import os
from huggingface_hub import hf_hub_download
conceptual_weight = hf_hub_download(repo_id="akhaliq/CLIP-prefix-captioning-conceptual-weights", filename="conceptual_weights.pt")
coco_weight = hf_hub_download(repo_id="akhaliq/CLIP-prefix-captioning-COCO-weights", filename="coco_weights.pt")
import clip
import os
from torch import nn
import numpy as np
import torch
import torch.nn.functional as nnf
import sys
from typing import Tuple, List, Union, Optional
from transformers import GPT2Tokenizer, GPT2LMHeadModel, AdamW, get_linear_schedule_with_warmup
from tqdm import tqdm, trange
import skimage.io as io
import PIL.Image
import gradio as gr

N = type(None)
V = np.array
ARRAY = np.ndarray
ARRAYS = Union[Tuple[ARRAY, ...], List[ARRAY]]
VS = Union[Tuple[V, ...], List[V]]
VN = Union[V, N]
VNS = Union[VS, N]
T = torch.Tensor
TS = Union[Tuple[T, ...], List[T]]
TN = Optional[T]
TNS = Union[Tuple[TN, ...], List[TN]]
TSN = Optional[TS]
TA = Union[T, ARRAY]


D = torch.device
CPU = torch.device('cpu')


def get_device(device_id: int) -> D:
    if not torch.cuda.is_available():
        return CPU
    device_id = min(torch.cuda.device_count() - 1, device_id)
    return torch.device(f'cuda:{device_id}')


CUDA = get_device

class MLP(nn.Module):

    def forward(self, x: T) -> T:
        return self.model(x)

    def __init__(self, sizes: Tuple[int, ...], bias=True, act=nn.Tanh):
        super(MLP, self).__init__()
        layers = []
        for i in range(len(sizes) -1):
            layers.append(nn.Linear(sizes[i], sizes[i + 1], bias=bias))
            if i < len(sizes) - 2:
                layers.append(act())
        self.model = nn.Sequential(*layers)


class ClipCaptionModel(nn.Module):

    #@functools.lru_cache #FIXME
    def get_dummy_token(self, batch_size: int, device: D) -> T:
        return torch.zeros(batch_size, self.prefix_length, dtype=torch.int64, device=device)

    def forward(self, tokens: T, prefix: T, mask: Optional[T] = None, labels: Optional[T] = None):
        embedding_text = self.gpt.transformer.wte(tokens)
        prefix_projections = self.clip_project(prefix).view(-1, self.prefix_length, self.gpt_embedding_size)
        #print(embedding_text.size()) #torch.Size([5, 67, 768])
        #print(prefix_projections.size()) #torch.Size([5, 1, 768])
        embedding_cat = torch.cat((prefix_projections, embedding_text), dim=1)
        if labels is not None:
            dummy_token = self.get_dummy_token(tokens.shape[0], tokens.device)
            labels = torch.cat((dummy_token, tokens), dim=1)
        out = self.gpt(inputs_embeds=embedding_cat, labels=labels, attention_mask=mask)
        return out

    def __init__(self, prefix_length: int, prefix_size: int = 512):
        super(ClipCaptionModel, self).__init__()
        self.prefix_length = prefix_length
        self.gpt = GPT2LMHeadModel.from_pretrained('gpt2')
        self.gpt_embedding_size = self.gpt.transformer.wte.weight.shape[1]
        if prefix_length > 10:  # not enough memory
            self.clip_project = nn.Linear(prefix_size, self.gpt_embedding_size * prefix_length)
        else:
            self.clip_project = MLP((prefix_size, (self.gpt_embedding_size * prefix_length) // 2, self.gpt_embedding_size * prefix_length))


class ClipCaptionPrefix(ClipCaptionModel):

    def parameters(self, recurse: bool = True):
        return self.clip_project.parameters()

    def train(self, mode: bool = True):
        super(ClipCaptionPrefix, self).train(mode)
        self.gpt.eval()
        return self
        

#@title Caption prediction

def generate_beam(model, tokenizer, beam_size: int = 5, prompt=None, embed=None,
                  entry_length=67, temperature=1., stop_token: str = '.'):

    model.eval()
    stop_token_index = tokenizer.encode(stop_token)[0]
    tokens = None
    scores = None
    device = next(model.parameters()).device
    seq_lengths = torch.ones(beam_size, device=device)
    is_stopped = torch.zeros(beam_size, device=device, dtype=torch.bool)
    with torch.no_grad():
        if embed is not None:
            generated = embed
        else:
            if tokens is None:
                tokens = torch.tensor(tokenizer.encode(prompt))
                tokens = tokens.unsqueeze(0).to(device)
                generated = model.gpt.transformer.wte(tokens)
        for i in range(entry_length):
            outputs = model.gpt(inputs_embeds=generated)
            logits = outputs.logits
            logits = logits[:, -1, :] / (temperature if temperature > 0 else 1.0)
            logits = logits.softmax(-1).log()
            if scores is None:
                scores, next_tokens = logits.topk(beam_size, -1)
                generated = generated.expand(beam_size, *generated.shape[1:])
                next_tokens, scores = next_tokens.permute(1, 0), scores.squeeze(0)
                if tokens is None:
                    tokens = next_tokens
                else:
                    tokens = tokens.expand(beam_size, *tokens.shape[1:])
                    tokens = torch.cat((tokens, next_tokens), dim=1)
            else:
                logits[is_stopped] = -float(np.inf)
                logits[is_stopped, 0] = 0
                scores_sum = scores[:, None] + logits
                seq_lengths[~is_stopped] += 1
                scores_sum_average = scores_sum / seq_lengths[:, None]
                scores_sum_average, next_tokens = scores_sum_average.view(-1).topk(beam_size, -1)
                next_tokens_source = next_tokens // scores_sum.shape[1]
                seq_lengths = seq_lengths[next_tokens_source]
                next_tokens = next_tokens % scores_sum.shape[1]
                next_tokens = next_tokens.unsqueeze(1)
                tokens = tokens[next_tokens_source]
                tokens = torch.cat((tokens, next_tokens), dim=1)
                generated = generated[next_tokens_source]
                scores = scores_sum_average * seq_lengths
                is_stopped = is_stopped[next_tokens_source]
            next_token_embed = model.gpt.transformer.wte(next_tokens.squeeze()).view(generated.shape[0], 1, -1)
            generated = torch.cat((generated, next_token_embed), dim=1)
            is_stopped = is_stopped + next_tokens.eq(stop_token_index).squeeze()
            if is_stopped.all():
                break
    scores = scores / seq_lengths
    output_list = tokens.cpu().numpy()
    output_texts = [tokenizer.decode(output[:int(length)]) for output, length in zip(output_list, seq_lengths)]
    order = scores.argsort(descending=True)
    output_texts = [output_texts[i] for i in order]
    return output_texts


def generate2(
        model,
        tokenizer,
        tokens=None,
        prompt=None,
        embed=None,
        entry_count=1,
        entry_length=67,  # maximum number of words
        top_p=0.8,
        temperature=1.,
        stop_token: str = '.',
):
    model.eval()
    generated_num = 0
    generated_list = []
    stop_token_index = tokenizer.encode(stop_token)[0]
    filter_value = -float("Inf")
    device = next(model.parameters()).device

    with torch.no_grad():

        for entry_idx in trange(entry_count):
            if embed is not None:
                generated = embed
            else:
                if tokens is None:
                    tokens = torch.tensor(tokenizer.encode(prompt))
                    tokens = tokens.unsqueeze(0).to(device)

                generated = model.gpt.transformer.wte(tokens)

            for i in range(entry_length):

                outputs = model.gpt(inputs_embeds=generated)
                logits = outputs.logits
                logits = logits[:, -1, :] / (temperature if temperature > 0 else 1.0)
                sorted_logits, sorted_indices = torch.sort(logits, descending=True)
                cumulative_probs = torch.cumsum(nnf.softmax(sorted_logits, dim=-1), dim=-1)
                sorted_indices_to_remove = cumulative_probs > top_p
                sorted_indices_to_remove[..., 1:] = sorted_indices_to_remove[
                                                    ..., :-1
                                                    ].clone()
                sorted_indices_to_remove[..., 0] = 0

                indices_to_remove = sorted_indices[sorted_indices_to_remove]
                logits[:, indices_to_remove] = filter_value
                next_token = torch.argmax(logits, -1).unsqueeze(0)
                next_token_embed = model.gpt.transformer.wte(next_token)
                if tokens is None:
                    tokens = next_token
                else:
                    tokens = torch.cat((tokens, next_token), dim=1)
                generated = torch.cat((generated, next_token_embed), dim=1)
                if stop_token_index == next_token.item():
                    break

            output_list = list(tokens.squeeze().cpu().numpy())
            output_text = tokenizer.decode(output_list)
            generated_list.append(output_text)

    return generated_list[0]
    
is_gpu = False 
device = CUDA(0) if is_gpu else "cpu"
clip_model, preprocess = clip.load("ViT-B/32", device=device, jit=False)
tokenizer = GPT2Tokenizer.from_pretrained("gpt2")

def inference(img,model_name):   
  prefix_length = 10
    
  model = ClipCaptionModel(prefix_length)
    
  if model_name == "COCO":
      model_path = coco_weight
  else:
      model_path = conceptual_weight
  model.load_state_dict(torch.load(model_path, map_location=CPU), strict=False) 
  model = model.eval() 
  device = CUDA(0) if is_gpu else "cpu"
  model = model.to(device)

  use_beam_search = False 
  pil_image = PIL.Image.fromarray(img)  
  image = preprocess(pil_image).unsqueeze(0).to(device)
  with torch.no_grad():
      prefix = clip_model.encode_image(image).to(device, dtype=torch.float32)
      prefix_embed = model.clip_project(prefix).reshape(1, prefix_length, -1)
  if use_beam_search:
      generated_text_prefix = generate_beam(model, tokenizer, embed=prefix_embed)[0]
  else:
      generated_text_prefix = generate2(model, tokenizer, embed=prefix_embed)
  return generated_text_prefix
  
title = "CLIP prefix captioning"
description = "Gradio demo for CLIP prefix captioning: a simple image captioning model. To use it, simply upload your image, or click one of the examples to load them. Read more at the links below."
article = "<p style='text-align: center'><a href='https://github.com/rmokady/CLIP_prefix_caption' target='_blank'>Github Repo</a></p>"

examples=[['water.jpeg',"COCO"]]
gr.Interface(
    inference, 
    inputs=[gr.Image(label="Input"),gr.Radio(choices=["COCO","Conceptual captions"], value="COCO", label="Model")], 
    outputs=gr.Textbox(label="Output"),
    title=title,
    description=description,
    article=article,
    examples=examples
    ).launch(debug=True)