from mercurial import cmdutil
from mercurial import node
from hgext import rebase

import util
import hg_delta_editor

@util.register_subcommand('url')
def print_wc_url(ui, repo, hg_repo_path, **opts):
    hge = hg_delta_editor.HgChangeReceiver(hg_repo_path,
                                           ui_=ui)
    ui.status(hge.url, '\n')


@util.register_subcommand('parent')
def print_parent_revision(ui, repo, hg_repo_path, **opts):
    """Prints the hg hash and svn revision info for the nearest svn parent of
    the current revision"""
    hge = hg_delta_editor.HgChangeReceiver(hg_repo_path,
                                           ui_=ui)
    svn_commit_hashes = dict(zip(hge.revmap.itervalues(),
                                 hge.revmap.iterkeys()))
    ha = repo.parents()[0]
    o_r = outgoing_revisions(ui, repo, hge, svn_commit_hashes)
    if o_r:
        ha = repo[o_r[-1]].parents()[0]
    if ha.node() != node.nullid:
        r, br = svn_commit_hashes[ha.node()]
        ui.status('Working copy parent revision is %s: r%s on %s\n' %
                  (ha, r, br or 'trunk'))
    else:
        ui.status('Working copy seems to have no parent svn revision.\n')
    return 0


@util.register_subcommand('rebase')
def rebase_commits(ui, repo, hg_repo_path, **opts):
    """Rebases the current unpushed revisions onto the top of the Subversion branch.
    
    This moves a line of development from making its own head to the top of 
    Subversion development, linearizing the changes. In order to make sure you
    rebase on top of the current top of Subversion work, you should probably run
    'hg svn pull' before running this.
    """
    hge = hg_delta_editor.HgChangeReceiver(hg_repo_path,
                                           ui_=ui)
    svn_commit_hashes = dict(zip(hge.revmap.itervalues(),
                                 hge.revmap.iterkeys()))
    o_r = outgoing_revisions(ui, repo, hge, svn_commit_hashes)
    if not o_r:
        ui.status('Nothing to rebase!\n')
        return 0
    if len(repo.parents()[0].children()):
        ui.status('Refusing to rebase non-head commit like a coward\n')
        return 0
    parent_rev = repo[o_r[-1]].parents()[0]
    target_rev = parent_rev
    p_n = parent_rev.node()
    exhausted_choices = False
    while target_rev.children() and not exhausted_choices:
        for c in target_rev.children():
            exhausted_choices = True
            n = c.node()
            if (n in svn_commit_hashes and
                svn_commit_hashes[n][1] == svn_commit_hashes[p_n][1]):
                target_rev = c
                exhausted_choices = False
                break
    if parent_rev == target_rev:
        ui.status('Already up to date!\n')
        return 0
    # TODO this is really hacky, there must be a more direct way
    return rebase.rebase(ui, repo, dest=node.hex(target_rev.node()),
                         base=node.hex(repo.parents()[0].node()))


@util.register_subcommand('outgoing')
def show_outgoing_to_svn(ui, repo, hg_repo_path, **opts):
    """Commit the current revision and any required parents back to svn.
    """
    hge = hg_delta_editor.HgChangeReceiver(hg_repo_path,
                                           ui_=ui)
    svn_commit_hashes = dict(zip(hge.revmap.itervalues(),
                                 hge.revmap.iterkeys()))
    o_r = outgoing_revisions(ui, repo, hge, svn_commit_hashes)
    if not (o_r and len(o_r)):
        ui.status('No outgoing changes found.\n')
        return 0
    displayer = cmdutil.show_changeset(ui, repo, opts, buffered=False)
    for rev in reversed(o_r):
        displayer.show(changenode=rev)


def outgoing_revisions(ui, repo, hg_editor, reverse_map):
    """Given a repo and an hg_editor, determines outgoing revisions for the
    current working copy state.
    """
    outgoing_rev_hashes = []
    working_rev = repo.parents()
    assert len(working_rev) == 1
    working_rev = working_rev[0]
    if working_rev.node() in reverse_map:
        return
    while (not working_rev.node() in reverse_map
           and working_rev.node() != node.nullid):
        outgoing_rev_hashes.append(working_rev.node())
        working_rev = working_rev.parents()
        assert len(working_rev) == 1
        working_rev = working_rev[0]
    if working_rev.node() != node.nullid:
        return outgoing_rev_hashes