#!/bin/bash
#---------------------------------------------------------------------
# Script to display unicode characters representing the level of
# some indicator.
#
# Designed to work with the wonderful byobu(1) but can be run
# stand-alone.
#---------------------------------------------------------------------
#
# Copyright (C) 2011 Canonical Ltd.
#
# Author: James Hunt <james.hunt@canonical.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#---------------------------------------------------------------------

#------------------------------
# Themes with 2 values.
#
# Two-value themes are handled differently to other n-value types of
# theme: the first array entry in each theme is generally some unfilled
# glyph, denoting an "off" value and the second value is the filled
# version of the unfilled glyph and denotes an "on" value.  Note that
# you can always change the ordering of these values using the 'invert'
# command-line option.

PKG="byobu"
[ -r "$HOME/.byoburc" ] && . "$HOME/.byoburc"
[ -z "${BYOBU_PREFIX}" ] && export BYOBU_PREFIX="/usr" || export BYOBU_PREFIX
. "${BYOBU_PREFIX}/lib/${PKG}/include/common"

circles_2=(○ ●)
diamonds_2=(◇ ◆)
flags_2=(⚐ ⚑)
hearts_2=(♡ ♥)
squares_2=(◻ ◼)
squares_small_2=(◽ ◾)
stars_2=(☆ ★)
faces_2=(☹ ☺)

#------------------------------
# Themes with 4 values.

vdots_thick_4=(⣀ ⣤ ⣶ ⣿)
vdots_thin_4=(⢀ ⢠ ⢰ ⢸)
fractions_4=(¼ ½ ¾ ¹)
quadrants_4=(◔ ◑ ◕ ●)
shades_4=(░ ▒ ▓ █)

#------------------------------
# Themes with 5 values.

circles_5=(◦ ○ ◎ ◉ ●)

#------------------------------
# Themes with 6 values.

dice_6=(⚀ ⚁ ⚂ ⚃ ⚄ ⚅)

#------------------------------
# Themes with 8 values.

hbars_8=(▏ ▎ ▍ ▌ ▋ ▊ ▉ █)
vbars_8=(▁ ▂ ▃ ▄ ▅ ▆ ▇ █)

#------------------------------
# Themes with 10 values.

circle_number_10=(➀ ➁ ➂ ➃ ➄ ➅ ➆ ➇ ➈ ➉)
solid_numbers_a_10=(➊ ➋ ➌ ➍ ➎ ➏ ➐ ➑ ➒ ➓)
solid_numbers_b_10=(❶ ❷ ❸ ❹ ❺ ❻ ❼ ❽ ❾ ❿)

#------------------------------
# XXX: remember to update if you add new themes above!

theme_list=\
(
   'circles_2 diamonds_2 flags_2 hearts_2 squares_2 squares_small_2 stars_2'
   'vdots_thick_4 vdots_thin_4 fractions_4 quadrants_4 shades_4'
   'circles_5'
   'dice_6'
   'hbars_8 vbars_8'
   'circle_number_10 solid_numbers_a_10 solid_numbers_b_10'
)

#------------------------------

default_decimal_places=2
a11y=n
a11y_variable=BYOBU_A11Y
debug_enabled=n
newline=
list=n
quiet=n
invert=n
reverse=n
script_name=${0##*/}
min_default=0
max_default=100
width_default=5
zero_as_space=n
theme_default=vbars_8
permissive=n

debug()
{
  msg="$*"
  [ $debug_enabled = y ] && echo "DEBUG: $msg"
}

error()
{
  msg="$*"
  echo "ERROR: $msg" >&2
}

die()
{
  error "$*"
  exit 1
}

check_a11y()
{
  eval result="\$$a11y_variable"
  [ ! -z "$result" ] && a11y=y
}

# return 1 if expression specified is true (no return if false)
bc_test()
{
  expr="$*"
  echo $(echo "if ( $expr ) { print \"1\" }"|bc -l)
}

assert()
{
  expr="$1"
  str="$2"

  debug "assert: expr='$expr'"
  ret=$(bc_test "$expr")

  [ ! -z "$ret" ] && return

  die "$str"
}

usage()
{
cat <<EOT
Description: Display unicode characters representing the relative
             level of some indicator value within a range.

Usage: $script_name [options] -c <current_num>
       $script_name [options] <current_num>
       $script_name <current_num>

Options:

 -a         : Accessibility mode: only output ASCII.
              (Also enabled if variable '$a11y_variable' set).
 -b         : Display current value as space if zero, rather than lowest
              'value' of theme.
 -c <num>   : Current value of your indicator.
 -d         : Enable debug output.
 -e <int>   : Number of decimal places to use for accessibility mode
              (default=$default_decimal_places).
 -h         : Show this help.
 -i         : Invert colour scheme (rating themes only).
 -l         : List available themes. If '-t' also specified,
              show all values for specified theme.
 -m <num>   : Minimum value (default=$min_default).
 -n         : Supress output of newline character.
 -p         : Permissive mode - if current value out of bounds, set it
              to the nearest bound (min or max).
 -q         : Suppress messages (requires '-t').
 -r         : Reverse 'direction' of display (rating theme only).
 -t <theme> : Name of theme (default=$theme_default).
 -u <chars> : Specify a user theme (2 or more values).
 -w <int>   : Width of rating theme (default=$width_default).
 -x <num>   : Maximum value (default=$max_default).


Examples:

  # Display character representing 27% using default theme.
  $script_name 27

  # As above.
  $script_name -c 27

  # Example showing floating-point and negative values.
  $script_name -c 1.100001 -m -5.00234 -x 2.71828 -t dice_6

  # Use accessibility mode to display a percentage value
  # (rounded to nearest percentage)
  $script_name -m -22.613 -x 5.00212 -c 0.10203 -a -e 0

  # Display value using a "rating theme" (displayed left-to-right).
  $script_name -c 83 -t stars_2

  # Display right-to-left inverted "rating theme".
  $script_name -c 60 -t diamonds_2 -ri

  # Display all glyphs in 'solid_numbers_a_10' theme.
  $script_name -l -t solid_numbers_a_10

  # Display a user-specified rating theme 10 glyphs wide.
  $script_name -c 666.321 -m -273.15 -x 1370 -u "· ☢" -w 10

  # A multi-element user theme (this prints 'e').
  $script_name -c 50 -u "a b c d e f g h i j"


Notes:

  - Arguments of type "<int>" denote an integer value, whereas arguments
    of type "<num>" denotes either an integer or a floating-point
    number.
  - The final '_<number>' in a theme name denotes the number of glyphs
    in it.
  - "Rating themes" are those with only 2 values.
  - The <chars> argument to '-u' must contain space-delimited
    characters.

EOT
}

# this is horribly inefficient - we should probably do some clever
# tricks using printf formats to avoid the silly while loop.
# Additionally, it is rather similar to show_theme_entry() but was split
# out from that in a vain attempt to make the overall logic clearer :)
show_rating_theme()
{
  theme="$1"
  min="$2"
  max="$3"
  current="$4"
  percent="$5"

  if [ $invert = n ]
  then
    on=1
    off=0
  else
    on=0
    off=1
  fi

  debug "width=$width"
  debug "percent=$percent"

  percent_per_glyph=$(echo "scale=4;100/${width}"|bc -l)
  assert "$percent_per_glyph > 1.0" "width ($width) too great"
  debug "percent_per_glyph=$percent_per_glyph"

  debug "glyph_count=$glyph_count"

  g=$percent_per_glyph
  i=0
  value=""
  while [ $i -lt $width ]
  do
    if [ ! -z "$(bc_test "$g <= $percent")" ]
    then
      eval content="\${$theme[${on}]}"
    else
      eval content="\${$theme[${off}]}"
    fi
    if [ $reverse = n ]
    then
      value="${value}${content}"
    else
      value="${content}${value}"
    fi
    g=$(echo "$g + $percent_per_glyph"|bc -l)
    i=$((i + 1))
  done
  echo $newline "$value"
}

show_theme_entry()
{
  theme="$1"
  min="$2"
  max="$3"
  current="$4"

  debug "theme=$theme"
  debug "min=$min"
  debug "max=$max"
  debug "current=$current"

  range=$(echo "($max - $min)"|bc -l)

  quotient=$(echo "scale=4;((${current} - ${min})/${range})"|bc -l)
  percent=$(echo "$quotient * 100"|bc -l)

  glyph_count=$(echo $theme|awk -F\_ '{print $NF}')

  debug "range=$range"
  debug "quotient=$quotient"
  debug "percent=$percent"
  debug "glyph_count=$glyph_count"

  # just ASCII please
  if [ $a11y = y ]
  then
    [ -z "$decimal_places" ] && decimal_places=$default_decimal_places
    val=$(echo|awk -v p=$percent -v dp=$decimal_places '{printf("%.*f", dp, p)}')
    echo $newline "$val"
    return
  fi

  if [ $glyph_count -eq 2 ]
  then
    show_rating_theme "$theme" "$min" "$max" "$current" "$percent"
    return
  fi

  percent_per_glyph=$(echo "100/$glyph_count"|bc -l)
  debug "percent_per_glyph=$percent_per_glyph"

  assert "$percent_per_glyph > 1.0" "width ($width) too great"

  # with this scheme, assuming current value is 0-100 and theme has 10
  # elements:
  #
  # current   glyph from theme
  #
  # 0-19      1st
  # 20-29     2nd
  # 30-39     3rd
  #  :
  # 90-99     9th
  # 100       10th
  i=$(echo|awk \
    -v quotient=$quotient \
    -v glyph_count=$glyph_count \
    '{
        x= int( (quotient * glyph_count) ) - 1;
        x = (x > (glyph_count-1) ? (glyph_count-1) : x);
        if ( x < 0 ) x = 0;
        printf("%d", x);
     }')

  debug "index=$i"
  eval content="\${$theme[$i]}"

  [ ! -z "$(bc_test "$current == 0")" -a $zero_as_space = y ] && content=' '
  echo $newline "$content"

  return
}

list_theme()
{
  theme="$1"
  eval content="\${$theme[@]}"
  echo
  for c in $content
  do
    printf "$c "
  done
  echo -e "\n"
}

list_themes()
{
  for entry in ${theme_list[@]}
  do
    for arg in "$entry"
    do
      echo "$arg"
    done
  done
}

theme_valid()
{
  theme="$1"
  [ -z "`list_themes|grep "^${theme}$"`" ] && return 1
  return 0
}

check_a11y

# XXX: the seemingly pointless 'tr' calls translate unicode dashes (look
# closely!) into ASCII dashes. This is required since 'bc' borks on
# unicode and it is easy to mistakenly pass unicode dashes if you paste
# characters from another application, such as a web-browser.
while getopts "abc:de:hilm:npqrt:u:w:x:" opt
do
  case "$opt" in
    a)
      a11y=y
    ;;

    b)
      zero_as_space=y
    ;;

    c)
      current=$(echo $OPTARG|tr '−' '-')
    ;;

    d)
      debug_enabled=y
    ;;

    e)
      decimal_places=$OPTARG
    ;;
      
    h)
      usage
      exit 0
    ;;

    i)
      invert=y
    ;;

    l)
      list=y
    ;;

    m)
      min=$(echo $OPTARG|tr '−' '-')
    ;;

    n)
      newline=-n
    ;;

    p)
      permissive=y
    ;;

    q)
      quiet=y
    ;;

    r)
      reverse=y
    ;;

    t)
      theme=$OPTARG
    ;;

    u)
      user_theme="$OPTARG"
    ;;

    w)
      width=$OPTARG
    ;;

    x)
      max=$(echo $OPTARG|tr '−' '-')
    ;;
  esac
done

shift $[$OPTIND-1]

if [ ! -z "$user_theme" ]
then
  elements=$(echo "$user_theme"|awk '{print NF}')

  assert "$elements >= 2" "user themes need >= 2 values"

  # create new theme
  name="_user_${elements}"
  eval "$name=($user_theme)"

  # add it to list
  theme_list=("${theme_list[@]}" $name)

  [ -z "$theme" ] && theme=$name
fi

if [ "$list" = y ]
then
  if [ -z "$theme" ]
  then
    list_themes && exit 0
  else
    theme_valid "$theme" || die "invalid theme: $theme"
    [ "$quiet" = n ] && echo "Listing theme '$theme'"
    list_theme $theme && exit 0
  fi
fi
[ -z "$min" ]   && min=$min_default
[ -z "$max" ]   && max=$max_default
[ -z "$width" ] && width=$width_default

assert "$min <= $max" "minimum ($min) > maximum ($max)"
assert "$min != $max" "minimum ($min) == maximum"

[ -z "$current" -a ! -z "$1" ] && current="$1"

if [ -z "$current" ]
then
  error "must specify current value"
  usage
  exit 1
fi

if [ $permissive = n ]
then
  assert "$current >= $min" "current ($current) < minimum ($min)"
  assert "$current <= $max" "current ($current) > maximum ($max)"
else
    [ ! -z "$(bc_test "$current < $min")" ] && current=$min
    [ ! -z "$(bc_test "$current > $max")" ] && current=$max
fi

[ -z "$theme" ] && theme=$theme_default

theme_valid "$theme" || die "invalid theme: $theme"

show_theme_entry $theme $min $max $current

exit 0