you-should-use.plugin.zsh
#!/bin/zsh

export YSU_VERSION='1.10.1'

if ! type "tput" > /dev/null; then
    printf "WARNING: tput command not found on your PATH.\n"
    printf "zsh-you-should-use will fallback to uncoloured messages\n"
else
    NONE="$(tput sgr0)"
    BOLD="$(tput bold)"
    RED="$(tput setaf 1)"
    YELLOW="$(tput setaf 3)"
    PURPLE="$(tput setaf 5)"
fi

function check_alias_usage() {
    # Optional parameter that limits how far back history is checked
    # I've chosen a large default value instead of bypassing tail because it's simpler
    local limit="${1:-${HISTSIZE:-9000000000000000}}"
    local key

    declare -A usage
    for key in "${(@k)aliases}"; do
        usage[$key]=0
    done

    # TODO:
    # Handle and (&&) + (&)
    # others? watch, time etc...

    local -a histfile_lines
    histfile_lines=("${(@f)$(<$HISTFILE)}")
    histfile_lines=("${histfile_lines[@]#*;}")

    local current=0
    local total=${#histfile_lines}
    if [[ $total -gt $limit ]]; then
        total=$limit
    fi

    local entry
    for line in ${histfile_lines[@]} ; do
        for entry in ${(@s/|/)line}; do
            # Remove leading whitespace
            entry=${entry##*[[:space:]]}

            # We only care about the first word because that's all aliases work with
            # (this does not count global and git aliases)
            local word=${entry[(w)1]}
            if [[ -n ${usage[$word]} ]]; then
                (( usage[$word]++ ))
            fi
        done

        # print current progress
        (( current++ ))
        printf "Analysing: [$current/$total]\r"
    done
    # Clear all previous line output
    printf "\r\033[K"

    # Print ordered usage
    for key in ${(k)usage}; do
        echo "${usage[$key]}: ${(q+)key}=${(q+)aliases[$key]}"
    done | sort -rn -k1
}

# Writing to a buffer rather than directly to stdout/stderr allows us to decide
# if we want to write the reminder message before or after a command has been executed
function _write_ysu_buffer() {
    _YSU_BUFFER+="$@"

    # Maintain historical behaviour by default
    local position="${YSU_MESSAGE_POSITION:-before}"
    if [[ "$position" = "before" ]]; then
        _flush_ysu_buffer
    elif [[ "$position" != "after" ]]; then
        (>&2 printf "${RED}${BOLD}Unknown value for YSU_MESSAGE_POSITION '$position'. ")
        (>&2 printf "Expected value 'before' or 'after'${NONE}\n")
        _flush_ysu_buffer
    fi
}

function _flush_ysu_buffer() {
    # It's important to pass $_YSU_BUFFER to printfs first argument
    # because otherwise all escape codes will not printed correctly
    (>&2 printf "$_YSU_BUFFER")
    _YSU_BUFFER=""
}

function ysu_message() {
    local DEFAULT_MESSAGE_FORMAT="${BOLD}${YELLOW}\
Found existing %alias_type for ${PURPLE}\"%command\"${YELLOW}. \
You should use: ${PURPLE}\"%alias\"${NONE}"

    local alias_type_arg="${1}"
    local command_arg="${2}"
    local alias_arg="${3}"

    # Escape arguments which will be interpreted by printf incorrectly
    # unfortunately there does not seem to be a nice way to put this into
    # a function because returning the values requires to be done by printf/echo!!
    command_arg="${command_arg//\%/%%}"
    command_arg="${command_arg//\\/\\\\}"

    local MESSAGE="${YSU_MESSAGE_FORMAT:-"$DEFAULT_MESSAGE_FORMAT"}"
    MESSAGE="${MESSAGE//\%alias_type/$alias_type_arg}"
    MESSAGE="${MESSAGE//\%command/$command_arg}"
    MESSAGE="${MESSAGE//\%alias/$alias_arg}"

    _write_ysu_buffer "$MESSAGE\n"
}


# Prevent command from running if hardcore mode enabled
function _check_ysu_hardcore() {
    local alias_name="$1"

    local hardcore_lookup="${YSU_HARDCORE_ALIASES[(r)$alias_name]}"
    if (( ${+YSU_HARDCORE} )) || [[ -n "$hardcore_lookup" && "$hardcore_lookup" == "$alias_name" ]]; then
        _write_ysu_buffer "${BOLD}${RED}You Should Use hardcore mode enabled. Use your aliases!${NONE}\n"
        kill -s INT $$
    fi
}


function _check_git_aliases() {
    local typed="$1"
    local expanded="$2"

    # sudo will use another user's profile and so aliases would not apply
    if [[ "$typed" = "sudo "* ]]; then
        return
    fi

    if [[ "$typed" = "git "* ]]; then
        local found=false
        git config --get-regexp "^alias\..+$" | sort | while read key value; do
            key="${key#alias.}"

            # if for some reason, read does not split correctly, we
            # detect that and manually split the key and value
            if [[ -z "$value" ]]; then
                value="${key#* }"
                key="${key%% *}"
            fi

            if [[ "$expanded" = "git $value" || "$expanded" = "git $value "* ]]; then
                ysu_message "git alias" "$value" "git $key"
                found=true
            fi
        done

        if $found; then
            _check_ysu_hardcore
        fi
    fi
}


function _check_global_aliases() {
    local typed="$1"
    local expanded="$2"

    local found=false
    local tokens
    local key
    local value
    local entry

    # sudo will use another user's profile and so aliases would not apply
    if [[ "$typed" = "sudo "* ]]; then
        return
    fi

    alias -g | sort | while IFS="=" read -r key value; do
        key="${key## }"
        key="${key%% }"
        value="${(Q)value}"

        # Skip ignored global aliases
        if [[ ${YSU_IGNORED_GLOBAL_ALIASES[(r)$key]} == "$key" ]]; then
            continue
        fi

        if [[ "$typed" = *" $value "* || \
              "$typed" = *" $value" || \
              "$typed" = "$value "* || \
              "$typed" = "$value" ]]; then
            ysu_message "global alias" "$value" "$key"
            found=true
        fi
    done

    if $found; then
        _check_ysu_hardcore
    fi
}


function _check_aliases() {
    local typed="$1"
    local expanded="$2"

    local found_aliases
    found_aliases=()
    local best_match=""
    local best_match_value=""
    local key
    local value

    # sudo will use another user's profile and so aliases would not apply
    if [[ "$typed" = "sudo "* ]]; then
        return
    fi

    # Find alias matches
    for key in "${(@k)aliases}"; do
        value="${aliases[$key]}"

        # Skip ignored aliases
        if [[ ${YSU_IGNORED_ALIASES[(r)$key]} == "$key" ]]; then
            continue
        fi

        if [[ "$typed" = "$value" || "$typed" = "$value "* ]]; then

        # if the alias longer or the same length as its command
        # we assume that it is there to cater for typos.
        # If not, then the alias would not save any time
        # for the user and so doesn't hold much value anyway
        if [[ "${#value}" -gt "${#key}" ]]; then

            found_aliases+="$key"

            # Match aliases to longest portion of command
            if [[ "${#value}" -gt "${#best_match_value}" ]]; then
                best_match="$key"
                best_match_value="$value"
            # on equal length, choose the shortest alias
            elif [[ "${#value}" -eq "${#best_match}" && ${#key} -lt "${#best_match}" ]]; then
                best_match="$key"
                best_match_value="$value"
            fi
        fi
        fi
    done

    # Print result matches based on current mode
    if [[ "$YSU_MODE" = "ALL" ]]; then
        for key in ${(@ok)found_aliases}; do
            value="${aliases[$key]}"
            ysu_message "alias" "$value" "$key"
            _check_ysu_hardcore "$key"
        done

    elif [[ (-z "$YSU_MODE" || "$YSU_MODE" = "BESTMATCH") && -n "$best_match" ]]; then
        # make sure that the best matched alias has not already
        # been typed by the user
        value="${aliases[$best_match]}"
        if [[ "$typed" = "$best_match" || "$typed" = "$best_match "* ]]; then
            return
        fi
        ysu_message "alias" "$value" "$best_match"
        _check_ysu_hardcore "$best_match"
    fi
}

function disable_you_should_use() {
    add-zsh-hook -D preexec _check_aliases
    add-zsh-hook -D preexec _check_global_aliases
    add-zsh-hook -D preexec _check_git_aliases
    add-zsh-hook -D precmd _flush_ysu_buffer
}

function enable_you_should_use() {
    disable_you_should_use   # Delete any possible pre-existing hooks
    add-zsh-hook preexec _check_aliases
    add-zsh-hook preexec _check_global_aliases
    add-zsh-hook preexec _check_git_aliases
    add-zsh-hook precmd _flush_ysu_buffer
}

autoload -Uz add-zsh-hook
enable_you_should_use
