prompt_command

#!/bin/bash

# -----------------------------------------------------------------------------
# Author: Paul Weaver (weaverp@ruthorn.co.uk)
#
# Assign the prompt_command function defined below to the PROMPT_COMMAND
# environment variable in your .bashrc/.bash_profile to get a pretty prompt
# containing a bunch of information.
#
# Note: I don't provide a warranty of any kind with this software! On the plus
# side, however, please feel free to distribute this file to your friends,
# family, pets etc. (So long as you keep this attribution)
# -----------------------------------------------------------------------------

# NOTE colours will just fail silently if not present aside from the intial
# warning that .bash_colours is missing.
source $HOME/.bash_colors

function _padding {
    # Creates a string of spaces of the passed size
    local size=$1
    local result
    printf -v result "%${size}s" ' '
    echo "$result"
}
function _repeat_chars {
    # Creates a string of <size> repeats of <char>
    local char=$1
    local size=$2
    local temp_str=$(_padding ${size})
    echo ${temp_str// /${char}}
}

function prompt_command {
    # Must be the first thing we do, otherwise other exit statuses overwrite $?
    local exit_status=$?
    if [[ $exit_status == 0 ]]; then
        local exit_status_text=${BGreen}✓${Color_Off}
    else
        local exit_status_text=${BRed}✗${Color_Off}
    fi

    # Must run this early because when we use $() this adds to our jobs count
    local total_jobs=$(jobs | wc -l | perl -pe 's/\s+//g')
    local stopped_jobs=$(jobs -s | wc -l | perl -pe 's/\s+//g')
    if [[ ${total_jobs} != 0 ]]; then
        if [[ ${stopped_jobs} == 0 ]]; then
            local jobs_text="${LightGray}[${total_jobs}] ${Color_Off}"
        else
            local jobs_text="${LightGray}[${BRed}${stopped_jobs}${LightGray}/${total_jobs}] ${Color_Off}"
        fi
    fi

    local hostname=`hostname -s`
    local username=$(whoami)
    local host_text=${username}@${hostname}

    local virtual_env_text=""
    if [[ -n $VIRTUAL_ENV ]]; then
        virtual_env_text="${DarkGray} $(basename $VIRTUAL_ENV)${Color_Off}"
    fi

    local git_text git_ahead
    if git branch &> /dev/null; then
        # git is working and we're on a git branch
        if git status | grep "nothing to commit" > /dev/null 2>&1; then
            # Clean repository - nothing to commit
            git_text="${Green} $(__git_ps1 "(%s)") ${Color_Off}"
        elif git status | grep "nothing added to commit but untracked files present" > /dev/null 2>&1; then
            # No changes but files to add
            git_text="${Cyan} $(__git_ps1 "[%s]") ${Color_Off}"
        else
            # Changes to working tree
            git_text="${Red} $(__git_ps1 "{%s}") ${Color_Off}"
        fi
        git_ahead=$(git status | awk '/Your branch is ahead/{print "→" $9 " "}\
            /Your branch is behind/{print $8 "← "}\
            /diverged/,/respectively/{if ($0 ~ /respectively/) print $6 "←→" $4 " "}')
        git_text="${git_text}${Yellow}${git_ahead%→*}${Red}${git_ahead#*←}${Color_Off}"
    else
        # prompt component when not in git
        git_text=' '
    fi

    local date_text=${DarkGray}$(date +%H:%M)${Color_Off}
    local prompt_char=${exit_status_text}
    local pwd_text="$(pwd | perl -pe "s|$HOME|~|")"

    local tmux_text tmux_session tmux_group num_tmux_attached_clients
    local num_tmux_group_clients num_tmux_clients
    if which tmux &> /dev/null && [[ -n $TMUX ]]; then
        tmux_session=$(tmux display-message -p '#S')
        num_tmux_attached_clients=$(tmux list-clients -t ${tmux_session} | wc -l)
        tmux_group=$(tmux list-sessions | grep "^${tmux_session}:" | grep -o "(group [0-9]*)" | grep -o "[0-9]*") 
        num_tmux_group_clients=$(tmux list-sessions | grep "group ${tmux_group}" | wc -l)
        # The main session will be counted in both attached clients and groups:
        let num_tmux_group_clients-=1
        num_tmux_clients=$((${num_tmux_attached_clients} + ${num_tmux_group_clients}))
        if [[ ${num_tmux_clients} -gt 1 ]]; then
            tmux_text="${Yellow}⎚ ${num_tmux_clients} ${Color_Off}"
        fi
    fi

    local remove_color_codes_regex="s/\\\\\[\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]\\\\\]//g"
    local length_elements=$(echo -e "${pwd_text}${virtual_env_text}${git_text}${tmux_text}${jobs_text}${date_text}" | perl -pe $remove_color_codes_regex)
    local rule_length=$(($COLUMNS - ${#length_elements} - 1))

    local rule
    if [[ ${rule_length} -gt 0 ]]; then
        # Everything fits on the info line
        rule="${DarkGray}$(_repeat_chars '─' ${rule_length}) "
    elif [[ ${rule_length} == 0 ]]; then
        # Everything JUST fits on the info line
        rule=""
    else
        # We need to truncate our path because the info line is too short
        pwd_text="…${pwd_text:$((${rule_length} * -1))}"
        rule=""
    fi
    pwd_text=${BBlue}${pwd_text}${Color_Off}
    local line_1="${pwd_text}${virtual_env_text}${git_text}${rule}${tmux_text}${jobs_text}${date_text}"
    local line_2="${host_text} ${prompt_char} "
    PS1="\n${line_1}\n${line_2}"
}