"""
# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""


from typing import Optional, List, Union, Awaitable
from redis.typing import Number, FieldT, KeyT, EncodableT, ResponseT
import redis
from packaging import version
import re


LUA_LPOP = """
local key = KEYS[1]
local count = tonumber(ARGV[1])
local elements = redis.call('LRANGE', key, 0, count - 1)
local elementsCount = #elements
if elementsCount > 0 then
    redis.call('LTRIM', key, count, -1)
end
return elements
"""

LUA_ZINCRBY = """
local key = KEYS[1]
local amount = tonumber(ARGV[1])
local value = ARGV[2]
local rem_amount = ARGV[5] == 'NIL' and nil or tonumber(ARGV[3])

local currentAmount = redis.call('ZINCRBY',key, amount, value)
currentAmount = tonumber(currentAmount) or 0

if rem_amount ~= nil and currentAmount == rem_amount then
    redis.call('ZREM', key, value)
    currentAmount = 0
end

return currentAmount
"""


class AdaptedRedis(redis.Redis):
    """
    A Redis client adapter that provides version-compatible operations.
    
    This class extends the standard Redis client to:
    - Handle version-specific behavior differences
    - Add TTL support for list operations
    - Provide atomic operations with expiration
    - Implement custom Lua scripts for enhanced functionality
    """

    def __init__(self, **kwargs):
        """
        Initialize the AdaptedRedis client.
        
        Args:
            **kwargs: Standard Redis client connection parameters
        """
        super().__init__(**kwargs)

        self._old_version = False
        self._parse_version()
        self._register_script()

    def _parse_version(self):
        """
        Parse and store the Redis server version.
        
        Determines if the server is an older version that requires
        special handling for certain operations.
        """
        server_info = self.info(section='server')
        version_string = server_info['redis_version']

        match = re.search(r'^(\d+\.\d+\.\d+)', version_string)
        if match:
            redis_version = match.group(1)
        else:
            redis_version = "0.0.0"

        current_version = version.parse(redis_version)
        target_version = version.parse("6.2.28")

        if current_version <= target_version:
            self._old_version = True

        self.version = redis_version

    def _register_script(self):
        """
        Register custom Lua scripts for enhanced Redis operations.
        
        Scripts include:
        - Atomic LPOP with count (for older Redis versions)
        - ZINCRBY with removal threshold
        """
        if self._old_version:
            self._lpop = self.register_script(LUA_LPOP)
        self._zincrby = self.register_script(LUA_ZINCRBY)

    def rpush(self, name: str, *values: FieldT, ttl: Optional[float] = None) -> Union[Awaitable[int], int]:
        """
        RPUSH operation with optional TTL.
        
        Args:
            name: List key
            *values: Values to push
            ttl: Optional time-to-live in seconds
            
        Returns:
            Length of the list after push
        """
        if ttl is None:
            return super().rpush(name, *values)

        with self.pipeline() as pipe:
            pipe.multi()
            pipe.rpush(name, *values)
            pipe.expire(name, ttl)
            result = pipe.execute()
            return result[0]

    def zincrby(self,
                name: KeyT,
                amount: float,
                value: EncodableT,
                rem_amount: Optional[float] = None,
                ttl: Optional[float] = None) -> ResponseT:
        """
        Atomic ZINCRBY with removal threshold and optional TTL.
        
        Args:
            name: Sorted set key
            amount: Increment amount
            value: Member to increment
            rem_amount: Optional threshold for member removal
            ttl: Optional time-to-live in seconds
            
        Returns:
            New score of the member
        """
        amount = str(amount)

        if ttl is None:
            if rem_amount is None:
                return super().zincrby(name, amount, value)
            rem_amount = 'NIL' if rem_amount is None else str(rem_amount)
            return self._zincrby(keys=[name], args=[amount, value, rem_amount])

        with self.pipeline() as pipe:
            pipe.multi()
            if rem_amount is None:
                pipe.zincrby(name, amount, value)
            else:
                rem_amount = 'NIL' if rem_amount is None else str(rem_amount)
                self._zincrby(keys=[name], args=[
                              amount, value, rem_amount], client=pipe)
            pipe.expire(name, ttl)
            result = pipe.execute()
            return result[0]

    def lpop(self,
             name: str,
             count: Optional[int] = None,
             ttl: Optional[float] = None,
             ) -> Union[Awaitable[Union[str, List, None]], Union[str, List, None]]:
        """
        LPOP operation with count support and optional TTL.
        
        Args:
            name: List key
            count: Number of elements to pop
            ttl: Optional time-to-live in seconds
            
        Returns:
            Popped elements (single or list)
        """
        if ttl is None:
            if self._old_version and count is not None:
                return self._lpop(keys=[name], args=[count])
            return super().lpop(name, count)

        with self.pipeline() as pipe:
            pipe.multi()
            if self._old_version and count is not None:
                self._lpop(keys=[name], args=[count], client=pipe)
            else:
                pipe.lpop(name, count)
            pipe.expire(name, ttl)
            result = pipe.execute()
            return result[0]

    def blpop(self, keys: List, timeout: Optional[Number] = 0):
        """
        BLPOP operation with version-specific timeout handling.
        
        Args:
            keys: List of keys to pop from
            timeout: Maximum wait time in seconds
            
        Returns:
            Tuple of (key, value) or None if timeout
        """
        if self._old_version:
            if timeout > 0 and timeout < 1:
                timeout = 1
            timeout = int(timeout)
            return super().blpop(keys=keys, timeout=timeout)

        if timeout > 0 and timeout < 0.01:
            timeout = 0.01
        return super().blpop(keys=keys, timeout=timeout)
