off_topic.py

import re
import time
import asyncio
from io import BytesIO
from typing import List, Optional

import httpx
import matplotlib.pyplot as plt
import numpy as np
import torch
import PIL
import imagehash
from transformers import AutoModelForSeq2SeqLM, AutoTokenizer, CLIPModel, CLIPProcessor
from PIL import Image


class Translator:
    def __init__(self, model_id: str, device: Optional[str] = None):
        self.device = device or ("cuda" if torch.cuda.is_available() else "cpu")
        self.model_id = model_id
        self.tokenizer = AutoTokenizer.from_pretrained(
            model_id)
        self.model = AutoModelForSeq2SeqLM.from_pretrained(model_id).to(self.device)
    
    @property
    def _bos_token_attr(self):
        if hasattr(self.tokenizer, "get_lang_id"):
            return self.tokenizer.get_lang_id
        elif hasattr(self.tokenizer, "lang_code_to_id"):
            return self.tokenizer.lang_code_to_id
        else:
            return

    @property
    def _language_code_mapper(self):
        if "nllb" in self.model_id.lower():
            return {"en": "eng_Latn",
                    "es": "spa_Latn",
                    "pt": "por_Latn"}
        elif "m2m" in self.model_id.lower():
            return {"en": "en",
                    "es": "es",
                    "pt": "pt"}
        else:
            return {"en": "eng",
                    "es": "spa",
                    "pt": "por"}

    def translate(self, texts: List[str], src_lang: str, dest_lang: str = "en", max_length: int = 100):
        self.tokenizer.src_lang = self._language_code_mapper[src_lang]
        inputs = self.tokenizer(texts, return_tensors="pt").to(self.device)
        if "opus" in self.model_id.lower():
            forced_bos_token_id = None
        else:
            forced_bos_token_id = self._bos_token_attr[self._language_code_mapper["en"]]
        translated_tokens = self.model.generate(
            **inputs, forced_bos_token_id=forced_bos_token_id, max_length=max_length
        )
        return self.tokenizer.batch_decode(translated_tokens, skip_special_tokens=True)


class OffTopicDetector:
    def __init__(self, model_id: str, device: Optional[str] = None, image_size: str = "E", translator: Optional[Translator] = None):
        self.device = device or ("cuda" if torch.cuda.is_available() else "cpu")
        self.processor = CLIPProcessor.from_pretrained(model_id)
        self.model = CLIPModel.from_pretrained(model_id).to(self.device)
        self.image_size = image_size
        self.translator = translator

    def predict_probas(self, images: List[PIL.Image.Image], domain: str, site: str,
                       title: Optional[str] = None,
                valid_templates: Optional[List[str]] = None,
                invalid_classes: Optional[List[str]] = None,
                autocast: bool = True):
        domain = domain.lower()
        if valid_templates:
            valid_classes = [template.format(domain) for template in valid_templates]
        else:
            valid_classes = [f"a photo of {domain}", f"brochure with {domain} image", f"instructions for {domain}", f"{domain} diagram"]
        if title:
            if site == "CBT":
                translated_title = title
            else:
                if site == "MLB":
                    src_lang = "pt"
                else:
                    src_lang = "es"
                translated_title = self.translator.translate(title, src_lang=src_lang, dest_lang="en", max_length=100)[0]
            valid_classes.append(translated_title.lower())
        if not invalid_classes:
            invalid_classes = ["promotional ad with store information", "promotional text", "google maps screenshot", "business card", "qr code"]
        
        n_valid = len(valid_classes)
        classes = valid_classes + invalid_classes
        print(f"Valid classes: {valid_classes}", f"Invalid classes: {invalid_classes}", sep="\n")
        n_classes = len(classes)

        if self.device == "cuda":
            torch.cuda.synchronize()
        start = time.time()
        inputs = self.processor(text=classes, images=images, return_tensors="pt", padding=True).to(self.device)
        if self.device == "cpu" and autocast is True:
            autocast = False
        with torch.autocast(self.device, enabled=autocast):
            with torch.no_grad():
                outputs = self.model(**inputs)
                probas = outputs.logits_per_image.softmax(dim=1).cpu().numpy() # we can take the softmax to get the label probabilities
        if self.device == "cuda":
            torch.cuda.synchronize()
        end = time.time()
        duration = end - start
        print(f"Model time: {round(duration, 2)} s",
              f"Model time per image: {round(duration/len(images) * 1000, 0)} ms",
              sep="\n")
        valid_probas = probas[:, 0:n_valid].sum(axis=1, keepdims=True)
        invalid_probas = probas[:, n_valid:n_classes].sum(axis=1, keepdims=True)
        return probas, valid_probas, invalid_probas

    def predict_probas_url(self, img_urls: List[str], domain: str, site:str, 
                           title: Optional[str] = None,
                valid_templates: Optional[List[str]] = None,
                invalid_classes: Optional[List[str]] = None,
                autocast: bool = True):
        images = self.get_images(img_urls)
        dedup_images = self._filter_dups(images)
        return dedup_images, self.predict_probas(dedup_images, domain, site, title, valid_templates, invalid_classes, autocast)

    def predict_probas_item(self, url_or_id: str,
                            use_title: bool = False,
                valid_templates: Optional[List[str]] = None,
                invalid_classes: Optional[List[str]] = None):
        images, domain, site, title = self.get_item_data(url_or_id)
        title = title if use_title else None
        probas, valid_probas, invalid_probas = self.predict_probas(images, domain, site, title, valid_templates,
                                                            invalid_classes)
        return images, domain, probas, valid_probas, invalid_probas

    def apply_threshold(self, valid_probas: np.ndarray, threshold: float = 0.4):
        return valid_probas >= threshold

    def get_item_data(self, url_or_id: str):
        if url_or_id.startswith("http"):
            item_id = "".join(url_or_id.split("/")[3].split("-")[:2])
        else:
            item_id = re.sub("-", "", url_or_id)
        start = time.time()
        response = httpx.get(f"https://api.mercadolibre.com/items/{item_id}").json()
        title = response["title"]
        site, domain = response["domain_id"].split("-")
        img_urls = [x["url"] for x in response["pictures"]]
        img_urls = [x.replace("-O.jpg", f"-{self.image_size}.jpg") for x in img_urls]
        domain_name = httpx.get(f"https://api.mercadolibre.com/catalog_domains/CBT-{domain}").json()["name"]
        end = time.time()
        duration = end - start
        print(f"Items API time: {round(duration * 1000, 0)} ms")
        images = self.get_images(img_urls)
        dedup_images = self._filter_dups(images)
        return dedup_images, domain_name, site, title

    def _filter_dups(self, images: List):
        if len(images) > 1:
            hashes = {}
            for img in images:
                hashes.update({str(imagehash.average_hash(img)): img})
            dedup_hashes = list(dict.fromkeys(hashes))
            dedup_images = [img for hash, img in hashes.items() if hash in dedup_hashes]
        else:
            dedup_images = images
        if (diff := len(images) - len(dedup_images)) > 0:
            print(f"Filtered {diff} images out of {len(images)} due to matching hashes.")
        return dedup_images

    def get_images(self, urls: List[str]):
        start = time.time()
        images = asyncio.run(self._gather_download_tasks(urls))
        end = time.time()
        duration = end - start
        print(f"Download time: {round(duration, 2)} s",
              f"Download time per image: {round(duration/len(urls) * 1000, 0)} ms",
              sep="\n")
        return asyncio.run(self._gather_download_tasks(urls))

    async def _gather_download_tasks(self, urls: List[str]):

        async def _process_download(url: str, client: httpx.AsyncClient):
            response = await client.get(url)
            return Image.open(BytesIO(response.content))

        async with httpx.AsyncClient() as client:
            tasks = [_process_download(url, client) for url in urls]
            return await asyncio.gather(*tasks)

    def show(self, images: List[PIL.Image.Image], valid_probas: np.ndarray, n_cols: int = 3,
             title: Optional[str] = None, threshold: Optional[float] = None):
        if threshold is not None:
            prediction = self.apply_threshold(valid_probas, threshold)
            title_scores = [f"Valid: {pred.squeeze()}" for pred in prediction]
        else:
            prediction = np.round(valid_probas[:, 0], 2)
            title_scores = [f"Valid: {pred:.2f}" for pred in prediction]
        n_images = len(images)
        n_rows = int(np.ceil(n_images / n_cols))
        fig, axes = plt.subplots(n_rows, n_cols, figsize=(16, 16))
        for i, ax in enumerate(axes.ravel()):
            ax.axis("off")
            try:
                ax.imshow(images[i])
                ax.set_title(title_scores[i])
            except IndexError:
                continue
        if title:
            fig.suptitle(title)
        fig.tight_layout()
        return