docs/functions.md

# Major  Functions used 

## in Text Classifier (`features/text_classifier/` and `features/text_classifier/`)

- **`load_model()`**  
  Loads the GPT-2 model and tokenizer from the specified directory paths.

- **`lifespan()`**  
  Manages the application lifecycle. Initializes the model at startup and handles cleanup on shutdown.

- **`classify_text_sync()`**  
  Synchronously tokenizes input text and predicts using the GPT-2 model. Returns classification and perplexity.

- **`classify_text()`**  
  Asynchronously runs `classify_text_sync()` in a thread pool for non-blocking text classification.

- **`analyze_text()`**  
  **POST** endpoint: Accepts text input, classifies it using `classify_text()`, and returns the result with perplexity.

- **`health()`**  
  **GET** endpoint: Simple health check for API liveness.

- **`parse_docx()`, `parse_pdf()`, `parse_txt()`**  
  Utilities to extract and convert `.docx`, `.pdf`, and `.txt` file contents to plain text.

- **`warmup()`**  
  Downloads the model repository and initializes the model/tokenizer using `load_model()`.

- **`download_model_repo()`**  
  Downloads the model files from the designated `MODEL` folder.

- **`get_model_tokenizer()`**  
  Checks if the model already exists; if not, downloads it—otherwise, loads the cached model.

- **`handle_file_upload()`**  
  Handles file uploads from the `/upload` route. Extracts text, classifies, and returns results.

- **`extract_file_contents()`**  
  Extracts and returns plain text from uploaded files (PDF, DOCX, TXT).

- **`handle_file_sentence()`**  
  Processes file uploads by analyzing each sentence (under 10,000 chars) before classification.

- **`handle_sentence_level_analysis()`**  
  Checks/strips each sentence, then computes AI/human likelihood for each.

- **`analyze_sentences()`**  
  Splits paragraphs into sentences, classifies each, and returns all results.

- **`analyze_sentence_file()`**  
  Like `handle_file_sentence()`—analyzes sentences in uploaded files.
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## for image_classifier

- **`Classify_Image_router()`** – Handles image classification requests by routing and coordinating preprocessing and inference.
- **`classify_image()`** – Performs AI vs human image classification using the loaded model.
- **`load_model()`** – Loads the pretrained model from Hugging Face at server startup.
- **`preprocess_image()`** – Applies all required preprocessing steps to the input image.

> Note: While many functions mirror those in the text classifier, the image classifier primarily uses TensorFlow rather than PyTorch.

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