# TUI user interface
#
# 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/>.

tui_init_ui()
{
	term_init
	term_raw
	term_noecho
	term_hide_cursor
	term_clear
}

tui_exit_ui()
{
	term_attr_reset
	term_clear
	term_show_cursor
	term_echo
	term_cooked
}

_tui_box()
{
	local w=${1}
	local h=${2}
	shift 2
	local y=
	local x=
	local i=
	local line=''

	# Clear the screen and set the cursor position to center the box.
	term_attr_reset
	term_clear
	y=$(expr \( $(term_lines) - ${h} \) / 2 + 1)
	x=$(expr \( $(term_columns) - ${w} \) / 2 + 1)
	term_cursor_position ${y} ${x}

	# Build the line.
	i=0
	while [ ${i} -lt ${w} ]; do
		line="${line} "
		i=$(($i + 1))
	done

	# Draw white box background lines.
	term_fg_color_set black
	term_bg_color_set white
	i=0
	while [ ${i} -lt ${h} ]; do
		term_write "${line}"
		term_cursor_back ${w}
		term_cursor_down 1
		i=$(($i + 1))
	done

	# Reset the cursor to the top-left corner of the box.
	term_cursor_up ${h}

	printf '%d %d' ${y} ${x}
	return 0
}

_tui_dialog()
{
	local lvl="${1}"
	local fmt="${2}"
	shift 2
	local msg=''

	# Format the message.
	msg="$(printf "${fmt}" "${@}")"

	# Draw the box.
	_tui_box $(expr ${#msg} + 8) 5 >/dev/null

	# Draw an icon.
	term_cursor_forward 2
	term_cursor_down 1
	case "${lvl}" in
		warn)
			term_fg_color_set yellow
			term_write '/!\'
			term_fg_color_set black
			;;
		err)
			term_fg_color_set red
			term_write '(x)'
			term_fg_color_set black
			;;
	esac

	# Write the message.
	term_cursor_forward 1
	term_write "${msg}"

	# Draw a (selected) button.
	term_cursor_back 4
	term_cursor_down 2
	term_attr_on reverse
	term_write '[OK]'
	term_attr_off reverse

	while :; do
		case "$(term_getch)" in
			KEY_ENTER | KEY_SPACE) break;;
		esac
	done

	return 0
}

tui_dbg()
{
	: No output.
}

tui_info()
{
	: No output.
}

tui_warn()
{
	local fmt="${1}"
	shift 1

	_tui_dialog warn "${fmt}" "${@}"
}

tui_err()
{
	local fmt="${1}"
	shift 1

	_tui_dialog err "${fmt}" "${@}"
}

tui_show_menu()
{
	local title="${1}"
	shift 1
	local w=
	local label=
	local lsth=
	local scrh=
	local scrbh=
	local h=
	local y=
	local x=
	local i=
	local bline=''
	local lline=''
	local focus=0
	local scrbpos=
	local scrpos=0
	local curpos=0

	# Calculate size and draw the box.
	w=$(expr ${#title} + 4)
	for label in "${@}"; do
		if [ $(expr ${#label} + 6) -gt ${w} ]; then
			w=$(expr ${#label} + 6)
		fi
	done
	lsth=${#}
	h=$(($lsth + 8))
	if [ ${h} -gt $(term_lines) ]; then
		h=$(term_lines)
	fi
	scrh=$(($h - 8))
	scrbh=$(($scrh * $scrh / $lsth))
	read -r y x <<-EOF
		$(_tui_box ${w} ${h})
		EOF

	# Build box and label lines.
	i=0
	while [ ${i} -lt $(($w - 6)) ]; do
		bline="${bline}-"
		lline="${lline} "
		i=$(($i + 1))
	done

	# Write the title.
	term_cursor_down 1
	term_cursor_forward 2
	term_write "${title}"

	# Event loop.
	while :; do
		# Draw a button.
		term_cursor_position $(($y + $h - 2)) $(($x + $w - 6))
		if [ ${focus} -eq 1 ]; then
			term_attr_on reverse
			term_write '[OK]'
			term_attr_off reverse
		else
			term_write '[OK]'
		fi

		# Draw a box.
		term_cursor_position $(($y + 3)) $(($x + 2))
		term_write "+${bline}+"
		term_cursor_position $(($y + $h - 4)) $(($x + 2))
		term_write "+${bline}+"
		i=0
		# Add ${lsth} - 1 to always round up to the next integer.
		scrbpos=$(expr \
			\( ${scrpos} \* ${scrh} + ${lsth} - 1 \) / ${lsth})
		while [ ${i} -lt ${scrh} ]; do
			term_cursor_position $(($y + 4 + $i)) $(($x + 2))
			term_write '|'
			term_cursor_position $(($y + 4 + $i)) $(($x + $w - 3))
			if [ ${i} -ge ${scrbpos} ] && \
					[ ${i} -lt $(($scrbpos + $scrbh)) ]
			then
				term_attr_on reverse
				term_write ' '
				term_attr_off reverse
			else
				term_write '|'
			fi
			i=$(($i + 1))
		done

		# Draw labels.
		i=-1
		for label in "${@}"; do
			i=$(($i + 1))
			[ ${i} -ge ${scrpos} ] || continue
			[ ${i} -lt $(($scrpos + $scrh)) ] || break
			if [ ${i} -eq ${curpos} ]; then
				term_attr_on reverse
				term_cursor_position \
					$(($y + 4 + $i - $scrpos)) $(($x + 3))
				term_write "${lline}"
				term_cursor_position \
					$(($y + 4 + $i - $scrpos)) $(($x + 3))
				term_write "${label}"
				term_attr_off reverse
			else
				term_cursor_position \
					$(($y + 4 + $i - $scrpos)) $(($x + 3))
				term_write "${lline}"
				term_cursor_position \
					$(($y + 4 + $i - $scrpos)) $(($x + 3))
				term_write "${label}"
			fi
		done

		# Input.
		key="$(term_getch)"
		if [ "x${key}" = xKEY_TAB ]; then
			focus=$(expr \( ${focus} + 1 \) % 2)
		elif [ ${focus} -eq 0 ]; then
			case "${key}" in
				KEY_ENTER) break;;
				KEY_UP | 'k')
					[ ${curpos} -gt 0 ] || continue
					curpos=$(($curpos - 1))
					if [ ${curpos} -lt ${scrpos} ]; then
						scrpos=${curpos}
					fi
					;;
				KEY_DOWN | 'j')
					[ $(($curpos + 1)) -lt ${lsth} ] || \
						continue
					curpos=$(($curpos + 1))
					if [ ${curpos} -ge $(($scrpos + \
							$scrh)) ]; then
						scrpos=$(($curpos - $scrh + 1))
					fi
					;;
				KEY_HOME | 'g')
					curpos=0
					scrpos=0
					;;
				KEY_END | 'G')
					curpos=$(($lsth - 1))
					scrpos=$(($lsth - $scrh))
					;;
				KEY_*);;
			esac
		elif [ ${focus} -eq 1 ]; then
			case "${key}" in
				KEY_ENTER | KEY_SPACE) break;;
			esac
		fi
	done

	return 0
}

tui_show_prompt()
{
	local title="${1}"
	local len=${2}
	shift 2
	local w=
	local y=
	local x=
	local i=
	local iline=''
	local bline=''
	local input=''
	local curpos=0
	local focus=0
	local key=
	local mask=
	local buffer=

	# Calculate width and draw the box.
	w=$(expr ${#title} + 4)
	if [ $(expr ${len} + 7) -gt ${w} ]; then
		w=$(expr ${len} + 7)
	fi
	read -r y x <<-EOF
		$(_tui_box ${w} 9)
		EOF

	# Write the title.
	term_cursor_down 1
	term_cursor_forward 2
	term_write "${title}"

	# Build blank input line.
	i=0
	while [ ${i} -le ${len} ]; do
		bline="${bline}-"
		iline="${iline} "
		i=$(($i + 1))
	done

	# Event loop.
	while :; do
		# Draw a button.
		term_cursor_position $(($y + 7)) $(($x + $w - 6))
		if [ ${focus} -eq 1 ]; then
			term_attr_on reverse
			term_write '[OK]'
			term_attr_off reverse
		else
			term_write '[OK]'
		fi

		# Draw a textbox.
		term_cursor_position $(($y + 3)) $(($x + 2))
		term_write "+${bline}+"
		term_cursor_position $(($y + 4)) $(($x + 2))
		term_write "|${iline}|"
		term_cursor_position $(($y + 5)) $(($x + 2))
		term_write "+${bline}+"

		# Draw input.
		term_cursor_position $(($y + 4)) $(($x + 3))
		term_write "${input}"

		# Put the cursor in the text box.
		if [ ${focus} -eq 0 ]; then
			term_show_cursor
			term_cursor_position $(($y + 4)) $(($x + 3 + $curpos))
		else
			term_hide_cursor
		fi

		# Input.
		key="$(term_getch)"
		if [ "x${key}" = xKEY_TAB ]; then
			focus=$(expr \( ${focus} + 1 \) % 2)
		elif [ ${focus} -eq 0 ]; then
			case "${key}" in
				KEY_ENTER) break;;
				KEY_LEFT)
					[ ${curpos} -gt 0 ] || continue
					curpos=$(($curpos - 1))
					;;
				KEY_RIGHT)
					[ ${curpos} -lt ${#input} ] || continue
					curpos=$(($curpos + 1))
					;;
				KEY_HOME)
					curpos=0
					;;
				KEY_END)
					curpos=${#input}
					;;
				KEY_BACKSPACE)
					[ ${curpos} -gt 0 ] || continue
					i=1
					mask=''
					while [ ${i} -lt ${curpos} ]; do
						mask="${mask}."
						i=$(($i + 1))
					done
					cmd="s/^\\(${mask}\\).\\(.*\\)\$/\1\2/"
					input="$(printf '%s' "${input}" | sed \
						"${cmd}")"
					curpos=$(($curpos - 1))
					;;
				KEY_DEL)
					[ ${curpos} -lt ${#input} ] || continue
					i=0
					mask=''
					while [ ${i} -lt ${curpos} ]; do
						mask="${mask}."
						i=$(($i + 1))
					done
					cmd="s/^\\(${mask}\\).\\(.*\\)\$/\1\2/"
					input="$(printf '%s' "${input}" | sed \
						"${cmd}")"
					;;
				KEY_SPACE)
					[ ${#input} -lt ${len} ] || continue
					key=' '
					i=0
					mask=''
					while [ ${i} -lt ${curpos} ]; do
						mask="${mask}."
						i=$(($i + 1))
					done
					cmd="s/^\\(${mask}\\).*\$/\1/"
					buffer="$(printf '%s' "${input}" | sed \
						"${cmd}")${key}"
					i=${curpos}
					mask=''
					while [ ${i} -lt ${#input} ]; do
						mask="${mask}."
						i=$(($i + 1))
					done
					cmd="s/^.*\\(${mask}\\)\$/\1/"
					input="${buffer}$(printf '%s' \
						"${input}" | sed "${cmd}")"
					curpos=$(($curpos + 1))
					;;
				KEY_*);;
				*)
					[ ${#input} -lt ${len} ] || continue
					i=0
					mask=''
					while [ ${i} -lt ${curpos} ]; do
						mask="${mask}."
						i=$(($i + 1))
					done
					cmd="s/^\\(${mask}\\).*\$/\1/"
					buffer="$(printf '%s' "${input}" | sed \
						"${cmd}")${key}"
					i=${curpos}
					mask=''
					while [ ${i} -lt ${#input} ]; do
						mask="${mask}."
						i=$(($i + 1))
					done
					cmd="s/^.*\\(${mask}\\)\$/\1/"
					input="${buffer}$(printf '%s' \
						"${input}" | sed "${cmd}")"
					curpos=$(($curpos + 1))
					;;
			esac
		elif [ ${focus} -eq 1 ]; then
			case "${key}" in
				KEY_ENTER | KEY_SPACE) break;;
			esac
		fi
	done

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