# -*- coding: utf-8 -*-

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""

Modified mercurial DAG graph functions that re-uses VCS structure

It allows to have a shared codebase for DAG generation for hg and git repos

"""

nullrev = -1

def _first_known_ancestors(parentrev_func, minrev, knownrevs, head):

    """

    Walk DAG defined by parentrev_func.

    Return most immediate ancestors of head that are in knownrevs.

    minrev is lower bound on knownrevs.

    """

    pending = set([head])

    seen = set()

    ancestors = set()

    while pending:

        r = pending.pop()

        if r < minrev:

        elif r in knownrevs:

            ancestors.add(r)

        elif r not in seen:

            pending.update(parentrev_func(r))

            seen.add(r)

    return ancestors

def graph_data(repo, revs):

    """Return a DAG with colored edge information for revs

    For each DAG node this function emits tuples::

      ((col, color), [(col, nextcol, color)])

    with the following new elements:

      - Tuple (col, color) with column and color index for the current node

      - A list of tuples indicating the edges between the current node and its

        parents.

    """

    dag = _dagwalker(repo, revs)

    return list(_colored(dag))

def _dagwalker(repo, revs):

    if not revs:

        return

    if repo.alias == 'hg':

        parentrev_func = repo._repo.changelog.parentrevs

    elif repo.alias == 'git':

        def parentrev_func(rev):

            return [x.revision for x in repo[rev].parents]

    minrev = revs[-1] # assuming sorted reverse

    knownrevs = set(revs)

    acache = {}

    for rev in revs:

        parents = set(parentrev_func(rev)) - set([nullrev])

        dagparents = parents & knownrevs

        # Calculate indirect parents

        for p in parents - dagparents:

            ancestors = acache.get(p)

            if ancestors is None:

                ancestors = acache[p] = _first_known_ancestors(parentrev_func, minrev, knownrevs, p)

            dagparents.update(ancestors)

        yield (rev, sorted(dagparents))

def _colored(dag):

    """annotates a DAG with colored edge information

    For each DAG node this function emits tuples::

      ((col, color), [(col, nextcol, color)])

    with the following new elements:

      - Tuple (col, color) with column and color index for the current node

      - A list of tuples indicating the edges between the current node and its

        parents.

    """

    row = []

    colors = {}

    newcolor = 1

    for (rev, dagparents) in dag:

        # Compute row and nextrow

        if rev not in row:

            row.append(rev)  # new head

            colors[rev] = newcolor

            newcolor += 1

        # Add unknown parents to nextrow

        # Set colors for the parents

        color = colors.pop(rev)

        for i, p in enumerate(addparents):

            if not i:

                colors[p] = color

            else:

                colors[p] = newcolor

                newcolor += 1

        # Add edges to the graph

        edges = []

        for ecol, ep in enumerate(row):

            if ep in nextrow:

                edges.append((ecol, nextrow.index(ep), colors[ep]))

            elif ep == rev:

                for p in dagparents:

                    edges.append((ecol, nextrow.index(p), colors[p] if len(dagparents) > 1 else color))

        # Yield and move on

        yield ((col, color), edges)

        row = nextrow