BASH: Fancy Autosizing Section Header

printSectionHeader.sh

# Prints a section header.
#
# Features
#   - Autosizes to terminal if $width -gt $COLUMNS
#   - Specifying width as 4000 works...
#   - Adjust first two sanities for stricter usage
#     * Currently sets width to half terminal width
#     * Currently rounds down odd to even width automatically
#   - Customizable outside and inside fill characters
#   - Nofill style option
#
# Usage:
#   printSectionHeader <width> <message>
#
# Examples:
#   printSectionHeader Hello World!
#   printSectionHeader 40 Hello World!
#
# Output:
#     # ------------------------------------ #
#     # //////////////////////////////////// #
#     # /////////// Hello World! /////////// #
#     # //////////////////////////////////// #
#     # ------------------------------------ #
#
function printSectionHeader() {
    local width=$1
    local wrap_char='#' # Examples: '$', '=', '-', '\', '%', '\*' (Must escape some chars)
    local outside_fill_char='=' 
    local inside_fill_char='-'
    local fill_style='fill' # 'fill' or 'nofill'
    local txt="${@:2}"
    if [[ ! $width =~ ^[0-9]+$ ]]; then
        #echo "ERROR: First argument must specify the width as an even number (int)."
        #return 1
        width=$((COLUMNS/2))
        local txt="$*"
    fi
    if [[ $((width%2)) -eq 1 ]]; then
        #echo "ERROR: The width must be an even number (int)."
        #return 1
        width=$(($width-($width%2)))
    fi
    local fill=$(($width-4))
    local txt_length=${#txt}
    local min_width=$((txt_length+8))
    if [[ $width -lt $min_width ]]; then
        echo "ERROR: Minimum width for text length ($txt_length) is $min_width."
        return 1
    fi
    local padding=8
    local cols=$((COLUMNS - (COLUMNS % 2)))
    [[ $fill -gt $((cols-padding)) ]] && fill=$((cols-$((padding/2))))
    local fill_width="$((cols-cols-fill))"
    local half_fill_width=$(( ((((fill_width/2))+((padding/ 2))))+$((txt_length/2))-1 ))
    local fill="$(printf '%*s' "${fill_width}" | tr ' ' $outside_fill_char)"
    local inside_fill="$(printf '%*s' "$((fill_width))" | tr ' ' $inside_fill_char)"
    [[ $fill_style == "nofill" ]] && local inside_fill="$(printf '%*s' "$((fill_width))")"
    local inside_half_fill="$(printf '%*s' "$((half_fill_width -2))" | tr ' ' $inside_fill_char)"
    [[ $fill_style == "nofill" ]] && local inside_half_fill="$(printf '%*s' "$((half_fill_width -2))")"
    printf "$wrap_char "; printf '%s' "${fill}"; printf " $wrap_char\n"
    printf "$wrap_char "; printf '%s' "${inside_fill}"; printf " $wrap_char\n"
    printf "$wrap_char "; printf '%s' "${inside_half_fill}"
    printf "\e[01;39m $txt \e[0m"
    [[ $((txt_length%2)) -eq 1 ]] && local inside_half_fill="$(printf '%*s' "$((half_fill_width -1))" | tr ' ' $inside_fill_char)"
    [[ $fill_style == "nofill" ]] && [[ $((txt_length%2)) -eq 1 ]] && local inside_half_fill="$(printf '%*s' "$((half_fill_width -1))")"
    printf '%s' "${inside_half_fill}"; printf " $wrap_char\n"
    printf "$wrap_char "; printf '%s' "${inside_fill}"; printf " $wrap_char\n"
    printf "$wrap_char "; printf '%s' "${fill}"; printf " $wrap_char\n"
}