viman

#!/usr/bin/env bash

# Use (neo)vim as your MANPAGER
# Set MANPAGER=/path/to/viman in your shellrc
#
# Copyright 2020-2022 Maddison Hellstrom <https://github.com/b0o>
# MIT License

set -Eeuo pipefail
shopt -s inherit_errexit

declare vim="nvim"
command -v nvim &>/dev/null || vim="vim"

if [[ ! -t /dev/stdin ]]; then
  MANPAGER='less' man "$@" -l -
elif [[ $# -gt 0 ]]; then
  args=()
  manpages=()
  cmd=""

  opts_ok=1
  while [[ $# -gt 0 ]]; do
    [[ "$1" =~ ^- ]] && {
      [[ $opts_ok -eq 0 ]] && {
        echo "unexpected option $1" >&2
        exit 1
      }
      args+=("$1")
      shift
      continue
    }
    opts_ok=0
    manpage=""
    if [[ "$1" =~ ^[[:digit:]]p?$ && $# -gt 1 ]]; then
      manpage="$1 $2"
      shift
    elif [[ "$1" =~ ^([[:graph:]]*)\(([[:graph:]])\)$ ]]; then
      manpage="${BASH_REMATCH[2]} ${BASH_REMATCH[1]}"
    else
      manpage="$1"
    fi
    manpages=("$manpage" "${manpages[@]}")
    shift
  done

  [[ ${#manpages[@]} -eq 0 ]] && {
    /bin/man "${args[@]}" || exit $?
    exit 0
  }

  for i in $(seq 1 $((${#manpages[@]}))); do
    p="${manpages[${#manpages[@]} - i]}"
    [[ ${#cmd} -gt 0 ]] && cmd+=" | "
    cmd+="M $p"
  done

  cmd+=" | tabfirst"

  "${NVIM:-$vim}" "${args[@]}" -c "$cmd"
else
  /bin/man
fi