# Copyright 2014 Facebook Inc.
#
"""reset the active bookmark and working copy to a desired revision"""

from mercurial.i18n import _
from mercurial.node import short, hex
from mercurial import extensions, merge, scmutil, hg
from mercurial import cmdutil, obsolete, repair, util, bundlerepo, error
from mercurial import exchange, phases
from mercurial import lock as lockmod
import struct, os, glob, binascii

cmdtable = {}
command = cmdutil.command(cmdtable)
testedwith = 'internal'

def _isevolverepo(repo):
    try:
        return extensions.find('evolve')
    except KeyError:
        return None

def _isahash(rev):
    try:
        binascii.unhexlify(rev)
        return True
    except TypeError:
        return False

@command("reset", [
        ('C', 'clean', None, _('wipe the working copy clean when resetting')),
        ('k', 'keep', None, _('keeps the old commits the bookmark pointed to')),
    ], _('hg reset [REV]'))
def reset(ui, repo, *args, **opts):
    """moves the active bookmark and working copy parent to the desired rev

    The reset command is for moving your active bookmark and working copy to a
    different location. This is useful for undoing commits, amends, etc.

    By default, the working copy content is not touched, so you will have
    pending changes after the reset. If --clean/-C is specified, the working
    copy contents will be overwritten to match the destination revision, and you
    will not have any pending changes.

    After your bookmark and working copy have been moved, the command will
    delete any commits that belonged only to that bookmark. Use --keep/-k to
    avoid deleting any commits.
    """
    rev = args[0] if args else '.'
    oldctx = repo['.']

    wlock = None
    try:
        wlock = repo.wlock()
        # Ensure we have an active bookmark
        bookmark = bmactive(repo)
        if not bookmark:
            ui.warn(_('resetting without an active bookmark\n'))

        ctx = _revive(repo, rev)
        _moveto(repo, bookmark, ctx, clean=opts.get('clean'))
        if not opts.get('keep'):
            _deleteunreachable(repo, oldctx)
    finally:
        wlock.release()

def _revive(repo, rev):
    """Brings the given rev back into the repository. Finding it in backup
    bundles if necessary.
    """
    if _isahash(rev):
        # If it appears to be a hash, just read it directly.
        try:
            rev = scmutil.revsingle(repo, rev).node()
            return repo[rev]
        except error.FilteredRepoLookupError:
            return _touch(repo, repo.unfiltered()[rev])
        except error.RepoLookupError:
            # It could either be a revset or a stripped commit.
            pass

    try:
        revs = scmutil.revrange(repo, [rev])
        if len(revs) > 1:
            raise error.Abort(_('exactly one revision must be specified'))
        if len(revs) == 1:
            return repo[revs.first()]
    except error.RepoLookupError:
        revs = []

    return _pullbundle(repo, rev)

def _touch(repo, rev):
    """Touch the given rev and any of its ancestors to bring it back into the
    repository.
    """
    unfi = repo.unfiltered()
    evolve = _isevolverepo(repo.ui)
    if evolve:
        needtouch = unfi.revs('::%d & obsolete()', rev)
        opts = {
            # Use 'duplicate' to avoid divergence. We may want something better
            # later.
            'allowdivergence': False,
            'duplicate': True,
            'rev': [],
        }
        evolve.touch(repo.ui, unfi, *needtouch, **opts)
        # Return the newly revived version of rev.
        # Use tip, since it's guaranteed to be the latest commit in the
        # repo, since it will have been the last commit revived.
        return repo['tip']
    else:
        raise error.Abort("unable to revive '%s' because it is hidden and "
                         "evolve is disabled" % rev)

def _pullbundle(repo, rev):
    """Find the given rev in a backup bundle and pull it back into the
    repository.
    """
    other, rev = _findbundle(repo, rev)
    if not other:
        raise error.Abort("could not find '%s' in the repo or the backup"
                         " bundles" % rev)
    lock = repo.lock()
    try:
        oldtip = len(repo)
        exchange.pull(repo, other, heads=[rev])

        tr = repo.transaction("phase")
        nodes = (c.node() for c in repo.set('%d:', oldtip))
        phases.retractboundary(repo, tr, 1, nodes)
        tr.close()
    finally:
        lock.release()

    if rev not in repo:
        raise error.Abort("unable to get rev %s from repo" % rev)

    return repo[rev]

def _findbundle(repo, rev):
    """Returns the backup bundle that contains the given rev. If found, it
    returns the bundle peer and the full rev hash. If not found, it return None
    and the given rev value.
    """
    ui = repo.ui
    backuppath = repo.join("strip-backup")
    backups = filter(os.path.isfile, glob.glob(backuppath + "/*.hg"))
    backups.sort(key=lambda x: os.path.getmtime(x), reverse=True)
    for backup in backups:
        # Much of this is copied from the hg incoming logic
        source = os.path.relpath(backup, os.getcwd())
        source = ui.expandpath(source)
        source, branches = hg.parseurl(source)
        other = hg.peer(repo, {}, source)

        quiet = ui.quiet
        try:
            ui.quiet = True
            ret = bundlerepo.getremotechanges(ui, repo, other, None, None, None)
            localother, chlist, cleanupfn = ret
            for node in chlist:
                if hex(node).startswith(rev):
                    return other, node
        except error.LookupError:
            continue
        finally:
            ui.quiet = quiet

    return None, rev

def _moveto(repo, bookmark, ctx, clean=False):
    """Moves the given bookmark and the working copy to the given revision.
    By default it does not overwrite the working copy contents unless clean is
    True.

    Assumes the wlock is already taken.
    """
    # Move working copy over
    if clean:
        merge.update(repo, ctx.node(),
                     False, # not a branchmerge
                     True, # force overwriting files
                     None) # not a partial update
    else:
        # Mark any files that are different between the two as normal-lookup
        # so they show up correctly in hg status afterwards.
        wctx = repo[None]
        m1 = wctx.manifest()
        m2 = ctx.manifest()
        diff = m1.diff(m2)

        changedfiles = []
        changedfiles.extend(diff.iterkeys())

        dirstate = repo.dirstate
        dirchanges = [f for f in dirstate if dirstate[f] != 'n']
        changedfiles.extend(dirchanges)

        if changedfiles or ctx.node() != repo['.'].node():
            dirstate.beginparentchange()
            dirstate.rebuild(ctx.node(), m2, changedfiles)
            dirstate.endparentchange()

    # Move bookmark over
    if bookmark:
        lock = tr = None
        try:
            lock = repo.lock()
            tr = repo.transaction('reset')
            repo._bookmarks[bookmark] = ctx.node()
            repo._bookmarks.recordchange(tr)
            tr.close()
        finally:
            lockmod.release(lock, tr)

def _deleteunreachable(repo, ctx):
    """Deletes all ancestor and descendant commits of the given revision that
    aren't reachable from another bookmark.
    """
    keepheads = "bookmark() + ."
    try:
        extensions.find('remotenames')
        keepheads += " + remotenames()"
    except KeyError:
        pass
    hiderevs = repo.revs('::%s - ::(%r)', ctx.rev(), keepheads)
    if hiderevs:
        lock = None
        try:
            lock = repo.lock()
            if _isevolverepo(repo.ui):
                markers = []
                for rev in hiderevs:
                    markers.append((repo[rev], ()))
                obsolete.createmarkers(repo, markers)
                repo.ui.status(_("%d changesets pruned\n") % len(hiderevs))
            else:
                repair.strip(repo.ui, repo,
                             [repo.changelog.node(r) for r in hiderevs])
        finally:
            lockmod.release(lock)

### bookmarks api compatibility layer ###
def bmactive(repo):
    try:
        return repo._activebookmark
    except AttributeError:
        return repo._bookmarkcurrent