"""
# 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 __future__ import annotations

import random
from dataclasses import dataclass, fields
from typing import Any, List, Optional, Union


@dataclass
class SamplingParams:
    """Sampling parameters for text generation.

    Overall, we follow the sampling parameters from the OpenAI text completion
    API (https://platform.openai.com/docs/api-reference/completions/create).
    In addition, we support beam search, which is not supported by OpenAI.

    Args:
        n: Number of output sequences to return for the given prompt.
        best_of: Number of output sequences that are generated from the prompt.
            From these `best_of` sequences, the top `n` sequences are returned.
            `best_of` must be greater than or equal to `n`. By default,
            `best_of` is set to `n`. Warning, this is only supported in V0.
        presence_penalty: Float that penalizes new tokens based on whether they
            appear in the generated text so far. Values > 0 encourage the model
            to use new tokens, while values < 0 encourage the model to repeat
            tokens.
        frequency_penalty: Float that penalizes new tokens based on their
            frequency in the generated text so far. Values > 0 encourage the
            model to use new tokens, while values < 0 encourage the model to
            repeat tokens.
        repetition_penalty: Float that penalizes new tokens based on whether
            they appear in the prompt and the generated text so far. Values > 1
            encourage the model to use new tokens, while values < 1 encourage
            the model to repeat tokens.
        temperature: Float that controls the randomness of the sampling. Lower
            values make the model more deterministic, while higher values make
            the model more random. Zero means greedy sampling.
        top_p: Float that controls the cumulative probability of the top tokens
            to consider. Must be in [0, 1]. Set to 1 to consider all tokens.
        top_k: Int that controls the number of top tokens to consider. Must be a positive integer.
        seed: Random seed to use for the generation.
        stop: list of strings that stop the generation when they are generated.
            The returned output will not contain the stop strings.
        stop_token_ids: list of tokens that stop the generation when they are
            generated. The returned output will contain the stop tokens unless
            the stop tokens are special tokens.
        bad_words: list of words that are not allowed to be generated.
            More precisely, only the last token of a corresponding
            token sequence is not allowed when the next generated token
            can complete the sequence.
        max_tokens: Maximum number of tokens to generate per output sequence.
        reasoning_max_tokens: Maximum number of tokens to generate for reasoning per output sequence.
        min_tokens: Minimum number of tokens to generate per output sequence
            before EOS or stop_token_ids can be generated
        logprobs: Number of log probabilities to return per output token.
            When set to None, no probability is returned. If set to a non-None
            value, the result includes the log probabilities of the specified
            number of most likely tokens, as well as the chosen tokens.
            Note that the implementation follows the OpenAI API: The API will
            always return the log probability of the sampled token, so there
            may be up to `logprobs+1` elements in the response.
    """

    n: int = 1
    best_of: Optional[int] = None
    presence_penalty: float = None
    frequency_penalty: float = None
    repetition_penalty: float = None
    temperature: float = None
    top_p: float = 1.0
    top_k: int = 0
    seed: Optional[int] = None
    stop: Optional[Union[str, List[str]]] = None
    stop_token_ids: Optional[Union[List[List[int]], List[int]]] = None
    max_tokens: Optional[int] = None
    reasoning_max_tokens: Optional[int] = None
    min_tokens: int = 1
    logprobs: Optional[int] = None
    bad_words: Optional[List[str]] = None

    @classmethod
    def from_dict(cls, req_dict: dict[str, Any]) -> "SamplingParams":
        """Create instance from command line arguments"""
        return cls(
            **{
                field.name:
                req_dict[field.name] if field.name in
                req_dict else field.default
                for field in fields(cls)
            })

    @classmethod
    def from_optional(cls,
                      n,
                      best_of,
                      presence_penalty,
                      frequency_penalty,
                      repetition_penalty,
                      temperature,
                      top_p,
                      top_k,
                      seed=None,
                      stop=None,
                      stop_token_ids=None,
                      max_tokens=None,
                      reasoning_max_tokens=None,
                      min_tokens=1,
                      logprobs=None,
                      bad_words=None) -> "SamplingParams":
        """Create instance from command line arguments"""
        return cls(n=1 if n is None else n,
                   best_of=best_of,
                   presence_penalty=presence_penalty
                   if presence_penalty is not None else 0.0,
                   frequency_penalty=frequency_penalty
                   if frequency_penalty is not None else 0.0,
                   repetition_penalty=repetition_penalty
                   if repetition_penalty is not None else 1.0,
                   temperature=temperature if temperature is not None else 1.0,
                   top_p=top_p if top_p is not None else 1.0,
                   top_k=top_k if top_k is not None else 0,
                   seed=seed,
                   stop=stop,
                   stop_token_ids=stop_token_ids,
                   max_tokens=max_tokens if max_tokens is not None else 8192,
                   reasoning_max_tokens=reasoning_max_tokens,
                   min_tokens=min_tokens,
                   logprobs=logprobs,
                   bad_words=bad_words)

    def __post_init__(self):
        if self.seed is None:
            self.seed = random.randint(0, 922337203685477580)
        if self.max_tokens is not None and self.reasoning_max_tokens is None:
            self.reasoning_max_tokens = max(int(self.max_tokens * 0.8), 1)
        self._verify_args()

    def _verify_args(self) -> None:
        if not isinstance(self.n, int):
            raise ValueError(
                f"n must be an int, but is of type {type(self.n)}")
        if self.n < 1:
            raise ValueError(f"n must be at least 1, got {self.n}.")
        if self.presence_penalty is not None and (
                not -2.0 <= self.presence_penalty <= 2.0):
            raise ValueError("presence_penalty must be in [-2, 2], got "
                             f"{self.presence_penalty}.")
        if self.frequency_penalty is not None and (
                not -2.0 <= self.frequency_penalty <= 2.0):
            raise ValueError("frequency_penalty must be in [-2, 2], got "
                             f"{self.frequency_penalty}.")
        if self.repetition_penalty is not None and self.repetition_penalty <= 0.0:
            raise ValueError(
                "repetition_penalty must be greater than zero, got "
                f"{self.repetition_penalty}.")
        if self.temperature is not None and self.temperature < 0.0:
            raise ValueError(
                f"temperature must be non-negative, got {self.temperature}.")
        if self.top_p is not None and not 0.0 <= self.top_p <= 1.0:
            raise ValueError(f"top_p must be in [0, 1], got {self.top_p}.")
        # quietly accept -1 as disabled, but prefer 0
        if self.top_k < -1:
            raise ValueError(f"top_k must be 0 (disable), or at least 1, "
                             f"got {self.top_k}.")
        if not isinstance(self.top_k, int):
            raise TypeError(
                f"top_k must be an integer, got {type(self.top_k).__name__}")

        if self.max_tokens is not None and self.max_tokens < 1:
            raise ValueError(
                f"max_tokens must be at least 1, got {self.max_tokens}.")

        if self.reasoning_max_tokens is not None and self.reasoning_max_tokens > self.max_tokens:
            raise ValueError(
                f"reasoning_max_tokens must be less than max_tokens, got {self.reasoning_max_tokens}.")

        if self.min_tokens < 0:
            raise ValueError(f"min_tokens must be greater than or equal to 0, "
                             f"got {self.min_tokens}.")
        if self.max_tokens is not None and self.min_tokens > self.max_tokens:
            raise ValueError(
                f"min_tokens must be less than or equal to "
                f"max_tokens={self.max_tokens}, got {self.min_tokens}.")
        if self.logprobs is not None and self.logprobs < 0:
            raise ValueError(
                f"logprobs must be non-negative, got {self.logprobs}.")
        if self.logprobs is not None and self.logprobs > 20:
            raise ValueError(
                "Invalid value for 'top_logprobs': must be less than or equal to 20.")

        if not 0 <= self.seed <= 922337203685477580:
            raise ValueError("seed must be in [0, 922337203685477580], got "
                             f"{self.seed}.")

    def update_from_tokenizer(self, tokenizer):
        """
        # TODO: Implement stop tokens and bad words support
        # Currently stop tokens and bad words are not supported yet
        """
        pass


@dataclass
class BeamSearchParams:
    """Beam search parameters for text generation."""
    beam_width: int
    max_tokens: int
    ignore_eos: bool = False
    temperature: float = 0.0
    length_penalty: float = 1.0
    include_stop_str_in_output: bool = False