app.py

import os
import io
import re # Still needed for some image filename manipulation if any, but not for text formatting
import logging
import subprocess
from datetime import datetime
import urllib.parse
import tempfile
import json # For streaming JSON messages
import time # For gevent.sleep

from flask import Flask, request, render_template, Response, stream_with_context
from werkzeug.utils import secure_filename

# Ensure gevent is imported and monkey patched if needed for other libraries
# from gevent import monkey
# monkey.patch_all() # Apply this early if you suspect issues with other libs

import requests # For requests.exceptions.HTTPError
from requests.exceptions import HTTPError as RequestsHTTPError # Specific import for clarity

# pdfplumber is no longer needed
import pdf2image 
from pdf2image import convert_from_path, convert_from_bytes 
# from pdf2image.exceptions import ... # If you need to catch specific pdf2image errors

import pytesseract
from PIL import Image
from huggingface_hub import HfApi, create_repo

# --- Flask App Initialization ---
app = Flask(__name__)
app.config['UPLOAD_FOLDER'] = tempfile.gettempdir()
app.config['MAX_CONTENT_LENGTH'] = 50 * 1024 * 1024  # 50 MB limit for uploads, adjust as needed

# --- Logging Configuration ---
logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s")
logger = logging.getLogger(__name__)

# --- Hugging Face Configuration ---
HF_TOKEN = os.getenv("HF_TOKEN")
HF_DATASET_REPO_NAME = os.getenv("HF_DATASET_REPO_NAME", "pdf-images-extracted")
hf_api = HfApi()

# --- Helper to yield messages for streaming ---
def yield_message(type, data):
    """Helper to format messages as JSON strings for streaming."""
    return json.dumps({"type": type, **data}) + "\n"

# --- PDF Processing Helper Functions (Adapted for Streaming) ---

def check_poppler():
    try:
        result = subprocess.run(["pdftoppm", "-v"], capture_output=True, text=True, check=False)
        version_info_log = result.stderr.strip() if result.stderr else result.stdout.strip()
        if version_info_log:
            logger.info(f"Poppler version check: {version_info_log.splitlines()[0] if version_info_log else 'No version output'}")
        else:
            logger.info("Poppler 'pdftoppm -v' ran. Assuming Poppler is present.")
        return True
    except FileNotFoundError:
        logger.error("Poppler (pdftoppm command) not found. Ensure poppler-utils is installed and in PATH.")
        return False
    except Exception as e:
        logger.error(f"An unexpected error occurred during Poppler check: {str(e)}")
        return False

def ensure_hf_dataset():
    if not HF_TOKEN:
        msg = "HF_TOKEN is not set. Cannot ensure Hugging Face dataset. Image uploads will fail."
        logger.warning(msg)
        return "Error: " + msg
    try:
        repo_id_obj = create_repo(repo_id=HF_DATASET_REPO_NAME, token=HF_TOKEN, repo_type="dataset", exist_ok=True)
        logger.info(f"Dataset repo ensured: {repo_id_obj.repo_id}")
        return repo_id_obj.repo_id
    except RequestsHTTPError as e: 
        if e.response is not None and e.response.status_code == 409: 
             logger.info(f"Dataset repo '{HF_DATASET_REPO_NAME}' already exists (HTTP 409).")
             try:
                 user_info = hf_api.whoami(token=HF_TOKEN) 
                 namespace = user_info.get('name') if user_info else None
                 if namespace:
                     return f"{namespace}/{HF_DATASET_REPO_NAME}"
                 else: 
                     logger.warning(f"Could not determine namespace for existing repo '{HF_DATASET_REPO_NAME}'. Using generic ID.")
                     return HF_DATASET_REPO_NAME 
             except Exception as whoami_e:
                 logger.error(f"Could not determine namespace for existing repo via whoami due to: {whoami_e}. Using generic ID.")
                 return HF_DATASET_REPO_NAME 
        else: 
            status_code = e.response.status_code if e.response is not None else "Unknown"
            logger.error(f"Hugging Face dataset HTTP error (Status: {status_code}): {str(e)}")
            return f"Error: Failed to access or create dataset '{HF_DATASET_REPO_NAME}' due to HTTP error: {str(e)}"
    except Exception as e: 
        logger.error(f"Hugging Face dataset general error: {str(e)}", exc_info=True)
        return f"Error: Failed to access or create dataset '{HF_DATASET_REPO_NAME}': {str(e)}"


def upload_image_to_hf_stream(image_pil, filename_base, page_num_for_log=""):
    repo_id_or_error = ensure_hf_dataset()
    if isinstance(repo_id_or_error, str) and repo_id_or_error.startswith("Error"):
        return repo_id_or_error

    repo_id = repo_id_or_error
    temp_image_path = None
    try:
        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S_%f")
        repo_filename = f"images/{filename_base}_{page_num_for_log}_{timestamp}.png"
        
        os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)
        with tempfile.NamedTemporaryFile(delete=False, suffix=".png", dir=app.config['UPLOAD_FOLDER']) as tmp_file:
            temp_image_path = tmp_file.name
        image_pil.save(temp_image_path, format="PNG")

        logger.info(f"Attempting to upload {temp_image_path} to {repo_id}/{repo_filename}")
        file_url = hf_api.upload_file(
            path_or_fileobj=temp_image_path, path_in_repo=repo_filename,
            repo_id=repo_id, repo_type="dataset", token=HF_TOKEN
        )
        logger.info(f"Successfully uploaded image: {file_url}")
        return file_url
    except Exception as e: 
        logger.error(f"Image upload error for {filename_base}{page_num_for_log}: {str(e)}", exc_info=True)
        return f"Error uploading image {filename_base}{page_num_for_log}: {str(e)}"
    finally:
        if temp_image_path and os.path.exists(temp_image_path):
            try: os.remove(temp_image_path)
            except OSError as ose: logger.error(f"Error removing temp image file {temp_image_path}: {ose}")

# format_page_text_to_markdown_chunk function is removed as it's no longer used.

# --- Main PDF Processing Logic (Generator Function for Streaming) ---

def generate_pdf_conversion_stream(pdf_input_source_path_or_url):
    try:
        yield yield_message("markdown_replace", {"content": "# Extracted Images and OCR Text\n\n"})
        time.sleep(0.01) 

        actual_pdf_input_for_images = None
        is_input_bytes = False

        source_is_url = isinstance(pdf_input_source_path_or_url, str) and \
                        pdf_input_source_path_or_url.startswith(('http://', 'https://'))
        
        if source_is_url:
            yield yield_message("status", {"message": f"Downloading PDF from URL..."})
            time.sleep(0.01)
            try:
                response = requests.get(pdf_input_source_path_or_url, stream=False, timeout=60) 
                response.raise_for_status()
                actual_pdf_input_for_images = response.content 
                is_input_bytes = True
                yield yield_message("status", {"message": f"PDF downloaded from URL ({len(actual_pdf_input_for_images)/1024:.2f} KB)."})
                time.sleep(0.01)
            except RequestsHTTPError as e: 
                logger.error(f"URL fetch HTTP error: {str(e)} (Status: {e.response.status_code if e.response else 'N/A'})", exc_info=True)
                yield yield_message("error", {"message": f"Error fetching PDF from URL (HTTP {e.response.status_code if e.response else 'N/A'}): {e.response.reason if e.response else str(e)}"})
                return
            except requests.RequestException as e: 
                logger.error(f"URL fetch network error: {str(e)}", exc_info=True)
                yield yield_message("error", {"message": f"Network error fetching PDF from URL: {str(e)}"})
                return 
        else: 
             actual_pdf_input_for_images = pdf_input_source_path_or_url 
             is_input_bytes = False
             yield yield_message("status", {"message": f"Processing local PDF file..."})
             time.sleep(0.01)

        # ----- Direct Text Extraction (using pdfplumber) is REMOVED -----

        # ----- Image Extraction and OCR -----
        if not check_poppler():
            yield yield_message("error", {"message": "Poppler (for image extraction) not found or not working."})
        else:
            yield yield_message("status", {"message": "Starting image extraction and OCR..."})
            # The "## Extracted Images" title is now more specific
            yield yield_message("markdown_chunk", {"content": "## Extracted Images & OCR Text from PDF Pages\n\n"})
            if not HF_TOKEN:
                 yield yield_message("markdown_chunk", {"content": "**Note:** `HF_TOKEN` not set. Images will be described but not uploaded.\n\n"})

            time.sleep(0.01)
            extracted_pil_images_overall_count = 0
            try:
                if actual_pdf_input_for_images:
                    try: # Batched conversion attempt
                        pdf_info = None
                        if is_input_bytes:
                            pdf_info = pdf2image.pdfinfo_from_bytes(actual_pdf_input_for_images, userpw=None, poppler_path=None)
                        else: 
                            pdf_info = pdf2image.pdfinfo_from_path(actual_pdf_input_for_images, userpw=None, poppler_path=None)
                        
                        num_image_pages = pdf_info.get("Pages", 0)
                        yield yield_message("status", {"message": f"PDF has {num_image_pages} page(s) for image conversion and OCR."})
                        
                        batch_size = 1 
                        for page_idx_start in range(1, num_image_pages + 1, batch_size):
                            page_idx_end = min(page_idx_start + batch_size - 1, num_image_pages)
                            yield yield_message("status", {"message": f"Converting PDF page(s) {page_idx_start}-{page_idx_end} to image(s)..."})
                            time.sleep(0.01)
                            
                            page_images_pil = []
                            if is_input_bytes:
                                page_images_pil = convert_from_bytes(actual_pdf_input_for_images, dpi=150, first_page=page_idx_start, last_page=page_idx_end)
                            else: 
                                page_images_pil = convert_from_path(actual_pdf_input_for_images, dpi=150, first_page=page_idx_start, last_page=page_idx_end)
                            
                            for img_idx_in_batch, img_pil in enumerate(page_images_pil):
                                extracted_pil_images_overall_count += 1
                                current_pdf_page_num = page_idx_start + img_idx_in_batch
                                page_num_for_log = f"pdfpage_{current_pdf_page_num}"

                                yield yield_message("status", {"message": f"Processing image {extracted_pil_images_overall_count} (from PDF page {current_pdf_page_num}) (OCR & Upload)..."})
                                time.sleep(0.01)
                                
                                ocr_text = ""
                                try:
                                    ocr_text = pytesseract.image_to_string(img_pil).strip()
                                    if ocr_text: yield yield_message("status", {"message": f"  OCR successful for image {extracted_pil_images_overall_count}."})
                                    else: yield yield_message("status", {"message": f"  OCR complete for image {extracted_pil_images_overall_count} (no text found)."})
                                except Exception as ocr_e:
                                    logger.error(f"OCR error for image {extracted_pil_images_overall_count}: {str(ocr_e)}")
                                    ocr_text = f"OCR failed: {str(ocr_e)}"
                                
                                image_md_chunk = f"### Image from PDF Page {current_pdf_page_num}\n"
                                if HF_TOKEN:
                                    image_url_or_error = upload_image_to_hf_stream(img_pil, "pdf_page_image", page_num_for_log)
                                    if isinstance(image_url_or_error, str) and not image_url_or_error.startswith("Error"):
                                        image_md_chunk += f"![Image from PDF Page {current_pdf_page_num}]({image_url_or_error})\n"
                                        yield yield_message("status", {"message": f"  Image {extracted_pil_images_overall_count} uploaded."})
                                    else:
                                        image_md_chunk += f"**Image {extracted_pil_images_overall_count} (Upload Error):** {str(image_url_or_error)}\n\n"
                                        yield yield_message("error", {"message": f"Failed to upload image {extracted_pil_images_overall_count}: {str(image_url_or_error)}"})
                                else:
                                    image_md_chunk += f"**Image {extracted_pil_images_overall_count} (not uploaded due to missing HF_TOKEN)**\n"

                                if ocr_text:
                                    image_md_chunk += f"**OCR Text (from PDF Page {current_pdf_page_num}):**\n```\n{ocr_text}\n```\n\n"
                                else:
                                    image_md_chunk += f"_(No text detected by OCR for image from PDF page {current_pdf_page_num})_\n\n"
                                
                                yield yield_message("image_md", {"content": image_md_chunk})
                                time.sleep(0.01)
                    except Exception as e_img_info:
                        logger.error(f"Could not get PDF info for image batching or during batched conversion: {e_img_info}", exc_info=True)
                        yield yield_message("error", {"message": f"Error preparing for image extraction: {e_img_info}. Trying bulk conversion."})
                        # Fallback to bulk conversion
                        bulk_images_pil = []
                        if is_input_bytes:
                            bulk_images_pil = convert_from_bytes(actual_pdf_input_for_images, dpi=150)
                        else: 
                            bulk_images_pil = convert_from_path(actual_pdf_input_for_images, dpi=150)
                        
                        yield yield_message("status", {"message": f"Fallback: Converted {len(bulk_images_pil)} PDF pages to images in bulk."})
                        for i, img_pil in enumerate(bulk_images_pil):
                            extracted_pil_images_overall_count +=1
                            page_num_for_log = f"bulk_image_{i+1}" 
                            yield yield_message("status", {"message": f"Processing image {extracted_pil_images_overall_count} (bulk page {i+1}) (OCR & Upload)..."})
                            ocr_text = ""
                            try: ocr_text = pytesseract.image_to_string(img_pil).strip()
                            except Exception as e: ocr_text = f"OCR Error: {e}"
                            
                            image_md_chunk = f"### Image from PDF Page (Bulk {i+1})\n"
                            if HF_TOKEN:
                                image_url_or_error = upload_image_to_hf_stream(img_pil, "pdf_page_image_fallback", page_num_for_log)
                                if isinstance(image_url_or_error, str) and not image_url_or_error.startswith("Error"):
                                    image_md_chunk += f"![Image {extracted_pil_images_overall_count} (Fallback)]({image_url_or_error})\n"
                                else:
                                    image_md_chunk += f"**Upload Error:** {str(image_url_or_error)}\n"
                            else:
                                 image_md_chunk += f"**Image {extracted_pil_images_overall_count} (Fallback - not uploaded)**\n"

                            if ocr_text: image_md_chunk += f"**OCR Text (Bulk Page {i+1}):**\n```\n{ocr_text}\n```\n\n"
                            else: image_md_chunk += f"_(No text detected by OCR for bulk image {i+1})_\n\n"
                            yield yield_message("image_md", {"content": image_md_chunk})
                            time.sleep(0.01)

                else: 
                    yield yield_message("status", {"message": "No valid PDF input source provided for image extraction."})

            except Exception as e: 
                logger.error(f"Error during image extraction/OCR processing: {str(e)}", exc_info=True)
                yield yield_message("error", {"message": f"Error during image extraction/OCR: {str(e)}"})
        
        yield yield_message("final_status", {"message": "Image extraction and OCR processing complete."})

    except Exception as e:
        logger.error(f"Unhandled error in PDF conversion stream: {str(e)}", exc_info=True)
        yield yield_message("error", {"message": f"Critical processing error: {str(e)}"})


# --- Flask Routes ---

@app.route('/', methods=['GET'])
def index():
    return render_template('index.html')

@app.route('/process-stream', methods=['POST'])
def process_pdf_stream():
    pdf_file = request.files.get('pdf_file')
    pdf_url = request.form.get('pdf_url', '').strip()
    
    outer_temp_pdf_path = None 

    def stream_processor():
        nonlocal outer_temp_pdf_path 
        pdf_input_source_for_generator = None

        try:
            if pdf_file and pdf_file.filename:
                if not pdf_file.filename.lower().endswith('.pdf'):
                    yield yield_message("error", {"message": "Uploaded file is not a PDF."})
                    return
                
                filename = secure_filename(pdf_file.filename)
                os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)
                # Save to a temporary file that generate_pdf_conversion_stream can access by path
                fd, temp_path = tempfile.mkstemp(suffix=".pdf", prefix="upload_", dir=app.config['UPLOAD_FOLDER'])
                os.close(fd) # Close the file descriptor from mkstemp
                pdf_file.save(temp_path) # Save the uploaded file's content to this path
                outer_temp_pdf_path = temp_path # Store for cleanup
                logger.info(f"Uploaded PDF saved to temporary path: {outer_temp_pdf_path}")
                pdf_input_source_for_generator = outer_temp_pdf_path # Pass the path
                yield yield_message("status", {"message": f"Processing uploaded PDF: {filename}"})
                time.sleep(0.01)

            elif pdf_url:
                unquoted_url = urllib.parse.unquote(pdf_url)
                if not (unquoted_url.startswith('http://') or unquoted_url.startswith('https://')):
                    yield yield_message("error", {"message": "Invalid URL scheme. Must be http or https."})
                    return
                
                pdf_input_source_for_generator = unquoted_url # Pass the URL string
                yield yield_message("status", {"message": f"Preparing to process PDF from URL: {unquoted_url}"})
                time.sleep(0.01)
            else:
                yield yield_message("error", {"message": "No PDF file uploaded and no PDF URL provided."})
                return

            for message_part in generate_pdf_conversion_stream(pdf_input_source_for_generator):
                yield message_part

        except Exception as e:
            logger.error(f"Error setting up stream or in initial validation: {str(e)}", exc_info=True)
            yield yield_message("error", {"message": f"Setup error: {str(e)}"})
        finally:
            if outer_temp_pdf_path and os.path.exists(outer_temp_pdf_path):
                try:
                    os.remove(outer_temp_pdf_path)
                    logger.info(f"Cleaned up temporary PDF: {outer_temp_pdf_path}")
                except OSError as ose:
                    logger.error(f"Error removing temporary PDF {outer_temp_pdf_path}: {ose}")
    
    return Response(stream_with_context(stream_processor()), mimetype='application/x-ndjson')


# --- Main Execution ---
if __name__ == '__main__':
    if not check_poppler(): 
        logger.warning("Poppler utilities might not be installed correctly. Image processing might fail.")
    os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)
    app.run(host='0.0.0.0', port=int(os.getenv("PORT", 7860)), debug=True, threaded=True)