from peft import PeftModel, PeftConfig
import torch
from transformers import (
    AutoModelForCausalLM,
    AutoTokenizer,
    BitsAndBytesConfig,
)


instruction = (
    "Generate Cypher statement to query a graph database. "
    "Use only the provided relationship types and properties in the schema. \n"
    "Schema: {schema} \n Question: {question}  \n Cypher output: "
)



def prepare_chat_prompt(question, schema) -> list[dict]:
    chat = [
        {
            "role": "user",
            "content": instruction.format(
                schema=schema, question=question
            ),
        }
    ]
    return chat

def _postprocess_output_cypher(output_cypher: str) -> str:
    # Remove any explanation. E.g.  MATCH...\n\n**Explanation:**\n\n -> MATCH...
    # Remove cypher indicator. E.g.```cypher\nMATCH...```` --> MATCH...
    # Note: Possible to have both:
    #   E.g. ```cypher\nMATCH...````\n\n**Explanation:**\n\n --> MATCH...
    partition_by = "**Explanation:**"
    output_cypher, _, _ = output_cypher.partition(partition_by)
    output_cypher = output_cypher.strip("`\n")
    output_cypher = output_cypher.lstrip("cypher\n")
    output_cypher = output_cypher.strip("`\n ")
    return output_cypher

# Model
model_name = "neo4j/text2cypher-gemma-2-9b-it-finetuned-2024v1"
bnb_config = BitsAndBytesConfig(
    load_in_4bit=True,
    bnb_4bit_use_double_quant=True,
    bnb_4bit_quant_type="nf4",
    bnb_4bit_compute_dtype=torch.bfloat16,
)
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(
    model_name,
    quantization_config=bnb_config,
    torch_dtype=torch.bfloat16,
    attn_implementation="eager",
    low_cpu_mem_usage=True,
)

# Question
question = "What are the movies of Tom Hanks?"
schema = "(:Actor)-[:ActedIn]->(:Movie)" # Check the NOTE below on creating your own schemas
new_message = prepare_chat_prompt(question=question, schema=schema)
prompt = tokenizer.apply_chat_template(new_message, add_generation_prompt=True, tokenize=False)
inputs = tokenizer(prompt, return_tensors="pt", padding=True)

# Any other parameters
model_generate_parameters = {
    "top_p": 0.9,
    "temperature": 0.2,
    "max_new_tokens": 512,
    "do_sample": True,
    "pad_token_id": tokenizer.eos_token_id,
}

inputs.to(model.device)
model.eval()
with torch.no_grad():
    tokens = model.generate(**inputs, **model_generate_parameters)
    tokens = tokens[:, inputs.input_ids.shape[1] :]
    raw_outputs = tokenizer.batch_decode(tokens, skip_special_tokens=True)
    outputs = [_postprocess_output_cypher(output) for output in raw_outputs]
    
print(outputs)
> ["MATCH (a:Actor {Name: 'Tom Hanks'})-[:ActedIn]->(m:Movie) RETURN m"]