cheats.sh

function cheats {
    local IFS;
    if [[ -f "$*" ]]; then
        history -s "cheats $*";
        __run_cheat "$*"; # mainly for debugging: absolute paths outside of ~/.cheats
    else
        IFS=' ';
        if [[ -f "$HOME/.cheats/$*" ]]; then
            history -s "cheats $*";
            __run_cheat "$HOME/.cheats/$*";
        else
            local visited="false";
            for file in ~/.cheats/"$*"*; do
                ! [[ -f "$file" ]] && continue; # skip things that aren't files
                if [[ "$visited" = "true" ]]; then
                    __print_separator_line;
                fi
                tput bold; # print filename in bold
                printf '%s\n' "${file##*/}" # print filename without other path parts
                tput sgr0; # reset
                { # print the first two lines: description and command
                    local description command;
                    IFS= read description;
                    IFS= read command;
                    printf '%s\n%s\n' "$description" "$command";
                } < "$file"
                visited="true";
            done
            if [[ $visited = "false" ]]; then
                echo "No cheats with prefix \"$*\" found in ~/.cheats";
            fi
        fi
    fi
}

function __run_cheat {
    # all variables start with a double underscore to avoid collisions with cheat variables
    # (which are placed into the current environment as local variables)
    local __description __command __line __input;
    exec 3< "$*";
    IFS= read <&3 -r __description;
    IFS= read <&3 -r __command;
    printf '%s\n%s\n' "$__description" "$__command";
    while IFS= read <&3 -r __line; do
        if [[ -z "$__line" || ${__line:0:1} == '#' ]]; then
            # blank line or comment line
            continue;
        fi
        # name is ${__line%%:*}, prompt is ${__line##*:}
        read -e -p "${__line##*:}$PS2" __input;
        local ${__line%%:*}="$__input";
    done
    __print_separator_line;
    history -s "$__command";
    eval "$__command";
}

function __print_separator_line {
    local cols=${COLUMNS:-$(tput cols)};
    for ((i=0; i<cols; i++)); do printf -; done # print a separator line with the width of the console
    printf '\n'
}

if shopt -q progcomp 2> /dev/null; then
    # bash completion
    # to understand how this function manipulates variables,
    # I recommend reading the sections "Parameter Expansion" and "Arrays" of the bash manpage.
    function _cheats {
        if [[ ! -d ~/.cheats ]]; then
            return 0;
        fi
        local IFS;
        IFS=' '; local compInput="${COMP_WORDS[*]:1}"; # strip away "cheats" command
        local compInputArray=( $compInput );
        IFS=$'\n'; local allCheats=(~/.cheats/*);
        j=0;
        shopt -q nullglob; hadNullglob=$?
        shopt -s nullglob
        for cheat in ~/.cheats/"$compInput"*; do
            # cheat matches completion input
            # we now need to translate
            # "git re" ($compInput) and
            # "~/.cheats/git rebase 1" ($cheat)
            # into "rebase 1"
            IFS=' ';
            local currentCheatArray=( ${cheat#~/.cheats/} );
            local firstDiffIndex=0;
            while [[ ${currentCheatArray[$firstDiffIndex]} == ${compInputArray[$firstDiffIndex]}
                            && $firstDiffIndex < ${#currentCheatArray} ]]; do
                ((firstDiffIndex++));
            done
            if [[ $COMP_CWORD == $firstDiffIndex ]]; then
                ((firstDiffIndex--)); # don’t override the current word; see #3
            fi
            COMPREPLY[$((j++))]="${currentCheatArray[*]:$firstDiffIndex}";
        done
        if ((hadNullglob==0)); then shopt -u nullglob; fi
    }
    complete -F _cheats cheats;
fi