import cStringIO
import getpass
import os
import pwd
import shutil
import sys
import tempfile

from svn import client
from svn import core
from svn import delta
from svn import ra

svn_config = core.svn_config_get_config(None)


def user_pass_prompt(realm, default_username, ms, pool):
    creds = core.svn_auth_cred_simple_t()
    creds.may_save = ms
    if default_username:
        sys.stderr.write('Auth realm: %s\n' % (realm,))
        creds.username = default_username
    else:
        sys.stderr.write('Auth realm: %s\n' % (realm,))
        sys.stderr.write('Username: ')
        sys.stderr.flush()
        creds.username = sys.stdin.readline().strip()
    creds.password = getpass.getpass('Password for %s: ' % creds.username)
    return creds

def _create_auth_baton(pool):
    """Create a Subversion authentication baton. """
    # Give the client context baton a suite of authentication
    # providers.h
    providers = [
        client.get_simple_provider(),
        client.get_username_provider(),
        client.get_ssl_client_cert_file_provider(),
        client.get_ssl_client_cert_pw_file_provider(),
        client.get_ssl_server_trust_file_provider(),
        ]
    # Platform-dependant authentication methods
    if hasattr(client, 'get_windows_simple_provider'):
        providers.append(client.get_windows_simple_provider())
    if hasattr(client, 'get_keychain_simple_provider'):
        providers.append(client.get_keychain_simple_provider())
    providers.extend([client.get_simple_prompt_provider(user_pass_prompt, 2),
                     ])
    return core.svn_auth_open(providers, pool)


class Revision(object):
    """Wrapper for a Subversion revision.
    """
    def __init__(self, revnum, author, message, date, paths, strip_path=''):
        self.revnum, self.author, self.message = revnum, author, message
        # TODO parse this into a datetime
        self.date = date
        self.paths = {}
        for p in paths:
            self.paths[p[len(strip_path):]] = paths[p]

    def __str__(self):
        return 'r%d by %s' % (self.revnum, self.author)

class SubversionRepo(object):
    """Wrapper for a Subversion repository.

    This uses the SWIG Python bindings, and will only work on svn >= 1.4.
    It takes a required param, the URL.
    """
    def __init__(self, url=''):
        self.svn_url = url
        self.auth_baton_pool = core.Pool()
        self.auth_baton = _create_auth_baton(self.auth_baton_pool)

        self.init_ra_and_client()
        self.uuid = ra.get_uuid(self.ra, self.pool)
        repo_root = ra.get_repos_root(self.ra, self.pool)
        # *will* have a leading '/', would not if we used get_repos_root2
        self.subdir = url[len(repo_root):]
        if not self.subdir or self.subdir[-1] != '/':
            self.subdir += '/'

    def init_ra_and_client(self):
        """Initializes the RA and client layers, because sometimes getting
        unified diffs runs the remote server out of open files.
        """
        # while we're in here we'll recreate our pool
        self.pool = core.Pool()
        self.client_context = client.create_context()
        self.uname = str(pwd.getpwuid(os.getuid())[0])
        core.svn_auth_set_parameter(self.auth_baton,
                                    core.SVN_AUTH_PARAM_DEFAULT_USERNAME,
                                    self.uname)

        self.client_context.auth_baton = self.auth_baton
        self.client_context.config = svn_config
        self.ra = client.open_ra_session(self.svn_url.encode('utf8'),
                                         self.client_context)


    @property
    def HEAD(self):
        return ra.get_latest_revnum(self.ra, self.pool)

    @property
    def START(self):
        return 0

    @property
    def branches(self):
        """Get the branches defined in this repo assuming a standard layout.
        """
        branches = self.list_dir('branches').keys()
        branch_info = {}
        head=self.HEAD
        for b in branches:
            b_path = 'branches/%s' %b
            hist_gen = self.fetch_history_at_paths([b_path], stop=head)
            hist = hist_gen.next()
            source, source_rev = self._get_copy_source(b_path, cached_head=head)
            # This if statement guards against projects that have non-ancestral
            # branches by not listing them has branches
            # Note that they probably are really ancestrally related, but there
            # is just no way for us to know how.
            if source is not None and source_rev is not None:
                branch_info[b] = (source, source_rev, hist.revnum)
        return branch_info

    @property
    def tags(self):
        """Get the current tags in this repo assuming a standard layout.

        This returns a dictionary of tag: (source path, source rev)
        """
        tags = self.list_dir('tags').keys()
        tag_info = {}
        head = self.HEAD
        for t in tags:
            tag_info[t] = self._get_copy_source('tags/%s' % t,
                                                cached_head=head)
        return tag_info

    def _get_copy_source(self, path, cached_head=None):
        """Get copy revision for the given path, assuming it was meant to be
        a copy of the entire tree.
        """
        if not cached_head:
            cached_head = self.HEAD
        hist_gen = self.fetch_history_at_paths([path], stop=cached_head)
        hist = hist_gen.next()
        if hist.paths[path].copyfrom_path is None:
            return None, None
        source = hist.paths[path].copyfrom_path
        source_rev = 0
        for p in hist.paths:
            if hist.paths[p].copyfrom_rev:
                # We assume that the revision of the source tree as it was
                # copied was actually the revision of the highest revision
                # copied item. This could be wrong, but in practice it will
                # *probably* be correct
                if source_rev < hist.paths[p].copyfrom_rev:
                    source_rev = hist.paths[p].copyfrom_rev
        source = source[len(self.subdir):]
        return source, source_rev

    def list_dir(self, dir, revision=None):
        """List the contents of a server-side directory.

        Returns a dict-like object with one dict key per directory entry.

        Args:
          dir: the directory to list, no leading slash
          rev: the revision at which to list the directory, defaults to HEAD
        """
        if dir[-1] == '/':
            dir = dir[:-1]
        if revision is None:
            revision = self.HEAD
        r = ra.get_dir2(self.ra, dir, revision, core.SVN_DIRENT_KIND, self.pool)
        folders, props, junk = r
        return folders

    def revisions(self, start=None, chunk_size=1000):
        """Load the history of this repo.

        This is LAZY. It returns a generator, and fetches a small number
        of revisions at a time.

        The reason this is lazy is so that you can use the same repo object
        to perform RA calls to get deltas.
        """
        # NB: you'd think this would work, but you'd be wrong. I'm pretty
        # convinced there must be some kind of svn bug here.
        #return self.fetch_history_at_paths(['tags', 'trunk', 'branches'],
        #                                   start=start)
        # this does the same thing, but at the repo root + filtering. It's
        # kind of tough cookies, sadly.
        for r in self.fetch_history_at_paths([''], start=start,
                                             chunk_size=chunk_size):
            should_yield = False
            i = 0
            paths = list(r.paths.keys())
            while i < len(paths) and not should_yield:
                p = paths[i]
                if (p.startswith('trunk') or p.startswith('tags')
                    or p.startswith('branches')):
                    should_yield = True
                i += 1
            if should_yield:
                yield r


    def fetch_history_at_paths(self, paths, start=None, stop=None,
                               chunk_size=1000):
        revisions = []
        def callback(paths, revnum, author, date, message, pool):
            r = Revision(revnum, author, message, date, paths,
                         strip_path=self.subdir)
            revisions.append(r)
        if not start:
            start = self.START
        if not stop:
            stop = self.HEAD
        while stop > start:
            ra.get_log(self.ra, paths,
                        start+1,
                        stop,
                        chunk_size, #limit of how many log messages to load
                        True, # don't need to know changed paths
                        True, # stop on copies
                        callback,
                        self.pool)
            if len(revisions) < chunk_size:
                # this means there was no history for the path, so force the
                # loop to exit
                start = stop
            else:
                start = revisions[-1].revnum
            while len(revisions) > 0:
                yield revisions[0]
                revisions.pop(0)

    def commit(self, paths, message, file_data, base_revision, dirs):
        """Commits the appropriate targets from revision in editor's store.
        """
        self.init_ra_and_client()
        commit_info = []
        def commit_cb(_commit_info, pool):
            commit_info.append(_commit_info)
        editor, edit_baton = ra.get_commit_editor2(self.ra,
                                                   message,
                                                   commit_cb,
                                                   None,
                                                   False)
        checksum = []
        def driver_cb(parent, path, pool):
            if path in dirs:
                return baton
            base_text, new_text, action = file_data[path]
            compute_delta = True
            if action == 'modify':
                baton = editor.open_file(path, parent, base_revision, pool)
            elif action == 'add':
                try:
                    baton = editor.add_file(path, parent, None, -1, pool)
                except (core.SubversionException, TypeError), e:
                    print e.message
                    raise
            elif action == 'delete':
                baton = editor.delete_entry(path, base_revision, parent, pool)
                compute_delta = False

            if compute_delta:
                handler, wh_baton = editor.apply_textdelta(baton, None,
                                                           self.pool)

                txdelta_stream = delta.svn_txdelta(
                    cStringIO.StringIO(base_text), cStringIO.StringIO(new_text),
                    self.pool)
                delta.svn_txdelta_send_txstream(txdelta_stream, handler,
                                                wh_baton, pool)

        delta.path_driver(editor, edit_baton, base_revision, paths, driver_cb,
                          self.pool)
        editor.close_edit(edit_baton, self.pool)

    def get_replay(self, revision, editor, oldest_rev_i_have=0):
        # this method has a tendency to chew through RAM if you don't re-init
        self.init_ra_and_client()
        e_ptr, e_baton = delta.make_editor(editor)
        try:
            ra.replay(self.ra, revision, oldest_rev_i_have, True, e_ptr,
                      e_baton, self.pool)
        except core.SubversionException, e:
            # can I depend on this number being constant?
            if (e.message == "Server doesn't support the replay command"
                or e.apr_err == 170003):
                raise SubversionRepoCanNotReplay, ('This Subversion server '
                   'is older than 1.4.0, and cannot satisfy replay requests.')
            else:
                raise

    def get_unified_diff(self, path, revision, other_path=None, other_rev=None,
                         deleted=True, ignore_type=False):
        """Gets a unidiff of path at revision against revision-1.
        """
        # works around an svn server keeping too many open files (observed
        # in an svnserve from the 1.2 era)
        self.init_ra_and_client()

        old_cwd = os.getcwd()
        assert path[0] != '/'
        url = self.svn_url + '/' + path
        url2 = url
        if other_path is not None:
            url2 = self.svn_url + '/' + other_path
        if other_rev is None:
            other_rev = revision - 1
        tmpdir = tempfile.mkdtemp('svnwrap_temp')
        # hot tip: the swig bridge doesn't like StringIO for these bad boys
        out_path = os.path.join(tmpdir, 'diffout')
        error_path = os.path.join(tmpdir, 'differr')
        out = open(out_path, 'w')
        err = open(error_path, 'w')
        rev_old = core.svn_opt_revision_t()
        rev_old.kind = core.svn_opt_revision_number
        rev_old.value.number = other_rev
        rev_new = core.svn_opt_revision_t()
        rev_new.kind = core.svn_opt_revision_number
        rev_new.value.number = revision
        client.diff3([], url2, rev_old, url, rev_new, True, True,
                     deleted, ignore_type, 'UTF-8', out, err,
                     self.client_context, self.pool)
        out.close()
        err.close()
        assert len(open(error_path).read()) == 0
        diff = open(out_path).read()
        os.chdir(old_cwd)
        shutil.rmtree(tmpdir)
        return diff

    def get_file(self, path, revision):
        out = cStringIO.StringIO()
        tmpdir = tempfile.mkdtemp('svnwrap_temp')
        # hot tip: the swig bridge doesn't like StringIO for these bad boys
        out_path = os.path.join(tmpdir, 'diffout')
        out = open(out_path, 'w')
        ra.get_file(self.ra, path,revision, out , None)
        out.close()
        x = open(out_path).read()
        shutil.rmtree(tmpdir)
        return x

    def proplist(self, path, revision, recurse=False):
        rev = core.svn_opt_revision_t()
        rev.kind = core.svn_opt_revision_number
        rev.value.number = revision
        if path[-1] == '/':
            path = path[:-1]
        if path[0] == '/':
            path = path[1:]
        pl = dict(client.proplist2(self.svn_url+'/'+path, rev, rev, True,
                                   self.client_context, self.pool))
        pl2 = {}
        for key, value in pl.iteritems():
            pl2[key[len(self.svn_url)+1:]] = value
        return pl2

    def fetch_all_files_to_dir(self, path, revision, checkout_path):
        rev = core.svn_opt_revision_t()
        rev.kind = core.svn_opt_revision_number
        rev.value.number = revision
        client.export3(self.svn_url+'/'+path, checkout_path, rev,
                       rev, True, True, True, 'LF', # should be 'CRLF' on win32
                       self.client_context, self.pool)

class SubversionRepoCanNotReplay(Exception):
    """Exception raised when the svn server is too old to have replay.
    """