# Copyright 2016 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 absolute_import

import os
import threading

from edenscm.mercurial import manifest, mdiff, revlog, util
from edenscm.mercurial.node import hex, nullid

from . import basestore, constants, shallowutil


try:
    xrange(0)
except NameError:
    xrange = range


class ChainIndicies(object):
    """A static class for easy reference to the delta chain indicies.
    """

    # The filename of this revision delta
    NAME = 0
    # The mercurial file node for this revision delta
    NODE = 1
    # The filename of the delta base's revision. This is useful when delta
    # between different files (like in the case of a move or copy, we can delta
    # against the original file content).
    BASENAME = 2
    # The mercurial file node for the delta base revision. This is the nullid if
    # this delta is a full text.
    BASENODE = 3
    # The actual delta or full text data.
    DATA = 4


class unioncontentstore(object):
    def __init__(self, *args, **kwargs):
        self.stores = list(args)

        # If allowincomplete==True then the union store can return partial
        # delta chains, otherwise it will throw a KeyError if a full
        # deltachain can't be found.
        self.allowincomplete = kwargs.get("allowincomplete", False)

    def get(self, name, node):
        """Fetches the full text revision contents of the given name+node pair.
        If the full text doesn't exist, throws a KeyError.

        Under the hood, this uses getdeltachain() across all the stores to build
        up a full chain to produce the full text.
        """
        chain = self.getdeltachain(name, node)

        if chain[-1][ChainIndicies.BASENODE] != nullid:
            # If we didn't receive a full chain, throw
            raise KeyError((name, hex(node)))

        # The last entry in the chain is a full text, so we start our delta
        # applies with that.
        fulltext = chain.pop()[ChainIndicies.DATA]

        text = fulltext
        while chain:
            delta = chain.pop()[ChainIndicies.DATA]
            text = mdiff.patches(text, [delta])

        return text

    def getdelta(self, name, node):
        """Return the single delta entry for the given name/node pair.
        """
        for store in self.stores:
            try:
                return store.getdelta(name, node)
            except KeyError:
                pass

        raise shallowutil.MissingNodesError([(name, node)])

    def getdeltachain(self, name, node):
        """Returns the deltachain for the given name/node pair.

        Returns an ordered list of:

          [(name, node, deltabasename, deltabasenode, deltacontent),...]

        where the chain is terminated by a full text entry with a nullid
        deltabasenode.
        """
        chain = self._getpartialchain(name, node)
        while chain[-1][ChainIndicies.BASENODE] != nullid:
            x, x, deltabasename, deltabasenode, x = chain[-1]
            try:
                morechain = self._getpartialchain(deltabasename, deltabasenode)
                chain.extend(morechain)
            except KeyError:
                # If we allow incomplete chains, don't throw.
                if not self.allowincomplete:
                    raise
                break

        return chain

    def getmeta(self, name, node):
        """Returns the metadata dict for given node."""
        for store in self.stores:
            try:
                return store.getmeta(name, node)
            except KeyError:
                pass
        raise KeyError((name, hex(node)))

    def getmetrics(self):
        metrics = [s.getmetrics() for s in self.stores]
        return shallowutil.sumdicts(*metrics)

    def _getpartialchain(self, name, node):
        """Returns a partial delta chain for the given name/node pair.

        A partial chain is a chain that may not be terminated in a full-text.
        """
        for store in self.stores:
            try:
                return store.getdeltachain(name, node)
            except KeyError:
                pass

        raise KeyError((name, hex(node)))

    def add(self, name, node, data):
        raise RuntimeError("cannot add content only to remotefilelog " "contentstore")

    def getmissing(self, keys):
        missing = keys
        for store in self.stores:
            if missing:
                missing = store.getmissing(missing)
        return missing

    def markledger(self, ledger, options=None):
        for store in self.stores:
            store.markledger(ledger, options)

    def markforrefresh(self):
        for store in self.stores:
            if util.safehasattr(store, "markforrefresh"):
                store.markforrefresh()

    def addstore(self, store):
        self.stores.append(store)

    def removestore(self, store):
        self.stores.remove(store)


class remotefilelogcontentstore(basestore.basestore):
    def __init__(self, *args, **kwargs):
        super(remotefilelogcontentstore, self).__init__(*args, **kwargs)
        self._threaddata = threading.local()

        storetype = "shared" if self._shared else "local"
        self._metricsprefix = "filestore_%s_blob" % storetype

    def get(self, name, node):
        # return raw revision text
        data = self._getdata(name, node)

        offset, size, flags = shallowutil.parsesizeflags(data)
        content = data[offset : offset + size]

        try:
            ancestormap = shallowutil.ancestormap(data)
        except ValueError:
            self.handlecorruption(name, node)

        p1, p2, linknode, copyfrom = ancestormap[node]
        copyrev = None
        if copyfrom:
            copyrev = hex(p1)

        self._updatemetacache(node, size, flags)

        # lfs tracks renames in its own metadata, remove hg copy metadata,
        # because copy metadata will be re-added by lfs flag processor.
        if flags & revlog.REVIDX_EXTSTORED:
            copyrev = copyfrom = None
        revision = shallowutil.createrevlogtext(content, copyfrom, copyrev)
        return revision

    def getdelta(self, name, node):
        # Since remotefilelog content stores only contain full texts, just
        # return that.
        revision = self.get(name, node)
        return revision, name, nullid, self.getmeta(name, node)

    def getdeltachain(self, name, node):
        # Since remotefilelog content stores just contain full texts, we return
        # a fake delta chain that just consists of a single full text revision.
        # The nullid in the deltabasenode slot indicates that the revision is a
        # fulltext.
        revision = self.get(name, node)
        return [(name, node, None, nullid, revision)]

    def getmeta(self, name, node):
        self._sanitizemetacache()
        if node != self._threaddata.metacache[0]:
            data = self._getdata(name, node)
            offset, size, flags = shallowutil.parsesizeflags(data)
            self._updatemetacache(node, size, flags)
        return self._threaddata.metacache[1]

    def add(self, name, node, data):
        raise RuntimeError("cannot add content only to remotefilelog " "contentstore")

    def _sanitizemetacache(self):
        metacache = getattr(self._threaddata, "metacache", None)
        if metacache is None:
            self._threaddata.metacache = (None, None)  # (node, meta)

    def _updatemetacache(self, node, size, flags):
        self._sanitizemetacache()
        if node == self._threaddata.metacache[0]:
            return
        meta = {constants.METAKEYFLAG: flags, constants.METAKEYSIZE: size}
        self._threaddata.metacache = (node, meta)

    def markforrefresh(self):
        pass

    def _reportmetrics(self, root, filename):
        filepath = os.path.join(root, filename)
        stats = os.stat(filepath)

        self.ui.metrics.gauge(self._metricsprefix + "size", stats.st_size)
        self.ui.metrics.gauge(self._metricsprefix + "num", 1)


class remotecontentstore(object):
    def __init__(self, ui, fileservice, shared):
        self._fileservice = fileservice
        # type(shared) is usually remotefilelogcontentstore
        self._shared = shared

    def _prefetch(self, name, node):
        self._fileservice.prefetch(
            [(name, hex(node))], force=True, fetchdata=True, fetchhistory=False
        )
        self._shared.markforrefresh()

    def get(self, name, node):
        self._prefetch(name, node)
        return self._shared.get(name, node)

    def getdelta(self, name, node):
        self._prefetch(name, node)
        return self._shared.getdelta(name, node)

    def getdeltachain(self, name, node):
        self._prefetch(name, node)
        return self._shared.getdeltachain(name, node)

    def getmeta(self, name, node):
        self._prefetch(name, node)
        return self._shared.getmeta(name, node)

    def add(self, name, node, data):
        raise RuntimeError("cannot add to a remote store")

    def getmissing(self, keys):
        return keys

    def markledger(self, ledger, options=None):
        pass


class manifestrevlogstore(object):
    def __init__(self, repo):
        # It's important that we store the repo, and not just the changelog,
        # since the changelog may be mutated in memory. So we need to refetch
        # the changelog each time we want to access it.
        self.repo = repo
        self._revlogs = util.lrucachedict(100)
        self._repackstartlinkrev = 0

    def get(self, name, node):
        return self._revlog(name).revision(node, raw=True)

    def getdelta(self, name, node):
        revision = self.get(name, node)
        return revision, name, nullid, self.getmeta(name, node)

    def getdeltachain(self, name, node):
        revision = self.get(name, node)
        return [(name, node, None, nullid, revision)]

    def getmeta(self, name, node):
        rl = self._revlog(name)
        rev = rl.rev(node)
        return {
            constants.METAKEYFLAG: rl.flags(rev),
            constants.METAKEYSIZE: rl.rawsize(rev),
        }

    def getancestors(self, name, node, known=None):
        if known is None:
            known = set()
        if node in known:
            return []

        rl = self._revlog(name)
        ancestors = {}
        missing = set((node,))
        for ancrev in rl.ancestors([rl.rev(node)], inclusive=True):
            ancnode = rl.node(ancrev)
            missing.discard(ancnode)

            p1, p2 = rl.parents(ancnode)
            if p1 != nullid and p1 not in known:
                missing.add(p1)
            if p2 != nullid and p2 not in known:
                missing.add(p2)

            linknode = self.repo.changelog.node(rl.linkrev(ancrev))
            ancestors[rl.node(ancrev)] = (p1, p2, linknode, "")
            if not missing:
                break
        return ancestors

    def getnodeinfo(self, name, node):
        cl = self.repo.changelog
        rl = self._revlog(name)
        parents = rl.parents(node)
        linkrev = rl.linkrev(rl.rev(node))
        return (parents[0], parents[1], cl.node(linkrev), None)

    def add(self, *args):
        raise RuntimeError("cannot add to a revlog store")

    def _revlog(self, name):
        rl = self._revlogs.get(name)
        if rl is None:
            indexfile = None
            if name == "":
                indexfile = "00manifesttree.i"
            rl = manifest.manifestrevlog(
                self.repo.svfs, dir=name, indexfile=indexfile, treemanifest=True
            )
            self._revlogs[name] = rl
        return rl

    def getmissing(self, keys):
        missing = []
        for name, node in keys:
            mfrevlog = self._revlog(name)
            if node not in mfrevlog.nodemap:
                missing.append((name, node))

        return missing

    def setrepacklinkrevrange(self, startrev, endrev):
        self._repackstartlinkrev = startrev
        self._repackendlinkrev = endrev

    def markledger(self, ledger, options=None):
        if options and options.get(constants.OPTION_PACKSONLY):
            return
        treename = ""
        rl = revlog.revlog(self.repo.svfs, "00manifesttree.i")
        startlinkrev = self._repackstartlinkrev
        endlinkrev = self._repackendlinkrev
        for rev in xrange(len(rl) - 1, -1, -1):
            linkrev = rl.linkrev(rev)
            if linkrev < startlinkrev:
                break
            if linkrev > endlinkrev:
                continue
            node = rl.node(rev)
            ledger.markdataentry(self, treename, node)
            ledger.markhistoryentry(self, treename, node)

        for path, encoded, size in self.repo.store.datafiles():
            if path[:5] != "meta/" or path[-2:] != ".i":
                continue

            treename = path[5 : -len("/00manifest.i")]

            rl = revlog.revlog(self.repo.svfs, path)
            for rev in xrange(len(rl) - 1, -1, -1):
                linkrev = rl.linkrev(rev)
                if linkrev < startlinkrev:
                    break
                if linkrev > endlinkrev:
                    continue
                node = rl.node(rev)
                ledger.markdataentry(self, treename, node)
                ledger.markhistoryentry(self, treename, node)

    def cleanup(self, ledger):
        pass