# Copyright 2019-2020 Free Software Foundation, Inc.

# 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/>.

# An ANSI terminal emulator for expect.

# The expect "spawn" function puts the tty name into the spawn_out
# array; but dejagnu doesn't export this globally.  So, we have to
# wrap spawn with our own function, so that we can capture this value.
# The value is later used in calls to stty.
rename spawn builtin_spawn
proc spawn {args} {
    set result [uplevel builtin_spawn $args]
    global gdb_spawn_name
    upvar spawn_out spawn_out
    set gdb_spawn_name $spawn_out(slave,name)
    return $result
}

namespace eval Term {
    variable _rows
    variable _cols
    variable _chars

    variable _cur_x
    variable _cur_y

    variable _attrs

    variable _last_char

    variable _resize_count

    # If ARG is empty, return DEF: otherwise ARG.  This is useful for
    # defaulting arguments in CSIs.
    proc _default {arg def} {
	if {$arg == ""} {
	    return $def
	}
	return $arg
    }

    # Erase in the line Y from SX to just before EX.
    proc _clear_in_line {sx ex y} {
	variable _attrs
	variable _chars
	set lattr [array get _attrs]
	while {$sx < $ex} {
	    set _chars($sx,$y) [list " " $lattr]
	    incr sx
	}
    }

    # Erase the lines from SY to just before EY.
    proc _clear_lines {sy ey} {
	variable _cols
	while {$sy < $ey} {
	    _clear_in_line 0 $_cols $sy
	    incr sy
	}
    }

    # Beep.
    proc _ctl_0x07 {} {
    }

    # Backspace.
    proc _ctl_0x08 {} {
	variable _cur_x
	incr _cur_x -1
	if {$_cur_x < 0} {
	    variable _cur_y
	    variable _cols
	    set _cur_x [expr {$_cols - 1}]
	    incr _cur_y -1
	    if {$_cur_y < 0} {
		set _cur_y 0
	    }
	}
    }

    # Linefeed.
    proc _ctl_0x0a {} {
	variable _cur_y
	variable _rows
	incr _cur_y 1
	if {$_cur_y >= $_rows} {
	    error "FIXME scroll"
	}
    }

    # Carriage return.
    proc _ctl_0x0d {} {
	variable _cur_x
	set _cur_x 0
    }

    # Make room for characters.
    proc _csi_@ {args} {
	set n [_default [lindex $args 0] 1]
	variable _cur_x
	variable _cur_y
	variable _chars
	set in_x $_cur_x
	set out_x [expr {$_cur_x + $n}]
	for {set i 0} {$i < $n} {incr i} {
	    set _chars($out_x,$_cur_y) $_chars($in_x,$_cur_y)
	    incr in_x
	    incr out_x
	}
    }

    # Cursor Up.
    proc _csi_A {args} {
	variable _cur_y
	set arg [_default [lindex $args 0] 1]
	set _cur_y [expr {max ($_cur_y - $arg, 0)}]
    }

    # Cursor Down.
    proc _csi_B {args} {
	variable _cur_y
	variable _rows
	set arg [_default [lindex $args 0] 1]
	set _cur_y [expr {min ($_cur_y + $arg, $_rows)}]
    }

    # Cursor Forward.
    proc _csi_C {args} {
	variable _cur_x
	variable _cols
	set arg [_default [lindex $args 0] 1]
	set _cur_x [expr {min ($_cur_x + $arg, $_cols)}]
    }

    # Cursor Back.
    proc _csi_D {args} {
	variable _cur_x
	set arg [_default [lindex $args 0] 1]
	set _cur_x [expr {max ($_cur_x - $arg, 0)}]
    }

    # Cursor Next Line.
    proc _csi_E {args} {
	variable _cur_x
	variable _cur_y
	variable _rows
	set arg [_default [lindex $args 0] 1]
	set _cur_x 0
	set _cur_y [expr {min ($_cur_y + $arg, $_rows)}]
    }

    # Cursor Previous Line.
    proc _csi_F {args} {
	variable _cur_x
	variable _cur_y
	variable _rows
	set arg [_default [lindex $args 0] 1]
	set _cur_x 0
	set _cur_y [expr {max ($_cur_y - $arg, 0)}]
    }

    # Cursor Horizontal Absolute.
    proc _csi_G {args} {
	variable _cur_x
	variable _cols
	set arg [_default [lindex $args 0] 1]
	set _cur_x [expr {min ($arg - 1, $_cols)}]
    }

    # Move cursor (don't know the official name of this one).
    proc _csi_H {args} {
	variable _cur_x
	variable _cur_y
	set _cur_y [expr {[_default [lindex $args 0] 1] - 1}]
	set _cur_x [expr {[_default [lindex $args 1] 1] - 1}]
    }

    # Cursor Forward Tabulation.
    proc _csi_I {args} {
	set n [_default [lindex $args 0] 1]
	variable _cur_x
	variable _cols
	incr _cur_x [expr {$n * 8 - $_cur_x % 8}]
	if {$_cur_x >= $_cols} {
	    set _cur_x [expr {$_cols - 1}]
	}
    }

    # Erase.
    proc _csi_J {args} {
	variable _cur_x
	variable _cur_y
	variable _rows
	variable _cols
	set arg [_default [lindex $args 0] 0]
	if {$arg == 0} {
	    _clear_in_line $_cur_x $_cols $_cur_y
	    _clear_lines [expr {$_cur_y + 1}] $_rows
	} elseif {$arg == 1} {
	    _clear_lines 0 [expr {$_cur_y - 1}]
	    _clear_in_line 0 $_cur_x $_cur_y
	} elseif {$arg == 2} {
	    _clear_lines 0 $_rows
	}
    }

    # Erase Line.
    proc _csi_K {args} {
	variable _cur_x
	variable _cur_y
	variable _cols
	set arg [_default [lindex $args 0] 0]
	if {$arg == 0} {
	    # From cursor to end.
	    _clear_in_line $_cur_x $_cols $_cur_y
	} elseif {$arg == 1} {
	    _clear_in_line 0 $_cur_x $_cur_y
	} elseif {$arg == 2} {
	    _clear_in_line 0 $_cols $_cur_y
	}
    }

    # Delete lines.
    proc _csi_M {args} {
	variable _cur_y
	variable _rows
	variable _cols
	variable _chars
	set count [_default [lindex $args 0] 1]
	set y $_cur_y
	set next_y [expr {$y + 1}]
	while {$count > 0 && $next_y < $_rows} {
	    for {set x 0} {$x < $_cols} {incr x} {
		set _chars($x,$y) $_chars($x,$next_y)
	    }
	    incr y
	    incr next_y
	    incr count -1
	}
	_clear_lines $next_y $_rows
    }

    # Erase chars.
    proc _csi_X {args} {
	set n [_default [lindex $args 0] 1]
	# Erase characters but don't move cursor.
	variable _cur_x
	variable _cur_y
	variable _attrs
	variable _chars
	set lattr [array get _attrs]
	set x $_cur_x
	for {set i 0} {$i < $n} {incr i} {
	    set _chars($x,$_cur_y) [list " " $lattr]
	    incr x
	}
    }

    # Backward tab stops.
    proc _csi_Z {args} {
	set n [_default [lindex $args 0] 1]
	variable _cur_x
	set _cur_x [expr {max (int (($_cur_x - 1) / 8) * 8 - ($n - 1) * 8, 0)}]
    }

    # Repeat.
    proc _csi_b {args} {
	variable _last_char
	set n [_default [lindex $args 0] 1]
	_insert [string repeat $_last_char $n]
    }

    # Line Position Absolute.
    proc _csi_d {args} {
	variable _cur_y
	set _cur_y [expr {[_default [lindex $args 0] 1] - 1}]
    }

    # Select Graphic Rendition.
    proc _csi_m {args} {
	variable _attrs
	foreach item $args {
	    switch -exact -- $item {
		"" - 0 {
		    set _attrs(intensity) normal
		    set _attrs(fg) default
		    set _attrs(bg) default
		    set _attrs(underline) 0
		    set _attrs(reverse) 0
		}
		1 {
		    set _attrs(intensity) bold
		}
		2 {
		    set _attrs(intensity) dim
		}
		4 {
		    set _attrs(underline) 1
		}
		7 {
		    set _attrs(reverse) 1
		}
		22 {
		    set _attrs(intensity) normal
		}
		24 {
		    set _attrs(underline) 0
		}
		27 {
		    set _attrs(reverse) 1
		}
		30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 {
		    set _attrs(fg) $item
		}
		39 {
		    set _attrs(fg) default
		}
		40 - 41 - 42 - 43 - 44 - 45 - 46 - 47 {
		    set _attrs(bg) $item
		}
		49 {
		    set _attrs(bg) default
		}
	    }
	}
    }

    # Insert string at the cursor location.
    proc _insert {str} {
	verbose "INSERT <<$str>>"
	variable _cur_x
	variable _cur_y
	variable _rows
	variable _cols
	variable _attrs
	variable _chars
	set lattr [array get _attrs]
	foreach char [split $str {}] {
	    set _chars($_cur_x,$_cur_y) [list $char $lattr]
	    incr _cur_x
	    if {$_cur_x >= $_cols} {
		set _cur_x 0
		incr _cur_y
		if {$_cur_y >= $_rows} {
		    error "FIXME scroll"
		}
	    }
	}
    }

    # Initialize.
    proc _setup {rows cols} {
	global stty_init
	set stty_init "rows $rows columns $cols"

	variable _rows
	variable _cols
	variable _cur_x
	variable _cur_y
	variable _attrs
	variable _resize_count

	set _rows $rows
	set _cols $cols
	set _cur_x 0
	set _cur_y 0
	set _resize_count 0
	array set _attrs {
	    intensity normal
	    fg default
	    bg default
	    underline 0
	    reverse 0
	}

	_clear_lines 0 $_rows
    }

    # Accept some output from gdb and update the screen.
    proc _accept {wait_for} {
	global expect_out
	global gdb_prompt
	variable _cur_x
	variable _cur_y

	set prompt_wait_for "$gdb_prompt \$"

	while 1 {
	    gdb_expect {
		-re "^\[\x07\x08\x0a\x0d\]" {
		    scan $expect_out(0,string) %c val
		    set hexval [format "%02x" $val]
		    verbose "+++ _ctl_0x${hexval}"
		    _ctl_0x${hexval}
		}
		-re "^\x1b(\[0-9a-zA-Z\])" {
		    verbose "+++ unsupported escape"
		    error "unsupported escape"
		}
		-re "^\x1b\\\[(\[0-9;\]*)(\[a-zA-Z@\])" {
		    set cmd $expect_out(2,string)
		    set params [split $expect_out(1,string) ";"]
		    verbose "+++ _csi_$cmd <<<$expect_out(1,string)>>>"
		    eval _csi_$cmd $params
		}
		-re "^\[^\x07\x08\x0a\x0d\x1b\]+" {
		    _insert $expect_out(0,string)
		    variable _last_char
		    set _last_char [string index $expect_out(0,string) end]
		}

		timeout {
		    # Assume a timeout means we somehow missed the
		    # expected result, and carry on.
		    return
		}
	    }

	    # If the cursor appears just after the prompt, return.  It
	    # isn't reliable to check this only after an insertion,
	    # because curses may make "unusual" redrawing decisions.
	    if {$wait_for == "$prompt_wait_for"} {
		set prev [get_line $_cur_y $_cur_x]
	    } else {
		set prev [get_line $_cur_y]
	    }
	    if {[regexp -- $wait_for $prev]} {
		if {$wait_for == "$prompt_wait_for"} {
		    break
		}
		set wait_for $prompt_wait_for
	    }
	}
    }

    # Like ::clean_restart, but ensures that gdb starts in an
    # environment where the TUI can work.  ROWS and COLS are the size
    # of the terminal.  EXECUTABLE, if given, is passed to
    # clean_restart.
    proc clean_restart {rows cols {executable {}}} {
	global env stty_init
	save_vars {env(TERM) stty_init} {
	    setenv TERM ansi
	    _setup $rows $cols
	    if {$executable == ""} {
		::clean_restart
	    } else {
		::clean_restart $executable
	    }
	}
    }

    # Start the TUI.  Returns 1 on success, 0 if TUI tests should be
    # skipped.
    proc enter_tui {} {
	if {[skip_tui_tests]} {
	    return 0
	}

	gdb_test_no_output "set tui border-kind ascii"
	gdb_test_no_output "maint set tui-resize-message on"
	command "tui enable"
	return 1
    }

    # Send the command CMD to gdb, then wait for a gdb prompt to be
    # seen in the TUI.  CMD should not end with a newline -- that will
    # be supplied by this function.
    proc command {cmd} {
	send_gdb "$cmd\n"
	_accept [string_to_regexp $cmd]
    }

    # Return the text of screen line N, without attributes.  Lines are
    # 0-based.  If C is given, stop before column C.  Columns are also
    # zero-based.
    proc get_line {n {c ""}} {
	variable _rows
	# This can happen during resizing, if the cursor seems to
	# temporarily be off-screen.
	if {$n >= $_rows} {
	    return ""
	}

	set result ""
	variable _cols
	variable _chars
	set c [_default $c $_cols]
	set x 0
	while {$x < $c} {
	    append result [lindex $_chars($x,$n) 0]
	    incr x
	}
	return $result
    }

    # Get just the character at (X, Y).
    proc get_char {x y} {
	variable _chars
	return [lindex $_chars($x,$y) 0]
    }

    # Get the entire screen as a string.
    proc get_all_lines {} {
	variable _rows
	variable _cols
	variable _chars

	set result ""
	for {set y 0} {$y < $_rows} {incr y} {
	    for {set x 0} {$x < $_cols} {incr x} {
		append result [lindex $_chars($x,$y) 0]
	    }
	    append result "\n"
	}

	return $result
    }

    # Get the text just before the cursor.
    proc get_current_line {} {
	variable _cur_x
	variable _cur_y
	return [get_line $_cur_y $_cur_x]
    }

    # Helper function for check_box.  Returns empty string if the box
    # is found, description of why not otherwise.
    proc _check_box {x y width height} {
	set x2 [expr {$x + $width - 1}]
	set y2 [expr {$y + $height - 1}]

	if {[get_char $x $y] != "+"} {
	    return "ul corner"
	}
	if {[get_char $x $y2] != "+"} {
	    return "ll corner"
	}
	if {[get_char $x2 $y] != "+"} {
	    return "ur corner"
	}
	if {[get_char $x2 $y2] != "+"} {
	    return "lr corner"
	}

	for {set i [expr {$x + 1}]} {$i < $x2 - 1} {incr i} {
	    # Note we do not check the top border of the box, because
	    # it will contain a title.
	    if {[get_char $i $y2] != "-"} {
		return "bottom border $i"
	    }
	}
	for {set i [expr {$y + 1}]} {$i < $y2 - 1} {incr i} {
	    if {[get_char $x $i] != "|"} {
		return "left side $i"
	    }
	    if {[get_char $x2 $i] != "|"} {
		return "right side $i"
	    }
	}

	return ""
    }

    # Check for a box at the given coordinates.
    proc check_box {test_name x y width height} {
	set why [_check_box $x $y $width $height]
	if {$why == ""} {
	    pass $test_name
	} else {
	    dump_screen
	    fail "$test_name ($why)"
	}
    }

    # Check whether the text contents of the terminal match the
    # regular expression.  Note that text styling is not considered.
    proc check_contents {test_name regexp} {
	set contents [get_all_lines]
	if {![gdb_assert {[regexp -- $regexp $contents]} $test_name]} {
	    dump_screen
	}
    }

    # A debugging function to dump the current screen, with line
    # numbers.
    proc dump_screen {} {
	variable _rows
	variable _cols
	verbose "Screen Dump ($_cols x $_rows):"
	for {set y 0} {$y < $_rows} {incr y} {
	    set fmt [format %5d $y]
	    verbose "$fmt [get_line $y]"
	}
    }

    # Resize the terminal.
    proc _do_resize {rows cols} {
	variable _chars
	variable _rows
	variable _cols

	set old_rows [expr {min ($_rows, $rows)}]
	set old_cols [expr {min ($_cols, $cols)}]

	# Copy locally.
	array set local_chars [array get _chars]
	unset _chars

	set _rows $rows
	set _cols $cols
	_clear_lines 0 $_rows

	for {set x 0} {$x < $old_cols} {incr x} {
	    for {set y 0} {$y < $old_rows} {incr y} {
		set _chars($x,$y) $local_chars($x,$y)
	    }
	}
    }

    proc resize {rows cols} {
	variable _rows
	variable _cols
	variable _resize_count

	global gdb_spawn_name
	# expect handles each argument to stty separately.  This means
	# that gdb will see SIGWINCH twice.  Rather than rely on this
	# behavior (which, after all, could be changed), we make it
	# explicit here.  This also simplifies waiting for the redraw.
	_do_resize $rows $_cols
	stty rows $_rows < $gdb_spawn_name
	# Due to the strange column resizing behavior, and because we
	# don't care about this intermediate resize, we don't check
	# the size here.
	_accept "@@ resize done $_resize_count"
	incr _resize_count
	# Somehow the number of columns transmitted to gdb is one less
	# than what we request from expect.  We hide this weird
	# details from the caller.
	_do_resize $_rows $cols
	stty columns [expr {$_cols + 1}] < $gdb_spawn_name
	_accept "@@ resize done $_resize_count, size = ${_cols}x${rows}"
	incr _resize_count
    }
}