#!/usr/pkg/bin/bash
#
# notmuch-emacs-mua - start composing a mail on the command line
#
# Copyright © 2014 Jani Nikula
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see https://www.gnu.org/licenses/ .
#
# Authors: Jani Nikula <jani@nikula.org>
#

set -eu

# escape: "expand" '\' as '\\' and '"' as '\"'
# calling convention: escape -v var "$arg" (like in bash printf).
escape ()
{
    local __escape_arg__=${3//\\/\\\\}
    printf -v $2 '%s' "${__escape_arg__//\"/\\\"}"
}

EMACS=${EMACS:-emacs}
EMACSCLIENT=${EMACSCLIENT:-emacsclient}

PRINT_ONLY=
NO_WINDOW=
USE_EMACSCLIENT=
AUTO_DAEMON=
CREATE_FRAME=
ELISP=
MAILTO=
HELLO=
TO_SEP=
CC_SEP=
BCC_SEP=

# Short options compatible with mutt(1).
while getopts :s:c:b:i:h opt; do
    # Handle errors and long options.
    case "${opt}" in
	:)
	    echo "$0: short option -${OPTARG} requires an argument." >&2
	    exit 1
	    ;;
	\?)
	    opt=$1
	    if [ "${OPTARG}" != "-" ]; then
		echo "$0: unknown short option -${OPTARG}." >&2
		exit 1
	    fi

	    case "${opt}" in
		# Long options with arguments.
		--subject=*|--to=*|--cc=*|--bcc=*|--body=*)
		    OPTARG=${opt#--*=}
		    opt=${opt%%=*}
		    ;;
		# Long options without arguments.
		--help|--print|--no-window-system|--client|--auto-daemon|--create-frame|--hello)
		    ;;
		*)
		    echo "$0: unknown long option ${opt}, or argument mismatch." >&2
		    exit 1
		    ;;
	    esac
	    # getopts does not do this for what it considers errors.
	    OPTIND=$((OPTIND + 1))
	    ;;
    esac

    escape -v OPTARG "${OPTARG-none}"

    case "${opt}" in
	--help|h)
	    exec man notmuch-emacs-mua
	    ;;
	--subject|s)
	    ELISP="${ELISP} (message-goto-subject) (insert \"${OPTARG}\")"
	    ;;
	--to)
	    ELISP="${ELISP} (message-goto-to) (insert \"${TO_SEP}${OPTARG}\")"
	    TO_SEP=", "
	    ;;
	--cc|c)
	    ELISP="${ELISP} (message-goto-cc) (insert \"${CC_SEP}${OPTARG}\")"
	    CC_SEP=", "
	    ;;
	--bcc|b)
	    ELISP="${ELISP} (message-goto-bcc) (insert \"${BCC_SEP}${OPTARG}\")"
	    BCC_SEP=", "
	    ;;
	--body|i)
	    ELISP="${ELISP} (message-goto-body) (insert-file \"${OPTARG}\")"
	    ;;
	--print)
	    PRINT_ONLY=1
	    ;;
	--no-window-system)
	    NO_WINDOW="-nw"
	    ;;
	--client)
	    USE_EMACSCLIENT="yes"
	    ;;
	--auto-daemon)
	    AUTO_DAEMON="--alternate-editor="
	    CREATE_FRAME="-c"
	    ;;
	--create-frame)
	    CREATE_FRAME="-c"
	    ;;
	--hello)
	    HELLO=1
	    ;;
	*)
	    # We should never end up here.
	    echo "$0: internal error (option ${opt})." >&2
	    exit 1
	    ;;
    esac

    shift $((OPTIND - 1))
    OPTIND=1
done

# Positional parameters.
for arg; do
    escape -v arg "${arg}"
    case $arg in
	mailto:*)
	    if [ -n "${MAILTO}" ]; then
		echo "$0: more than one mailto: argument." >&2
		exit 1
	    fi
	    MAILTO="${arg}"
	    ;;
	*)
	    ELISP="${ELISP} (message-goto-to) (insert \"${arg}, \")"
	    ;;
    esac
done

if [ -n "${MAILTO}" ]; then
    if [ -n "${ELISP}" ]; then
	echo "$0: mailto: is not compatible with other message parameters." >&2
	exit 1
    fi
    ELISP="(browse-url-mail \"${MAILTO}\")"
elif [ -z "${ELISP}" -a -n "${HELLO}" ]; then
    ELISP="(notmuch)"
else
    ELISP="(notmuch-mua-new-mail) ${ELISP}"
fi

# Kill the terminal/frame if we're creating one.
if [ -z "$USE_EMACSCLIENT" -o -n "$CREATE_FRAME" -o -n "$NO_WINDOW" ]; then
    ELISP="${ELISP} (message-add-action #'save-buffers-kill-terminal 'exit)"
fi

escape -v pwd "$PWD"

# The crux of it all: construct an elisp progn and eval it.
ELISP="(prog1 'done (require 'notmuch) (cd \"$pwd\") ${ELISP})"

if [ -n "$PRINT_ONLY" ]; then
    echo ${ELISP}
    exit 0
fi

if [ -n "$USE_EMACSCLIENT" ]; then
    # Evaluate the progn.
    exec ${EMACSCLIENT} ${NO_WINDOW} ${CREATE_FRAME} ${AUTO_DAEMON} --eval "${ELISP}"
else
    exec ${EMACS} ${NO_WINDOW} --eval "${ELISP}"
fi
