dotfiles/.config/zsh/functions/cat-highlight

#!/usr/bin/env zsh
# Highlight cat output with either $CATOPEN, ~/.lessfilter or $LESSOPEN. The
# command needs to have %s in it that will be replaced with input files (one by
# one). Some programs that are known to not work will be ignored in $LESSOPEN
# but not in $CATOPEN.

# Example:
# export CATOPEN="highlight --force --out-format=truecolor --stdout %s"
# alias cat='cat-highlight'

setopt LOCAL_OPTIONS PIPE_FAIL

# Check if we are in a terminal
if [[ ! -t 1 ]]; then
    \cat ${@}
    return ${?}
fi

# Try to find highlighter
if [[ -v CATOPEN && -n ${CATOPEN} ]]; then
    local catopen=${CATOPEN}
elif [[ -x ~/.lessfilter ]]; then
    local catopen="~/.lessfilter %s"
elif [[ -v LESSOPEN && -n ${LESSOPEN} ]]; then
    local catopen="${LESSOPEN/|/}"
    # Programs that won't work with cat
    local -a known_bad=("lesspipe")
    for baddy in ${known_bad}; do
        if [[ ${LESSOPEN} =~ ${baddy} ]]; then
            unset catopen
        fi
    done
fi

if [[ ! -v catopen ]]; then
    \cat ${@}
    return ${?}
fi

local -a args
local -a files
for arg in ${@}; do
    # Filter out file names
    if [[ ${arg[1]} != "-" ]]; then
        files+=${(q)arg}
    else
        args+=${arg}
    fi
done

for file in ${files}; do
    eval "${catopen/\%s/${file}}" 2>& -
    [[ ${?} -eq 0 ]] || \cat ${file}
done | \cat ${args}