# shallowbundle.py - bundle10 implementation for use with shallow repositories
#
# Copyright 2013 Facebook, Inc.
#
# 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

from mercurial.i18n import _
from mercurial.node import bin, hex
from mercurial import (
    bundlerepo,
    changegroup,
    error,
    match,
    mdiff,
)
from . import (
    constants,
    remotefilelog,
    shallowutil,
)

NoFiles = 0
LocalFiles = 1
AllFiles = 2


def shallowgroup(cls, self, nodelist, rlog, lookup, units=None, reorder=None):
    if not isinstance(rlog, remotefilelog.remotefilelog):
        yield from super(cls, self).group(nodelist, rlog, lookup, units=units)
        return

    if len(nodelist) == 0:
        yield self.close()
        return

    nodelist = shallowutil.sortnodes(nodelist, rlog.parents)

    # add the parent of the first rev
    p = rlog.parents(nodelist[0])[0]
    nodelist.insert(0, p)

    # build deltas
    for i in range(len(nodelist) - 1):
        prev, curr = nodelist[i], nodelist[i + 1]
        linknode = lookup(curr)
        yield from self.nodechunk(rlog, curr, prev, linknode)

    yield self.close()


class shallowcg1packer(changegroup.cgpacker):
    def generate(self, commonrevs, clnodes, fastpathlinkrev, source, **kwargs):
        if shallowutil.isenabled(self._repo):
            fastpathlinkrev = False

        return super().generate(
            commonrevs, clnodes, fastpathlinkrev, source, **kwargs
        )

    def group(self, nodelist, rlog, lookup, units=None, reorder=None):
        return shallowgroup(
            shallowcg1packer, self, nodelist, rlog, lookup, units=units
        )

    def generatefiles(self, changedfiles, *args, **kwargs):
        try:
            linknodes, commonrevs, source = args
        except ValueError:
            commonrevs, source, mfdicts, fastpathlinkrev, fnodes, clrevs = args
        if shallowutil.isenabled(self._repo):
            repo = self._repo
            if isinstance(repo, bundlerepo.bundlerepository):
                # If the bundle contains filelogs, we can't pull from it, since
                # bundlerepo is heavily tied to revlogs. Instead require that
                # the user use unbundle instead.
                # Force load the filelog data.
                bundlerepo.bundlerepository.file(repo, b'foo')
                if repo._cgfilespos:
                    raise error.Abort(
                        b"cannot pull from full bundles",
                        hint=b"use `hg unbundle` instead",
                    )
                return []
            filestosend = self.shouldaddfilegroups(source)
            if filestosend == NoFiles:
                changedfiles = list(
                    [f for f in changedfiles if not repo.shallowmatch(f)]
                )

        return super().generatefiles(changedfiles, *args, **kwargs)

    def shouldaddfilegroups(self, source):
        repo = self._repo
        if not shallowutil.isenabled(repo):
            return AllFiles

        if source == b"push" or source == b"bundle":
            return AllFiles

        # We won't actually strip the files, but we should put them in any
        # backup bundle generated by strip (especially for cases like narrow's
        # `hg tracked --removeinclude`, as failing to do so means that the
        # "saved" changesets during a strip won't have their files reapplied and
        # thus their linknode adjusted, if necessary).
        if source == b"strip":
            cfg = repo.ui.config(b'remotefilelog', b'strip.includefiles')
            if cfg == b'local':
                return LocalFiles
            elif cfg != b'none':
                return AllFiles

        caps = self._bundlecaps or []
        if source == b"serve" or source == b"pull":
            if constants.BUNDLE2_CAPABLITY in caps:
                return LocalFiles
            else:
                # Serving to a full repo requires us to serve everything
                repo.ui.warn(_(b"pulling from a shallow repo\n"))
                return AllFiles

        return NoFiles

    def prune(self, rlog, missing, commonrevs):
        if not isinstance(rlog, remotefilelog.remotefilelog):
            return super().prune(rlog, missing, commonrevs)

        repo = self._repo
        results = []
        for fnode in missing:
            fctx = repo.filectx(rlog.filename, fileid=fnode)
            if fctx.linkrev() not in commonrevs:
                results.append(fnode)
        return results

    def nodechunk(self, revlog, node, prevnode, linknode):
        prefix = b''
        if prevnode == revlog.nullid:
            delta = revlog.rawdata(node)
            prefix = mdiff.trivialdiffheader(len(delta))
        else:
            # Actually uses remotefilelog.revdiff which works on nodes, not revs
            delta = revlog.revdiff(prevnode, node)
        p1, p2 = revlog.parents(node)
        flags = revlog.flags(node)
        meta = self.builddeltaheader(node, p1, p2, prevnode, linknode, flags)
        meta += prefix
        l = len(meta) + len(delta)
        yield changegroup.chunkheader(l)
        yield meta
        yield delta


def makechangegroup(orig, repo, outgoing, version, source, *args, **kwargs):
    if not shallowutil.isenabled(repo):
        return orig(repo, outgoing, version, source, *args, **kwargs)

    original = repo.shallowmatch
    try:
        # if serving, only send files the clients has patterns for
        if source == b'serve':
            bundlecaps = kwargs.get('bundlecaps')
            includepattern = None
            excludepattern = None
            for cap in bundlecaps or []:
                if cap.startswith(b"includepattern="):
                    raw = cap[len(b"includepattern=") :]
                    if raw:
                        includepattern = raw.split(b'\0')
                elif cap.startswith(b"excludepattern="):
                    raw = cap[len(b"excludepattern=") :]
                    if raw:
                        excludepattern = raw.split(b'\0')
            if includepattern or excludepattern:
                repo.shallowmatch = match.match(
                    repo.root, b'', None, includepattern, excludepattern
                )
            else:
                repo.shallowmatch = match.always()
        return orig(repo, outgoing, version, source, *args, **kwargs)
    finally:
        repo.shallowmatch = original


def addchangegroupfiles(
    orig, repo, source, revmap, trp, expectedfiles, *args, **kwargs
):
    if not shallowutil.isenabled(repo):
        return orig(repo, source, revmap, trp, expectedfiles, *args, **kwargs)

    newfiles = 0
    visited = set()
    revisiondatas = {}
    queue = []

    # Normal Mercurial processes each file one at a time, adding all
    # the new revisions for that file at once. In remotefilelog a file
    # revision may depend on a different file's revision (in the case
    # of a rename/copy), so we must lay all revisions down across all
    # files in topological order.

    # read all the file chunks but don't add them
    progress = repo.ui.makeprogress(_(b'files'), total=expectedfiles)
    while True:
        chunkdata = source.filelogheader()
        if not chunkdata:
            break
        f = chunkdata[b"filename"]
        repo.ui.debug(b"adding %s revisions\n" % f)
        progress.increment()

        if not repo.shallowmatch(f):
            fl = repo.file(f, writable=True)
            deltas = source.deltaiter()
            fl.addgroup(deltas, revmap, trp)
            continue

        chain = None
        while True:
            # returns: None or (
            #   node,
            #   p1,
            #   p2,
            #   cs,
            #   deltabase,
            #   delta,
            #   flags,
            #   sidedata,
            #   proto_flags
            # )
            revisiondata = source.deltachunk(chain)
            if not revisiondata:
                break

            chain = revisiondata.node

            revisiondatas[(f, chain)] = revisiondata
            queue.append((f, chain))

            if f not in visited:
                newfiles += 1
                visited.add(f)

        if chain is None:
            raise error.Abort(_(b"received file revlog group is empty"))

    processed = set()

    def available(f, node, depf, depnode):
        if depnode != repo.nullid and (depf, depnode) not in processed:
            if not (depf, depnode) in revisiondatas:
                # It's not in the changegroup, assume it's already
                # in the repo
                return True
            # re-add self to queue
            queue.insert(0, (f, node))
            # add dependency in front
            queue.insert(0, (depf, depnode))
            return False
        return True

    skipcount = 0

    # Prefetch the non-bundled revisions that we will need
    prefetchfiles = []
    for f, node in queue:
        revisiondata = revisiondatas[(f, node)]
        # revisiondata: (node, p1, p2, cs, deltabase, delta, flags, sdata, pfl)
        dependents = [revisiondata.p1, revisiondata.p2, revisiondata.delta_base]

        for dependent in dependents:
            if dependent == repo.nullid or (f, dependent) in revisiondatas:
                continue
            prefetchfiles.append((f, hex(dependent)))

    repo.fileservice.prefetch(prefetchfiles)

    # Apply the revisions in topological order such that a revision
    # is only written once it's deltabase and parents have been written.
    while queue:
        f, node = queue.pop(0)
        if (f, node) in processed:
            continue

        skipcount += 1
        if skipcount > len(queue) + 1:
            raise error.Abort(_(b"circular node dependency"))

        fl = repo.file(f)

        rdata = revisiondatas[(f, node)]
        if not available(f, rdata.node, f, rdata.delta_base):
            continue

        base = fl.rawdata(rdata.delta_base)
        text = mdiff.patch(base, rdata.delta)
        if not isinstance(text, bytes):
            text = bytes(text)

        meta, text = shallowutil.parsemeta(text)
        if b'copy' in meta:
            copyfrom = meta[b'copy']
            copynode = bin(meta[b'copyrev'])
            if not available(f, rdata.node, copyfrom, copynode):
                continue

        for p in [rdata.p1, rdata.p2]:
            if p != repo.nullid:
                if not available(f, rdata.node, f, p):
                    continue

        # XXX why don't we use the flag field !
        fl.add(text, meta, trp, rdata.link_node, rdata.p1, rdata.p2)
        processed.add((f, rdata.node))
        skipcount = 0

    progress.complete()

    return len(revisiondatas), newfiles
