from __future__ import absolute_import

import struct

import zlib

from mercurial.i18n import _

from mercurial import (

    pycompat,

    util,

)

from . import (

    basepack,

    constants,

    shallowutil,

)

NODELENGTH = 20

# The indicator value in the index for a fulltext entry.

FULLTEXTINDEXMARK = -1

NOBASEINDEXMARK = -2

INDEXSUFFIX = b'.dataidx'

PACKSUFFIX = b'.datapack'

class datapackstore(basepack.basepackstore):

    INDEXSUFFIX = INDEXSUFFIX

    PACKSUFFIX = PACKSUFFIX

    def __init__(self, ui, path):

        super(datapackstore, self).__init__(ui, path)

    def getpack(self, path):

        return datapack(path)

    def get(self, name, node):

        raise RuntimeError(b"must use getdeltachain with datapackstore")

    def getmeta(self, name, node):

        for pack in self.packs:

            try:

                return pack.getmeta(name, node)

            except KeyError:

                pass

        for pack in self.refresh():

            try:

                return pack.getmeta(name, node)

            except KeyError:

                pass

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

    def getdelta(self, name, node):

        for pack in self.packs:

            try:

                return pack.getdelta(name, node)

            except KeyError:

                pass

        for pack in self.refresh():

            try:

                return pack.getdelta(name, node)

            except KeyError:

                pass

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

    def getdeltachain(self, name, node):

        for pack in self.packs:

            try:

                return pack.getdeltachain(name, node)

            except KeyError:

                pass

        for pack in self.refresh():

            try:

                return pack.getdeltachain(name, node)

            except KeyError:

                pass

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

    def add(self, name, node, data):

        raise RuntimeError(b"cannot add to datapackstore")

class datapack(basepack.basepack):

    INDEXSUFFIX = INDEXSUFFIX

    PACKSUFFIX = PACKSUFFIX

    # Format is <node><delta offset><pack data offset><pack data size>

    # See the mutabledatapack doccomment for more details.

    INDEXFORMAT = b'!20siQQ'

    INDEXENTRYLENGTH = 40

    SUPPORTED_VERSIONS = [2]

    def getmissing(self, keys):

        missing = []

        for name, node in keys:

            value = self._find(node)

            if not value:

                missing.append((name, node))

        return missing

    def get(self, name, node):

        raise RuntimeError(

            b"must use getdeltachain with datapack (%s:%s)" % (name, hex(node))

        )

    def getmeta(self, name, node):

        value = self._find(node)

        if value is None:

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

        node, deltabaseoffset, offset, size = value

        rawentry = self._data[offset : offset + size]

        # see docstring of mutabledatapack for the format

        offset = 0

        offset += struct.unpack_from(b'!H', rawentry, offset)[0] + 2  # filename

        offset += 40  # node, deltabase node

        offset += struct.unpack_from(b'!Q', rawentry, offset)[0] + 8  # delta

        metalen = struct.unpack_from(b'!I', rawentry, offset)[0]

        offset += 4

        meta = shallowutil.parsepackmeta(rawentry[offset : offset + metalen])

        return meta

    def getdelta(self, name, node):

        value = self._find(node)

        if value is None:

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

        node, deltabaseoffset, offset, size = value

        entry = self._readentry(offset, size, getmeta=True)

        filename, node, deltabasenode, delta, meta = entry

        # If we've read a lot of data from the mmap, free some memory.

        self.freememory()

        return delta, filename, deltabasenode, meta

    def getdeltachain(self, name, node):

        value = self._find(node)

        if value is None:

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

        params = self.params

        # Precompute chains

        chain = [value]

        deltabaseoffset = value[1]

        entrylen = self.INDEXENTRYLENGTH

        while (

            deltabaseoffset != FULLTEXTINDEXMARK

            and deltabaseoffset != NOBASEINDEXMARK

        ):

            loc = params.indexstart + deltabaseoffset

            value = struct.unpack(

                self.INDEXFORMAT, self._index[loc : loc + entrylen]

            )

            deltabaseoffset = value[1]

            chain.append(value)

        # Read chain data

        deltachain = []

        for node, deltabaseoffset, offset, size in chain:

            filename, node, deltabasenode, delta = self._readentry(offset, size)

            deltachain.append((filename, node, filename, deltabasenode, delta))

        # If we've read a lot of data from the mmap, free some memory.

        self.freememory()

        return deltachain

    def _readentry(self, offset, size, getmeta=False):

        rawentry = self._data[offset : offset + size]

        self._pagedin += len(rawentry)

        # <2 byte len> + <filename>

        lengthsize = 2

        filenamelen = struct.unpack(b'!H', rawentry[:2])[0]

        filename = rawentry[lengthsize : lengthsize + filenamelen]

        # <20 byte node> + <20 byte deltabase>

        nodestart = lengthsize + filenamelen

        deltabasestart = nodestart + NODELENGTH

        node = rawentry[nodestart:deltabasestart]

        deltabasenode = rawentry[deltabasestart : deltabasestart + NODELENGTH]

        # <8 byte len> + <delta>

        deltastart = deltabasestart + NODELENGTH

        rawdeltalen = rawentry[deltastart : deltastart + 8]

        deltalen = struct.unpack(b'!Q', rawdeltalen)[0]

        delta = rawentry[deltastart + 8 : deltastart + 8 + deltalen]

        delta = self._decompress(delta)

        if getmeta:

            metastart = deltastart + 8 + deltalen

            metalen = struct.unpack_from(b'!I', rawentry, metastart)[0]

            rawmeta = rawentry[metastart + 4 : metastart + 4 + metalen]

            meta = shallowutil.parsepackmeta(rawmeta)

            return filename, node, deltabasenode, delta, meta

        else:

            return filename, node, deltabasenode, delta

    def _decompress(self, data):

        return zlib.decompress(data)

    def add(self, name, node, data):

        raise RuntimeError(b"cannot add to datapack (%s:%s)" % (name, node))

    def _find(self, node):

        params = self.params

        fanoutkey = struct.unpack(

            params.fanoutstruct, node[: params.fanoutprefix]

        )[0]

        fanout = self._fanouttable

        start = fanout[fanoutkey] + params.indexstart

        indexend = self._indexend

        # Scan forward to find the first non-same entry, which is the upper

        # bound.

        for i in pycompat.xrange(fanoutkey + 1, params.fanoutcount):

            end = fanout[i] + params.indexstart

            if end != start:

                break

        else:

            end = indexend

        # Bisect between start and end to find node

        index = self._index

        startnode = index[start : start + NODELENGTH]

        endnode = index[end : end + NODELENGTH]

        entrylen = self.INDEXENTRYLENGTH

        if startnode == node:

            entry = index[start : start + entrylen]

        elif endnode == node:

            entry = index[end : end + entrylen]

        else:

            while start < end - entrylen:

                mid = start + (end - start) // 2

                mid = mid - ((mid - params.indexstart) % entrylen)

                midnode = index[mid : mid + NODELENGTH]

                if midnode == node:

                    entry = index[mid : mid + entrylen]

                    break

                if node > midnode:

                    start = mid

                elif node < midnode:

                    end = mid

            else:

                return None

        return struct.unpack(self.INDEXFORMAT, entry)

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

        for filename, node in self:

            ledger.markdataentry(self, filename, node)

    def cleanup(self, ledger):

        entries = ledger.sources.get(self, [])

        allkeys = set(self)

        repackedkeys = {

            (e.filename, e.node) for e in entries if e.datarepacked or e.gced

        }

        if len(allkeys - repackedkeys) == 0:

            if self.path not in ledger.created:

                util.unlinkpath(self.indexpath, ignoremissing=True)

                util.unlinkpath(self.packpath, ignoremissing=True)

    def __iter__(self):

        for f, n, deltabase, deltalen in self.iterentries():

            yield f, n

    def iterentries(self):

        # Start at 1 to skip the header

        offset = 1

        data = self._data

        while offset < self.datasize:

            oldoffset = offset

            # <2 byte len> + <filename>

            filenamelen = struct.unpack(b'!H', data[offset : offset + 2])[0]

            offset += 2

            filename = data[offset : offset + filenamelen]

            offset += filenamelen

            # <20 byte node>

            node = data[offset : offset + constants.NODESIZE]

            offset += constants.NODESIZE

            # <20 byte deltabase>

            deltabase = data[offset : offset + constants.NODESIZE]

            offset += constants.NODESIZE

            # <8 byte len> + <delta>

            rawdeltalen = data[offset : offset + 8]

            deltalen = struct.unpack(b'!Q', rawdeltalen)[0]

            offset += 8

            # TODO(augie): we should store a header that is the

            # uncompressed size.

            uncompressedlen = len(

                self._decompress(data[offset : offset + deltalen])

            )

            offset += deltalen

            # <4 byte len> + <metadata-list>

            metalen = struct.unpack_from(b'!I', data, offset)[0]

            offset += 4 + metalen

            yield (filename, node, deltabase, uncompressedlen)

            # If we've read a lot of data from the mmap, free some memory.

            self._pagedin += offset - oldoffset

            if self.freememory():

                data = self._data

class mutabledatapack(basepack.mutablebasepack):

    """A class for constructing and serializing a datapack file and index.

    A datapack is a pair of files that contain the revision contents for various

    file revisions in Mercurial. It contains only revision contents (like file

    contents), not any history information.

    It consists of two files, with the following format. All bytes are in

    network byte order (big endian).

    .datapack

        The pack itself is a series of revision deltas with some basic header

        information on each. A revision delta may be a fulltext, represented by

        a deltabasenode equal to the nullid.

        datapack = <version: 1 byte>

                   [<revision>,...]

        revision = <filename len: 2 byte unsigned int>

                   <filename>

                   <node: 20 byte>

                   <deltabasenode: 20 byte>

                   <delta len: 8 byte unsigned int>

                   <delta>

                   <metadata-list len: 4 byte unsigned int> [1]

                   <metadata-list>                          [1]

        metadata-list = [<metadata-item>, ...]

        metadata-item = <metadata-key: 1 byte>

                        <metadata-value len: 2 byte unsigned>

                        <metadata-value>

        metadata-key could be METAKEYFLAG or METAKEYSIZE or other single byte

        value in the future.

    .dataidx

        The index file consists of two parts, the fanout and the index.

        The index is a list of index entries, sorted by node (one per revision

        in the pack). Each entry has:

        - node (The 20 byte node of the entry; i.e. the commit hash, file node

                hash, etc)

        - deltabase index offset (The location in the index of the deltabase for

                                  this entry. The deltabase is the next delta in

                                  the chain, with the chain eventually

                                  terminating in a full-text, represented by a

                                  deltabase offset of -1. This lets us compute

                                  delta chains from the index, then do

                                  sequential reads from the pack if the revision

                                  are nearby on disk.)

        - pack entry offset (The location of this entry in the datapack)

        - pack content size (The on-disk length of this entry's pack data)

        The fanout is a quick lookup table to reduce the number of steps for

        bisecting the index. It is a series of 4 byte pointers to positions

        within the index. It has 2^16 entries, which corresponds to hash

        prefixes [0000, 0001,..., FFFE, FFFF]. Example: the pointer in slot

        4F0A points to the index position of the first revision whose node

        starts with 4F0A. This saves log(2^16)=16 bisect steps.

        dataidx = <fanouttable>

                  <index>

        fanouttable = [<index offset: 4 byte unsigned int>,...] (2^16 entries)

        index = [<index entry>,...]

        indexentry = <node: 20 byte>

                     <deltabase location: 4 byte signed int>

                     <pack entry offset: 8 byte unsigned int>

                     <pack entry size: 8 byte unsigned int>

    [1]: new in version 1.

    """

    INDEXSUFFIX = INDEXSUFFIX