from huggingface_hub import login
import os
import gc

os.environ['HF_HOME'] = './cache_huggingface'  # or just "." for directly in current folder
#os.environ['PYTORCH_CUDA_ALLOC_CONF'] = 'expandable_segments:True'

# Login into Hugging Face Hub
hf_token = "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"#userdata.get('gemma3') # If you are running inside a Google Colab
print("Logging into Hugging Face Hub...")
login(hf_token)
print("Logged in.")
from datasets import load_dataset
from PIL import Image

# System message for the assistant
system_message = "You are an expert product description writer for Amazon."
print("System message set.")

# User prompt that combines the user query and the schema
user_prompt = """Create a Short Product description based on the provided <PRODUCT> and <CATEGORY> and image.
Only return description. The description should be SEO optimized and for a better mobile search experience.

<PRODUCT>
{product}
</PRODUCT>

<CATEGORY>
{category}
</CATEGORY>
"""

# Convert dataset to OAI messages
def format_data(sample):
    return {
        "messages": [
            {
                "role": "system",
                "content": [{"type": "text", "text": system_message}],#esempio unsloth non ha system message
            },
            {
                "role": "user",
                "content": [
                    {
                        "type": "text",
                        "text": user_prompt.format(
                            product=sample["Product Name"],
                            category=sample["Category"],
                        ),
                    },
                    {
                        "type": "image",
                        "image": sample["image"],
                    },
                ],
            },
            {
                "role": "assistant",
                "content": [{"type": "text", "text": sample["description"]}],#vedi ruolo assistente per la risposta aspettata
            },
        ],
    }

def process_vision_info(messages: list[dict]) -> list[Image.Image]:
    image_inputs = []
    # Iterate through each conversation
    for msg in messages:
        # Get content (ensure it's a list)
        content = msg.get("content", [])
        if not isinstance(content, list):
            content = [content]

        # Check each content element for images
        for element in content:
            if isinstance(element, dict) and (
                "image" in element or element.get("type") == "image"
            ):
                # Get the image and convert to RGB
                if "image" in element:
                    image = element["image"]
                else:
                    image = element
                image_inputs.append(image.convert("RGB"))#converte in rgb !
    return image_inputs

print("Loading dataset...")
# Load dataset from the hub
dataset = load_dataset("philschmid/amazon-product-descriptions-vlm", split="train",cache_dir="./dataset_cache")

# Convert dataset to OAI messages
# need to use list comprehension to keep Pil.Image type, .mape convert image to bytes
dataset = [format_data(sample) for sample in dataset]

print(dataset[345]["messages"])

import torch
torch.cuda.get_device_capability()

print("Freeing up memory...")
torch.cuda.empty_cache()
gc.collect()

# Get free memory in bytes
free_memory = torch.cuda.mem_get_info()[0]
total_memory = torch.cuda.mem_get_info()[1]

# Convert to GB for readability
free_gb = free_memory / (1024**3)
total_gb = total_memory / (1024**3)

print(f"Free: {free_gb:.2f} GB / Total: {total_gb:.2f} GB")

from transformers import AutoProcessor, AutoModelForImageTextToText, BitsAndBytesConfig

# Hugging Face model id
model_id = "google/gemma-3-4b-pt" # or `google/gemma-3-12b-pt`, `google/gemma-3-27-pt`

# Check if GPU benefits from bfloat16
#if torch.cuda.get_device_capability()[0] < 8:
#    raise ValueError("GPU does not support bfloat16, please use a GPU that supports bfloat16.")

# Define model init arguments
model_kwargs = dict(
    attn_implementation="eager", # Use "flash_attention_2" when running on Ampere or newer GPU
    torch_dtype=torch.bfloat16,#torch.float16,#torch.bfloat16, # What torch dtype to use, defaults to auto
    device_map="auto", # Let torch decide how to load the model
   
)

# BitsAndBytesConfig int-4 config
model_kwargs["quantization_config"] = BitsAndBytesConfig(
    load_in_4bit=True,
    bnb_4bit_use_double_quant=True,
    bnb_4bit_quant_type="nf4",
    bnb_4bit_compute_dtype=model_kwargs["torch_dtype"],
    bnb_4bit_quant_storage=model_kwargs["torch_dtype"],
)

# Load model and tokenizer
#model = AutoModelForImageTextToText.from_pretrained(model_id, **model_kwargs)
#processor = AutoProcessor.from_pretrained("google/gemma-3-4b-it")




# Set the cache directory to current folder
cache_dir = "./model_cache"  # or just "." for directly in current folder

print("Loading model... This may take a while.")
model = AutoModelForImageTextToText.from_pretrained(
    model_id, 
    cache_dir=cache_dir,
    **model_kwargs
)
print("Model loaded.")


proc_cache_dir = "./proc_cache"
print("Loading processor...")
processor = AutoProcessor.from_pretrained(
    "google/gemma-3-4b-it",#model_id, # nel file originale prende -it e non -pt (cambia poco comunque)
    cache_dir=proc_cache_dir
)
print("Processor loaded.")

# Download and save to current folder
print("Saving model and processor locally...")
save_path = "./local_model"
#model.save_pretrained(save_path)
#processor.save_pretrained(save_path)
print("Model and processor saved.")

from peft import LoraConfig

peft_config = LoraConfig(
    lora_alpha=16,
    lora_dropout=0.05,
    r=16,
    bias="none",
    target_modules="all-linear",
    task_type="CAUSAL_LM",
    #modules_to_save=[ #quello che mi prendeva
    #    "lm_head",
    #    "embed_tokens",
    #],
)

from trl import SFTConfig

args = SFTConfig(
    output_dir="./gemma-finetuned",     # directory to save and repository id
    num_train_epochs=1,                         # number of training epochs
    per_device_train_batch_size=1,              # batch size per device during training
    gradient_accumulation_steps=8,#4,              # number of steps before performing a backward/update pass
    gradient_checkpointing=True,                # use gradient checkpointing to save memory
    optim="adamw_torch_fused",                  # use fused adamw optimizer
    logging_steps=5,                            # log every 5 steps
    save_strategy="epoch",                      # save checkpoint every epoch
    learning_rate=2e-4,                         # learning rate, based on QLoRA paper
    bf16=True,#False,#True,                                  # use bfloat16 precision
    max_grad_norm=0.3,                          # max gradient norm based on QLoRA paper
    warmup_ratio=0.03,                          # warmup ratio based on QLoRA paper
    lr_scheduler_type="constant",               # use constant learning rate scheduler
    push_to_hub=True,                           # push model to hub
    report_to="tensorboard",                    # report metrics to tensorboard
    gradient_checkpointing_kwargs={
        "use_reentrant": False
    },  # use reentrant checkpointing
    dataset_text_field="",                      # need a dummy field for collator
    dataset_kwargs={"skip_prepare_dataset": True},  # important for collator
)
args.remove_unused_columns = False # important for collator

# Create a data collator to encode text and image pairs
def collate_fn(examples):
    texts = []
    images = []
    for example in examples:
        image_inputs = process_vision_info(example["messages"])
        text = processor.apply_chat_template(
            example["messages"], add_generation_prompt=False, tokenize=False
        )
        texts.append(text.strip())
        images.append(image_inputs)

    # Tokenize the texts and process the images
    batch = processor(text=texts, images=images, return_tensors="pt", padding=True)

    # The labels are the input_ids, and we mask the padding tokens and image tokens in the loss computation
    labels = batch["input_ids"].clone()

    # Mask image tokens
    image_token_id = [
        processor.tokenizer.convert_tokens_to_ids(
            processor.tokenizer.special_tokens_map["boi_token"]
        )
    ]
    # Mask tokens for not being used in the loss computation
    labels[labels == processor.tokenizer.pad_token_id] = -100
    labels[labels == image_token_id] = -100
    labels[labels == 262144] = -100

    batch["labels"] = labels
    return batch

from trl import SFTTrainer

trainer = SFTTrainer(
    model=model,
    args=args,
    train_dataset=dataset,
    peft_config=peft_config,
    processing_class=processor,
    data_collator=collate_fn,
)

# Start training, the model will be automatically saved to the Hub and the output directory
trainer.train()

# Save the final model again to the Hugging Face Hub
trainer.save_model()

# free the memory again
del model
del trainer
torch.cuda.empty_cache()

from peft import PeftModel

# Load Model base model
model = AutoModelForImageTextToText.from_pretrained(model_id, low_cpu_mem_usage=True)

# Merge LoRA and base model and save
peft_model = PeftModel.from_pretrained(model, args.output_dir)
merged_model = peft_model.merge_and_unload()
merged_model.save_pretrained("merged_model", safe_serialization=True, max_shard_size="2GB")

processor = AutoProcessor.from_pretrained(args.output_dir)
processor.save_pretrained("merged_model")

import torch

# Load Model with PEFT adapter
model = AutoModelForImageTextToText.from_pretrained(
  args.output_dir,
  device_map="auto",
  torch_dtype=torch.bfloat16,
  attn_implementation="eager",
)
processor = AutoProcessor.from_pretrained(args.output_dir)

import requests
from PIL import Image

# Test sample with Product Name, Category and Image
sample = {
  "product_name": "Hasbro Marvel Avengers-Serie Marvel Assemble Titan-Held, Iron Man, 30,5 cm Actionfigur",
  "category": "Toys & Games | Toy Figures & Playsets | Action Figures",
  "image": Image.open(requests.get("https://m.media-amazon.com/images/I/81+7Up7IWyL._AC_SY300_SX300_.jpg", stream=True).raw).convert("RGB")
}


# NB: inferenza fatta con input immagine e i due campi testuali (e stessa instruction del finetuning)
def generate_description(sample, model, processor):
    # Convert sample into messages and then apply the chat template
    messages = [
        {"role": "system", "content": [{"type": "text", "text": system_message}]},
        {"role": "user", "content": [
            {"type": "image","image": sample["image"]},
            {"type": "text", "text": user_prompt.format(product=sample["product_name"], category=sample["category"])},
        ]},
    ]
    text = processor.apply_chat_template(
        messages, tokenize=False, add_generation_prompt=True
    )
    # Process the image and text
    image_inputs = process_vision_info(messages)# converte immagine in rgb anche se sembra lo faccia già sopra nel sample .convert("RGB")
    # Tokenize the text and process the images
    inputs = processor(
        text=[text],
        images=image_inputs,
        padding=True,
        return_tensors="pt",
    )
    # Move the inputs to the device
    inputs = inputs.to(model.device)

    # Generate the output
    stop_token_ids = [processor.tokenizer.eos_token_id, processor.tokenizer.convert_tokens_to_ids("<end_of_turn>")]
    generated_ids = model.generate(**inputs, max_new_tokens=256, top_p=1.0, do_sample=True, temperature=0.8, eos_token_id=stop_token_ids, disable_compile=True)
    # Trim the generation and decode the output to text
    generated_ids_trimmed = [out_ids[len(in_ids) :] for in_ids, out_ids in zip(inputs.input_ids, generated_ids)]
    output_text = processor.batch_decode(
        generated_ids_trimmed, skip_special_tokens=True, clean_up_tokenization_spaces=False
    )
    return output_text[0]

# generate the description

description = generate_description(sample, model, processor)
print(description)