# Copyright 2009-2010 Gregory P. Ward

# Copyright 2009-2010 Intelerad Medical Systems Incorporated

# Copyright 2010-2011 Fog Creek Software

# Copyright 2010-2011 Unity Technologies

#

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

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

'''base class for store implementations and store-related utility code'''

from mercurial.i18n import _

import lfutil

class StoreError(Exception):

    '''Raised when there is a problem getting files from or putting

    files to a central store.'''

    def __init__(self, filename, hash, url, detail):

        self.filename = filename

        self.hash = hash

        self.url = url

        self.detail = detail

    def longmessage(self):

        return (_("error getting id %s from url %s for file %s: %s\n") %

                 (self.hash, util.hidepassword(self.url), self.filename,

                  self.detail))

    def __str__(self):

        return "%s: %s" % (util.hidepassword(self.url), self.detail)

class basestore(object):

    def __init__(self, ui, repo, url):

        self.ui = ui

        self.repo = repo

        self.url = url

    def put(self, source, hash):

        '''Put source file into the store so it can be retrieved by hash.'''

        raise NotImplementedError('abstract method')

    def exists(self, hashes):

        '''Check to see if the store contains the given hashes. Given an

        iterable of hashes it returns a mapping from hash to bool.'''

        raise NotImplementedError('abstract method')

    def get(self, files):

        '''Get the specified largefiles from the store and write to local

        files under repo.root.  files is a list of (filename, hash)

        tuples.  Return (success, missing), lists of files successfully

        downloaded and those not found in the store.  success is a list

        of (filename, hash) tuples; missing is a list of filenames that

        we could not get.  (The detailed error message will already have

        been presented to the user, so missing is just supplied as a

        summary.)'''

        success = []

        missing = []

        ui = self.ui

        at = 0

        available = self.exists(set(hash for (_filename, hash) in files))

        for filename, hash in files:

            ui.progress(_('getting largefiles'), at, unit=_('files'),

                total=len(files))

            at += 1

            ui.note(_('getting %s:%s\n') % (filename, hash))

            if not available.get(hash):

                ui.warn(_('%s: largefile %s not available from %s\n')

                        % (filename, hash, util.hidepassword(self.url)))

                missing.append(filename)

                continue

            if self._gethash(filename, hash):

                success.append((filename, hash))

            else:

                missing.append(filename)

        ui.progress(_('getting largefiles'), None)

        return (success, missing)

    def _gethash(self, filename, hash):

        """Get file with the provided hash and store it in the local repo's

        store and in the usercache.

        filename is for informational messages only.

        """

        util.makedirs(lfutil.storepath(self.repo, ''))

        storefilename = lfutil.storepath(self.repo, hash)

        tmpname = storefilename + '.tmp'

        tmpfile = util.atomictempfile(tmpname,

                                      createmode=self.repo.store.createmode)

        try:

            gothash = self._getfile(tmpfile, filename, hash)

        except StoreError as err:

            self.ui.warn(err.longmessage())

            gothash = ""

        tmpfile.close()

        if gothash != hash:

            if gothash != "":

                self.ui.warn(_('%s: data corruption (expected %s, got %s)\n')

                             % (filename, hash, gothash))

            util.unlink(tmpname)

            return False

        util.rename(tmpname, storefilename)

        lfutil.linktousercache(self.repo, hash)

        return True

    def verify(self, revs, contents=False):

        '''Verify the existence (and, optionally, contents) of every big

        file revision referenced by every changeset in revs.

        Return 0 if all is well, non-zero on any errors.'''

        self.ui.status(_('searching %d changesets for largefiles\n') %

                       len(revs))

        verified = set()                # set of (filename, filenode) tuples

        filestocheck = []               # list of (cset, filename, expectedhash)

        for rev in revs:

            cctx = self.repo[rev]

            cset = "%d:%s" % (cctx.rev(), node.short(cctx.node()))

            for standin in cctx:

                filename = lfutil.splitstandin(standin)

                if filename:

                    fctx = cctx[standin]

                    key = (filename, fctx.filenode())

                    if key not in verified:

                        verified.add(key)

                        expectedhash = fctx.data()[0:40]

                        filestocheck.append((cset, filename, expectedhash))

        failed = self._verifyfiles(contents, filestocheck)

        numrevs = len(verified)

        numlfiles = len(set([fname for (fname, fnode) in verified]))

        if contents:

            self.ui.status(

                _('verified contents of %d revisions of %d largefiles\n')

                % (numrevs, numlfiles))

        else:

            self.ui.status(

                _('verified existence of %d revisions of %d largefiles\n')

                % (numrevs, numlfiles))

        return int(failed)

    def _getfile(self, tmpfile, filename, hash):

        '''Fetch one revision of one file from the store and write it

        to tmpfile.  Compute the hash of the file on-the-fly as it

        downloads and return the hash.  Close tmpfile.  Raise

        StoreError if unable to download the file (e.g. it does not

        exist in the store).'''

        raise NotImplementedError('abstract method')

    def _verifyfiles(self, contents, filestocheck):

        '''Perform the actual verification of files in the store.

        'contents' controls verification of content hash.

        'filestocheck' is list of files to check.

        Returns _true_ if any problems are found!

        '''

        raise NotImplementedError('abstract method')