#!/bin/bash

function usage {
echo -e ' High Beam Highlighter 
- a trial to create a very generic modifyable 
syntax highlighter.

Example rules: ( ~/.highbeamrc )
--------------------
RULES=( 
    "[0-9]"      "$c" # Show numbers with Cyan color. NOTE: since the colors are represented with numbers, having this later in the rules will break coloring!
    "$USER[ ]\+$USER"  "$BC$K" # Use quotes to have rules with spaces. This colors the "ls -la" usernames. background cyan, black text
    status       "$g" # simple word matching, coloring green
    "^d[^ ]*"    "$G" # color words at the beginning of line, starting with d.  color bright green
    "q.\{0,3\}r" "$Y" # q*r with maximum 3 characters in between. color bright yellow
)
--------------------
Rules can be also exressed as a space separated list variable:
export HB_RULES='\''"[0-9]" "$C" "g" "$Y"'\''
   HB_RULES are appended to other rules

Bright colors:  $R $G $B $Y $M $C $W $K
Dark colors:    $r $g $b $y $m $c $w $k
Modify to bright version by prefixing with $H  (e.g. $H$g)
Background colors: $BR $BG $BB $BY $BC $BM $BW 
Underline: $U

Usage:   highbeam [-c] [-h] [-f config]
   -c    Be case sensitive
   -D    Print current rules, not the input
   -s    Simple highlight a string (as argument)
   -h    Help
   -f    Define config file (default ~/.highbeamrc)
   -r    Define rules with a string, replaces the other rules
            -r '\''"land[^[:space:]]\+" "$G" "sky" "$B"'\''

'

}

E='\x1b['
H="${E}1m"
Z="${E}0m"

# list of text colors:
K="${E}1;30m"
R="${E}1;31m"
G="${E}1;32m"
B="${E}1;34m"
Y="${E}1;33m"
M="${E}1;35m"
C="${E}1;36m"
W="${E}1;37m"
k="${E}30m"
r="${E}31m"
g="${E}32m"
b="${E}34m"
y="${E}33m"
m="${E}35m"
c="${E}36m"
w="${E}37m"

# list of BG colors:
BR="${E}41m"
BG="${E}42m"
BB="${E}44m"
BY="${E}43m"
BM="${E}45m"
BC="${E}46m"
BW="${E}47m"

# lines
U="${E}4m"

CONF_FILE=~/.highbeamrc
CONF_LINE=""
FLAGS="ig"
PRINT=0
while getopts chf:r:s:D opt
do  case "$opt" in
    c)
        FLAGS="g"
    ;;
    h)
        usage
        exit
    ;;
    f)
        CONF_FILE=$OPTARG
    ;;
    r)
        CONF_LINE=( $( eval echo $OPTARG ) )
    ;;
    s)
        HB_RULES='"'"$OPTARG"'" "$U$Y"' exec "$0"
        exit $?
    ;;
    D)
        PRINT=1
    ;;
    esac
done
    
[[ -z "$CONF_LINE" ]] && {
    # user rules:
    [[ -e "${CONF_FILE}" ]] && {
        . "${CONF_FILE}" || {
            echo You may have wrong format in "${CONF_FILE}" >&2 
            usage >&2
            exit 1
        }
    } 
    for (( rIndex=0; rIndex<${#RULES[@]}; rIndex++ ));
    do  REGEX="$REGEX -e 's/\(${RULES[$rIndex]}\)/${RULES[$(( $rIndex + 1 ))]}\1${Z}/${FLAGS}'"
        rIndex=$(( $rIndex + 1 ))
    done    
} || {
    # string fed rules
    for (( rIndex=0; rIndex<${#CONF_LINE[@]}; rIndex++ ));
    do  REGEX="$REGEX -e 's/\(${CONF_LINE[$rIndex]}\)/${CONF_LINE[$(( $rIndex + 1 ))]}\1${Z}/${FLAGS}'"
        rIndex=$(( $rIndex + 1 ))
    done
}
# env variable fed rules
[[ -z "$HB_RULES" ]] || {
    CONF_ENV=( $( eval echo "$HB_RULES" ) )
    for (( rIndex=0; rIndex<${#CONF_ENV[@]}; rIndex++ ));
    do  REGEX="$REGEX -e 's/\(${CONF_ENV[$rIndex]}\)/${CONF_ENV[$(( $rIndex + 1 ))]}\1${Z}/${FLAGS}'"
        rIndex=$(( $rIndex + 1 ))
    done
}
[[ $PRINT -eq 1 ]] && {
    echo "From $CONF_FILE:"
        for (( rIndex=0; rIndex<${#RULES[@]}; rIndex++ ));
        do  printf "%s\\t%s" "${RULES[$rIndex]}" "${RULES[$(( $rIndex + 1 ))]}"
            rIndex=$(( $rIndex + 1 ))
        done    
    echo "From argument switches:"
        for (( rIndex=0; rIndex<${#CONF_LINE[@]}; rIndex++ ));
        do  printf "%s\\t%s" "${CONF_LINE[$rIndex]}" "${CONF_LINE[$(( $rIndex + 1 ))]}"
            rIndex=$(( $rIndex + 1 ))
        done
    echo "From HB_RULES environment:"
        for (( rIndex=0; rIndex<${#CONF_ENV[@]}; rIndex++ ));
        do  printf "%s\\t%s" "${CONF_ENV[$rIndex]}" "${CONF_ENV[$(( $rIndex + 1 ))]}"
            rIndex=$(( $rIndex + 1 ))
        done
#~ echo ${CONF_ENV[@]}
#~ echo $HB_RULES
#~ echo $REGEX
    exit
}

[[ -z "$REGEX" ]] && {
    cat -
} || {
    eval sed $REGEX || echo Maybe errors in your rules: "$REGEX" >&2
}