wrap

#!/bin/bash
source /home/fabian/d/programs/bash_scripts/sane
# Once the bug in coreutils is fixed that causes escape sequences to be included in character counts, this entire script (except for the width argument, which has to replace "$(tput cols)") can be replaced with just this:
# IFS=$'\n'; for line in $*; do echo $line | fold -sw$(tput cols); done

# split between arguments and on \n, but not on spaces
IFS=$'\n'
# disable * expansion
set -f
if [[ "$1" =~ ^(\-\-?|\/)?(h(elp)?|\?)$ && "$2" == "" ]]; then
 # Ooohh, recursion! Should be fine, because none of these lines is "--help" or similar.
 wrap "Wraps a text on spaces. A width after which to wrap can be given as first argument, the default is the console's width."
 wrap "Deals better with escape sequences than \"fold\". Does not handle fullwidth characters yet."
 echo
 echo "Usage:"
 echo "wrap [\e[3mWIDTH\e[0m] \e[3mTEXT\e[0m…"
 echo
 echo "Example:"
 echo "wrap 10 \"a bc defff  ghij kp u\\\\e[101mvwx yzä  öüßlmnopqrstuvwxyzäöüßx a\""
 echo "Output:"
 wrap 10 "a bc defff  ghij kp u\e[101mvwx yzä  öüßlmnopqrstuvwxyzäöüßx a\e[0m"
 exit
elif [[ "$1" =~ ^[1-9][0-9]*$ && "$2" != "" ]]; then
 width=$1
 shift
else
 width=$(tput cols)
fi
for line in $*; do
 arr=($(echo -n "$line" | sed "s/(.)/\\1\\n/g"))
 line_start=0
 space_pos=-1
 # don't print empty line if last line exactly fills limit
 while((line_start<${#arr[@]})); do
  curr=$line_start
  # This goes one further than you might expect, in case there's a space at a line end, which then does not need to be printed. Off-by-one errors are handled at the end.
  for((out_col=0; out_col<=width; out_col++)); do
   if((curr>=${#arr[@]})); then
    # end of line reached, print the rest
    echo "${arr[@]:line_start}" | sed "s/(.) /\\1/g"
    continue 3 # for line …
   fi
   # Behold, horrible (and yet incomplete) escape sequence detection! Just skips forwards through (known) escape sequences, because extra rounds through the main loop would be more confusing.
   # "\e"…
    while [[ "${arr[curr]}" == $'\e' ]]; do
     ((curr++))
     # "\e["…
     if [[ "${arr[curr]}" == "[" ]]; then
      ((curr++))
      # "\e[0"…/"\e[93"…/"\e[101"…
      while [[ "${arr[curr]}" =~ [0-9] ]]; do
       ((curr++))
      done
     fi
     # final character: "\em"/"\e[m"/"\e[0m"
     ((curr++))
    done
   # remember last space position
   if [[ "${arr[curr]}" == " " ]]; then
    space_pos=$curr;
   fi
   # regular scanning progress
   ((curr++))
  done
  # if there was a space in this line…
  if((space_pos>line_start)); then
   # confusingly, the second index in array slicing is a length, not an end
   echo "${arr[@]:line_start:space_pos-line_start}" | sed "s/(.) /\\1/g"
   line_start=$((space_pos+1))
  else
   echo "${arr[@]:line_start:curr-line_start-1}" | sed "s/(.) /\\1/g"
   line_start=$((curr-1))
  fi
 done
done