# 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,
    localrepo,
    scmutil,
    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%s\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)}))

    ui.debug('fastannotate: server returned\n')
    for result in results:
        r = result.result()
        for path in sorted(r):
            # ignore malicious paths
            if not path.startswith('fastannotate/') or '/../' in (path + '/'):
                ui.debug('fastannotate: ignored malicious path %s\n' % path)
                continue
            content = r[path]
            if ui.debugflag:
                ui.debug('fastannotate: writing %d bytes to %s\n'
                         % (len(content), path))
            repo.vfs.makedirs(os.path.dirname(path))
            with repo.vfs(path, 'wb') as f:
                f.write(content)

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

    master = repo.ui.config('fastannotate', 'mainbranch') or 'default'

    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 isinstance(repo, localrepo.localrepository):
        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)