#!/bin/sh

# Print the contents of all tracked text files to stdout,
# each preceded by a header with its filename
#
# With "-a", binary files are included as well
#
# With "-m", only files with unstaged modifications are printed
#
# With "-n", the headers are omitted
#
# Usage: git cat-all [-a] [-m] [-n] [<pathspec> ...]

set -eu



# Error if we are not in a `git` repository
git rev-parse --git-dir >/dev/null

# Without any commit, there is nothing to print reliably
git rev-parse --verify --quiet HEAD >/dev/null || {
    echo "fatal: no commits yet" >&2
    exit 1
}



_textonly=yes
_lsflags=
_cmd='printf "\n\n===== %s =====\n\n" "{}"; cat "{}"'
_headers=yes


while [ $# -gt 0 ]; do
    case $1 in
        -a) _textonly=no
            shift
            ;;
        -m) _lsflags=-m
            shift
            ;;
        -n) _cmd='printf "\n\n"; cat "{}"'
            _headers=no
            shift
            ;;
        --) shift
            break
            ;;
        -*) echo "Usage: git cat-all [-a] [-m] [-n] [<pathspec> ...]" >&2
            exit 2
            ;;
        *)  break
            ;;
    esac
done



# Because `git` runs scripts on the `$PATH` in the current directory
cd "$(git rev-parse --show-toplevel)"


# An empty file counts as text
# => `grep` alone would misjudge it
#    because it never matches in a file without any lines
if [ "$_textonly" = "yes" ]; then
    _cmd='if [ ! -s "{}" ] || grep -Iq "" "{}"; then '"$_cmd"'; fi'
fi


# `git ls-files -m` also lists files deleted from the working tree
# => Skip them because `cat` would fail
if [ -n "$_lsflags" ]; then
    _cmd='if [ -f "{}" ]; then '"$_cmd"'; fi'
fi



if [ "$_headers" = "yes" ]; then
    printf "Repository: %s\n" "$(basename "$PWD")"
    printf "Branch: %s @ %s\n" \
        "$(git rev-parse --abbrev-ref HEAD)" \
        "$(git rev-parse --short HEAD)"
fi



git ls-files \
    -z $_lsflags \
    -- \
    "$@" \
    | xargs -0 -I{} sh -c "$_cmd"