app.py

import streamlit as st
import base64
import tempfile
import os
from mistralai import Mistral
from PIL import Image
import io
from mistralai import DocumentURLChunk, ImageURLChunk
from mistralai.models import OCRResponse
#from dotenv import find_dotenv, load_dotenv

from openai import OpenAI
import os
from dotenv import load_dotenv

# OCR Processing Functions
def upload_pdf(client, content, filename):
    """Uploads a PDF to Mistral's API and retrieves a signed URL for processing."""
    if client is None:
        raise ValueError("Mistral client is not initialized")

    with tempfile.TemporaryDirectory() as temp_dir:
        temp_path = os.path.join(temp_dir, filename)

        with open(temp_path, "wb") as tmp:
            tmp.write(content)

        try:
            with open(temp_path, "rb") as file_obj:
                file_upload = client.files.upload(
                    file={"file_name": filename, "content": file_obj},
                    purpose="ocr"
                )

            signed_url = client.files.get_signed_url(file_id=file_upload.id)
            return signed_url.url
        except Exception as e:
            raise ValueError(f"Error uploading PDF: {str(e)}")
        finally:
            if os.path.exists(temp_path):
                os.remove(temp_path)

def replace_images_in_markdown(markdown_str: str, images_dict: dict) -> str:
    """Replace image placeholders with base64 encoded images in markdown."""
    for img_name, base64_str in images_dict.items():
        markdown_str = markdown_str.replace(f"![{img_name}]({img_name})", f"![{img_name}]({base64_str})")
    return markdown_str

def get_combined_markdown(ocr_response: OCRResponse) -> str:
    """Combine markdown from all pages with their respective images."""
    markdowns: list[str] = []
    for page in ocr_response.pages:
        image_data = {}
        for img in page.images:
            image_data[img.id] = img.image_base64
        markdowns.append(replace_images_in_markdown(page.markdown, image_data))

    return "\n\n".join(markdowns)


def process_ocr(client, document_source):
    """Process document with OCR API based on source type"""
    if client is None:
        raise ValueError("Mistral client is not initialized")

    if document_source["type"] == "document_url":
        return client.ocr.process(
            document=DocumentURLChunk(document_url=document_source["document_url"]),
            model="mistral-ocr-latest",
            include_image_base64=True
        )
    elif document_source["type"] == "image_url":
        return client.ocr.process(
            document=ImageURLChunk(image_url=document_source["image_url"]),
            model="mistral-ocr-latest",
            include_image_base64=True
        )
    else:
        raise ValueError(f"Unsupported document source type: {document_source['type']}")


load_dotenv()

def generate_response(context, query):
    """Generate a response using OpenRouter API"""
    try:
        # Initialize OpenRouter client
        openrouter_api_key = os.getenv("OPENROUTER_API_KEY")
        if not openrouter_api_key:
            return "Error: OpenRouter API key not found in environment variables."

        openrouter_client = OpenAI(
            base_url="https://openrouter.ai/api/v1",
            api_key=openrouter_api_key,
            default_headers={
                "HTTP-Referer": "EnhancedRag",
                "X-Title": "DocumentChatApp",
                "User-Agent": "YourApp/1.0"
            }
        )

        # Check for empty context
        if not context or len(context) < 10:
            return "Error: No document content available to answer your question."

        # Create a prompt with the document content and query
        prompt = f"""I have a document with the following content:

{context}

Based on this document, please answer the following question:
{query}

If you can find information related to the query in the document, please answer based on that information.
If the document doesn't specifically mention the exact information asked, please try to infer from related content or clearly state that the specific information isn't available in the document.
"""

        # Generate response using OpenRouter
        response = openrouter_client.chat.completions.create(
            model="meta-llama/llama-3.3-70b-instruct:free",
            messages=[
                {"role": "system", "content": "You are a helpful document analysis assistant."},
                {"role": "user", "content": prompt}
            ],
            temperature=0.7,
            max_tokens=2048
        )

        return response.choices[0].message.content

    except Exception as e:
        print(f"Error generating response: {str(e)}")
        import traceback
        print(traceback.format_exc())
        return f"Error generating response: {str(e)}"


def initialize_mistral_client(api_key):
    """
    Initialize and return a Mistral client

    Args:
        api_key (str): Mistral API key

    Returns:
        Mistral client object
    """
    try:
        from mistralai import Mistral

        # Validate API key
        if not api_key:
            raise ValueError("API key cannot be empty")

        # Create and return Mistral client
        return Mistral(api_key=api_key)

    except ImportError:
        raise ImportError("Mistral AI library is not installed. Please install it using 'pip install mistralai'")
    except Exception as e:
        raise ValueError(f"Error initializing Mistral client: {str(e)}")


def display_pdf(file_path):
    """
    Display PDF in Streamlit app

    Args:
        file_path (str): Path to the PDF file
    """
    try:
        # Open the PDF file in binary read mode
        with open(file_path, "rb") as file:
            # Read the file
            base64_pdf = base64.b64encode(file.read()).decode('utf-8')

        # Embedding PDF in HTML
        pdf_display = f'<iframe src="data:application/pdf;base64,{base64_pdf}" width="700" height="1000" type="application/pdf"></iframe>'

        # Render PDF
        st.markdown(pdf_display, unsafe_allow_html=True)

    except FileNotFoundError:
        st.error(f"PDF file not found at {file_path}")
    except PermissionError:
        st.error(f"Permission denied accessing the PDF file at {file_path}")
    except Exception as e:
        st.error(f"Error displaying PDF: {str(e)}")

def main():
    # Load environment variables
    load_dotenv()

    # Get API keys from environment variables
    mistral_api_key = os.getenv("MISTRAL_API_KEY")
    openrouter_api_key = os.getenv("OPENROUTER_API_KEY")

    st.set_page_config(page_title="Document OCR & Chat", layout="wide")

    # Remove API key input sections from sidebar
    st.sidebar.header("Document Processing")

    # Initialize Mistral client
    mistral_client = None
    if mistral_api_key:
        try:
            mistral_client = initialize_mistral_client(mistral_api_key)
            st.sidebar.success("✅ Mistral API connected successfully")
        except Exception as e:
            st.sidebar.error(f"Failed to initialize Mistral client: {str(e)}")

    # Check OpenRouter API key
    if not openrouter_api_key:
        st.sidebar.warning("⚠️ OpenRouter API key is missing. Please check your .env file.")

    # Initialize session state
    if "messages" not in st.session_state:
        st.session_state.messages = []

    if "document_content" not in st.session_state:
        st.session_state.document_content = ""

    if "document_loaded" not in st.session_state:
        st.session_state.document_loaded = False

    # Document upload section
    st.subheader("Document Upload")

    # Only show document upload if Mistral client is initialized
    if mistral_client:
        input_method = st.radio("Select Input Type:", ["PDF Upload", "Image Upload", "URL"])

        document_source = None

        if input_method == "URL":
            url = st.text_input("Document URL:")
            if url and st.button("Load Document from URL"):
                document_source = {
                    "type": "document_url",
                    "document_url": url
                }

        elif input_method == "PDF Upload":
            uploaded_file = st.file_uploader("Choose PDF file", type=["pdf"])
            if uploaded_file and st.button("Process PDF"):
                content = uploaded_file.read()

                # Save the uploaded PDF temporarily for display purposes
                with tempfile.NamedTemporaryFile(delete=False, suffix=".pdf") as tmp:
                    tmp.write(content)
                    pdf_path = tmp.name

                try:
                    # Prepare document source for OCR processing
                    document_source = {
                        "type": "document_url",
                        "document_url": upload_pdf(mistral_client, content, uploaded_file.name)
                    }

                    # Display the uploaded PDF
                    st.header("Uploaded PDF")
                    display_pdf(pdf_path)
                except Exception as e:
                    st.error(f"Error processing PDF: {str(e)}")
                    # Clean up the temporary file
                    if os.path.exists(pdf_path):
                        os.unlink(pdf_path)

        elif input_method == "Image Upload":
            uploaded_image = st.file_uploader("Choose Image file", type=["png", "jpg", "jpeg"])
            if uploaded_image and st.button("Process Image"):
                try:
                    # Display the uploaded image
                    image = Image.open(uploaded_image)
                    st.image(image, caption="Uploaded Image", use_column_width=True)

                    # Convert image to base64
                    buffered = io.BytesIO()
                    image.save(buffered, format="PNG")
                    img_str = base64.b64encode(buffered.getvalue()).decode()

                    # Prepare document source for OCR processing
                    document_source = {
                        "type": "image_url",
                        "image_url": f"data:image/png;base64,{img_str}"
                    }
                except Exception as e:
                    st.error(f"Error processing image: {str(e)}")

        # Process document if source is provided
        if document_source:
            with st.spinner("Processing document..."):
                try:
                    ocr_response = process_ocr(mistral_client, document_source)

                    if ocr_response and ocr_response.pages:
                        # Extract all text without page markers for clean content
                        raw_content = []
                        display_content = []

                        for i, page in enumerate(ocr_response.pages):
                            page_content = page.markdown.strip()
                            if page_content:  # Only add non-empty pages
                                raw_content.append(page_content)
                                display_content.append(f"Page {i + 1}:\n{page_content}")

                        # Join all content into one clean string for the model
                        final_content = "\n\n".join(raw_content)
                        display_formatted = "\n\n----------\n\n".join(display_content)

                        # Store both versions
                        st.session_state.document_content = final_content
                        st.session_state.display_content = display_formatted
                        st.session_state.document_loaded = True
                        st.session_state.ocr_response = ocr_response

                        # Markdown Download Section
                        st.subheader("Download Markdown")

                        # Full Document Download
                        full_markdown = "\n\n----------\n\n".join(display_content)
                        st.download_button(
                            label="Download Full Document Markdown",
                            data=full_markdown,
                            file_name="document_ocr_output.md",
                            mime="text/markdown"
                        )

                        # Page-wise Download Dropdown
                        page_options = [f"Page {i + 1}" for i in range(len(ocr_response.pages)) if
                                        ocr_response.pages[i].markdown.strip()]
                        selected_page = st.selectbox("Select a page to download", page_options)

                        if selected_page:
                            page_index = page_options.index(selected_page)
                            page_markdown = ocr_response.pages[page_index].markdown.strip()

                            st.download_button(
                                label=f"Download {selected_page} Markdown",
                                data=page_markdown,
                                file_name=f"{selected_page.lower().replace(' ', '_')}_ocr_output.md",
                                mime="text/markdown"
                            )

                        # Success message
                        st.success(
                            f"Document processed successfully! Extracted {len(final_content)} characters from {len(raw_content)} pages."
                        )
                    else:
                        st.warning("No content extracted from document.")

                except Exception as e:
                    st.error(f"Processing error: {str(e)}")

    # Main area: Display chat interface
    st.title("Document OCR & Chat")

    # Document preview area
    if "document_loaded" in st.session_state and st.session_state.document_loaded:
        with st.expander("Document Content", expanded=False):
            # Show the display version with page numbers
            if "display_content" in st.session_state:
                st.markdown(st.session_state.display_content)
            else:
                st.markdown(st.session_state.document_content)

        # Chat interface
        st.subheader("Chat with your document")

        # Display chat messages
        for message in st.session_state.messages:
            with st.chat_message(message["role"]):
                st.markdown(message["content"])

        # Input for user query
        if prompt := st.chat_input("Ask a question about your document..."):
            # Check if Google API key is available
            if not openrouter_api_key :
                st.error("Openrouter API key is required for generating responses.")
            else:
                # Add user message to chat history
                st.session_state.messages.append({"role": "user", "content": prompt})

                # Display user message
                with st.chat_message("user"):
                    st.markdown(prompt)

                # Show thinking spinner
                with st.chat_message("assistant"):
                    with st.spinner("Thinking..."):
                        # Get document content from session state
                        document_content = st.session_state.document_content

                        # Generate response directly
                        response = generate_response(document_content, prompt)

                        # Display response
                        st.markdown(response)

                # Add assistant message to chat history
                st.session_state.messages.append({"role": "assistant", "content": response})
    else:
        # Show a welcome message if no document is loaded
        st.info("👈 Please upload a document using the sidebar to start chatting.")


if __name__ == "__main__":
    main()