import os
import torch

from transformers import AutoModelForCausalLM, AutoTokenizer, TrainingArguments,BitsAndBytesConfig
from datasets import load_dataset
from trl import SFTTrainer
from peft import AutoPeftModelForCausalLM, LoraConfig, get_peft_model, prepare_model_for_kbit_training
from utils import find_all_linear_names, print_trainable_parameters

output_dir="./results"
model_name ="codellama/CodeLlama-7b-hf"

dataset = load_dataset('timdettmers/openassistant-guanaco', split="train")

bnb_config = BitsAndBytesConfig(
    load_in_4bit=True,
    bnb_4bit_quant_type="nf4",
    bnb_4bit_compute_dtype=torch.bfloat16,
    bnb_4bit_use_double_quant=True,
)

base_model = AutoModelForCausalLM.from_pretrained(model_name, torch_dtype=torch.bfloat16, quantization_config=bnb_config)
base_model.config.use_cache = False
base_model = prepare_model_for_kbit_training(base_model)

tokenizer = AutoTokenizer.from_pretrained(model_name)
tokenizer.pad_token = tokenizer.eos_token
tokenizer.padding_side = "right"  # Fix weird overflow issue with fp16 training

# Change the LORA hyperparameters accordingly to fit your use case
peft_config = LoraConfig(
    r=32,
    lora_alpha=16,
    target_modules=find_all_linear_names(base_model),
    lora_dropout=0.05,
    bias="none",
    task_type="CAUSAL_LM",
)

base_model = get_peft_model(base_model, peft_config)
print_trainable_parameters(base_model)

# Parameters for training arguments details => https://github.com/huggingface/transformers/blob/main/src/transformers/training_args.py#L158
training_args = TrainingArguments(
    per_device_train_batch_size=1,
    gradient_accumulation_steps=1,
    gradient_checkpointing =True,
    max_grad_norm= 0.3,
    num_train_epochs=3, 
    learning_rate=1e-4,
    bf16=True,
    save_total_limit=3,
    logging_steps=300,
    output_dir=output_dir,
    optim="paged_adamw_32bit",
    lr_scheduler_type="constant",
    warmup_ratio=0.05,
)

trainer = SFTTrainer(
    base_model,
    train_dataset=dataset,
    dataset_text_field="text",
    tokenizer=tokenizer,
    max_seq_length=512,
    args=training_args
)

trainer.train() 
trainer.save_model(output_dir)

output_dir = os.path.join(output_dir, "final_checkpoint")
trainer.model.save_pretrained(output_dir)
tokenizer.save_pretrained(output_dir)