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import re


class InterfaceConfiguration:
    def __init__(self):
        self.commands = []
        self.merged = False

    def has_same_commands(self, interface):
        len1 = len(self.commands)
        len2 = len(interface.commands)
        return len1 == len2 and len1 == len(frozenset(self.commands).intersection(interface.commands))


def merge_interfaces(interfaces):
    """ to reduce commands generated by an edgeswitch module
        we take interfaces one by one and we try to merge them with neighbors if everyone has same commands to run
    """
    merged = {}

    for i, interface in interfaces.items():
        if interface.merged:
            continue
        interface.merged = True

        match = re.match(r'(\d+)\/(\d+)', i)
        group = int(match.group(1))
        start = int(match.group(2))
        end = start

        while True:
            try:
                start = start - 1
                key = '{0}/{1}'.format(group, start)
                neighbor = interfaces[key]
                if not neighbor.merged and interface.has_same_commands(neighbor):
                    neighbor.merged = True
                else:
                    break
            except KeyError:
                break
        start = start + 1

        while True:
            try:
                end = end + 1
                key = '{0}/{1}'.format(group, end)
                neighbor = interfaces[key]
                if not neighbor.merged and interface.has_same_commands(neighbor):
                    neighbor.merged = True
                else:
                    break
            except KeyError:
                break
        end = end - 1

        if end == start:
            key = '{0}/{1}'.format(group, start)
        else:
            key = '{0}/{1}-{2}/{3}'.format(group, start, group, end)

        merged[key] = interface
    return merged