#       Licensed to the Apache Software Foundation (ASF) under one
#       or more contributor license agreements.  See the NOTICE file
#       distributed with this work for additional information
#       regarding copyright ownership.  The ASF licenses this file
#       to you under the Apache License, Version 2.0 (the
#       "License"); you may not use this file except in compliance
#       with the License.  You may obtain a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#       Unless required by applicable law or agreed to in writing,
#       software distributed under the License is distributed on an
#       "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
#       KIND, either express or implied.  See the License for the
#       specific language governing permissions and limitations
#       under the License.

import logging
from itertools import chain
from cPickle import dumps
from collections import OrderedDict

import bson

import tg
import jinja2
from pylons import tmpl_context as c, app_globals as g

from ming.base import Object
from ming.orm import mapper, session, ThreadLocalORMSession

from allura.lib import utils
from allura.lib import helpers as h
from allura.model.repo import CommitDoc, TreeDoc, TreesDoc, DiffInfoDoc
from allura.model.repo import CommitRunDoc
from allura.model.repo import Commit, Tree, LastCommit, ModelCache
from allura.model.index import ArtifactReferenceDoc, ShortlinkDoc
from allura.model.auth import User

log = logging.getLogger(__name__)

QSIZE = 100


def refresh_repo(repo, all_commits=False, notify=True, new_clone=False):
    all_commit_ids = commit_ids = list(repo.all_commit_ids())
    if not commit_ids:
        # the repo is empty, no need to continue
        return
    new_commit_ids = unknown_commit_ids(commit_ids)
    stats_log = h.log_action(log, 'commit')
    for ci in new_commit_ids:
        stats_log.info(
            '',
            meta=dict(
                module='scm-%s' % repo.repo_id,
                read='0'))
    if not all_commits:
        # Skip commits that are already in the DB
        commit_ids = new_commit_ids
    log.info('Refreshing %d commits on %s', len(commit_ids), repo.full_fs_path)

    # Refresh commits
    seen = set()
    for i, oid in enumerate(commit_ids):
        repo.refresh_commit_info(oid, seen, not all_commits)
        if (i + 1) % 100 == 0:
            log.info('Refresh commit info %d: %s', (i + 1), oid)

    refresh_commit_repos(all_commit_ids, repo)

    # Refresh child references
    for i, oid in enumerate(commit_ids):
        ci = CommitDoc.m.find(dict(_id=oid), validate=False).next()
        refresh_children(ci)
        if (i + 1) % 100 == 0:
            log.info('Refresh child info %d for parents of %s',
                     (i + 1), ci._id)

    if repo._refresh_precompute:
        # Refresh commit runs
        commit_run_ids = commit_ids
        # Check if the CommitRuns for the repo are in a good state by checking for
        # a CommitRunDoc that contains the last known commit. If there isn't one,
        # the CommitRuns for this repo are in a bad state - rebuild them
        # entirely.
        if commit_run_ids != all_commit_ids:
            last_commit = last_known_commit_id(all_commit_ids, new_commit_ids)
            log.info('Last known commit id: %s', last_commit)
            if not CommitRunDoc.m.find(dict(commit_ids=last_commit)).count():
                log.info('CommitRun incomplete, rebuilding with all commits')
                commit_run_ids = all_commit_ids
        log.info('Starting CommitRunBuilder for %s', repo.full_fs_path)
        rb = CommitRunBuilder(commit_run_ids)
        rb.run()
        rb.cleanup()
        log.info('Finished CommitRunBuilder for %s', repo.full_fs_path)

    # Refresh trees
    # Like diffs below, pre-computing trees for some SCMs is too expensive,
    # so we skip it here, then do it on-demand later.
    if repo._refresh_precompute:
        cache = {}
        for i, oid in enumerate(commit_ids):
            ci = CommitDoc.m.find(dict(_id=oid), validate=False).next()
            cache = refresh_commit_trees(ci, cache)
            if (i + 1) % 100 == 0:
                log.info('Refresh commit trees %d: %s', (i + 1), ci._id)

    # Compute diffs
    cache = {}
    # For some SCMs, we don't want to pre-compute the diffs because that
    # would be too expensive, so we skip them here and do them on-demand
    # with caching.
    if repo._refresh_precompute:
        for i, oid in enumerate(commit_ids):
            cid = CommitDoc.m.find(dict(_id=oid), validate=False).next()
            ci = mapper(Commit).create(cid, dict(instrument=False))
            ci.set_context(repo)
            compute_diffs(repo._id, cache, ci)
            if (i + 1) % 100 == 0:
                log.info('Compute diffs %d: %s', (i + 1), ci._id)

    if repo._refresh_precompute:
        model_cache = ModelCache()
        lcid_cache = {}
        for i, oid in enumerate(reversed(commit_ids)):
            ci = model_cache.get(Commit, dict(_id=oid))
            ci.set_context(repo)
            compute_lcds(ci, model_cache, lcid_cache)
            ThreadLocalORMSession.flush_all()
            if (i + 1) % 100 == 0:
                log.info('Compute last commit info %d: %s', (i + 1), ci._id)

    if not all_commits and not new_clone:
        for commit in commit_ids:
            new = repo.commit(commit)
            user = User.by_email_address(new.committed.email)
            if user is None:
                user = User.by_username(new.committed.name)
            if user is not None:
                g.statsUpdater.newCommit(new, repo.app_config.project, user)
                g.director.create_activity(user, 'committed', new,
                                           related_nodes=[repo.app_config.project])

    log.info('Refresh complete for %s', repo.full_fs_path)
    g.post_event('repo_refreshed', len(commit_ids), all_commits, new_clone)

    # Send notifications
    if notify:
        send_notifications(repo, commit_ids)


def refresh_commit_trees(ci, cache):
    '''Refresh the list of trees included withn a commit'''
    if ci.tree_id is None:
        return cache
    trees_doc = TreesDoc(dict(
        _id=ci._id,
        tree_ids=list(trees(ci.tree_id, cache))))
    trees_doc.m.save(safe=False)
    new_cache = dict(
        (oid, cache[oid])
        for oid in trees_doc.tree_ids)
    return new_cache


def refresh_commit_repos(all_commit_ids, repo):
    '''Refresh the list of repositories within which a set of commits are
    contained'''
    for oids in utils.chunked_iter(all_commit_ids, QSIZE):
        for ci in CommitDoc.m.find(dict(
                _id={'$in': list(oids)},
                repo_ids={'$ne': repo._id})):
            oid = ci._id
            ci.repo_ids.append(repo._id)
            index_id = 'allura.model.repo.Commit#' + oid
            ref = ArtifactReferenceDoc(dict(
                _id=index_id,
                artifact_reference=dict(
                    cls=bson.Binary(dumps(Commit)),
                    project_id=repo.app.config.project_id,
                    app_config_id=repo.app.config._id,
                    artifact_id=oid),
                references=[]))
            link0 = ShortlinkDoc(dict(
                _id=bson.ObjectId(),
                ref_id=index_id,
                project_id=repo.app.config.project_id,
                app_config_id=repo.app.config._id,
                link=repo.shorthand_for_commit(oid)[1:-1],
                url=repo.url_for_commit(oid)))
            # Always create a link for the full commit ID
            link1 = ShortlinkDoc(dict(
                _id=bson.ObjectId(),
                ref_id=index_id,
                project_id=repo.app.config.project_id,
                app_config_id=repo.app.config._id,
                link=oid,
                url=repo.url_for_commit(oid)))
            ci.m.save(safe=False, validate=False)
            ref.m.save(safe=False, validate=False)
            link0.m.save(safe=False, validate=False)
            link1.m.save(safe=False, validate=False)


def refresh_children(ci):
    '''Refresh the list of children of the given commit'''
    CommitDoc.m.update_partial(
        dict(_id={'$in': ci.parent_ids}),
        {'$addToSet': dict(child_ids=ci._id)},
        multi=True)


class CommitRunBuilder(object):

    '''Class used to build up linear runs of single-parent commits'''

    def __init__(self, commit_ids):
        self.commit_ids = commit_ids
        self.run_index = {}  # by commit ID
        self.runs = {}          # by run ID
        self.reasons = {}    # reasons to stop merging runs

    def run(self):
        '''Build up the runs'''
        for oids in utils.chunked_iter(self.commit_ids, QSIZE):
            oids = list(oids)
            for ci in CommitDoc.m.find(dict(_id={'$in': oids})):
                if ci._id in self.run_index:
                    continue
                self.run_index[ci._id] = ci._id
                self.runs[ci._id] = CommitRunDoc(dict(
                    _id=ci._id,
                    parent_commit_ids=ci.parent_ids,
                    commit_ids=[ci._id],
                    commit_times=[ci.authored['date']]))
            self.merge_runs()
        log.info('%d runs', len(self.runs))
        for rid, run in sorted(self.runs.items()):
            log.info('%32s: %r', self.reasons.get(rid, 'none'), run._id)
        for run in self.runs.itervalues():
            run.m.save()
        return self.runs

    def _all_runs(self):
        '''Find all runs containing this builder's commit IDs'''
        runs = {}
        for oids in utils.chunked_iter(self.commit_ids, QSIZE):
            oids = list(oids)
            for run in CommitRunDoc.m.find(dict(commit_ids={'$in': oids})):
                runs[run._id] = run
            for run in CommitRunDoc.m.find(dict(parent_commit_ids={'$in': oids})):
                runs[run._id] = run
        seen_run_ids = set()
        runs = runs.values()
        while runs:
            run = runs.pop()
            if run._id in seen_run_ids:
                continue
            seen_run_ids.add(run._id)
            yield run
            for run in CommitRunDoc.m.find(
                    dict(commit_ids={'$in': run.parent_commit_ids})):
                runs.append(run)

    def cleanup(self):
        '''Delete non-maximal runs and merge any new runs with existing runs'''
        runs = dict(
            (run['commit_ids'][0], run)
            for run in self._all_runs())
        for rid, run in runs.items():
            p_cis = run['parent_commit_ids']
            if len(p_cis) != 1:
                continue
            parent_run = runs.get(p_cis[0], None)
            if parent_run is None:
                continue
            run['commit_ids'] += parent_run['commit_ids']
            run['commit_times'] += parent_run['commit_times']
            run['parent_commit_ids'] = parent_run['parent_commit_ids']
            run.m.save()
            parent_run.m.delete()
            del runs[p_cis[0]]
        for run1 in runs.values():
            # if run1 is a subset of another run, delete it
            if CommitRunDoc.m.find(dict(commit_ids={'$all': run1.commit_ids},
                                        _id={'$ne': run1._id})).count():
                log.info('... delete %r (subset of another run)', run1)
                run1.m.delete()
                continue
            for run2 in CommitRunDoc.m.find(dict(
                    commit_ids=run1.commit_ids[0])):
                if run1._id == run2._id:
                    continue
                log.info('... delete %r (part of %r)', run2, run1)
                run2.m.delete()

    def merge_runs(self):
        '''Find partial runs that may be merged and merge them'''
        while True:
            for run_id, run in self.runs.iteritems():
                if len(run.parent_commit_ids) != 1:
                    self.reasons[run_id] = '%d parents' % len(
                        run.parent_commit_ids)
                    continue
                p_oid = run.parent_commit_ids[0]
                p_run_id = self.run_index.get(p_oid)
                if p_run_id is None:
                    self.reasons[run_id] = 'parent commit not found'
                    continue
                p_run = self.runs.get(p_run_id)
                if p_run is None:
                    self.reasons[run_id] = 'parent run not found'
                    continue
                if p_run.commit_ids[0] != p_oid:
                    self.reasons[
                        run_id] = 'parent does not start with parent commit'
                    continue
                run.commit_ids += p_run.commit_ids
                run.commit_times += p_run.commit_times
                run.parent_commit_ids = p_run.parent_commit_ids
                for oid in p_run.commit_ids:
                    self.run_index[oid] = run_id
                break
            else:
                break
            del self.runs[p_run_id]


def trees(id, cache):
    '''Recursively generate the list of trees contained within a given tree ID'''
    yield id
    entries = cache.get(id, None)
    if entries is None:
        t = TreeDoc.m.get(_id=id)
        entries = [o.id for o in t.tree_ids]
        cache[id] = entries
    for i in entries:
        for x in trees(i, cache):
            yield x


def unknown_commit_ids(all_commit_ids):
    '''filter out all commit ids that have already been cached'''
    result = []
    for chunk in utils.chunked_iter(all_commit_ids, QSIZE):
        chunk = list(chunk)
        q = CommitDoc.m.find(dict(_id={'$in': chunk}))
        known_commit_ids = set(ci._id for ci in q)
        result += [oid for oid in chunk if oid not in known_commit_ids]
    return result


def compute_diffs(repo_id, tree_cache, rhs_ci):
    '''compute simple differences between a commit and its first parent'''
    if rhs_ci.tree_id is None:
        return tree_cache

    def _update_cache(lhs_tree_ids, rhs_tree_ids):
        # crazy cache logic that I'm not certain I understand
        new_tree_ids = [
            tid for tid in chain(lhs_tree_ids, rhs_tree_ids)
            if tid not in tree_cache]
        tree_index = dict(
            (t._id, t) for t in TreeDoc.m.find(dict(_id={'$in': new_tree_ids}), validate=False))
        tree_index.update(tree_cache)
        rhs_tree_ids_set = set(rhs_tree_ids)
        tree_cache.clear()
        tree_cache.update(
            (id, t) for id, t in tree_index.iteritems() if id in rhs_tree_ids_set)
        return tree_index

    empty_tree = Object(_id=None, tree_ids=[], blob_ids=[], other_ids=[])
    commit_info = get_commit_info(rhs_ci)
    differences = []
    rhs_treesdoc = TreesDoc.m.get(_id=rhs_ci._id)
    if not rhs_treesdoc:
        # FIXME: These sometimes don't exist for unknown reasons; they should
        # be auto-gen'ed
        log.error('Missing TreesDoc: %s', rhs_ci)
        return tree_cache
    for lhs_cid in rhs_ci.parent_ids:
        lhs_ci = CommitDoc.m.get(_id=lhs_cid)
        if lhs_ci is None:
            log.error(
                'Commit ID referenced as parent but not found: %s parent of %s', lhs_cid, rhs_ci)
            continue
        lhs_treesdoc = TreesDoc.m.get(_id=lhs_cid)
        if not lhs_treesdoc:
            # FIXME: These sometimes don't exist for unknown reasons; they
            # should be auto-gen'ed
            log.error('Missing TreesDoc: %s', rhs_ci)
            continue
        tree_index = _update_cache(
            lhs_treesdoc.tree_ids, rhs_treesdoc.tree_ids)
        rhs_tree = tree_index[rhs_ci.tree_id]
        lhs_tree = tree_index.get(lhs_ci.tree_id, empty_tree)
        for name, lhs_id, rhs_id in _diff_trees(lhs_tree, rhs_tree, tree_index):
            differences.append(
                dict(name=name, lhs_id=lhs_id, rhs_id=rhs_id))
    if not rhs_ci.parent_ids:
        # no parents, so everything in rhs is new
        tree_index = _update_cache([], rhs_treesdoc.tree_ids)
        rhs_tree = tree_index[rhs_ci.tree_id]
        for name, lhs_id, rhs_id in _diff_trees(empty_tree, rhs_tree, tree_index):
            differences.append(
                dict(name=name, lhs_id=lhs_id, rhs_id=rhs_id))
    # Build the diffinfo
    di = DiffInfoDoc(dict(
        _id=rhs_ci._id,
        differences=differences))
    di.m.save()
    return tree_cache


def send_notifications(repo, commit_ids):
    '''Create appropriate notification and feed objects for a refresh'''
    from allura.model import Feed, Notification
    commit_msgs = []
    base_url = tg.config['base_url']
    for oids in utils.chunked_iter(commit_ids, QSIZE):
        chunk = list(oids)
        index = dict(
            (doc._id, doc)
            for doc in Commit.query.find(dict(_id={'$in': chunk})))
        for oid in chunk:
            ci = index[oid]
            href = repo.url_for_commit(oid)
            title = _title(ci.message)
            summary = _summarize(ci.message)
            Feed.post(
                repo, title=title,
                description='%s<br><a href="%s">View Changes</a>' % (
                    summary, href),
                author_link=ci.author_url,
                author_name=ci.authored.name,
                link=href,
                unique_id=href)
            branches = repo.symbolics_for_commit(ci)[0]
            commit_msgs.append('%s: %s by %s %s%s' % (
                ",".join(b for b in branches),
                summary, ci.authored.name, base_url, ci.url()))
    if commit_msgs:
        if len(commit_msgs) > 1:
            subject = '%d new commits to %s %s' % (
                len(commit_msgs), repo.app.project.name, repo.app.config.options.mount_label)
            text = '\n\n'.join(commit_msgs)
        else:
            subject = '{0} - {1}: {2}'.format(
                repo.shorthand_for_commit(ci._id),
                ci.authored.name,
                summary)
            branches = repo.symbolics_for_commit(ci)[0]
            text_branches = ('%s: ' % ",".join(b for b in branches)
                             if branches else '')
            text = "%s%s %s%s" % (text_branches,
                                  ci.message,
                                  base_url, ci.url())

        Notification.post(
            artifact=repo,
            topic='metadata',
            subject=subject,
            text=text)


def _title(message):
    if not message:
        return ''
    line = message.splitlines()[0]
    return jinja2.filters.do_truncate(line, 200, True)


def _summarize(message):
    if not message:
        return ''
    summary = []
    for line in message.splitlines():
        line = line.rstrip()
        if line:
            summary.append(line)
        else:
            break
    return ' '.join(summary)


def _diff_trees(lhs, rhs, index, *path):
    def _fq(name):
        return '/'.join(reversed(
            (name,) + path))
    # Diff the trees (and keep deterministic order)
    rhs_tree_ids = OrderedDict(
        (o.name, o.id)
        for o in rhs.tree_ids)
    for o in lhs.tree_ids:
        # remove so won't be picked up as added, below
        rhs_id = rhs_tree_ids.pop(o.name, None)
        if rhs_id == o.id:  # no change
            continue
        elif rhs_id is None:  # removed
            yield (_fq(o.name), o.id, None)
            rhs_tree = Object(_id=None, tree_ids=[], blob_ids=[], other_ids=[])
        else:  # changed
            rhs_tree = index[rhs_id]
        for difference in _diff_trees(index[o.id], rhs_tree, index, o.name, *path):
            yield difference
    for name, id in rhs_tree_ids.items():  # added
        yield (_fq(name), None, id)
        lhs_tree = Object(_id=None, tree_ids=[], blob_ids=[], other_ids=[])
        for difference in _diff_trees(lhs_tree, index[id], index, name, *path):
            yield difference
    # Diff the blobs (and keep deterministic order)
    rhs_blob_ids = OrderedDict(
        (o.name, o.id)
        for o in rhs.blob_ids)
    for o in lhs.blob_ids:
        rhs_id = rhs_blob_ids.pop(o.name, None)
        if rhs_id == o.id:
            continue  # no change
        elif rhs_id is None:
            yield (_fq(o.name), o.id, None)
        else:
            yield (_fq(o.name), o.id, rhs_id)
    for name, id in rhs_blob_ids.items():
        yield (_fq(name), None, id)


def get_commit_info(commit):
    if not isinstance(commit, Commit):
        commit = mapper(Commit).create(commit, dict(instrument=False))
    sess = session(commit)
    if sess:
        sess.expunge(commit)
    return dict(
        id=commit._id,
        author=commit.authored.name,
        author_email=commit.authored.email,
        date=commit.authored.date,
        author_url=commit.author_url,
        shortlink=commit.shorthand_id(),
        summary=commit.summary
    )


def last_known_commit_id(all_commit_ids, new_commit_ids):
    """
    Return the newest "known" (cached in mongo) commit id.

    Params:
        all_commit_ids: Every commit id from the repo on disk, sorted oldest to
                        newest.
        new_commit_ids: Commit ids that are not yet cached in mongo, sorted
                        oldest to newest.
    """
    if not all_commit_ids:
        return None
    if not new_commit_ids:
        return all_commit_ids[-1]
    return all_commit_ids[all_commit_ids.index(new_commit_ids[0]) - 1]


def compute_lcds(commit, model_cache, lcid_cache):
    '''
    Compute LastCommit data for every Tree node under this tree.
    '''
    trees = model_cache.get(TreesDoc, dict(_id=commit._id))
    if not trees:
        log.error('Missing TreesDoc for %s; skipping compute_lcd' % commit)
        return
    with h.push_config(c, model_cache=model_cache, lcid_cache=lcid_cache):
        _update_tree_cache(trees.tree_ids, model_cache)
        tree = _pull_tree(model_cache, commit.tree_id, commit)
        _compute_lcds(tree, model_cache)
        for changed_path in tree.commit.changed_paths:
            lcid_cache[changed_path] = tree.commit._id


def _compute_lcds(tree, cache):
    path = tree.path().strip('/')
    if path not in tree.commit.changed_paths:
        return
    if not cache.get(LastCommit, dict(commit_id=tree.commit._id, path=path)):
        lcd = LastCommit._build(tree)
    for x in tree.tree_ids:
        sub_tree = _pull_tree(cache, x.id, tree, x.name)
        _compute_lcds(sub_tree, cache)


def _pull_tree(cache, tree_id, *context):
    '''
    Since the Tree instances stick around in our cache,
    subsequent calls to set_context are overwriting our
    in-use copies and confusing the walk.  So, make an
    memory-only copy for our use.
    '''
    cache_tree = cache.get(Tree, dict(_id=tree_id))
    new_tree = Tree(
        _id=cache_tree._id,
        tree_ids=cache_tree.tree_ids,
        blob_ids=cache_tree.blob_ids,
        other_ids=cache_tree.other_ids,
    )
    session(new_tree).expunge(new_tree)
    new_tree.set_context(*context)
    return new_tree


def _update_tree_cache(tree_ids, cache):
    current_ids = set(tree_ids)
    cached_ids = set(cache.instance_ids(Tree))
    new_ids = current_ids - cached_ids
    cache.batch_load(Tree, {'_id': {'$in': list(new_ids)}})