# Manipulation of ECMA-48 (ANSI X3.64) terminals with DEC extensions
#
# Copyright (C) 2015  Patrick "P. J." McDermott
#
# 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 <http://www.gnu.org/licenses/>.

term_tty=
term_byte=
term_num_lines=
term_num_columns=

term_init()
{
	term_tty="$(tty)"
	read -r term_num_lines term_num_columns <<-EOF
		$(stty size)
		EOF

	return 0
}

term_lines()
{
	printf '%d' ${term_num_lines}
	return 0
}

term_columns()
{
	printf '%d' ${term_num_columns}
	return 0
}

term_echo()
{
	stty echo

	return 0
}

term_noecho()
{
	stty -echo

	return 0
}

term_raw()
{
	stty raw

	return 0
}

term_cooked()
{
	stty cooked

	return 0
}

term_cursor_up()
{
	local n="${1}"
	shift 1

	# CUU
	printf '\033[%dA' ${n} >"${term_tty}"

	return 0
}

term_cursor_down()
{
	local n="${1}"
	shift 1

	# CUD
	printf '\033[%dB' ${n} >"${term_tty}"

	return 0
}

term_cursor_forward()
{
	local n="${1}"
	shift 1

	# CUF
	printf '\033[%dC' ${n} >"${term_tty}"

	return 0
}

term_cursor_back()
{
	local n="${1}"
	shift 1

	# CUB
	printf '\033[%dD' ${n} >"${term_tty}"

	return 0
}

term_cursor_position()
{
	local row="${1}"
	local col="${2}"
	shift 2

	# CUP
	printf '\033[%d;%dH' ${row} ${col} >"${term_tty}"

	return 0
}

term_clear()
{
	# ED with n=2
	printf '\033[2J' >"${term_tty}"
	term_cursor_position 1 1

	return 0
}

term_hide_cursor()
{
	# DECTCEM with code "l"
	printf '\033[?25l' >"${term_tty}"

	return 0
}

term_show_cursor()
{
	# DECTCEM with code "h"
	printf '\033[?25h' >"${term_tty}"

	return 0
}

term_attr_on()
{
	local attr="${1}"
	shift 1
	local attr_code=

	case "${attr}" in
		blink)     attr_code=5;;
		bold)      attr_code=1;;
		dim)       attr_code=2;;
		invis)     attr_code=8;;
		reverse)   attr_code=7;;
		underline) attr_code=4;;
		*) return 1;;
	esac

	# SGR
	printf '\033[%dm' ${attr_code} >"${term_tty}"

	return 0
}

term_attr_off()
{
	local attr="${1}"
	shift 1
	local attr_code=

	case "${attr}" in
		blink)     attr_code=25;;
		bold)      attr_code=22;;
		dim)       attr_code=22;;
		invis)     attr_code=28;;
		reverse)   attr_code=27;;
		underline) attr_code=24;;
		*) return 1;;
	esac

	# SGR
	printf '\033[%dm' ${attr_code} >"${term_tty}"

	return 0
}

term_fg_color_set()
{
	local color="${1}"
	shift 1

	case "${color}" in
		black)   color=0;;
		red)     color=1;;
		green)   color=2;;
		yellow)  color=3;;
		blue)    color=4;;
		magenta) color=5;;
		cyan)    color=6;;
		white)   color=7;;
		*) return 1;;
	esac

	# SGR
	printf '\033[%dm' $((30 + $color)) >"${term_tty}"

	return 0
}

term_bg_color_set()
{
	local color="${1}"
	shift 1

	case "${color}" in
		black)   color=0;;
		red)     color=1;;
		green)   color=2;;
		yellow)  color=3;;
		blue)    color=4;;
		magenta) color=5;;
		cyan)    color=6;;
		white)   color=7;;
		*) return 1;;
	esac

	# SGR
	printf '\033[%dm' $((40 + $color)) >"${term_tty}"

	return 0
}

term_attr_reset()
{
	# SGR
	printf '\033[0m' >"${term_tty}"

	return 0
}

term_write()
{
	local s="${1}"
	shift 1

	printf '%s' "${s}" >"${term_tty}"

	return 0
}

_term_get_byte()
{
	# Damn command substitutions eat trailing whitespace.  Even if
	# whitespace is the /only/ thing printed and exactly what we want from
	# the command.
	term_byte="$(dd bs=1 count=1 2>/dev/null; printf '.')"
	term_byte="${term_byte%.}"

	return 0
}

_term_get_escseq()
{
	local key=KEY_INVALID

	_term_get_byte
	case "${term_byte}" in
		'[')
			_term_get_byte
			case "${term_byte}" in
				'A') key=KEY_UP;;
				'B') key=KEY_DOWN;;
				'C') key=KEY_RIGHT;;
				'D') key=KEY_LEFT;;
				'H') key=KEY_HOME;;   # XTerm
				'F') key=KEY_END;;    # XTerm
				'1')
					_term_get_byte
					case "${term_byte}" in
						'~') key=KEY_HOME;;  # Linux
					esac
					;;
				'3')
					_term_get_byte
					case "${term_byte}" in
						'~') key=KEY_DEL;;
					esac
					;;
				'4')
					_term_get_byte
					case "${term_byte}" in
						'~') key=KEY_END;;  # Linux
					esac
					;;
			esac
			;;
		'O')
			_term_get_byte
			case "${term_byte}" in
				'H') key=KEY_HOME;;  # VTE
				'F') key=KEY_END;;   # VTE
			esac
			;;
	esac

	printf '%s' "${key}"
	return 0
}

term_getch()
{
	local key=KEY_INVALID

	_term_get_byte
	case "${term_byte}" in
		"$(printf '\033')")
			key="$(_term_get_escseq)"
			;;
		' ') key=KEY_SPACE;;
		"${HT}") key=KEY_TAB;;
		"$(printf '\015')") key=KEY_ENTER;;
		"$(printf '\177')") key=KEY_BACKSPACE;;
		*) key="${term_byte}";;
	esac

	printf '%s' "${key}"
	return 0
}