#!/hint/bash

if [[ $TERM == eterm* ]]; then
	SELECTED_EDITOR='emacsclient'
	EDITOR=$SELECTED_EDITOR
	VISUAL=$SELECTED_EDITOR
	export SELECTED_EDITOR EDITOR VISUAL
	export PAGER=cat

	## Primatives for interacting with Emacs ###############################

	# _emacs_run LISP
	_emacs_run() {
		emacsclient -a false -e "$*" 2>/dev/null
	}
	# _emacs_quote UNQUOTED_STRING
	_emacs_quote() {
		local str="$*"
		str="${str//\\/\\\\}" # \ -> \\
		str="${str//\"/\\\"}" # " -> \"
		str="\"${str}\""      # wrap it in quotes
		printf '%s' "$str"
	}
	# _emacs_unquote QUOTED_STRING
	_emacs_unquote() {

		local str="$*"
		if [[ $str =~ ^\"(.*)\"$ ]]; then
			str=${BASH_REMATCH[1]} # un-quote it
			str="${str//\\\\/\\}" # \\ -> \
			str="${str//\\\"/\"}" # \" -> "
		fi
		printf '%s' "$str"
	}

	## Deal with renaming the terminal #####################################

	# _emacs_rename_terminal NEW_BUFFER_NAME
	# This function uses the variable _EMACS_BUFFER to store some state
	_emacs_rename_terminal() {
		local name=$(_emacs_quote "$*")
		if [[ -n $_EMACS_BUFFER ]]; then
			local buffer="(get-buffer $_EMACS_BUFFER)"
		else
			local buffer='(window-buffer (selected-window))'
		fi
		_EMACS_BUFFER=$(_emacs_run "(with-current-buffer ${buffer} (rename-buffer ${name} t))")
	}
	# _emacs_get_short_cwd
	_emacs_get_short_cwd() {
		local base=$PWD
		local suffix=''
		# The regex here is a list of directory names
		# that aren't really helpful, and that the
		# parent directory should be included also.
		if [[ $base =~ (/(src|pkg|doc|pkg-libre|src-libre|trunk|tags|branches))*$ ]]; then
			suffix=$BASH_REMATCH
			base=${base%$suffix}
		fi
		base=${base##*/}
		echo ${base}${suffix}
	}
	# _emacs_get_desired_buffer_name
	_emacs_get_desired_buffer_name() {
		echo "*ansi-term*<$(_emacs_get_short_cwd)>"
	}

	## High-level tasks ####################################################

	# Like uniquify on the buffer name (shell -> emacs)
	_emacs_set_buffer_name() {
		# This doesn't work correctly on remote hosts.
		# The "correct" solution is probably to hook into
		# default-directory being set in term.el
		_emacs_rename_terminal "$(_emacs_get_desired_buffer_name)"
	}
	# Set the TRAMP directory for remote hosts (shell -> emacs)
	_emacs_set_remote_dir() {
		if [[ -n $SSH_CONNECTION ]]; then
			printf '\eAnSiT%s %s\n' \
				u "$USER" \
				c "$PWD" \
				h "$HOSTNAME"
		fi
	}
	# Set the shell's X11 display (emacs -> shell)
	_emacs_set_shell_DISPLAY() {
		export DISPLAY=$(_emacs_unquote "$(_emacs_run "(cdr (assoc 'display (frame-parameters)))")")
		[[ $DISPLAY != nil ]] || unset DISPLAY
	}

	## Do those things #####################################################

	_emacs_PROMPT_COMMAND() {
		_emacs_set_buffer_name
		_emacs_set_remote_dir
		_emacs_set_shell_DISPLAY
	}
	if _emacs_run '()' >/dev/null; then
		PROMPT_COMMAND=_emacs_PROMPT_COMMAND
	fi
fi