W "$(list_staged)" "$2") )
        ;;
        rm | diff)
            COMPREPLY=( $(compgen -W "$(list_tracked)" "$2") )
        ;;
        # <untracked path>
        add)
            compopt -o nospace
            COMPREPLY=( $(compgen -W "$(list_untracked)" -W "STAGE" -W "HEAD" "$2") )
        ;;
    esac
;;
3)
    case "${COMP_WORDS[COMP_CWORD-2]}" in
        diff)
            compopt -o nospace
            COMPREPLY=( $(compgen -W "$(list_tracked)" "$2") )
        ;;
    esac
;;
*)
    COMPREPLY=()
;;
esac
}
complete -F _get_complete get