import string

from idlelib.delegator import Delegator

# tkinter import not needed because module does not create widgets,
# although many methods operate on text widget arguments.

#$ event <<redo>>
#$ win <Control-y>
#$ unix <Alt-z>

#$ event <<undo>>
#$ win <Control-z>
#$ unix <Control-z>

#$ event <<dump-undo-state>>
#$ win <Control-backslash>
#$ unix <Control-backslash>


class UndoDelegator(Delegator):

 max_undo = 1000

 def __init__(self):
 Delegator.__init__(self)
 self.reset_undo()

 def setdelegate(self, delegate):
 if self.delegate is not None:
 self.unbind("<<undo>>")
 self.unbind("<<redo>>")
 self.unbind("<<dump-undo-state>>")
 Delegator.setdelegate(self, delegate)
 if delegate is not None:
 self.bind("<<undo>>", self.undo_event)
 self.bind("<<redo>>", self.redo_event)
 self.bind("<<dump-undo-state>>", self.dump_event)

 def dump_event(self, event):
 from pprint import pprint
 pprint(self.undolist[:self.pointer])
 print("pointer:", self.pointer, end=' ')
 print("saved:", self.saved, end=' ')
 print("can_merge:", self.can_merge, end=' ')
 print("get_saved():", self.get_saved())
 pprint(self.undolist[self.pointer:])
 return "break"

 def reset_undo(self):
 self.was_saved = -1
 self.pointer = 0
 self.undolist = []
 self.undoblock = 0 # or a CommandSequence instance
 self.set_saved(1)

 def set_saved(self, flag):
 if flag:
 self.saved = self.pointer
 else:
 self.saved = -1
 self.can_merge = False
 self.check_saved()

 def get_saved(self):
 return self.saved == self.pointer

 saved_change_hook = None

 def set_saved_change_hook(self, hook):
 self.saved_change_hook = hook

 was_saved = -1

 def check_saved(self):
 is_saved = self.get_saved()
 if is_saved != self.was_saved:
 self.was_saved = is_saved
 if self.saved_change_hook:
 self.saved_change_hook()

 def insert(self, index, chars, tags=None):
 self.addcmd(InsertCommand(index, chars, tags))

 def delete(self, index1, index2=None):
 self.addcmd(DeleteCommand(index1, index2))

 # Clients should call undo_block_start() and undo_block_stop()
 # around a sequence of editing cmds to be treated as a unit by
 # undo & redo. Nested matching calls are OK, and the inner calls
 # then act like nops. OK too if no editing cmds, or only one
 # editing cmd, is issued in between: if no cmds, the whole
 # sequence has no effect; and if only one cmd, that cmd is entered
 # directly into the undo list, as if undo_block_xxx hadn't been
 # called. The intent of all that is to make this scheme easy
 # to use: all the client has to worry about is making sure each
 # _start() call is matched by a _stop() call.

 def undo_block_start(self):
 if self.undoblock == 0:
 self.undoblock = CommandSequence()
 self.undoblock.bump_depth()

 def undo_block_stop(self):
 if self.undoblock.bump_depth(-1) == 0:
 cmd = self.undoblock
 self.undoblock = 0
 if len(cmd) > 0:
 if len(cmd) == 1:
 # no need to wrap a single cmd
 cmd = cmd.getcmd(0)
 # this blk of cmds, or single cmd, has already
 # been done, so don't execute it again
 self.addcmd(cmd, 0)

 def addcmd(self, cmd, execute=True):
 if execute:
 cmd.do(self.delegate)
 if self.undoblock != 0:
 self.undoblock.append(cmd)
 return
 if self.can_merge and self.pointer > 0:
 lastcmd = self.undolist[self.pointer-1]
 if lastcmd.merge(cmd):
 return
 self.undolist[self.pointer:] = [cmd]
 if self.saved > self.pointer:
 self.saved = -1
 self.pointer = self.pointer + 1
 if len(self.undolist) > self.max_undo:
 ##print "truncating undo list"
 del self.undolist[0]
 self.pointer = self.pointer - 1
 if self.saved >= 0:
 self.saved = self.saved - 1
 self.can_merge = True
 self.check_saved()

 def undo_event(self, event):
 if self.pointer == 0:
 self.bell()
 return "break"
 cmd = self.undolist[self.pointer - 1]
 cmd.undo(self.delegate)
 self.pointer = self.pointer - 1
 self.can_merge = False
 self.check_saved()
 return "break"

 def redo_event(self, event):
 if self.pointer >= len(self.undolist):
 self.bell()
 return "break"
 cmd = self.undolist[self.pointer]
 cmd.redo(self.delegate)
 self.pointer = self.pointer + 1
 self.can_merge = False
 self.check_saved()
 return "break"


class Command:
 # Base class for Undoable commands

 tags = None

 def __init__(self, index1, index2, chars, tags=None):
 self.marks_before = {}
 self.marks_after = {}
 self.index1 = index1
 self.index2 = index2
 self.chars = chars
 if tags:
 self.tags = tags

 def __repr__(self):
 s = self.__class__.__name__
 t = (self.index1, self.index2, self.chars, self.tags)
 if self.tags is None:
 t = t[:-1]
 return s + repr(t)

 def do(self, text):
 pass

 def redo(self, text):
 pass

 def undo(self, text):
 pass

 def merge(self, cmd):
 return 0

 def save_marks(self, text):
 marks = {}
 for name in text.mark_names():
 if name != "insert" and name != "current":
 marks[name] = text.index(name)
 return marks

 def set_marks(self, text, marks):
 for name, index in marks.items():
 text.mark_set(name, index)


class InsertCommand(Command):
 # Undoable insert command

 def __init__(self, index1, chars, tags=None):
 Command.__init__(self, index1, None, chars, tags)

 def do(self, text):
 self.marks_before = self.save_marks(text)
 self.index1 = text.index(self.index1)
 if text.compare(self.index1, ">", "end-1c"):
 # Insert before the final newline
 self.index1 = text.index("end-1c")
 text.insert(self.index1, self.chars, self.tags)
 self.index2 = text.index("%s+%dc" % (self.index1, len(self.chars)))
 self.marks_after = self.save_marks(text)
 ##sys.__stderr__.write("do: %s\n" % self)

 def redo(self, text):
 text.mark_set('insert', self.index1)
 text.insert(self.index1, self.chars, self.tags)
 self.set_marks(text, self.marks_after)
 text.see('insert')
 ##sys.__stderr__.write("redo: %s\n" % self)

 def undo(self, text):
 text.mark_set('insert', self.index1)
 text.delete(self.index1, self.index2)
 self.set_marks(text, self.marks_before)
 text.see('insert')
 ##sys.__stderr__.write("undo: %s\n" % self)

 def merge(self, cmd):
 if self.__class__ is not cmd.__class__:
 return False
 if self.index2 != cmd.index1:
 return False
 if self.tags != cmd.tags:
 return False
 if len(cmd.chars) != 1:
 return False
 if self.chars and \
 self.classify(self.chars[-1]) != self.classify(cmd.chars):
 return False
 self.index2 = cmd.index2
 self.chars = self.chars + cmd.chars
 return True

 alphanumeric = string.ascii_letters + string.digits + "_"

 def classify(self, c):
 if c in self.alphanumeric:
 return "alphanumeric"
 if c == "\n":
 return "newline"
 return "punctuation"


class DeleteCommand(Command):
 # Undoable delete command

 def __init__(self, index1, index2=None):
 Command.__init__(self, index1, index2, None, None)

 def do(self, text):
 self.marks_before = self.save_marks(text)
 self.index1 = text.index(self.index1)
 if self.index2:
 self.index2 = text.index(self.index2)
 else:
 self.index2 = text.index(self.index1 + " +1c")
 if text.compare(self.index2, ">", "end-1c"):
 # Don't delete the final newline
 self.index2 = text.index("end-1c")
 self.chars = text.get(self.index1, self.index2)
 text.delete(self.index1, self.index2)
 self.marks_after = self.save_marks(text)
 ##sys.__stderr__.write("do: %s\n" % self)

 def redo(self, text):
 text.mark_set('insert', self.index1)
 text.delete(self.index1, self.index2)
 self.set_marks(text, self.marks_after)
 text.see('insert')
 ##sys.__stderr__.write("redo: %s\n" % self)

 def undo(self, text):
 text.mark_set('insert', self.index1)
 text.insert(self.index1, self.chars)
 self.set_marks(text, self.marks_before)
 text.see('insert')
 ##sys.__stderr__.write("undo: %s\n" % self)


class CommandSequence(Command):
 # Wrapper for a sequence of undoable cmds to be undone/redone
 # as a unit

 def __init__(self):
 self.cmds = []
 self.depth = 0

 def __repr__(self):
 s = self.__class__.__name__
 strs = []
 for cmd in self.cmds:
 strs.append(" %r" % (cmd,))
 return s + "(\n" + ",\n".join(strs) + "\n)"

 def __len__(self):
 return len(self.cmds)

 def append(self, cmd):
 self.cmds.append(cmd)

 def getcmd(self, i):
 return self.cmds[i]

 def redo(self, text):
 for cmd in self.cmds:
 cmd.redo(text)

 def undo(self, text):
 cmds = self.cmds[:]
 cmds.reverse()
 for cmd in cmds:
 cmd.undo(text)

 def bump_depth(self, incr=1):
 self.depth = self.depth + incr
 return self.depth


def _undo_delegator(parent): # htest #
 from tkinter import Toplevel, Text, Button
 from idlelib.percolator import Percolator
 undowin = Toplevel(parent)
 undowin.title("Test UndoDelegator")
 x, y = map(int, parent.geometry().split('+')[1:])
 undowin.geometry("+%d+%d" % (x, y + 175))

 text = Text(undowin, height=10)
 text.pack()
 text.focus_set()
 p = Percolator(text)
 d = UndoDelegator()
 p.insertfilter(d)

 undo = Button(undowin, text="Undo", command=lambda:d.undo_event(None))
 undo.pack(side='left')
 redo = Button(undowin, text="Redo", command=lambda:d.redo_event(None))
 redo.pack(side='left')
 dump = Button(undowin, text="Dump", command=lambda:d.dump_event(None))
 dump.pack(side='left')

if __name__ == "__main__":
 from unittest import main
 main('idlelib.idle_test.test_undo', verbosity=2, exit=False)

 from idlelib.idle_test.htest import run
 run(_undo_delegator)