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########################################################################################################################
#    File: cache.py
#  Author: Dan Huckson, https://github.com/unodan
#    Date: 2019-09-07
########################################################################################################################

from os import path, makedirs
from json import load, dump
from copy import deepcopy
from importlib.util import module_from_spec, spec_from_file_location


def uri2dict(uri, *args, **kwargs):
    node = output = {}
    parts = uri.split('/')

    while parts:
        node[parts.pop(0)] = node = {}

    _args = args[0] if args else kwargs
    if not isinstance(_args, dict) and uri:
        return Cache(**output).set(uri, _args).get()
    return Cache(**output).set(uri, **_args).get()


class Cache:
    def __init__(self, *args, **kwargs):
        self.nodes = {}
        _args = args[0] if args else kwargs

        if _args and isinstance(_args, dict):
            key = next(iter(_args.keys()))
            if '/' in key:
                self.set(key, next(iter(_args.values())))
            else:
                self.nodes = deepcopy(_args)

        elif isinstance(_args, str):
            kwargs = args[1] if len(args) > 1 else kwargs
            if isinstance(kwargs, dict):
                self.nodes = deepcopy(uri2dict(_args, **kwargs))
            else:
                self.nodes = deepcopy(uri2dict(args[0], args[1]))

        self.indent = '.'

    def __eq__(self, other):
        if self.nodes == other.nodes:
            return True
        return False

    def __str__(self):
        return str(self.nodes.items())

    def __repr__(self):
        data = "**{'key': 'value'}"
        return f"{self.__class__.__name__}({data})"

    def get(self, uri=None):
        if not uri:
            return self.nodes

        def walk(_uri, nodes):
            parts = _uri.split('/', 1)
            key = parts.pop(0)

            if key in nodes:
                node = nodes[key]

                if not parts:
                    return node
                else:
                    return walk(parts[0], node)

        return walk(uri, self.nodes)

    def set(self, uri, *args, **kwargs):
        data = args[0] if args else kwargs
        data = deepcopy(data)

        def walk(_uri, nodes):
            parts = _uri.split('/', 1)
            key = parts.pop(0)

            if key in nodes and parts:
                walk(parts[0], nodes[key])
            elif len(_uri.split('/')) == 1:
                nodes[key] = data
            else:
                self.nodes.update(**uri2dict(_uri, data))

        walk(uri, self.nodes)

        return self

    def copy(self):
        return Cache(**deepcopy(self.nodes))

    def dump(self, indent=None):
        """ Dumps the contents of the cache to the screen.
        The output from dump goes stdout and is used to view the cache contents.
        Default indentation is a dot for each level.
        :param indent:
            indent (str): String to be use for indenting levels.
        :return:
            Nothing.
        """
        indent = indent if indent else '.'

        print('-------------------------------------------------------------------------------------------------------')
        print('id =', id(self), '\nnodes =', self)
        if self.nodes:
            def walk(_cfg, count):
                count += 1
                for key, value in _cfg.items():
                    if isinstance(value, dict):
                        print(indent * count, key)
                        walk(value, count)
                    else:
                        if isinstance(value, str):
                            value = f'"{value}"'
                        print(indent * count, key, f'value={value}')
            walk(self.nodes, 0)
        else:
            print(' (No Data)')

        print('-------------------------------------------------------------------------------------------------------')

    def save(self, file=None):
        if file:
            dirname = path.dirname(file)

            if dirname and not path.exists(dirname):
                makedirs(dirname)

            with open(file, 'w') as f:
                dump(self.nodes, f, indent=3)

    def load(self, file=None):
        file_type = path.splitext(file)[1].lstrip('.').lower()

        if file_type == 'py' and path.exists(file):
            spec = spec_from_file_location("module.name", file)
            module = module_from_spec(spec)
            spec.loader.exec_module(module)
            self.nodes = module.config

        if file_type == 'json' and path.exists(file):
            with open(file) as f:
                self.nodes = load(f)

    def merge(self, src):
        def walk(data, parent=''):
            if isinstance(data, dict):
                for key, value in data.items():
                    _uri = f'{parent}/{key}'.lstrip('/')
                    if self.exists(_uri):
                        walk(src.get(_uri), key)
                    else:
                        parts = _uri.rsplit("/", 1)
                        key = parts[1] if len(parts) > 1 else _uri
                        self.set(f'{parent}/{key}'.lstrip('/'), data[key])
            else:
                print(12345, parent, data)

        walk(src.get())

    def remove(self, uri):
        """ Remove entree from cache.
        Removes an entree from the cache if it exists.
        :param uri:
            uri (str): URI that points to the entree to remove.
        :return:
            Nothing.
        """

        uri = uri.lstrip('/')
        if self.exists(uri):
            node = self.get('/'.join(uri.split('/')[:-1]))
            del node[uri.split('/')[-1]]

    def exists(self, uri):
        """ Test if URI exists in the cache.

        :param uri:
        :return:
        """
        return True if self.get(uri) else False

    def destroy(self):
        """ Destroy cache.
        Deletes all entries in the cache.
        :return:
            Nothing.
        """
        del self.nodes
        self.nodes = {}

    def has_nodes(self):
        if len(self.nodes):
            return True
        return False

# If uncommented the cache will ba a singleton.
# class Cache:
#     instance = None
#
#     def __new__(cls, **kwargs):
#         if not cls.instance:
#             cls.instance = super(Cache, cls).__new__(cls)
#             cls.instance.cache = _Cache(**kwargs)
#
#         return cls.instance.cache


cache = Cache()
cache.load('data.py')
cache.dump()

print('\nlevel_1/level_2/item2 = ', cache.get('level_1/level_2/item2'))
cache.set('level_1/level_2/item2', 200)
print('level_1/level_2/item2 = ', cache.get('level_1/level_2/item2'))

level_4 = {
    'level_4': {
        'item3': 10,
        'item4': 20,
    }
}

cache.set('level_1/level_2/level_3', 100)
print(cache.get('level_1/level_2/level_3'))
cache.dump()

cache.set('level_1/level_2/level_3', level_4)
cache.dump()

cache.get('level_1/level_2/level_3').update({'level_5': {'name': 'Dan'}})

if cache.exists('level_1/level_2/level_3'):
    print('level_1/level_2/level_3 =', cache.get('level_1/level_2/level_3'), '\n')

cache.save('data.json')
cache.dump()

my_cache = cache.copy()
my_cache.dump()

cache.destroy()
cache.set('p1', {'first_name': 'Dan', 'last_name': 'Huckson'})
cache.set('p2', {'first_name': 'Geoff', 'last_name': 'Skerlan'})
cache.dump()

my_cache.remove('level_1/level_2/item1')
my_cache.remove('level_1/level_2/level_3')
my_cache.dump()

your_cache = Cache()
your_cache.load('data.json')
your_cache.dump()

# Test equality code below.
my_cache2 = my_cache.copy()

# uncomment the line below to test inequality.
# my_cache.set('level_1/level_2/item2', 201)
if my_cache == my_cache2:
    print('\nThe contents of both caches are the same!')

    if my_cache is my_cache2:
        print('my_cache2 is the same instance as my_cache.')
    else:
        print('my_cache2 is not the same instance as my_cache, but the contents are the same.')

else:
    print('\nThe contents of both caches are not exactly same!')

my_cache.dump()
my_cache2.dump()

print()
my_cache3 = my_cache2
if my_cache3 is my_cache2:
    print('my_cache3 is the same instance as my_cache2, notice ids.')
    my_cache3.dump()

print()
print('your_cache =', str(your_cache))
print('your_cache =', repr(your_cache))
print()

x = Cache(abc={'item': 123}, xyx={'item': 456}, **{'123': 'abc'})
x.dump()

# New features added 2019/09/12
c = Cache()
c.set('aa/bb', **{'ddd': 'test'})
c.dump()

c = Cache({'abc/xyz/aaa': {'xxx': 1000}})
c.dump()

x = Cache('aa1/bb1', **{'ddd1': 'test 1'})
x.dump()

y = Cache('aa1/bb2', 123456)
y.dump()

x.merge(y)
x.dump()

y.merge(x)
y.dump()