import os
import json
import torch
import argparse
from tqdm import tqdm

from transformers import AutoTokenizer, AutoModelForCausalLM


PROMPT_DICT_NONE = {
    "prompt_input": (
        "{instruction}\n{input}\n"
    ),
    "prompt_no_input": (
        "{instruction}\n"
    ),
}
# Used to get the ppl and emb for the whole input
def get_perplexity_and_embedding_whole_text(tokenizer, model, text, max_length, device):

    input_ids = tokenizer.encode(text, return_tensors="pt", truncation=True, max_length=max_length).to(device)

    with torch.no_grad(): 
        outputs = model(input_ids, labels=input_ids.contiguous())
    loss = outputs.loss
    perplexity = torch.exp(loss)

    return perplexity.to('cpu').item(), loss.to('cpu').item()


# Used to get the ppl and emb for part of input, used in conditional version, and token-wise loss
def get_perplexity_and_embedding_part_text(tokenizer, model, text, target_span, max_length, device):

    try:
        input_ids = tokenizer.encode(text, return_tensors="pt", truncation=True, max_length=max_length).to(device)

        start_index = text.rfind(target_span)
        start_token = len(tokenizer.encode(text[:start_index]))
        end_token = input_ids.shape[1]

        labels = input_ids.clone()
        labels[0, :start_token] = -100

        with torch.no_grad():
            outputs = model(input_ids, labels=labels)

        loss = outputs.loss
        perplexity = torch.exp(loss)

        return perplexity.to('cpu').item(), loss.to('cpu').item()
    
    except Exception:
        return 0, 0
