import os
from pathlib import Path
import fitz  # PyMuPDF for PDF handling
from PIL import Image
from transformers import Qwen2VLForConditionalGeneration, AutoProcessor  # For Qwen2.5 VL
import torch
import gradio as gr

# Create output directory
OUTPUT_DIR = Path("outputs")
OUTPUT_DIR.mkdir(exist_ok=True)

def generate_page_image(pdf_path, page_num):
    """
    Generate an image from a specific PDF page for analysis
    """
    try:
        # Open the PDF
        pdf_document = fitz.open(pdf_path)
        page = pdf_document[page_num]
        
        # Get the page dimensions to determine appropriate resolution
        rect = page.rect
        width = rect.width
        height = rect.height
        
        # Calculate appropriate zoom factor to get good quality images
        # Aim for approximately 1000 pixels on the longest side (reduced for efficiency)
        zoom = 1000 / max(width, height)
        
        # Create a transformation matrix
        mat = fitz.Matrix(zoom, zoom)
        
        # Render page to an image
        pix = page.get_pixmap(matrix=mat)
        
        # Convert to PIL Image
        img = Image.frombytes("RGB", [pix.width, pix.height], pix.samples)
        
        # Save image
        image_path = OUTPUT_DIR / f"page_{page_num + 1}.png"
        img.save(image_path, "PNG")
        
        pdf_document.close()
        return image_path
    except Exception as e:
        print(f"Error generating image for page {page_num + 1}: {str(e)}")
        return None

def extract_text_from_pdf(pdf_path, page_num):
    """
    Extract text directly from a specific PDF page
    """
    try:
        # Open the PDF
        pdf_document = fitz.open(pdf_path)
        page = pdf_document[page_num]
        
        # Extract text
        text = page.get_text("text")
        
        pdf_document.close()
        return text.strip()
    except Exception as e:
        print(f"Error extracting text from page {page_num + 1}: {str(e)}")
        return ""

def analyze_image(image_path):
    """
    Analyze image content using Qwen2.5 VL model for detailed description
    """
    try:
        # Load Qwen2.5 VL model and processor
        model = Qwen2VLForConditionalGeneration.from_pretrained(
            "Qwen/Qwen2-VL-72B-Instruct",
            torch_dtype=torch.float16,  # Use float16 for efficiency
            device_map="auto"  # Automatically distribute across available GPUs
        )
        processor = AutoProcessor.from_pretrained("Qwen/Qwen2-VL-72B-Instruct")

        # Load and process image
        image = Image.open(image_path).convert('RGB')

        # Prepare input for the model (image + prompt)
        messages = [
            {
                "role": "user",
                "content": [
                    {"type": "image", "image": image},
                    {"type": "text", "text": "Provide a detailed description of the content in this image, focusing on text, layout, and any diagrams or figures."}
                ]
            }
        ]

        # Process the input
        text_prompt = processor.apply_chat_template(messages, add_generation_prompt=True)
        inputs = processor(
            text=text_prompt,
            images=[image],
            padding=True,
            return_tensors="pt"
        )

        # Move inputs to the appropriate device
        inputs = inputs.to("cuda" if torch.cuda.is_available() else "cpu")

        # Generate description
        with torch.no_grad():
            output_ids = model.generate(**inputs, max_new_tokens=512)
        generated_text = processor.decode(output_ids[0], skip_special_tokens=True)

        # Extract only the assistant's response (remove the prompt)
        response = generated_text.split("Assistant: ")[1] if "Assistant: " in generated_text else generated_text

        return response
    except Exception as e:
        print(f"Error during image analysis: {str(e)}")
        return "Image content could not be analyzed."

def process_pdf(pdf_path, output_txt_path):
    """
    Main function to process the PDF and generate output
    """
    try:
        # Open the PDF to get page count
        pdf_document = fitz.open(pdf_path)
        num_pages = len(pdf_document)
        pdf_document.close()
        
        if num_pages == 0:
            print("The PDF is empty.")
            return
        
        # Prepare output file
        with open(output_txt_path, 'w', encoding='utf-8') as f:
            f.write(f"Analysis of {os.path.basename(pdf_path)}\n")
            f.write("=" * 50 + "\n\n")
            
            # Process each page
            for page_num in range(num_pages):
                print(f"Processing page {page_num + 1}...")
                
                # Write page header
                f.write(f"Page {page_num + 1}\n")
                f.write("-" * 30 + "\n\n")
                
                # Extract and write text
                text = extract_text_from_pdf(pdf_path, page_num)
                if text:
                    f.write("Extracted Text:\n")
                    f.write(text)
                    f.write("\n\n")
                else:
                    f.write("No text could be extracted from this page.\n\n")
                
                # Generate image for analysis and write description
                image_path = generate_page_image(pdf_path, page_num)
                if image_path:
                    description = analyze_image(image_path)
                    f.write("Image Description:\n")
                    f.write(f"{description}\n")
                    f.write("\n" + "=" * 50 + "\n\n")
                else:
                    f.write("Image Description:\n")
                    f.write("Could not generate image for analysis.\n")
                    f.write("\n" + "=" * 50 + "\n\n")
        
        print(f"Processing complete. Results saved to {output_txt_path}")
    except Exception as e:
        print(f"Error processing PDF: {str(e)}")

def process_uploaded_pdf(pdf_file):
    if pdf_file is None:
        return "Please upload a PDF file."
    
    output_txt = OUTPUT_DIR / "analysis_results.txt"
    process_pdf(pdf_file.name, output_txt)
    
    # Read and return the results
    with open(output_txt, 'r', encoding='utf-8') as f:
        results = f.read()
    
    return results

# Create Gradio interface
interface = gr.Interface(
    fn=process_uploaded_pdf,
    inputs=gr.File(label="Upload PDF"),
    outputs=gr.Textbox(label="Analysis Results"),
    title="PDF Analyzer",
    description="Upload a PDF file to extract text directly and analyze images using Qwen2.5 VL."
)

interface.launch()