# store.py - repository store handling for Mercurial

#

# Copyright 2008 Matt Mackall <mpm@selenic.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from i18n import _

import osutil, util

import os, stat

_sha = util.sha1

# This avoids a collision between a file named foo and a dir named

# foo.i or foo.d

def encodedir(path):

    if not path.startswith('data/'):

        return path

    return (path

            .replace(".hg/", ".hg.hg/")

            .replace(".i/", ".i.hg/")

            .replace(".d/", ".d.hg/"))

def decodedir(path):

    if not path.startswith('data/') or ".hg/" not in path:

        return path

    return (path

            .replace(".d.hg/", ".d/")

            .replace(".i.hg/", ".i/")

            .replace(".hg.hg/", ".hg/"))

def _buildencodefun():

    e = '_'

    win_reserved = [ord(x) for x in '\\:*?"<>|']

    cmap = dict([(chr(x), chr(x)) for x in xrange(127)])

    for x in (range(32) + range(126, 256) + win_reserved):

        cmap[chr(x)] = "~%02x" % x

    for x in range(ord("A"), ord("Z")+1) + [ord(e)]:

        cmap[chr(x)] = e + chr(x).lower()

    dmap = {}

    for k, v in cmap.iteritems():

        dmap[v] = k

    def decode(s):

        i = 0

        while i < len(s):

            for l in xrange(1, 4):

                try:

                    yield dmap[s[i:i + l]]

                    i += l

                    break

                except KeyError:

                    pass

            else:

                raise KeyError

    return (lambda s: "".join([cmap[c] for c in encodedir(s)]),

            lambda s: decodedir("".join(list(decode(s)))))

encodefilename, decodefilename = _buildencodefun()

def _build_lower_encodefun():

    win_reserved = [ord(x) for x in '\\:*?"<>|']

    cmap = dict([(chr(x), chr(x)) for x in xrange(127)])

    for x in (range(32) + range(126, 256) + win_reserved):

        cmap[chr(x)] = "~%02x" % x

    for x in range(ord("A"), ord("Z")+1):

        cmap[chr(x)] = chr(x).lower()

    return lambda s: "".join([cmap[c] for c in s])

lowerencode = _build_lower_encodefun()

_windows_reserved_filenames = '''con prn aux nul

    com1 com2 com3 com4 com5 com6 com7 com8 com9

    lpt1 lpt2 lpt3 lpt4 lpt5 lpt6 lpt7 lpt8 lpt9'''.split()

def _auxencode(path, dotencode):

    res = []

    for n in path.split('/'):

        if n:

            base = n.split('.')[0]

            if base and (base in _windows_reserved_filenames):

                # encode third letter ('aux' -> 'au~78')

                ec = "~%02x" % ord(n[2])

                n = n[0:2] + ec + n[3:]

            if n[-1] in '. ':

                # encode last period or space ('foo...' -> 'foo..~2e')

                n = n[:-1] + "~%02x" % ord(n[-1])

            if dotencode and n[0] in '. ':

                n = "~%02x" % ord(n[0]) + n[1:]

        res.append(n)

    return '/'.join(res)

MAX_PATH_LEN_IN_HGSTORE = 120

DIR_PREFIX_LEN = 8

_MAX_SHORTENED_DIRS_LEN = 8 * (DIR_PREFIX_LEN + 1) - 4

def _hybridencode(path, auxencode):

    '''encodes path with a length limit

    Encodes all paths that begin with 'data/', according to the following.

    Default encoding (reversible):

    Encodes all uppercase letters 'X' as '_x'. All reserved or illegal

    characters are encoded as '~xx', where xx is the two digit hex code

    of the character (see encodefilename).

    Relevant path components consisting of Windows reserved filenames are

    masked by encoding the third character ('aux' -> 'au~78', see auxencode).

    Hashed encoding (not reversible):

    If the default-encoded path is longer than MAX_PATH_LEN_IN_HGSTORE, a

    non-reversible hybrid hashing of the path is done instead.

    This encoding uses up to DIR_PREFIX_LEN characters of all directory

    levels of the lowerencoded path, but not more levels than can fit into

    _MAX_SHORTENED_DIRS_LEN.

    Then follows the filler followed by the sha digest of the full path.

    The filler is the beginning of the basename of the lowerencoded path

    (the basename is everything after the last path separator). The filler

    is as long as possible, filling in characters from the basename until

    the encoded path has MAX_PATH_LEN_IN_HGSTORE characters (or all chars

    of the basename have been taken).

    The extension (e.g. '.i' or '.d') is preserved.

    The string 'data/' at the beginning is replaced with 'dh/', if the hashed

    encoding was used.

    '''

    if not path.startswith('data/'):

        return path

    # escape directories ending with .i and .d

    path = encodedir(path)

    ndpath = path[len('data/'):]

    res = 'data/' + auxencode(encodefilename(ndpath))

    if len(res) > MAX_PATH_LEN_IN_HGSTORE:

        digest = _sha(path).hexdigest()

        aep = auxencode(lowerencode(ndpath))

        _root, ext = os.path.splitext(aep)

        parts = aep.split('/')

        basename = parts[-1]

        sdirs = []

        for p in parts[:-1]:

            d = p[:DIR_PREFIX_LEN]

            if d[-1] in '. ':

                # Windows can't access dirs ending in period or space

                d = d[:-1] + '_'

            t = '/'.join(sdirs) + '/' + d

            if len(t) > _MAX_SHORTENED_DIRS_LEN:

                break

            sdirs.append(d)

        dirs = '/'.join(sdirs)

        if len(dirs) > 0:

            dirs += '/'

        res = 'dh/' + dirs + digest + ext

        space_left = MAX_PATH_LEN_IN_HGSTORE - len(res)

        if space_left > 0:

            filler = basename[:space_left]

            res = 'dh/' + dirs + filler + digest + ext

    return res

def _calcmode(path):

    try:

        # files in .hg/ will be created using this mode

        mode = os.stat(path).st_mode

            # avoid some useless chmods

        if (0777 & ~util.umask) == (0777 & mode):

            mode = None

    except OSError:

        mode = None

    return mode

_data = 'data 00manifest.d 00manifest.i 00changelog.d 00changelog.i'

class basicstore(object):

    '''base class for local repository stores'''

    def __init__(self, path, opener, pathjoiner):

        self.pathjoiner = pathjoiner

        self.path = path

        self.createmode = _calcmode(path)

        op = opener(self.path)

        op.createmode = self.createmode

        self.opener = lambda f, *args, **kw: op(encodedir(f), *args, **kw)

    def join(self, f):

        return self.pathjoiner(self.path, encodedir(f))

    def _walk(self, relpath, recurse):

        '''yields (unencoded, encoded, size)'''

        path = self.pathjoiner(self.path, relpath)

        striplen = len(self.path) + len(os.sep)

        l = []

        if os.path.isdir(path):

            visit = [path]

            while visit:

                p = visit.pop()

                for f, kind, st in osutil.listdir(p, stat=True):

                    fp = self.pathjoiner(p, f)

                    if kind == stat.S_IFREG and f[-2:] in ('.d', '.i'):

                        n = util.pconvert(fp[striplen:])

                        l.append((decodedir(n), n, st.st_size))

                    elif kind == stat.S_IFDIR and recurse:

                        visit.append(fp)

        return sorted(l)

    def datafiles(self):

        return self._walk('data', True)

    def walk(self):

        '''yields (unencoded, encoded, size)'''

        # yield data files first

        for x in self.datafiles():

            yield x

        # yield manifest before changelog

        for x in reversed(self._walk('', False)):

            yield x

    def copylist(self):

        return ['requires'] + _data.split()

class encodedstore(basicstore):

    def __init__(self, path, opener, pathjoiner):

        self.pathjoiner = pathjoiner

        self.path = self.pathjoiner(path, 'store')

        self.createmode = _calcmode(self.path)

        op = opener(self.path)

        op.createmode = self.createmode

        self.opener = lambda f, *args, **kw: op(encodefilename(f), *args, **kw)

    def datafiles(self):

        for a, b, size in self._walk('data', True):

            try:

                a = decodefilename(a)

            except KeyError:

                a = None

            yield a, b, size

    def join(self, f):

        return self.pathjoiner(self.path, encodefilename(f))

    def copylist(self):

        return (['requires', '00changelog.i'] +

                [self.pathjoiner('store', f) for f in _data.split()])

class fncache(object):

    # the filename used to be partially encoded

    # hence the encodedir/decodedir dance

    def __init__(self, opener):

        self.opener = opener

        self.entries = None

    def _load(self):

        '''fill the entries from the fncache file'''

        self.entries = set()

        try:

            fp = self.opener('fncache', mode='rb')

        except IOError:

            # skip nonexistent file

            return

        for n, line in enumerate(fp):

            if (len(line) < 2) or (line[-1] != '\n'):

                t = _('invalid entry in fncache, line %s') % (n + 1)

                raise util.Abort(t)

            self.entries.add(decodedir(line[:-1]))

        fp.close()

    def rewrite(self, files):

        fp = self.opener('fncache', mode='wb')

        for p in files:

            fp.write(encodedir(p) + '\n')

        fp.close()

        self.entries = set(files)

    def add(self, fn):

        if self.entries is None:

            self._load()

        if fn not in self.entries:

            self.opener('fncache', 'ab').write(encodedir(fn) + '\n')

            self.entries.add(fn)

    def __contains__(self, fn):

        if self.entries is None:

            self._load()

        return fn in self.entries

    def __iter__(self):

        if self.entries is None:

            self._load()

        return iter(self.entries)

class fncachestore(basicstore):

    def __init__(self, path, opener, pathjoiner, encode):

        self.encode = encode

        self.pathjoiner = pathjoiner

        self.path = self.pathjoiner(path, 'store')

        self.createmode = _calcmode(self.path)

        op = opener(self.path)

        op.createmode = self.createmode

        fnc = fncache(op)

        self.fncache = fnc

        def fncacheopener(path, mode='r', *args, **kw):

            if mode not in ('r', 'rb') and path.startswith('data/'):

                fnc.add(path)

            return op(self.encode(path), mode, *args, **kw)

        self.opener = fncacheopener

    def join(self, f):

        return self.pathjoiner(self.path, self.encode(f))

    def datafiles(self):

        rewrite = False

        existing = []

        pjoin = self.pathjoiner

        spath = self.path

        for f in self.fncache:

            ef = self.encode(f)

            try:

                st = os.stat(pjoin(spath, ef))

                yield f, ef, st.st_size

                existing.append(f)

            except OSError:

                # nonexistent entry

                rewrite = True

        if rewrite:

            # rewrite fncache to remove nonexistent entries

            # (may be caused by rollback / strip)

            self.fncache.rewrite(existing)

    def copylist(self):

        d = ('data dh fncache'

             ' 00manifest.d 00manifest.i 00changelog.d 00changelog.i')

        return (['requires', '00changelog.i'] +

                [self.pathjoiner('store', f) for f in d.split()])

def store(requirements, path, opener, pathjoiner=None):

    pathjoiner = pathjoiner or os.path.join

    if 'store' in requirements:

        if 'fncache' in requirements:

            auxencode = lambda f: _auxencode(f, 'dotencode' in requirements)

            encode = lambda f: _hybridencode(f, auxencode)

            return fncachestore(path, opener, pathjoiner, encode)

        return encodedstore(path, opener, pathjoiner)

    return basicstore(path, opener, pathjoiner)