# Copyright 2016-present Facebook. All Rights Reserved.

#

# protocol: logic for a server providing fastannotate support

#

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

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

from __future__ import absolute_import

import contextlib

import os

from mercurial.i18n import _

from mercurial import (

    error,

    extensions,

    hg,

    util,

    wireprotov1peer,

    wireprotov1server,

)

from . import context

# common

def _getmaster(ui):

    """get the mainbranch, and enforce it is set"""

    master = ui.config('fastannotate', 'mainbranch')

    if not master:

        raise error.Abort(_('fastannotate.mainbranch is required '

                            'for both the client and the server'))

    return master

# server-side

def _capabilities(orig, repo, proto):

    result = orig(repo, proto)

    result.append('getannotate')

    return result

def _getannotate(repo, proto, path, lastnode):

    # output:

    #   FILE := vfspath + '\0' + str(size) + '\0' + content

    #   OUTPUT := '' | FILE + OUTPUT

    result = ''

    buildondemand = repo.ui.configbool('fastannotate', 'serverbuildondemand',

                                       True)

    with context.annotatecontext(repo, path) as actx:

        if buildondemand:

            # update before responding to the client

            master = _getmaster(repo.ui)

            try:

                if not actx.isuptodate(master):

                    actx.annotate(master, master)

            except Exception:

                # non-fast-forward move or corrupted. rebuild automically.

                actx.rebuild()

                try:

                    actx.annotate(master, master)

                except Exception:

                    actx.rebuild() # delete files

            finally:

                # although the "with" context will also do a close/flush, we

                # need to do it early so we can send the correct respond to

                # client.

                actx.close()

        # send back the full content of revmap and linelog, in the future we

        # may want to do some rsync-like fancy updating.

        # the lastnode check is not necessary if the client and the server

        # agree where the main branch is.

        if actx.lastnode != lastnode:

            for p in [actx.revmappath, actx.linelogpath]:

                if not os.path.exists(p):

                    continue

                content = ''

                with open(p, 'rb') as f:

                    content = f.read()

                vfsbaselen = len(repo.vfs.base + '/')

                relpath = p[vfsbaselen:]

                result += '%s\0%d\0%s' % (relpath, len(content), content)

    return result

def _registerwireprotocommand():

    if 'getannotate' in wireprotov1server.commands:

        return

    wireprotov1server.wireprotocommand(

        'getannotate', 'path lastnode')(_getannotate)

def serveruisetup(ui):

    _registerwireprotocommand()

    extensions.wrapfunction(wireprotov1server, '_capabilities', _capabilities)

# client-side

def _parseresponse(payload):

    result = {}

    i = 0

    l = len(payload) - 1

    state = 0 # 0: vfspath, 1: size

    vfspath = size = ''

    while i < l:

        ch = payload[i]

        if ch == '\0':

            if state == 1:

                result[vfspath] = buffer(payload, i + 1, int(size))

                i += int(size)

                state = 0

                vfspath = size = ''

            elif state == 0:

                state = 1

        else:

            if state == 1:

                size += ch

            elif state == 0:

                vfspath += ch

        i += 1

    return result

def peersetup(ui, peer):

    class fastannotatepeer(peer.__class__):

        @wireprotov1peer.batchable

        def getannotate(self, path, lastnode=None):

            if not self.capable('getannotate'):

                ui.warn(_('remote peer cannot provide annotate cache\n'))

                yield None, None

            else:

                args = {'path': path, 'lastnode': lastnode or ''}

                f = wireprotov1peer.future()

                yield args, f

                yield _parseresponse(f.value)

    peer.__class__ = fastannotatepeer

@contextlib.contextmanager

def annotatepeer(repo):

    ui = repo.ui

    remotepath = ui.expandpath(

        ui.config('fastannotate', 'remotepath', 'default'))

    peer = hg.peer(ui, {}, remotepath)

    try:

        yield peer

    finally:

        peer.close()

def clientfetch(repo, paths, lastnodemap=None, peer=None):

    """download annotate cache from the server for paths"""

    if not paths:

        return

    if peer is None:

        with annotatepeer(repo) as peer:

            return clientfetch(repo, paths, lastnodemap, peer)

    if lastnodemap is None:

        lastnodemap = {}

    ui = repo.ui

    results = []

    with peer.commandexecutor() as batcher:

        ui.debug('fastannotate: requesting %d files\n' % len(paths))

        for p in paths:

            results.append(batcher.callcommand(

                'getannotate',

                {'path': p, 'lastnode':lastnodemap.get(p)}))

def _filterfetchpaths(repo, paths):

    """return a subset of paths whose history is long and need to fetch linelog

    from the server. works with remotefilelog and non-remotefilelog repos.

    """

    threshold = repo.ui.configint('fastannotate', 'clientfetchthreshold', 10)

    if threshold <= 0:

        return paths

    result = []

    for path in paths:

        try:

            if len(repo.file(path)) >= threshold:

                result.append(path)

        except Exception: # file not found etc.

            result.append(path)

    return result

def localreposetup(ui, repo):

    class fastannotaterepo(repo.__class__):

        def prefetchfastannotate(self, paths, peer=None):

            master = _getmaster(self.ui)

            needupdatepaths = []

            lastnodemap = {}

            try:

                for path in _filterfetchpaths(self, paths):

                    with context.annotatecontext(self, path) as actx:

                        if not actx.isuptodate(master, strict=False):

                            needupdatepaths.append(path)

                            lastnodemap[path] = actx.lastnode

                if needupdatepaths:

                    clientfetch(self, needupdatepaths, lastnodemap, peer)

            except Exception as ex:

                # could be directory not writable or so, not fatal

                self.ui.debug('fastannotate: prefetch failed: %r\n' % ex)

    repo.__class__ = fastannotaterepo

def clientreposetup(ui, repo):

    _registerwireprotocommand()

    if repo.local():

        localreposetup(ui, repo)

    # TODO: this mutates global state, but only if at least one repo

    # has the extension enabled. This is probably bad for hgweb.

    if peersetup not in hg.wirepeersetupfuncs:

        hg.wirepeersetupfuncs.append(peersetup)