#! /usr/bin/env python3.3
"""Remember which changelists we already integrated."""

from   p4gf_l10n      import NTR


class IntegratedUpTo:

    """After integrating across branches, remember the source changelist number so
    that you can use it to accelerate future 'p4 integ' requests.

    A little bookkeeping on our side can save the Perforce server from scanning
    far back in history to look for unintegrated file actions.
    """

    def __init__(self):
        self._key_to_change_num = {}

    def set(self, from_branch, to_branch, change_num):
        """Remember."""
        self._key_to_change_num[_key( from_branch = from_branch
                                    , to_branch   = to_branch  )] = change_num

    def get(self, from_branch, to_branch):
        """Tell me."""
        r = self._key_to_change_num.get(_key( from_branch = from_branch
                                            , to_branch   = to_branch  ), None)
        return r


def _to_str(branch):
    """Convert a branch to a string, which we use internally as part of our dict key."""
    if not (branch and branch.branch_id):
        return None
    return branch.branch_id


def _key(from_branch, to_branch):
    """Convert a pair of branches to a key for our dict."""
    return NTR('{f} {t}').format(f=_to_str(from_branch), t=_to_str(to_branch))