#!/bin/zsh
#
# Figure out where to get the best help, and get it.
#
# Install this function by placing it in your FPATH and then
# adding to your .zshrc the lines:
#	unalias run-help
#	autoload -Uz run-help
#

emulate -RL zsh

local HELPDIR="${HELPDIR:-/usr/share/zsh/$ZSH_VERSION/help}"

[[ $1 == "." ]] && 1="dot"
[[ $1 == ":" ]] && 1="colon"

# Check whether Util/helpfiles has been used to generate zsh help
if [[ $# == 0 || $1 == "-l" ]]
then
    if [[ -d $HELPDIR ]]
    then
	echo "Here is a list of topics for which special help is available:"
	echo ""
	print -rc $HELPDIR/*(:t)
    else
	echo "There is no list of special help topics available at this time."
    fi
    return 0
elif [[ -n "${HELPDIR:-}" && -r $HELPDIR/$1 && $1 != compctl ]]
then
    ${=PAGER:-more} $HELPDIR/$1
    return $?
fi

# No zsh help; use "whence" to figure out where else we might look
local what places noalias newline='
'
integer i=0 didman=0

places=( "${(@f)$(builtin whence -va $1)}" )
if [[ $places = *"not found"* && $1 != ${(Q)1} ]]; then
  # Different when unquoted, so try stripping quotes.
  places=( "${(@f)$(builtin whence -va ${(Q)1})}" )
  if (( ${#places} )); then
      set -- "${(Q)@}"
  fi
  # Quotation is significant to aliases, so suppress lookup.
  noalias=1
fi

{
while ((i++ < $#places))
do
    what=$places[$i]
    [[ -n $noalias && $what = *" is an alias "* ]] && continue
    builtin print -r $what
    case $what in
    (*( is an alias)*)
	[[ ${what[(w)6]:t} != ${what[(w)1]} ]] &&
	  run_help_orig_cmd=${what[(w)1]} run-help ${what[(w)6]:t}
	;;
    (*( is a * function))
	case ${what[(w)1]} in
	(comp*) man zshcompsys;;
	(zf*) man zshftpsys;;
	(run-help) man zshcontrib;;
	(*) builtin functions ${what[(w)1]} | ${=PAGER:-more};;
	esac;;
    (*( is a * builtin))
	case ${what[(w)1]} in
	(compctl) man zshcompctl;;
	(comp*) man zshcompwid;;
	(bindkey|vared|zle) man zshzle;;
	(*setopt) man zshoptions;;
	(cap|getcap|setcap) ;&
	(clone) ;&
	(ln|mkdir|mv|rm|rmdir|sync) ;&
	(sched) ;&
	(echotc|echoti|sched|stat|zprof|zpty|zsocket|zstyle|ztcp) man zshmodules;;
	(zftp) man zshftpsys;;
	(*) man zshbuiltins;;
	esac
	;;
    (*( is hashed to *))
	man ${what[(w)-1]:t}
	;;
    (*( is a reserved word))
	man zshmisc
	;;
    (*)
	if ((! didman++))
	then
	    if whence "run-help-$1:t" >/dev/null
	    then
		local cmd_args
		builtin getln cmd_args
		builtin print -z "$cmd_args"
		cmd_args=( ${(z)cmd_args} )
		# Discard environment assignments, etc.
		while [[ $cmd_args[1] != ${run_help_orig_cmd:-$1} ]]
		do
		    shift cmd_args || return 1
		done
		eval "run-help-$1:t ${(q@)cmd_args[2,-1]}"
	    else
		POSIXLY_CORRECT=1 man $@:t
	    fi
	fi
	;;
    esac
    if ((i < $#places && ! didman))
    then
	builtin print -nP "%SPress any key for more help or q to quit%s"
	builtin read -k what
	[[ $what != $newline ]] && echo
	[[ $what == [qQ] ]] && break
    fi
done
} always {
  unset run_help_orig_cmd
}