# 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 annotations

import contextlib
import os

from mercurial.i18n import _
from mercurial import (
    error,
    extensions,
    hg,
    util,
    wireprotov1peer,
    wireprotov1server,
)
from mercurial.repo import (
    factory as repo_factory,
)
from mercurial.utils import (
    urlutil,
)
from . import context

# common


def _getmaster(ui):
    """get the mainbranch, and enforce it is set"""
    master = ui.config(b'fastannotate', b'mainbranch')
    if not master:
        raise error.Abort(
            _(
                b'fastannotate.mainbranch is required '
                b'for both the client and the server'
            )
        )
    return master


# server-side


def _capabilities(orig, repo, proto):
    result = orig(repo, proto)
    result.append(b'getannotate')
    return result


def _getannotate(repo, proto, path, lastnode):
    # output:
    #   FILE := vfspath + '\0' + str(size) + '\0' + content
    #   OUTPUT := '' | FILE + OUTPUT
    result = b''
    buildondemand = repo.ui.configbool(
        b'fastannotate', b'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
                with open(p, 'rb') as f:
                    content = f.read()
                vfsbaselen = len(repo.vfs.base + b'/')
                relpath = p[vfsbaselen:]
                result += b'%s\0%d\0%s' % (relpath, len(content), content)
    return result


def _registerwireprotocommand():
    if b'getannotate' in wireprotov1server.commands:
        return
    wireprotov1server.wireprotocommand(b'getannotate', b'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 = b''
    while i < l:
        ch = payload[i : i + 1]
        if ch == b'\0':
            if state == 1:
                result[vfspath] = payload[i + 1 : i + 1 + int(size)]
                i += int(size)
                state = 0
                vfspath = size = b''
            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(b'getannotate'):
                ui.warn(_(b'remote peer cannot provide annotate cache\n'))
                return None, None
            else:
                args = {b'path': path, b'lastnode': lastnode or b''}
                return args, _parseresponse

    peer.__class__ = fastannotatepeer


@contextlib.contextmanager
def annotatepeer(repo):
    ui = repo.ui

    remotedest = ui.config(b'fastannotate', b'remotepath', b'default')
    remotepath = urlutil.get_unique_pull_path_obj(
        b'fastannotate',
        ui,
        remotedest,
    )
    peer = repo_factory.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(b'fastannotate: requesting %d files\n' % len(paths))
        for p in paths:
            results.append(
                batcher.callcommand(
                    b'getannotate',
                    {b'path': p, b'lastnode': lastnodemap.get(p)},
                )
            )

        for result in results:
            r = result.result()
            # TODO: pconvert these paths on the server?
            r = {util.pconvert(p): v for p, v in r.items()}
            for path in sorted(r):
                # ignore malicious paths
                if not path.startswith(b'fastannotate/') or b'/../' in (
                    path + b'/'
                ):
                    ui.debug(
                        b'fastannotate: ignored malicious path %s\n' % path
                    )
                    continue
                content = r[path]
                if ui.debugflag:
                    ui.debug(
                        b'fastannotate: writing %d bytes to %s\n'
                        % (len(content), path)
                    )
                repo.vfs.makedirs(os.path.dirname(path))
                with repo.vfs(path, b'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(b'fastannotate', b'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(b'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)
