# histedit.py - interactive history editing for mercurial

#

# Copyright 2009 Augie Fackler <raf@durin42.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

"""interactive history editing

With this extension installed, Mercurial gains one new command: histedit. Usage

is as follows, assuming the following history::

 @  3[tip]   7c2fd3b9020c   2009-04-27 18:04 -0500   durin42

 |    Add delta

 |

 o  2   030b686bedc4   2009-04-27 18:04 -0500   durin42

 |    Add gamma

 |

 o  1   c561b4e977df   2009-04-27 18:04 -0500   durin42

 |    Add beta

 |

 o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42

      Add alpha

If you were to run ``hg histedit c561b4e977df``, you would see the following

file open in your editor::

 pick c561b4e977df Add beta

 pick 030b686bedc4 Add gamma

 pick 7c2fd3b9020c Add delta

 # Edit history between c561b4e977df and 7c2fd3b9020c

 #

 # Commits are listed from least to most recent

 #

 # Commands:

 #  p, pick = use commit

 #  e, edit = use commit, but stop for amending

 #  f, fold = use commit, but combine it with the one above

 #  r, roll = like fold, but discard this commit's description

 #  d, drop = remove commit from history

 #  m, mess = edit message without changing commit content

 #

In this file, lines beginning with ``#`` are ignored. You must specify a rule

for each revision in your history. For example, if you had meant to add gamma

before beta, and then wanted to add delta in the same revision as beta, you

would reorganize the file to look like this::

 pick 030b686bedc4 Add gamma

 pick c561b4e977df Add beta

 fold 7c2fd3b9020c Add delta

 # Edit history between c561b4e977df and 7c2fd3b9020c

 #

 # Commits are listed from least to most recent

 #

 # Commands:

 #  p, pick = use commit

 #  e, edit = use commit, but stop for amending

 #  f, fold = use commit, but combine it with the one above

 #  r, roll = like fold, but discard this commit's description

 #  d, drop = remove commit from history

 #  m, mess = edit message without changing commit content

 #

At which point you close the editor and ``histedit`` starts working. When you

specify a ``fold`` operation, ``histedit`` will open an editor when it folds

those revisions together, offering you a chance to clean up the commit message::

 Add beta

 ***

 Add delta

Edit the commit message to your liking, then close the editor. For

this example, let's assume that the commit message was changed to

``Add beta and delta.`` After histedit has run and had a chance to

remove any old or temporary revisions it needed, the history looks

like this::

 @  2[tip]   989b4d060121   2009-04-27 18:04 -0500   durin42

 |    Add beta and delta.

 |

 o  1   081603921c3f   2009-04-27 18:04 -0500   durin42

 |    Add gamma

 |

 o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42

      Add alpha

Note that ``histedit`` does *not* remove any revisions (even its own temporary

ones) until after it has completed all the editing operations, so it will

probably perform several strip operations when it's done. For the above example,

it had to run strip twice. Strip can be slow depending on a variety of factors,

so you might need to be a little patient. You can choose to keep the original

revisions by passing the ``--keep`` flag.

The ``edit`` operation will drop you back to a command prompt,

allowing you to edit files freely, or even use ``hg record`` to commit

some changes as a separate commit. When you're done, any remaining

uncommitted changes will be committed as well. When done, run ``hg

histedit --continue`` to finish this step. You'll be prompted for a

new commit message, but the default commit message will be the

original message for the ``edit`` ed revision.

The ``message`` operation will give you a chance to revise a commit

message without changing the contents. It's a shortcut for doing

``edit`` immediately followed by `hg histedit --continue``.

If ``histedit`` encounters a conflict when moving a revision (while

handling ``pick`` or ``fold``), it'll stop in a similar manner to

``edit`` with the difference that it won't prompt you for a commit

message when done. If you decide at this point that you don't like how

much work it will be to rearrange history, or that you made a mistake,

you can use ``hg histedit --abort`` to abandon the new changes you

have made and return to the state before you attempted to edit your

history.

If we clone the histedit-ed example repository above and add four more

changes, such that we have the following history::

   @  6[tip]   038383181893   2009-04-27 18:04 -0500   stefan

   |    Add theta

   |

   o  5   140988835471   2009-04-27 18:04 -0500   stefan

   |    Add eta

   |

   o  4   122930637314   2009-04-27 18:04 -0500   stefan

   |    Add zeta

   |

   o  3   836302820282   2009-04-27 18:04 -0500   stefan

   |    Add epsilon

   |

   o  2   989b4d060121   2009-04-27 18:04 -0500   durin42

   |    Add beta and delta.

   |

   o  1   081603921c3f   2009-04-27 18:04 -0500   durin42

   |    Add gamma

   |

   o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42

        Add alpha

If you run ``hg histedit --outgoing`` on the clone then it is the same

as running ``hg histedit 836302820282``. If you need plan to push to a

repository that Mercurial does not detect to be related to the source

repo, you can add a ``--force`` option.

Histedit rule lines are truncated to 80 characters by default. You

can customise this behaviour by setting a different length in your

configuration file::

  [histedit]

  linelen = 120      # truncate rule lines at 120 characters

"""

try:

    import cPickle as pickle

    pickle.dump # import now

except ImportError:

    import pickle

import errno

import os

import sys

from mercurial import cmdutil

from mercurial import discovery

from mercurial import error

from mercurial import changegroup

from mercurial import copies

from mercurial import context

from mercurial import exchange

from mercurial import extensions

from mercurial import hg

from mercurial import node

from mercurial import repair

from mercurial import scmutil

from mercurial import util

from mercurial import obsolete

from mercurial import merge as mergemod

from mercurial.lock import release

from mercurial.i18n import _

cmdtable = {}

command = cmdutil.command(cmdtable)

# Note for extension authors: ONLY specify testedwith = 'internal' for

# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should

# be specifying the version(s) of Mercurial they are tested with, or

# leave the attribute unspecified.

testedwith = 'internal'

# i18n: command names and abbreviations must remain untranslated

editcomment = _("""# Edit history between %s and %s

#

# Commits are listed from least to most recent

#

# Commands:

#  p, pick = use commit

#  e, edit = use commit, but stop for amending

#  f, fold = use commit, but combine it with the one above

#  r, roll = like fold, but discard this commit's description

#  d, drop = remove commit from history

#  m, mess = edit message without changing commit content

#

""")

class histeditstate(object):

    def __init__(self, repo, parentctxnode=None, rules=None, keep=None,

            topmost=None, replacements=None, lock=None, wlock=None):

        self.repo = repo

        self.rules = rules

        self.keep = keep

        self.topmost = topmost

        self.parentctxnode = parentctxnode

        self.lock = lock

        self.wlock = wlock

        self.backupfile = None

        if replacements is None:

            self.replacements = []

        else:

            self.replacements = replacements

    def read(self):

        """Load histedit state from disk and set fields appropriately."""

        try:

            fp = self.repo.vfs('histedit-state', 'r')

        except IOError as err:

            if err.errno != errno.ENOENT:

                raise

            raise util.Abort(_('no histedit in progress'))

        try:

            data = pickle.load(fp)

            parentctxnode, rules, keep, topmost, replacements = data

            backupfile = None

        except pickle.UnpicklingError:

            data = self._load()

            parentctxnode, rules, keep, topmost, replacements, backupfile = data

        self.parentctxnode = parentctxnode

        self.rules = rules

        self.keep = keep

        self.topmost = topmost

        self.replacements = replacements

        self.backupfile = backupfile

    def write(self):

        fp = self.repo.vfs('histedit-state', 'w')

        fp.write('v1\n')

        fp.write('%s\n' % node.hex(self.parentctxnode))

        fp.write('%s\n' % node.hex(self.topmost))

        fp.write('%s\n' % self.keep)

        fp.write('%d\n' % len(self.rules))

        for rule in self.rules:

            fp.write('%s\n' % rule[0]) # action

            fp.write('%s\n' % rule[1]) # remainder

        fp.write('%d\n' % len(self.replacements))

        for replacement in self.replacements:

            fp.write('%s%s\n' % (node.hex(replacement[0]), ''.join(node.hex(r)

                for r in replacement[1])))

        backupfile = self.backupfile

        if not backupfile:

            backupfile = ''

        fp.write('%s\n' % backupfile)

        fp.close()

    def _load(self):

        fp = self.repo.vfs('histedit-state', 'r')

        lines = [l[:-1] for l in fp.readlines()]

        index = 0

        lines[index] # version number

        index += 1

        parentctxnode = node.bin(lines[index])

        index += 1

        topmost = node.bin(lines[index])

        index += 1

        keep = lines[index] == 'True'

        index += 1

        # Rules

        rules = []

        rulelen = int(lines[index])

        index += 1

        for i in xrange(rulelen):

            ruleaction = lines[index]

            index += 1

            rule = lines[index]

            index += 1

            rules.append((ruleaction, rule))

        # Replacements

        replacements = []

        replacementlen = int(lines[index])

        index += 1

        for i in xrange(replacementlen):

            replacement = lines[index]

            original = node.bin(replacement[:40])

            succ = [node.bin(replacement[i:i + 40]) for i in

                    range(40, len(replacement), 40)]

            replacements.append((original, succ))

            index += 1

        backupfile = lines[index]

        index += 1

        fp.close()

        return parentctxnode, rules, keep, topmost, replacements, backupfile

    def clear(self):

        self.repo.vfs.unlink('histedit-state')

class histeditaction(object):

    def __init__(self, state, node):

        self.state = state

        self.repo = state.repo

        self.node = node

    @classmethod

    def fromrule(cls, state, rule):

        """Parses the given rule, returning an instance of the histeditaction.

        """

        repo = state.repo

        rulehash = rule.strip().split(' ', 1)[0]

        try:

            node = repo[rulehash].node()

        except error.RepoError:

            raise util.Abort(_('unknown changeset %s listed') % rulehash[:12])

        return cls(state, node)

    def run(self):

        """Runs the action. The default behavior is simply apply the action's

        rulectx onto the current parentctx."""

        self.applychange()

        self.continuedirty()

        return self.continueclean()

    def applychange(self):

        """Applies the changes from this action's rulectx onto the current

        parentctx, but does not commit them."""

        repo = self.repo

        rulectx = repo[self.node]

        hg.update(repo, self.state.parentctxnode)

        stats = applychanges(repo.ui, repo, rulectx, {})

        if stats and stats[3] > 0:

            raise error.InterventionRequired(_('Fix up the change and run '

                                            'hg histedit --continue'))

    def continuedirty(self):

        """Continues the action when changes have been applied to the working

        copy. The default behavior is to commit the dirty changes."""

        repo = self.repo

        rulectx = repo[self.node]

        editor = self.commiteditor()

        commit = commitfuncfor(repo, rulectx)

        commit(text=rulectx.description(), user=rulectx.user(),

               date=rulectx.date(), extra=rulectx.extra(), editor=editor)

    def commiteditor(self):

        """The editor to be used to edit the commit message."""

        return False

    def continueclean(self):

        """Continues the action when the working copy is clean. The default

        behavior is to accept the current commit as the new version of the

        rulectx."""

        ctx = self.repo['.']

        if ctx.node() == self.state.parentctxnode:

            self.repo.ui.warn(_('%s: empty changeset\n') %

                              node.short(self.node))

            return ctx, [(self.node, tuple())]

        if ctx.node() == self.node:

            # Nothing changed

            return ctx, []

        return ctx, [(self.node, (ctx.node(),))]

def commitfuncfor(repo, src):

    """Build a commit function for the replacement of <src>

    This function ensure we apply the same treatment to all changesets.

    - Add a 'histedit_source' entry in extra.

    Note that fold has its own separated logic because its handling is a bit

    different and not easily factored out of the fold method.

    """

    phasemin = src.phase()

    def commitfunc(**kwargs):

        phasebackup = repo.ui.backupconfig('phases', 'new-commit')

        try:

            repo.ui.setconfig('phases', 'new-commit', phasemin,

                              'histedit')

            extra = kwargs.get('extra', {}).copy()

            extra['histedit_source'] = src.hex()

            kwargs['extra'] = extra

            return repo.commit(**kwargs)

        finally:

            repo.ui.restoreconfig(phasebackup)

    return commitfunc