# Code dedicated to display and exploration of the obsolescence history

#

# This module content aims at being upstreamed enventually.

#

# Copyright 2017 Octobus SAS <contact@octobus.net>

#

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

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

from mercurial import (

    cmdutil,

    commands,

    error,

    graphmod,

    obsolete,

    node as nodemod,

    scmutil,

)

from mercurial.i18n import _

from . import (

    exthelper,

)

eh = exthelper.exthelper()

@eh.command(

    'obslog|olog',

    [('G', 'graph', True, _("show the revision DAG")),

     ('r', 'rev', [], _('show the specified revision or revset'), _('REV'))

    ] + commands.formatteropts,

    _('hg olog [OPTION]... [REV]'))

def cmdobshistory(ui, repo, *revs, **opts):

    """show the obsolescence history of the specified revisions.

    If no revision range is specified, we display the log for the current

    working copy parent.

    By default this command prints the selected revisions and all its

    precursors. For precursors pointing on existing revisions in the repository,

    it will display revisions node id, revision number and the first line of the

    description. For precursors pointing on non existing revisions in the

    repository (that can happen when exchanging obsolescence-markers), display

    only the node id.

    In both case, for each node, its obsolescence marker will be displayed with

    the obsolescence operation (rewritten or pruned) in addition of the user and

    date of the operation.

    The output is a graph by default but can deactivated with the option '--no-

    graph'.

    'o' is a changeset, '@' is a working directory parent, 'x' is obsolete,

    and '+' represents a fork where the changeset from the lines below is a

    parent of the 'o' merge on the same line.

    Paths in the DAG are represented with '|', '/' and so forth.

    Returns 0 on success.

    """

    revs = list(revs) + opts['rev']

    if not revs:

        revs = ['.']

    revs = scmutil.revrange(repo, revs)

    if opts['graph']:

        return _debugobshistorygraph(ui, repo, revs, opts)

    fm = ui.formatter('debugobshistory', opts)

    revs.reverse()

    _debugobshistorysingle(fm, repo, revs)

    fm.end()

class obsmarker_printer(cmdutil.changeset_printer):

    """show (available) information about a node

    We display the node, description (if available) and various information

    about obsolescence markers affecting it"""

    def show(self, ctx, copies=None, matchfn=None, **props):

        if self.buffered:

            self.ui.pushbuffer(labeled=True)

            changenode = ctx.node()

            fm = self.ui.formatter('debugobshistory', props)

            _debugobshistorydisplaynode(fm, self.repo, changenode)

            succs = self.repo.obsstore.successors.get(changenode, ())

            markerfm = fm.nested("debugobshistory.markers")

            for successor in sorted(succs):

                _debugobshistorydisplaymarker(markerfm, self.repo, successor)

            markerfm.end()

            markerfm.plain('\n')

            self.hunk[ctx.node()] = self.ui.popbuffer()

        else:

            ### graph output is buffered only

            msg = 'cannot be used outside of the graphlog (yet)'

            raise error.ProgrammingError(msg)

    def flush(self, ctx):

        ''' changeset_printer has some logic around buffering data

        in self.headers that we don't use

        '''

        pass

class missingchangectx(object):

    ''' a minimal object mimicking changectx for change contexts

    references by obs markers but not available locally '''

    def __init__(self, repo, nodeid):

        self._repo = repo

        self._node = nodeid

    def node(self):

        return self._node

    def obsolete(self):

        # If we don't have it locally, it's obsolete

        return True

def cyclic(graph):

    """Return True if the directed graph has a cycle.

    The graph must be represented as a dictionary mapping vertices to

    iterables of neighbouring vertices. For example:

    >>> cyclic({1: (2,), 2: (3,), 3: (1,)})

    True

    >>> cyclic({1: (2,), 2: (3,), 3: (4,)})

    False

    Taken from: https://codereview.stackexchange.com/a/86067

    """

    visited = set()

    o = object()

    path = [o]

    path_set = set(path)

    stack = [iter(graph)]

    while stack:

        for v in sorted(stack[-1]):

            if v in path_set:

                path_set.remove(o)

                return path_set

            elif v not in visited:

                visited.add(v)

                path.append(v)

                path_set.add(v)

                stack.append(iter(graph.get(v, ())))

                break

        else:

            path_set.remove(path.pop())

            stack.pop()

    return False

def _obshistorywalker(repo, revs):

    """ Directly inspired by graphmod.dagwalker,

    walk the obs marker tree and yield

    (id, CHANGESET, ctx, [parentinfo]) tuples

    """

    # Get the list of nodes and links between them

    candidates, nodesucc, nodeprec = _obshistorywalker_links(repo, revs)

    # Shown, set of nodes presents in items

    shown = set()

    def isvalidcandidate(candidate):

        """ Function to filter candidates, check the candidate succ are

        in shown set

        """

        return nodesucc.get(candidate, set()).issubset(shown)

    # While we have some nodes to show

    while candidates:

        # Filter out candidates, returns only nodes with all their successors

        # already shown

        validcandidates = filter(isvalidcandidate, candidates)

        # If we likely have a cycle

        if not validcandidates:

            cycle = cyclic(nodesucc)

            assert cycle

            # Then choose a random node from the cycle

            breaknode = sorted(cycle)[0]

            # And display it by force

            repo.ui.debug('obs-cycle detected, forcing display of %s\n'

                          % nodemod.short(breaknode))

            validcandidates = [breaknode]

        # Display all valid candidates

        for cand in sorted(validcandidates):

            # Remove candidate from candidates set

            candidates.remove(cand)

            # And remove it from nodesucc in case of future cycle detected

            try:

                del nodesucc[cand]

            except KeyError:

                pass

            shown.add(cand)

            # Add the right changectx class

            if cand in repo:

                changectx = repo[cand]

            else:

                changectx = missingchangectx(repo, cand)

            childrens = [(graphmod.PARENT, x) for x in nodeprec.get(cand, ())]

            yield (cand, 'M', changectx, childrens)

def _obshistorywalker_links(repo, revs):

    """ Iterate the obs history tree starting from revs, traversing

    each revision precursors recursively.

    Return a tuple of:

    - The list of node crossed

    - The dictionnary of each node successors, values are a set

    - The dictionnary of each node precursors, values are a list

    """

    precursors = repo.obsstore.precursors

    nodec = repo.changelog.node

    # Parents, set of parents nodes seen during walking the graph for node

    nodesucc = dict()

    # Childrens

    nodeprec = dict()

    nodes = [nodec(r) for r in revs]

    seen = set(nodes)

    # Iterate on each node

    while nodes:

        node = nodes.pop()

        precs = precursors.get(node, ())

        nodeprec[node] = []

        for prec in sorted(precs):

            precnode = prec[0]

            # Mark node as prec successor

            nodesucc.setdefault(precnode, set()).add(node)

            # Mark precnode as node precursor

            nodeprec[node].append(precnode)

            # Add prec for future processing if not node already processed

            if precnode not in seen:

                seen.add(precnode)

                nodes.append(precnode)

    return sorted(seen), nodesucc, nodeprec

def _debugobshistorygraph(ui, repo, revs, opts):

    displayer = obsmarker_printer(ui, repo.unfiltered(), None, opts, buffered=True)

    edges = graphmod.asciiedges

    cmdutil.displaygraph(ui, repo, _obshistorywalker(repo.unfiltered(), revs), displayer, edges)

def _debugobshistorysingle(fm, repo, revs):

    """ Display the obsolescence history for a single revision

    """

    precursors = repo.obsstore.precursors

    successors = repo.obsstore.successors

    nodec = repo.changelog.node

    nodes = [nodec(r) for r in revs]

    seen = set(nodes)

    while nodes:

        ctxnode = nodes.pop()

        _debugobshistorydisplaynode(fm, repo, ctxnode)

        succs = successors.get(ctxnode, ())

        markerfm = fm.nested("debugobshistory.markers")

        for successor in sorted(succs):

            _debugobshistorydisplaymarker(markerfm, repo, successor)

        markerfm.end()

        precs = precursors.get(ctxnode, ())

        for p in sorted(precs):

            # Only show nodes once

            if p[0] not in seen:

                seen.add(p[0])

                nodes.append(p[0])

def _debugobshistorydisplaynode(fm, repo, node):

    if node in repo.unfiltered():

        _debugobshistorydisplayctx(fm, repo.unfiltered()[node])

    else:

        _debugobshistorydisplaymissingctx(fm, node)

def _debugobshistorydisplayctx(fm, ctx):

    shortdescription = ctx.description().splitlines()[0]

    fm.startitem()

    fm.write('debugobshistory.node', '%s', str(ctx),

             label="evolve.node")

    fm.plain(' ')

    fm.write('debugobshistory.rev', '(%d)', int(ctx),

             label="evolve.rev")

    fm.plain(' ')

    fm.write('debugobshistory.shortdescription', '%s', shortdescription,

             label="evolve.short_description")

    fm.plain('\n')

def _debugobshistorydisplaymissingctx(fm, nodewithoutctx):

    hexnode = nodemod.short(nodewithoutctx)

    fm.startitem()

    fm.write('debugobshistory.node', '%s', hexnode,

             label="evolve.node evolve.missing_change_ctx")

    fm.plain('\n')

def _debugobshistorydisplaymarker(fm, repo, marker):

    succnodes = marker[1]

    date = marker[4]

    metadata = dict(marker[3])

    fm.startitem()

    fm.plain('  ')

    # Detect pruned revisions

    if len(succnodes) == 0:

        verb = 'pruned'

    else:

        verb = 'rewritten'

    fm.write('debugobshistory.verb', '%s', verb,

             label="evolve.verb")

    fm.plain(' by ')

    fm.write('debugobshistory.marker_user', '%s', metadata['user'],

             label="evolve.user")

    fm.plain(' ')

    fm.write('debugobshistory.marker_date', '(%s)', fm.formatdate(date),

             label="evolve.date")

    if len(succnodes) > 0:

        fm.plain(' as ')

        shortsnodes = (nodemod.short(succnode) for succnode in sorted(succnodes))

        nodes = fm.formatlist(shortsnodes, 'debugobshistory.succnodes', sep=', ')

        fm.write('debugobshistory.succnodes', '%s', nodes,

                 label="evolve.node")

    fm.plain("\n")

# logic around storing and using effect flags

DESCCHANGED = 1 << 0 # action changed the description

def geteffectflag(relation):

    """compute the effect flag by comparing the source and destination"""

    effects = 0

    source = relation[0]

    for changectx in relation[1]:

        # Check if description has changed

        if changectx.description() != source.description():

            effects |= DESCCHANGED

    return effects

@eh.wrapfunction(obsolete, 'createmarkers')

def createmarkerswithbits(orig, repo, relations, flag=0, date=None, metadata=None):

    """compute 'effect-flag' and augment the created markers

    Wrap obsolete.createmarker in order to compute the effect of each

    relationship and store them as flag in the metadata.

    While we experiment, we store flag in a metadata field. This field is

    "versionned" to easilly allow moving to other meaning for flags.

    The comparison of description or other infos just before creating the obs

    marker might induce overhead in some cases. However it is a good place to

    start since it automatically makes all markers creation recording more

    meaningful data. In the future, we can introduce way for commands to

    provide precomputed effect to avoid the overhead.

    """