'''
CREDIT:
script adapted from [alpaca](https://huggingface.co/spaces/tloen/alpaca-lora/blob/main/app.py).
'''

import gradio as gr
import random
import time
import transformers
import os
import json
import torch
import argparse
from tqdm import tqdm
from transformers import LlamaTokenizer, LlamaForCausalLM, GenerationConfig


def apply_delta(base_model_path, target_model_path, delta_path):
    print(f"Loading the delta weights from {delta_path}")
    delta_tokenizer = LlamaTokenizer.from_pretrained(delta_path, use_fast=False)
    delta = LlamaForCausalLM.from_pretrained(
        delta_path, low_cpu_mem_usage=True, torch_dtype=torch.float16
    )

    print(f"Loading the base model from {base_model_path}")
    base_tokenizer = LlamaTokenizer.from_pretrained(base_model_path, use_fast=False)
    base = LlamaForCausalLM.from_pretrained(
        base_model_path, low_cpu_mem_usage=True, torch_dtype=torch.float16
    )

    # following alpaca training recipe, we have added new initialized tokens
    DEFAULT_PAD_TOKEN = "[PAD]"
    DEFAULT_EOS_TOKEN = "</s>"
    DEFAULT_BOS_TOKEN = "<s>"
    DEFAULT_UNK_TOKEN = "<unk>"
    special_tokens_dict = {
        "pad_token": DEFAULT_PAD_TOKEN,
        "eos_token": DEFAULT_EOS_TOKEN,
        "bos_token": DEFAULT_BOS_TOKEN,
        "unk_token": DEFAULT_UNK_TOKEN,
    }
    num_new_tokens = base_tokenizer.add_special_tokens(special_tokens_dict)
    base.resize_token_embeddings(len(base_tokenizer))
    input_embeddings = base.get_input_embeddings().weight.data
    output_embeddings = base.get_output_embeddings().weight.data

    input_embeddings[-num_new_tokens:] = 0
    output_embeddings[-num_new_tokens:] = 0

    print("Applying the delta")
    target_weights = {}
    for name, param in tqdm(base.state_dict().items(), desc="Applying delta"):
        assert name in delta.state_dict()
        param.data += delta.state_dict()[name]
        target_weights[name] = param.data

    print(f"Saving the target model to {target_model_path}")
    base.load_state_dict(target_weights)
    # base.save_pretrained(target_model_path)
    # delta_tokenizer.save_pretrained(target_model_path)

    delta = None
    
    return base, delta_tokenizer


base_weights = 'decapoda-research/llama-7b-hf'
target_weights = 'expertllama' # local path
delta_weights = 'OFA-Sys/expertllama-7b-delta'
model, tokenizer = apply_delta(base_weights, target_weights, delta_weights)
model = model.to(torch.float)

if torch.__version__ >= "2":
    model = torch.compile(model)
    
def respond(
    instruction,
    temperature=0.1,
    top_p=0.75,
    top_k=40,
    num_beams=4,
    max_new_tokens=128,
    **kwargs,
):
    # prompt wrapper, only single-turn is allowed for now
    prompt = f"### Human:\n{instruction}\n\n### Assistant:\n"
    inputs = tokenizer(
        prompt,
        return_tensors="pt", 
        add_special_tokens=False
    )
    generation_config = GenerationConfig(
        temperature=temperature,
        top_p=top_p,
        top_k=top_k,
        num_beams=num_beams,
        **kwargs,
    )
    with torch.no_grad():
        generation_output = model.generate(
            input_ids=inputs["input_ids"],
            generation_config=generation_config,
            return_dict_in_generate=True,
            output_scores=True,
            max_new_tokens=max_new_tokens,
        )
    response = tokenizer.decode(generation_output.sequences[0][:-1]).split("### Assistant:\n", 1)[1]
    return response

    
g = gr.Interface(
    fn=respond,
    inputs=[
        gr.components.Textbox(
            lines=2, label="Instruction"
        ),
        gr.components.Slider(minimum=0, maximum=1, value=0.1, label="Temperature"),
        gr.components.Slider(minimum=0, maximum=1, value=0.75, label="Top p"),
        gr.components.Slider(minimum=0, maximum=100, step=1, value=40, label="Top k"),
        gr.components.Slider(minimum=1, maximum=4, step=1, value=4, label="Beams"),
        gr.components.Slider(
            minimum=1, maximum=768, step=1, value=512, label="Max tokens"
        ),
    ],
    outputs=[
        gr.inputs.Textbox(
            lines=8,
            label="Output",
        )
    ],
    title="ExpertLLaMA",
    description="ExpertLLaMA is an open-source chatbot trained on expert-like data produced with GPT-3.5, see our [project repo](https://github.com/OFA-Sys/ExpertLLaMA) for details.",
)
g.queue(concurrency_count=1)
g.launch()