#---------------
# gnoclTextUndoRedo.tcl
#---------------
# Created by WIlliam J Giddings
# 03/08/2008
#---------------
# Description:
# Provide undo/redo functionality for the gnocl text widget.
#---------------
# Notes:
#
#---------------

# use arrays to create stacks to contain details of the events
# this is more efficient than using lists
# see Welch, Jones & Hobbs(2003, pp101)

proc push {stack value} {
        upvar $stack S
        if { ! [info exists S(top)] } {
                set S(top) 0
        }
        set S($S(top)) $value
        incr S(top)
}

proc pop { stack } {
        upvar $stack S
        if { ![info exists S(top)] } {
                return {}
        }
        if {$S(top) == 0 } {
                return {}
        } else {
                incr S(top) -1
                set x $S($S(top))
                unset S($S(top))
                return $x
        }
}

#
# UNDO / REDO procedures
#

# Notes:
# -----
# Create undo/redo buffers unique to the widget.
proc on_undo { w } {

        global ${w}.UNDO
        global ${w}.REDO

        if { [array size ${w}.UNDO] == 0 } {
                return
        }
        set action [pop ${w}.UNDO]

        switch [lindex $action 0 ] {
                "insert-text"
                        {
                                # determine the end of range to delete from length of text inserted
                                set col [expr [lindex [lindex $action 1] 1]  +[lindex $action 3] ]
                                set row [lindex [lindex $action 1] 0]
                                $w erase [lindex $action 1] [list $row $col]

                                # resposition the cursor
                                $w setCursor [list $row $col]
                        }
                "delete-range"
                        {
                                # strip leading and trailing braces from the string
                                $w insert [lindex $action 1] [string trim [lindex $action 3] \{\}]

                                # resposition the cursor to the end of the inserted text
                                $w setCursor  [lindex $action 1]
                                $w setCursor cursor+[string length [lindex $action 2]]
                        }
        }
        # display the changes
        $w scrollToPosition cursor
        $w configure -hasFocus 1
        push ${w}.REDO $action
}

proc on_redo { w } {

        global ${w}.UNDO
        global ${w}.REDO

        if { [array size ${w}.REDO] == 0 } {
                return
        }
        set action [pop ${w}.REDO]
        switch [lindex $action 0 ] {
                "insert-text"
                        {

                                # determine the end of range to delete from length of text inserted
                                # The text is returned as a list, so if there is purely whitespace this
                                # will re mis-read as a sub-list by the interpreter.
                                # So, get the text as the first item to prevent this.
                                $w insert [lindex $action 1] [lindex [lindex $action 2] 0]

                            # reposition the cursor to the end of the inserted text
                                $w setCursor  [lindex $action 1]
                                $w setCursor cursor+[string length [lindex $action 2]]
                        }
                "delete-range"
                        {

                                # determine the end of range to delete from length of text inserted
                                set col [expr [lindex [lindex $action 1] 1]  +[lindex $action 3] ]
                                set row [lindex [lindex $action 1] 0]
                                $w erase [lindex $action 1] [list $row $col]

                                # reposition the cursor
                                $w setCursor [list $row $col]
                        }
        }

        # display the changes
        $w scrollToPosition cursor
        $w configure -hasFocus 1
        push ${w}.UNDO $action

}

#---------------
# UndoRedoDemo.tcl
#---------------
# Created by WIlliam J Giddings
# March, 2008
#---------------
# Description:
# Demonstrates simple textBuffer undo/redo functionality.
#---------------
# Notes:
# cd /Desktop/GnoclEdit_2/undoer/wjgstuff
#
# This version has a single buffer to show edit history
#
#---------------

# basic Tcl/Gnocl Script
#! /bin/sh/
#\
exec tclsh "$0" "$@"

package require Gnocl

source gnoclTextUndoRedo.tcl
source gnoclBind.tcl

set text [gnocl::text]
set box1 [gnocl::box -orientation vertical]
set box2 [gnocl::box -orientation horizontal ]
set undo [gnocl::button -text "%#Undo" -onClicked { on_undo $text } ]
set redo [gnocl::button -text "%#Redo" -onClicked { on_redo $text } ]

$box2 add [list $undo $redo]
$box1 add $box2
$box1 add $text -fill {1 1} -expand 1

gnocl::window -title "Text" -child $box1

set userAction 1

#----------------
# UNDO/REDO STUFF
#----------------

# respond to text insert signals
$text configure -onInsertText {
    if { $userAction } {
        # add the event details to the undo stack
        push ${text}.UNDO "insert-text \{%r %c\} \{%t\} \{%l\}"
        # clear the redo stack
        catch { unset ${text}.REDO }
    }
}

# respond to text insert signals
$text configure -onDeleteRange {
    if { $userAction } {
        push ${text}.UNDO "delete-range \{%r %c\} \{%l %o\} \{%t\}"
    }
}

# respond to text action signals
$text configure -onBeginUserAction { 
    set userAction 1
}

$text configure -onEndUserAction {
    set userAction 0
}

# there are no default Undo/Redo bindings, so set your own
# (GtkSourceView widget defaults to Ctrl-z & Ctrl-Z
gnocl::bind $text <Ctrl-Key-z> "on_undo $text"
gnocl::bind $text <Ctrl-Key-y> "on_redo $text"

$text insert end "Ctrl-z undo\nCtrl-y redo"

#-----------------
gnocl::mainLoop