# -*- coding: utf-8 -*-
#
# Copyright (C) 2012 Edgewall Software
# Copyright (C) 2006-2011, Herbert Valerio Riedel <hvr@gnu.org>
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://trac.edgewall.org/wiki/TracLicense.
#
# This software consists of voluntary contributions made by many
# individuals. For the exact contribution history, see the revision
# history and logs, available at http://trac.edgewall.org/log/.

from __future__ import with_statement 

from datetime import datetime
import os
import sys

from genshi.builder import tag

from trac.config import BoolOption, IntOption, PathOption, Option
from trac.core import *
from trac.util import TracError, shorten_line
from trac.util.datefmt import FixedOffset, to_timestamp, format_datetime
from trac.util.text import to_unicode
from trac.versioncontrol.api import Changeset, Node, Repository, \
                                    IRepositoryConnector, NoSuchChangeset, \
                                    NoSuchNode, IRepositoryProvider
from trac.versioncontrol.cache import CachedRepository, CachedChangeset
from trac.versioncontrol.web_ui import IPropertyRenderer
from trac.web.chrome import Chrome
from trac.wiki import IWikiSyntaxProvider

from tracopt.versioncontrol.git import PyGIT


class GitCachedRepository(CachedRepository):
    """Git-specific cached repository.

    Passes through {display,short,normalize}_rev
    """

    def display_rev(self, rev):
        return self.short_rev(rev)

    def short_rev(self, path):
        return self.repos.short_rev(path)

    def normalize_rev(self, rev):
        if not rev:
            return self.repos.get_youngest_rev()
        normrev = self.repos.git.verifyrev(rev)
        if normrev is None:
            raise NoSuchChangeset(rev)
        return normrev

    def get_changeset(self, rev):
        return GitCachedChangeset(self, self.normalize_rev(rev), self.env)


class GitCachedChangeset(CachedChangeset):
    """Git-specific cached changeset.

    Handles get_branches()
    """
    def get_branches(self):
        _rev = self.rev

        return [(k, v == _rev) for k, v in
                 self.repos.repos.git.get_branch_contains(_rev, resolve=True)]


def _last_iterable(iterable):
    """helper for detecting last iteration in for-loop"""
    i = iter(iterable)
    v = i.next()
    for nextv in i:
        yield False, v
        v = nextv
    yield True, v

def intersperse(sep, iterable):
    """The 'intersperse' generator takes an element and an iterable and
    intersperses that element between the elements of the iterable.

    inspired by Haskell's ``Data.List.intersperse``
    """

    for i, item in enumerate(iterable):
        if i: yield sep
        yield item

# helper
def _parse_user_time(s):
    """Parse author or committer attribute lines and return
    corresponding ``(user, timestamp)`` pair.
    """

    user, time, tz_str = s.rsplit(None, 2)
    tz = FixedOffset((int(tz_str) * 6) / 10, tz_str)
    time = datetime.fromtimestamp(float(time), tz)
    return user, time


class GitConnector(Component):

    implements(IRepositoryConnector, IWikiSyntaxProvider)

    def __init__(self):
        self._version = None

        try:
            self._version = PyGIT.Storage.git_version(git_bin=self.git_bin)
        except PyGIT.GitError, e:
            self.log.error("GitError: " + str(e))

        if self._version:
            self.log.info("detected GIT version %s" % self._version['v_str'])
            self.env.systeminfo.append(('GIT', self._version['v_str']))
            if not self._version['v_compatible']:
                self.log.error("GIT version %s installed not compatible"
                               "(need >= %s)" %
                               (self._version['v_str'],
                                self._version['v_min_str']))

    # IWikiSyntaxProvider methods

    def _format_sha_link(self, formatter, sha, label):
        # FIXME: this function needs serious rethinking...

        reponame = ''

        context = formatter.context
        while context:
            if context.resource.realm in ('source', 'changeset'):
                reponame = context.resource.parent.id
                break
            context = context.parent

        try:
            repos = self.env.get_repository(reponame)

            if not repos:
                raise Exception("Repository '%s' not found" % reponame)

            sha = repos.normalize_rev(sha) # in case it was abbreviated
            changeset = repos.get_changeset(sha)
            return tag.a(label, class_='changeset',
                         title=shorten_line(changeset.message),
                         href=formatter.href.changeset(sha, repos.reponame))
        except Exception, e:
            return tag.a(label, class_='missing changeset',
                         title=to_unicode(e), rel='nofollow')

    def get_wiki_syntax(self):
        yield (r'(?:\b|!)r?[0-9a-fA-F]{%d,40}\b' % self.wiki_shortrev_len,
               lambda fmt, sha, match:
                    self._format_sha_link(fmt, sha.startswith('r')
                                          and sha[1:] or sha, sha))

    def get_link_resolvers(self):
        yield ('sha', lambda fmt, _, sha, label, match=None:
                        self._format_sha_link(fmt, sha, label))

    # IRepositoryConnector methods

    persistent_cache = BoolOption('git', 'persistent_cache', 'false',
        """Enable persistent caching of commit tree.""")

    cached_repository = BoolOption('git', 'cached_repository', 'false',
        """Wrap `GitRepository` in `CachedRepository`.""")

    shortrev_len = IntOption('git', 'shortrev_len', 7,
        """The length at which a sha1 should be abbreviated to (must
        be >= 4 and <= 40).
        """)

    wiki_shortrev_len = IntOption('git', 'wikishortrev_len', 40,
        """The minimum length of an hex-string for which
        auto-detection as sha1 is performed (must be >= 4 and <= 40).
        """)

    trac_user_rlookup = BoolOption('git', 'trac_user_rlookup', 'false',
        """Enable reverse mapping of git email addresses to trac user ids
        (costly if you have many users).""")

    use_committer_id = BoolOption('git', 'use_committer_id', 'true',
        """Use git-committer id instead of git-author id for the
        changeset ''Author'' field.
        """)

    use_committer_time = BoolOption('git', 'use_committer_time', 'true',
        """Use git-committer timestamp instead of git-author timestamp
        for the changeset ''Timestamp'' field.
        """)

    git_fs_encoding = Option('git', 'git_fs_encoding', 'utf-8',
        """Define charset encoding of paths within git repositories.""")

    git_bin = PathOption('git', 'git_bin', '/usr/bin/git',
        """Path to git executable (relative to the Trac configuration folder,
        so better use an absolute path here).""")


    def get_supported_types(self):
        yield ('git', 8)

    def get_repository(self, type, dir, params):
        """GitRepository factory method"""
        assert type == 'git'

        if not (4 <= self.shortrev_len <= 40):
            raise TracError("[git] shortrev_len setting must be within [4..40]")

        if not (4 <= self.wiki_shortrev_len <= 40):
            raise TracError("[git] wikishortrev_len must be within [4..40]")

        if not self._version:
            raise TracError("GIT backend not available")
        elif not self._version['v_compatible']:
            raise TracError("GIT version %s installed not compatible"
                            "(need >= %s)" %
                            (self._version['v_str'],
                             self._version['v_min_str']))

        if self.trac_user_rlookup:
            def rlookup_uid(email):
                """Reverse map 'real name <user@domain.tld>' addresses to trac
                user ids.

                :return: `None` if lookup failed
                """

                try:
                    _, email = email.rsplit('<', 1)
                    email, _ = email.split('>', 1)
                    email = email.lower()
                except Exception:
                    return None

                for _uid, _name, _email in self.env.get_known_users():
                    try:
                        if email == _email.lower():
                            return _uid
                    except Exception:
                        continue

        else:
            def rlookup_uid(_):
                return None

        repos = GitRepository(dir, params, self.log,
                              persistent_cache=self.persistent_cache,
                              git_bin=self.git_bin,
                              git_fs_encoding=self.git_fs_encoding,
                              shortrev_len=self.shortrev_len,
                              rlookup_uid=rlookup_uid,
                              use_committer_id=self.use_committer_id,
                              use_committer_time=self.use_committer_time,
                              )

        if self.cached_repository:
            repos = GitCachedRepository(self.env, repos, self.log)
            self.log.debug("enabled CachedRepository for '%s'" % dir)
        else:
            self.log.debug("disabled CachedRepository for '%s'" % dir)

        return repos


class CsetPropertyRenderer(Component):

    implements(IPropertyRenderer)

    # relied upon by GitChangeset
    def match_property(self, name, mode):
        # default renderer has priority 1
        return (name in ('Parents',
                         'Children',
                         'Branches',
                         'git-committer',
                         'git-author',
                         ) and mode == 'revprop') and 4 or 0

    def render_property(self, name, mode, context, props):

        def sha_link(sha, label=None):
            # sha is assumed to be a non-abbreviated 40-chars sha id
            try:
                reponame = context.resource.parent.id
                repos = self.env.get_repository(reponame)
                cset = repos.get_changeset(sha)
                if label is None:
                    label = repos.display_rev(sha)

                return tag.a(label, class_='changeset',
                             title=shorten_line(cset.message),
                             href=context.href.changeset(sha, repos.reponame))

            except Exception, e:
                return tag.a(sha, class_='missing changeset',
                             title=to_unicode(e), rel='nofollow')

        if name == 'Branches':
            branches = props[name]

            # simple non-merge commit
            return tag(*intersperse(', ', (sha_link(rev, label)
                                           for label, rev in branches)))

        elif name in ('Parents', 'Children'):
            revs = props[name] # list of commit ids

            if name == 'Parents' and len(revs) > 1:
                # we got a merge...
                current_sha = context.resource.id
                reponame = context.resource.parent.id

                parent_links = intersperse(', ', \
                    ((sha_link(rev),
                      ' (',
                      tag.a('diff',
                            title="Diff against this parent (show the " \
                                  "changes merged from the other parents)",
                            href=context.href.changeset(current_sha, reponame,
                                                        old=rev)),
                      ')')
                     for rev in revs))

                return tag(list(parent_links),
                           tag.br(),
                           tag.span(tag("Note: this is a ",
                                        tag.strong("merge"), " changeset, "
                                        "the changes displayed below "
                                        "correspond to the merge itself."),
                                    class_='hint'),
                           tag.br(),
                           tag.span(tag("Use the ", tag.tt("(diff)"),
                                        " links above to see all the changes "
                                        "relative to each parent."),
                                    class_='hint'))

            # simple non-merge commit
            return tag(*intersperse(', ', map(sha_link, revs)))

        elif name in ('git-committer', 'git-author'):
            user_, time_ = props[name]
            _str = "%s (%s)" % (
                Chrome(self.env).format_author(context.req, user_),
                format_datetime(time_, tzinfo=context.req.tz))
            return unicode(_str)

        raise TracError("Internal error")


class GitRepository(Repository):
    """Git repository"""

    def __init__(self, path, params, log,
                 persistent_cache=False,
                 git_bin='git',
                 git_fs_encoding='utf-8',
                 shortrev_len=7,
                 rlookup_uid=lambda _: None,
                 use_committer_id=False,
                 use_committer_time=False,
                 ):

        self.logger = log
        self.gitrepo = path
        self.params = params
        self.shortrev_len = max(4, min(shortrev_len, 40))
        self.rlookup_uid = rlookup_uid
        self.use_committer_time = use_committer_time
        self.use_committer_id = use_committer_id

        self.git = PyGIT.StorageFactory(path, log, not persistent_cache,
                                        git_bin=git_bin,
                                        git_fs_encoding=git_fs_encoding) \
                        .getInstance()

        Repository.__init__(self, 'git:'+path, self.params, log)

    def close(self):
        self.git = None

    def get_youngest_rev(self):
        return self.git.youngest_rev()

    def get_oldest_rev(self):
        return self.git.oldest_rev()

    def normalize_path(self, path):
        return path and path.strip('/') or '/'

    def normalize_rev(self, rev):
        if not rev:
            return self.get_youngest_rev()
        normrev = self.git.verifyrev(rev)
        if normrev is None:
            raise NoSuchChangeset(rev)
        return normrev

    def display_rev(self, rev):
        return self.short_rev(rev)

    def short_rev(self, rev):
        return self.git.shortrev(self.normalize_rev(rev),
                                 min_len=self.shortrev_len)

    def get_node(self, path, rev=None, historian=None):
        return GitNode(self, path, rev, self.log, None, historian)

    def get_quickjump_entries(self, rev):
        for bname, bsha in self.git.get_branches():
            yield 'branches', bname, '/', bsha
        for t in self.git.get_tags():
            yield 'tags', t, '/', t

    def get_path_url(self, path, rev):
        return self.params.get('url')

    def get_changesets(self, start, stop):
        for rev in self.git.history_timerange(to_timestamp(start),
                                              to_timestamp(stop)):
            yield self.get_changeset(rev)

    def get_changeset(self, rev):
        """GitChangeset factory method"""
        return GitChangeset(self, rev)

    def get_changes(self, old_path, old_rev, new_path, new_rev,
                    ignore_ancestry=0):
        # TODO: handle renames/copies, ignore_ancestry
        if old_path != new_path:
            raise TracError("not supported in git_fs")

        with self.git.get_historian(old_rev,
                                    old_path.strip('/')) as old_historian:
            with self.git.get_historian(new_rev,
                                        new_path.strip('/')) as new_historian:
                for chg in self.git.diff_tree(old_rev, new_rev,
                                              self.normalize_path(new_path)):
                    mode1, mode2, obj1, obj2, action, path, path2 = chg

                    kind = Node.FILE
                    if mode2.startswith('04') or mode1.startswith('04'):
                        kind = Node.DIRECTORY

                    change = GitChangeset.action_map[action]

                    old_node = None
                    new_node = None

                    if change != Changeset.ADD:
                        old_node = self.get_node(path, old_rev, old_historian)
                    if change != Changeset.DELETE:
                        new_node = self.get_node(path, new_rev, new_historian)

                    yield old_node, new_node, kind, change

    def next_rev(self, rev, path=''):
        return self.git.hist_next_revision(rev)

    def previous_rev(self, rev, path=''):
        return self.git.hist_prev_revision(rev)

    def parent_revs(self, rev):
        return self.git.parents(rev)

    def child_revs(self, rev):
        return self.git.children(rev)

    def rev_older_than(self, rev1, rev2):
        rc = self.git.rev_is_anchestor_of(rev1, rev2)
        return rc

    # def clear(self, youngest_rev=None):
    #     self.youngest = None
    #     if youngest_rev is not None:
    #         self.youngest = self.normalize_rev(youngest_rev)
    #     self.oldest = None

    def clear(self, youngest_rev=None):
        self.sync()

    def sync(self, rev_callback=None, clean=None):
        if rev_callback:
            revs = set(self.git.all_revs())

        if not self.git.sync():
            return None # nothing expected to change

        if rev_callback:
            revs = set(self.git.all_revs()) - revs
            for rev in revs:
                rev_callback(rev)


class GitNode(Node):

    def __init__(self, repos, path, rev, log, ls_tree_info=None,
                 historian=None):
        self.log = log
        self.repos = repos
        self.fs_sha = None # points to either tree or blobs
        self.fs_perm = None
        self.fs_size = None
        rev = rev and str(rev) or 'HEAD'

        kind = Node.DIRECTORY
        p = path.strip('/')
        if p: # ie. not the root-tree
            if not ls_tree_info:
                ls_tree_info = repos.git.ls_tree(rev, p) or None
                if ls_tree_info:
                    [ls_tree_info] = ls_tree_info

            if not ls_tree_info:
                raise NoSuchNode(path, rev)

            self.fs_perm, k, self.fs_sha, self.fs_size, _ = ls_tree_info

            # fix-up to the last commit-rev that touched this node
            rev = repos.git.last_change(rev, p, historian)

            if k == 'tree':
                pass
            elif k == 'commit':
                # FIXME: this is a workaround for missing git submodule
                #        support in the plugin
                pass
            elif k == 'blob':
                kind = Node.FILE
            else:
                raise TracError("Internal error (got unexpected object " \
                                "kind '%s')" % k)

        self.created_path = path
        self.created_rev = rev

        Node.__init__(self, repos, path, rev, kind)

    def __git_path(self):
        """return path as expected by PyGIT"""
        p = self.path.strip('/')
        if self.isfile:
            assert p
            return p
        if self.isdir:
            return p and (p + '/')

        raise TracError("internal error")

    def get_content(self):
        if not self.isfile:
            return None

        return self.repos.git.get_file(self.fs_sha)

    def get_properties(self):
        return self.fs_perm and {'mode': self.fs_perm } or {}

    def get_annotations(self):
        if not self.isfile:
            return

        return [rev for rev, lineno in \
                self.repos.git.blame(self.rev,self.__git_path())]

    def get_entries(self):
        if not self.isdir:
            return

        with self.repos.git.get_historian(self.rev,
                                          self.path.strip('/')) as historian:
            for ent in self.repos.git.ls_tree(self.rev, self.__git_path()):
                yield GitNode(self.repos, ent[-1], self.rev, self.log, ent,
                              historian)

    def get_content_type(self):
        if self.isdir:
            return None

        return ''

    def get_content_length(self):
        if not self.isfile:
            return None

        if self.fs_size is None:
            self.fs_size = self.repos.git.get_obj_size(self.fs_sha)

        return self.fs_size

    def get_history(self, limit=None):
        # TODO: find a way to follow renames/copies
        for is_last, rev in _last_iterable(self.repos.git.history(self.rev,
                                                self.__git_path(), limit)):
            yield (self.path, rev, Changeset.EDIT if not is_last else
                                   Changeset.ADD)

    def get_last_modified(self):
        if not self.isfile:
            return None

        try:
            msg, props = self.repos.git.read_commit(self.rev)
            user, ts = _parse_user_time(props['committer'][0])
        except:
            self.log.error("internal error (could not get timestamp from "
                           "commit '%s')" % self.rev)
            return None

        return ts


class GitChangeset(Changeset):
    """A Git changeset in the Git repository.

    Corresponds to a Git commit blob.
    """

    action_map = { # see also git-diff-tree(1) --diff-filter
        'A': Changeset.ADD,
        'M': Changeset.EDIT, # modified
        'T': Changeset.EDIT, # file type (mode) change
        'D': Changeset.DELETE,
        'R': Changeset.MOVE, # renamed
        'C': Changeset.COPY
        } # TODO: U, X, B

    def __init__(self, repos, sha):
        if sha is None:
            raise NoSuchChangeset(sha)
        
        try:
            msg, props = repos.git.read_commit(sha)
        except PyGIT.GitErrorSha:
            raise NoSuchChangeset(sha)

        self.props = props

        assert 'children' not in props
        _children = list(repos.git.children(sha))
        if _children:
            props['children'] = _children

        committer, author = self._get_committer_and_author()
        # use 1st author/committer as changeset owner/timestamp
        c_user = a_user = c_time = a_time = None
        if committer:
            c_user, c_time = _parse_user_time(committer)
        if author:
            a_user, a_time = _parse_user_time(author)

        if repos.use_committer_time:
            time = c_time or a_time
        else:
            time = a_time or c_time

        if repos.use_committer_id:
            user = c_user or a_user
        else:
            user = a_user or c_user

        # try to resolve email address to trac uid
        user = repos.rlookup_uid(user) or user

        Changeset.__init__(self, repos, rev=sha, message=msg, author=user,
                           date=time)

    def _get_committer_and_author(self):
        committer = author = None
        if 'committer' in self.props:
            committer = self.props['committer'][0]
        if 'author' in self.props:
            author = self.props['author'][0]
        return committer, author

    def get_properties(self):
        properties = {}

        if 'parent' in self.props:
            properties['Parents'] = self.props['parent']

        if 'children' in self.props:
            properties['Children'] = self.props['children']

        committer, author = self._get_committer_and_author()
        if author != committer:
            properties['git-committer'] = _parse_user_time(committer)
            properties['git-author'] = _parse_user_time(author)

        branches = list(self.repos.git.get_branch_contains(self.rev,
                                                           resolve=True))
        if branches:
            properties['Branches'] = branches

        return properties

    def get_changes(self):
        paths_seen = set()
        for parent in self.props.get('parent', [None]):
            for mode1, mode2, obj1, obj2, action, path1, path2 in \
                    self.repos.git.diff_tree(parent, self.rev,
                                             find_renames=True):
                path = path2 or path1
                p_path, p_rev = path1, parent

                kind = Node.FILE
                if mode2.startswith('04') or mode1.startswith('04'):
                    kind = Node.DIRECTORY

                action = GitChangeset.action_map[action[0]]

                if action == Changeset.ADD:
                    p_path = ''
                    p_rev = None

                # CachedRepository expects unique (rev, path, change_type) key
                # this is only an issue in case of merges where files required
                # editing
                if path in paths_seen:
                    continue

                paths_seen.add(path)

                yield path, kind, action, p_path, p_rev


    def get_branches(self):
        _rev = self.rev

        return [(k, v == _rev)
                for k, v in self.repos.git.get_branch_contains(_rev,
                                                               resolve=True)]


class GitwebProjectsRepositoryProvider(Component):

    implements(IRepositoryProvider)

    projects_list = PathOption('git', 'projects_list', doc=
        """Path to a gitweb-formatted projects.list""")

    projects_base = PathOption('git', 'projects_base', doc=
        """Path to the base of your git projects""")

    projects_url = Option('git', 'projects_url', doc=
        """Template for project URLs. %s will be replaced with the repo
        name""")

    def get_repositories(self):
        if not self.projects_list:
            return

        for line in open(self.projects_list):
            line = line.strip()
            name = line
            if name.endswith('.git'):
                name = name[:-4]
            repo = {
                'dir': os.path.join(self.projects_base, line),
                'type': 'git',
            }
            description_path = os.path.join(repo['dir'], 'description')
            if os.path.exists(description_path):
                repo['description'] = open(description_path).read().strip()
            if self.projects_url:
                repo['url'] = self.projects_url % name
            yield name, repo
