from core.global_symbols import NotFound


class FastCache:
    """
    Simplest LRU cache
    """

    def __init__(self, max_size=256, default=None):
        self.max_size = max_size
        self.cache = {}
        self.lru = []
        self.default = default
        self.calls = {}

    def __contains__(self, item):
        return self.has(item)

    def __iter__(self):
        yield from self.cache

    def __next__(self):
        return next(iter(self.cache))

    def __len__(self):
        return len(self.cache)

    def put(self, key, value):
        if len(self.cache) == self.max_size:
            del self.cache[self.lru.pop(0)]

        if key in self.cache:
            self.lru.remove(key)

        self.cache[key] = value
        self.lru.append(key)
        self.calls[key] = 0

    def has(self, key):
        return key in self.cache

    def get(self, key):
        try:
            res = self.cache[key]
            self.calls[key] += 1
            return res
        except KeyError:
            if self.default:
                value = self.default(key)
                self.put(key, value)
                return value

            return NotFound

    def evict_by_key(self, predicate):
        to_remove = []

        for k, v in self.cache.items():
            if predicate(k):
                to_remove.append(k)

        for k in to_remove:
            self.lru.remove(k)
            del self.cache[k]

    def copy(self):
        return self.cache.copy()

    def clear(self):
        self.cache.clear()
        self.lru.clear()