from unsloth import FastLanguageModel, PatchFastRL
PatchFastRL("GRPO", FastLanguageModel)

from unsloth import is_bfloat16_supported
import torch
import wandb  # Import wandb for logging

# Initialize wandb with your project name
wandb.init(project="unsloth-grpo")

max_seq_length = 1024  # Can increase for longer reasoning traces
lora_rank = 64  # Larger rank = smarter, but slower

model, tokenizer = FastLanguageModel.from_pretrained(
    model_name = "Qwen/Qwen2.5-3B-Instruct",
    max_seq_length=max_seq_length,
    load_in_4bit=True,  # False for LoRA 16bit
    fast_inference=True,  # Enable vLLM fast inference
    max_lora_rank=lora_rank,
    gpu_memory_utilization=0.6,  # Reduce if out of memory
)

model = FastLanguageModel.get_peft_model(
    model,
    r=lora_rank,  # Choose any number > 0 ! Suggested 8, 16, 32, 64, 128
    target_modules=[
        "q_proj", "k_proj", "v_proj", "o_proj",
        "gate_proj", "up_proj", "down_proj",
    ],  # Remove QKVO if out of memory
    lora_alpha=lora_rank,
    use_gradient_checkpointing="unsloth",  # Enable long context finetuning
    random_state=3407,
)

import re
from datasets import load_dataset, Dataset

# Load and prep dataset
SYSTEM_PROMPT = """
Respond in the following format:
<reasoning>
...
</reasoning>
<answer>
...
</answer>
"""

XML_COT_FORMAT = """\
<reasoning>
{reasoning}
</reasoning>
<answer>
{answer}
</answer>
"""

def extract_xml_answer(text: str) -> str:
    answer = text.split("<answer>")[-1]
    answer = answer.split("</answer>")[0]
    return answer.strip()

def extract_hash_answer(text: str) -> str | None:
    if "####" not in text:
        return None
    return text.split("####")[1].strip()

# Uncomment middle messages for 1-shot prompting
def get_gsm8k_questions(split="train") -> Dataset:
    data = load_dataset('openai/gsm8k', 'main')[split]  # type: ignore
    data = data.map(lambda x: {  # type: ignore
        'prompt': [
            {'role': 'system', 'content': SYSTEM_PROMPT},
            {'role': 'user', 'content': x['question']}
        ],
        'answer': extract_hash_answer(x['answer'])
    })  # type: ignore
    return data  # type: ignore

dataset = get_gsm8k_questions()

# Reward functions
def correctness_reward_func(prompts, completions, answer, **kwargs) -> list[float]:
    responses = [completion[0]['content'] for completion in completions]
    q = prompts[0][-1]['content']
    extracted_responses = [extract_xml_answer(r) for r in responses]
    print('-' * 20, f"Question:\n{q}", f"\nAnswer:\n{answer[0]}", f"\nResponse:\n{responses[0]}", f"\nExtracted:\n{extracted_responses[0]}")
    return [2.0 if r == a else 0.0 for r, a in zip(extracted_responses, answer)]

def int_reward_func(completions, **kwargs) -> list[float]:
    responses = [completion[0]['content'] for completion in completions]
    extracted_responses = [extract_xml_answer(r) for r in responses]
    return [0.5 if r.isdigit() else 0.0 for r in extracted_responses]

def strict_format_reward_func(completions, **kwargs) -> list[float]:
    """Reward function that checks if the completion has a specific format."""
    pattern = r"^<reasoning>\n.*?\n</reasoning>\n<answer>\n.*?\n</answer>\n$"
    responses = [completion[0]["content"] for completion in completions]
    matches = [re.match(pattern, r) for r in responses]
    return [0.5 if match else 0.0 for match in matches]

def soft_format_reward_func(completions, **kwargs) -> list[float]:
    """Reward function that checks if the completion has a specific format."""
    pattern = r"<reasoning>.*?</reasoning>\s*<answer>.*?</answer>"
    responses = [completion[0]["content"] for completion in completions]
    matches = [re.match(pattern, r) for r in responses]
    return [0.5 if match else 0.0 for match in matches]

def count_xml(text) -> float:
    count = 0.0
    if text.count("<reasoning>\n") == 1:
        count += 0.125
    if text.count("\n</reasoning>\n") == 1:
        count += 0.125
    if text.count("\n<answer>\n") == 1:
        count += 0.125
        count -= len(text.split("\n</answer>\n")[-1]) * 0.001
    if text.count("\n</answer>") == 1:
        count += 0.125
        count -= (len(text.split("\n</answer>")[-1]) - 1) * 0.001
    return count

def xmlcount_reward_func(completions, **kwargs) -> list[float]:
    contents = [completion[0]["content"] for completion in completions]
    return [count_xml(c) for c in contents]

from trl import GRPOConfig, GRPOTrainer
training_args = GRPOConfig(
    use_vllm=True,  # use vLLM for fast inference!
    learning_rate=5e-6,
    adam_beta1=0.9,
    adam_beta2=0.99,
    weight_decay=0.1,
    warmup_steps=25,
    lr_scheduler_type="cosine",
    optim="adamw_8bit",
    logging_steps=1,
    bf16=is_bfloat16_supported(),
    fp16=not is_bfloat16_supported(),
    per_device_train_batch_size=1,
    gradient_accumulation_steps=1,  # Increase to 4 for smoother training
    num_generations=8,  # Decrease if out of memory
    max_prompt_length=256,
    max_completion_length=256,
    # num_train_epochs=1,  # Set to 1 for a full training run
    max_steps=65536,
    save_steps=250,
    max_grad_norm=0.1,
    report_to="wandb",  # Change from "none" to "wandb" to log to wandb
    output_dir="outputs",
)

trainer = GRPOTrainer(
    model=model,
    processing_class=tokenizer,
    reward_funcs=[
        xmlcount_reward_func,
        soft_format_reward_func,
        strict_format_reward_func,
        int_reward_func,
        correctness_reward_func,
    ],
    args=training_args,
    train_dataset=dataset,
)
trainer.train()
model.save_lora("grpo_saved_lora")