sh-prompt.sh

# Copyright (C) 2015 Craig E. Shea
# Distributed under the GNU General Public License, version 2.0.
#
# This script allows you to customize your bash prompt in much the same way
# as you can customize the git prompt using __git_ps1 as defined in git-prompt.sh.
# Furthermore, if __git_ps1 is available, your git repository status will also be
# shown when the PWD contains a git repository.
#
# NOTE: This does not yet work on Zsh!! Submit a pull request or wait until I
#       finally get around to it.
#
# To enable:
#
#    1) Copy this file to somewhere (e.g. ~/.bash-prompt.sh).
#    2) Add the following line to your .bashrc/.zshrc:
#        source ~/.bash-prompt.sh
#	 3) If you also have git installed, add the following line to
#       your ./bashrc/.zshrc:
#        source ~/.git-prompt.sh
#
#       Be sure to use the correct path to the git-prompt.sh file.
#       Also, source git-prompt.sh before bash-prompt.sh since
#       this script calls __git_ps1 directly--so __git_ps1 needs
#       to be defined before __bash_ps1.
#        
#    4a) Change your PS1 to call __bash_ps1 as
#        command-substitution:
#          Bash: PS1='$(__bash_ps1 "${BASH_PS1_FORMAT_STRING-}")'
#        the optional argument will be used as the bash prompt format
#        string.
#    4b) Alternatively, for a slightly faster prompt, __bash_ps1 can
#        be used for PROMPT_COMMAND in Bash with two parameters, 
#        <pre> and <post>, which are strings you would put in $PS1 
#        before and after the prompt string generated by the bash-prompt
#        machinery.  e.g.
#        Bash: PROMPT_COMMAND='__bash_ps1 "Hello " "Ready to accept commands." "${SH_PS1_FORMAT_STRING}"'
#          will show:
#
#              Hello <username@hostname> ~
#              Ready to accept commands.
#              $ 
#
#          as your prompt.
#
#        Optionally, you can supply a fourth argument with a printf
#        format string to finetune the output of the git branch status
#
#
# What follows are the environment variables you can set in your .bashrc
# file prior to sourcing this script to customize the appearance of your
# bash prompt.
#
# SH PROMPT CUSTOMIZATION VARIABLES
#-----------------------------------------------------
#
# SH_PS1_USERNAME
#    Sets the string to be used for the username portion of the
#    prompt string.
#
#    If not declared, null, or empty, then this defaults to the
#    username placeholder token for the shell prompt.
#
#    Otherwise, the username portion of the shell prompt will contain
#    this text. NOTE: if the format string does not contain \u (for bash,
#    for example), then the username of the current interactive user
#    will not be displayed; however, any other text in this variable 
#    will still be displayed.
#
#    If you don't want to display the username portion of the shell prompt, 
#    omit the %u format specifier in SH_PS1_FORMAT_STRING. 
#    See below for more details.
#
#    Example:
#       SH_PS1_USERNAME="\n$(tput setaf 170)$MSYSTEM \u"
#
#       - This results, on MINGW64 system, MINGW64 (displayed in a
#         light purple on a 256-color terminal) followed by a space-separated
#         followed by the bash username of the current interactive user.
#
# SH_PS1_USER_HOST_SEPARATOR
#    Sets the string to be used for separating the username from the hostname.
#
#    If not declared, null, or empty, then this defaults to the @ character.
#    Otherwise, the value defined is used between the username and hostname
#    portions of the shell prompt fromat string.
#
#    If for whatever reason you want no separator between the username and
#    hostname portions of the shell prompt, then omit the %z format specifier
#    in SH_PS1_FORMAT_STRING instead. See below for more details.
#
# SH_PS1_HOSTNAME
#    Sets the string to be used for the hostname portion of the
#    prompt string.
#
#    If not declared, null, or empty, then this defaults to the
#    hostname placeholder token for the shell prompt.
#
#    Otherwise, the hostname portion of the shell prompt will contain
#    this text. NOTE: if the format string does not contain \h (for bash,
#    for example), then the hostname will not be displayed; however, any
#    other text in this variable will still be displayed.
#
#    If you don't want to display the hostname portion of the shell prompt, 
#    omit the %h format specifier in SH_PS1_FORMAT_STRING. 
#    See below for more details.
#
# SH_PS1_PWD
#    Sets the string to be used for the pwd portion of the
#    prompt string.
#
#    If not declared, null, or empty, then this defaults to the
#    pwd placeholder token for the shell prompt.
#
#    Otherwise, the pwd portion of the shell prompt will contain
#    this text. NOTE: if the format string does not contain \w (for bash,
#    for example), then the pwd will not be displayed; however, any other
#    text in this variable will still be displayed.
#
#    If you don't want to display the pwd portion of the shell prompt, 
#    omit the %w format specifier in SH_PS1_FORMAT_STRING. 
#    See below for more details.
#
# SH_PS1_PROMPT
#    Sets the string to be used for the prompt portion of the
#    prompt string (i.e. the $ or # that is displayed indicating the
#    shell is ready for user input).
#
#    If not declared, null, or empty, then this defaults to "\n$ " 
#    for the shell prompt (e.g. a $ on a new line followed by a space).
#
#    Any other text can be used for this variable. But as you may have
#    noticed, something must be displayed. There is no way to not
#    have some sort of prompt be displayed.
#
# SH_PS1_FORMAT_STRING
#    Defines the tokens that define what portions of the bash prompt
#    should be displayed, and in what order. The SH_PS1_PROMPT is
#    always appended to this string.
#
#    If this variable is undeclared, null, or empty, it defaults to
#    "%u%z%h%w%v". By default, this results in the following prompt:
#
#        username@host pwd [git_repository_info]
#        $
#
#    If you are not inside a git repository (or __git_ps1 is not defined),
#    then the [git_repository_info] is not displayed.
#
#    The meanings of the format specifier tokens are:
#
#        %u - Gets replaced with SH_PS1_USERNAME
#        %z - Gets replaced with SH_PS1_USER_HOST_SEPARATOR
#        %h - Gets replaced with SH_PS1_HOSTNAME
#        %w - Gets replaced with SH_PS1_PWD
#        %v - If __git_ps1 is defined, and you are in a directory
#             that houses a git repository, displays the git
#             repository information.
#
#    Some notes regarding the use of this variable:
#
#    1. You can place these tokens in any order.
#    2. All whitespace between tokens is stripped out.
#    3. This variable should only contain these tokens and no 
#       other text. Any other text included in this variable
#       may result in unpredictable and unsupported behavior.
#    4. Any spacing and formatting should occur within the
#       individual format string variables (e.g. SH_PS1_*
#       variables discussed above).
#
# SH_PS1_DONT_COLORIZE_PROMPT
#    If set to 1, the bash prompt will not be colorized (unless any
#    format strings contain tput commands--but then just that
#    particular part of the format string will be colored).
#
#    If this variable is not declared or has any value other than 1
#    (including null), then the bash prompt will be colorized.
#
# SH_PS1_USERNAME_COLOR
#    Set the color the username portion of the shell prompt.
#    If this variable is not declared and SH_PS1_DONT_COLORIZE_PROMPT is not
#    set to 1, the default color is green, $(tput setaf 2).
#    If this variable is null or empty, it results in $(tput sgr0).
#
# SH_PS1_USER_HOST_SEPARATOR_COLOR
#    Set the color for the text which separates the username/hostname portions
#    of the shell prompt.
#    If this variable is not declared and SH_PS1_DONT_COLORIZE_PROMPT is not
#    set to 1, the default color is green, $(tput setaf 2).
#    If this variable is null or empty, it results in $(tput sgr0).
#
# SH_PS1_HOSTNAME_COLOR
#    Set the color for the hostname portion of the shell prompt.
#    If this variable is not declared and SH_PS1_DONT_COLORIZE_PROMPT is not
#    set to 1, the default color is green, $(tput setaf 2).
#    If this variable is null or empty, it results in $(tput sgr0).
#
# SH_PS1_PWD_COLOR
#    Set the color for the present working directory portion of the
#    shell prompt.
#    If this variable is not declared and SH_PS1_DONT_COLORIZE_PROMPT is not
#    set to 1, the default color is dim yellow $(tput setaf 3) (or
#    brown, as I think it was called for 8/16-color mode)
#    If this variable is null or empty, it results in $(tput sgr0).
#
# SH_PROMPT_COLOR
#    Set the color for the prompt character portion of the shell
#    prompt (e.g. the $ or # that appears indicating the shell is
#    awaiting user input).
#    If this variable is not declared, is null, or empty, then the
#    prompt string's resulting color is $(tput sgr0). Otherwise, its
#    the specified color.
#
# NOTE: There's nothing stopping you from placing other text in the
#       variables discussed above, but they're intended only to contain
#       color information for the various pieces of the prompt string.
#       You can experiment with other values other than purely color
#       information, but you do so at your own risk. This is unsupported
#       behavior.
#

# If the user has .git-prompt.sh or git-prompt.sh in their home directory,
# source these versions of git-prompt (which contains __git_ps1).
#
# Otherwise, I used the code used by Git for Windows located in
# /etc/profile.d/git-prompt.sh that attempts to find the Git for Windows
# supplied version of git-prompt.sh and sources that.
if [[ -e ~/.git-prompt.sh ]]; then
	. ~/.git-prompt.sh
elif [[ -e ~/git-prompt.sh ]]; then
	. ~/git-prompt.sh
elif test -z "$WINELOADERNOEXEC"; then
	GIT_EXEC_PATH="$(git --exec-path 2>/dev/null)"
	COMPLETION_PATH="${GIT_EXEC_PATH%/libexec/git-core}"
	COMPLETION_PATH="${COMPLETION_PATH%/lib/git-core}"
	COMPLETION_PATH="$COMPLETION_PATH/share/git/completion"
	if test -f "$COMPLETION_PATH/git-prompt.sh"; then
		. "$COMPLETION_PATH/git-completion.bash"
		. "$COMPLETION_PATH/git-prompt.sh"
	fi
fi

function is_function_defined()
{
	declare -Ff "$1" >/dev/null && echo "yes" || echo "no"
}

function is_variable_declared()
{
	declare | grep -c "^$1=" >/dev/null && echo "yes" || echo "no"
}

function __sh_ps1_colorize_promptstring()
{
	local user_host_color="$(tput setaf 2)"
	local pwd_color="$(tput setaf 3)"
	local prompt_color="$(tput sgr0)"
	
	# If any sh prompt color variable is not declared, then use the default color.
	# Else, if it is declared and is null, or it is defined but empty, then use $(tput sgr0), otherwise, use the given color.
	#
	# Additionally, you'll notice that we're trying to preserve any other colorizing that may be occurring
	# within any of the prompt variables. For example, if you specify SH_PS1_USERNAME="$(tput setaf 14)Hello! \u"
	# and subsequently also set SH_PS1_USERNAME_COLOR="$(tput setaf 2)", then you would expect that
	# Hello! would still by displayed in cyan while the username would be displayed in green.
	case "$(is_variable_declared SH_PS1_USERNAME_COLOR)" in
		"yes") u="${u//\\u/${SH_PS1_USERNAME_COLOR:-$(tput sgr0)}\\u}" ;;
		"no" ) u="${u//\\u/$user_host_color\\u}" ;;
	esac
	
	# TL;DR : Don't need to "preserve" color formatting for the username/hostname separator character.
	#
	# Since this is meant to be a separator character (or characters) between the
	# username and hostname, no "color preservation" needs to be done.
	# If the user wants a highly customized, colorized username/hostname separator,
	# they would simply set SH_PS1_USER_HOST_SEPARATOR to some complex string embedded
	# with color info. Additionally, SH_PS1_USER_HOST_SEPARATOR_COLOR provides the overall
	# base color for the username/hostname separator.	
	case "$(is_variable_declared SH_PS1_USER_HOST_SEPARATOR_COLOR)" in
		"yes") z="${SH_PS1_USER_HOST_SEPARATOR_COLOR-$(tput sgr0)}$z" ;;
		"no" ) z="$user_host_color$z" ;;
	esac
	
	case "$(is_variable_declared SH_PS1_HOSTNAME_COLOR)" in
		"yes") h="${h//\\h/${SH_PS1_HOSTNAME_COLOR:-$(tput sgr0)}\\h}" ;;
		"no" ) h="${h//\\h/$user_host_color\\h}" ;;
	esac
	
	case "$(is_variable_declared SH_PS1_PWD_COLOR)" in
		"yes") w="${w//\\w/${SH_PS1_PWD_COLOR:-$(tput sgr0)}\\w}" ;;
		"no" ) w="${w//\\w/$pwd_color\\w}" ;;
	esac
	
	p="${SH_PS1_PROMPT_COLOR-$prompt_color}$p$(tput sgr0)"
}

function __sh_ps1_printf_format_contains()
{
	case $(echo "$1" | grep -c $2) in
		0)		return 1 ;;
		*)		return 0 ;;
	esac
}

# __sh_ps1 accepts 0, 1, 2, or 3 arguments (i.e., format string)
# when called from PS1 using command substitution.
# In this mode it sets the text to use for the bash PS1 prompt.
# The optional third argument sets the title of the bash window.
#
# __sh_ps1 requires 0, 1, 2, 4, or 5 arguments when called from 
# PROMPT_COMMAND (pc).
#
# In this case it _sets_ PS1 (either directly, or via __git_ps1, if the
# function is defined). The arguments are parts of a PS1 string. 
#
# When no arguments are given, a standard shell prompt is displayed. If
# __git_ps1 is available (via git-prompt.sh being sourced in your .bashrc
# file), then when you are in a directory which contains a git repository,
# the git repository information is appended to the shell prompt.
# An example of the standard shell prompt that would be displayed is shown
# below:
#
#    username@hostname pwd [git_repository_information]
#    $
#
# When one argument is given, this argument specifies a format string
# that is used to determine the order in which the pieces of a typical
# shell prompt appear. If this argument is the empty string,  it
# defaults to "%u%z%h%w%v", which results in the standard shell prompt
# being displayed as shown above.
#
# When two arguments are given, the first argument specifies a format
# string used to determining the order in which the pieces of a 
# typical shell prompt appear. The second argument defines a format
# string for displaying git repository information in the prompt when
# inside of a git repository (via __git_ps1, if it is defined).
#
# When four arguments are given, the first two arguments are as defined
# above. The third argument is pre-pended to the shell prompt, while the
# fourth argument is appended to the shell prompt.
#
# If an optional fifth argument is provided, the argument is used to set
# the title of the bash window. NOTE: currently only works for xterm
# based terminals.
#
# Any other arguments provided after the fifth argument are simply
# ignored.
function __sh_ps1()
{
	# Preserve exit status.
	local exit=$?
	
	local sh_ps1pc_start=""
	local sh_ps1pc_end=""
	
	# TODO: Determine if we're running in bash vs. zsh and set this variable appropriately.
	
	# Set the initial sh string, defaulted to "\u@\h \w\n\\\$"
	# The "format specifiers" have the following interpretation:
	#
	#   u :  Username. Will get substituted to \u or the value provided in SH_PS1_USERNAME
	#   z :  Username/hostname separator. Will get substituted to @ or the value provided in SH_PS1_USER_HOST_SEPARATOR
	#   h :  Hostname. Will get substituted to \h or the value provided in SH_PS1_HOSTNAME
	#   w :  Present working directory. Will get substituted to \w or the value provided in SH_PS1_PWD
	#   v :  Version Control Prompt. Place this format specifier where ever in your bash prompt you want 
	#        your source code version control prompt to be displayed. This specifier will be replaced by,
	#        executing __git_ps1 from git-prompt.sh (or your local sourced version), for example, when git
	#	     is your source code control management system.
	local sh_printf_format="uzhwv"
	local title
	local git_printf_format
	
	# Process function arguments.
	case "$#" in
		0|1|2)
				sh_printf_format="${1:-$sh_printf_format}"
				git_printf_format="${2:-}"
			;;
		3)		title="${3+\033]2;$3\a}"
				sh_printf_format="${1:-$sh_printf_format}"
				git_printf_format="${2:-}"
			;;
		4)		sh_printf_format="${1:-$sh_printf_format}"
				git_printf_format="${2:-}"
				sh_ps1pc_start="${3:-$sh_ps1pc_start}"
				sh_ps1pc_end="${4:-$sh_ps1pc_end}"
			;;
		5)		sh_printf_format="${1:-$sh_printf_format}"
				git_printf_format="${2:-}"
				sh_ps1pc_start="${3:-$sh_ps1pc_start}"
				sh_ps1pc_end="${4:-$sh_ps1pc_end}"
				title="${5+\033]2;$5\a}"
			;;
	esac

	# Setup the default sh_prinf_format format specifier variable substitutions.
	# This should result, by default, with a prompt like:  "user@host pwd\n$ "
	local u="${SH_PS1_USERNAME:-\\u}"
	local z="${SH_PS1_USER_HOST_SEPARATOR:-@}"
	local h="${SH_PS1_HOSTNAME:-\\h}"
	local w="${SH_PS1_PWD:- \\w}"
	local p="$sh_ps1pc_end${SH_PS1_PROMPT:-\n\\\$ }"

	case "${SH_PS1_DONT_COLORIZE_PROMPT:-0}" in
		0)	__sh_ps1_colorize_promptstring ;;
	esac	
	
	# Substitute the "format specifiers" u, h, etc. with $u, $h, etc.
	# I couldn't use the exact same method as __git_ps1 because the end user has flexility to
	# display their shell prompt components in any order they choose, hence this more awkward
	# substitution syntax.
	#
	# NOTE: %v in the format string will be substituted with your vcs prompt formatter, 
	# i.e. __git_ps1, so we don't substitute it here.
	sh_printf_format="${sh_printf_format//u/$u}"
	sh_printf_format="${sh_printf_format//z/$z}"
	sh_printf_format="${sh_printf_format//h/$h}"
	sh_printf_format="${sh_printf_format//w/$w}"
	sh_printf_format="$sh_printf_format$p"
	
	case "$(is_function_defined __git_ps1)" in
		"yes")
			# Split the sh_printf_format on %v and pass the part before %v to the __git_ps1pc_start param
			# and the part after %v to the __git_ps1pc_end param.
			local __git_ps1pc_end="${sh_printf_format##*v}"
			local __git_ps1pc_start="${sh_ps1pc_start}${sh_printf_format%v*}$(tput sgr0)"
			
			# Call __git_ps1 to set the PS1 variable.
			__git_ps1 "$title$__git_ps1pc_start" "$__git_ps1pc_end" ${git_printf_format+"${git_printf_format}"}
			;;
		"no" )
			PS1="${title}${sh_printf_format}"
			;;
	esac
	
	return $exit
}