# ui_components.py
"""
Defines functions for creating distinct UI sections of the Streamlit application.
"""

import streamlit as st
from typing import Tuple, Dict, Any, Optional
from PIL import Image
import io

# Constants
MAX_PREVIEW_HEIGHT = 10000 # Maximum height in pixels for full-size preview

def render_sidebar() -> Tuple[int, str]:
    """
    Renders the sidebar UI elements for settings.

    Returns
    -------
    Tuple[int, str]
        A tuple containing:
        - dpi (int): The selected resolution in DPI.
        - output_format (str): The selected output format ('PNG' or 'JPG').
    """
    with st.sidebar:
        st.header("⚙️ Settings")
        # DPI Slider
        dpi = st.slider(
            "Resolution (DPI)",
            min_value=72,
            max_value=600,
            value=300,
            step=1,
            help="Dots Per Inch. Higher DPI means better quality but larger file size and longer processing time."
        )
        # Output Format Radio Buttons
        output_format = st.radio(
            "Output Format",
            ["PNG", "JPG"],
            index=0, # Default to PNG
            help="PNG offers lossless quality (larger file). JPG uses lossy compression (smaller file)."
        )

        st.write("---")
        st.write("### About")
        st.info(
            "This app converts multi-page PDFs into a single, vertically stitched image file. "
            "Useful for sharing or archiving documents as images."
        )
        st.write("Made with ❤️ using [Streamlit](https://streamlit.io) & [PyMuPDF](https://pymupdf.readthedocs.io/en/latest/)")
        st.write("Tim might be a 🧙")
        # A little fun :)
        # st.write("Tim might be a 🧙") # Uncomment if desired

    return dpi, output_format

def display_file_details(uploaded_file: st.runtime.uploaded_file_manager.UploadedFile) -> None:
    """
    Displays details of the uploaded file.

    Parameters
    ----------
    uploaded_file : st.runtime.uploaded_file_manager.UploadedFile
        The file uploaded by the user via st.file_uploader.
    """
    file_details = {
        "Filename": uploaded_file.name,
        "Type": uploaded_file.type,
        "Size": f"{uploaded_file.size / (1024*1024):.2f} MB" # Show size in MB
    }
    st.write("### File Details")
    # Use columns for better layout
    col1, col2 = st.columns(2)
    with col1:
        st.write(f"**Filename:**")
        st.write(f"**Type:**")
        st.write(f"**Size:**")
    with col2:
        st.write(f"{file_details['Filename']}")
        st.write(f"{file_details['Type']}")
        st.write(f"{file_details['Size']}")


def display_results(
    img_buffer: io.BytesIO,
    output_filename: str,
    output_format: str,
    processing_time: float
) -> None:
    """
    Displays the conversion results: success message, download button, and image preview.

    Parameters
    ----------
    img_buffer : io.BytesIO
        The buffer containing the generated image data.
    output_filename : str
        The suggested filename for the downloaded image.
    output_format : str
        The format of the output image ('PNG' or 'JPG').
    processing_time : float
        The time taken for the conversion process in seconds.
    """
    st.success(f"✅ Conversion completed in {processing_time:.2f} seconds!")

    # Determine MIME type based on format
    mime_type = f"image/{output_format.lower()}"

    # Provide download button
    st.download_button(
        label=f"⬇️ Download {output_format} Image",
        data=img_buffer,
        file_name=output_filename,
        mime=mime_type
    )

    # Image preview section
    st.write("---")
    st.write("### 🖼️ Image Preview")
    try:
        # Open image from buffer for preview
        img = Image.open(img_buffer)
        width, height = img.size
        st.write(f"**Image dimensions:** {width}x{height} pixels")

        # Warn and scale down preview if the image is excessively tall
        if height > MAX_PREVIEW_HEIGHT:
            st.warning(f"⚠️ Image is very tall ({height}px). Preview is scaled down.")
            # Calculate width based on a max preview width (e.g., 800px) to maintain aspect ratio
            preview_width = min(width, 800)
            st.image(img, caption=f"Scaled Preview of {output_filename}", width=preview_width)
        else:
            # Show image using Streamlit's default width handling or a fixed width
            st.image(img, caption=f"Preview of {output_filename}", use_column_width='auto')

    except Exception as e:
        st.error(f"Could not display image preview: {e}")
        st.warning("The image file might be corrupted or too large for preview.")


def render_initial_info() -> None:
    """
    Displays the initial instructions and placeholder content when no file is uploaded.
    """
    st.info("👆 Upload a PDF file using the sidebar to get started.")
    st.write("---")
    # Placeholder or example section (optional)
    # st.write("### Example Output Structure")
    # st.image("https://via.placeholder.com/600x800/ccc/888?text=Page+1", caption="Page 1")
    # st.image("https://via.placeholder.com/600x800/eee/777?text=Page+2", caption="Page 2")
    # st.caption("...(Pages are stitched vertically)")

def display_installation_info() -> None:
    """Displays the installation requirements and run command."""
    st.write("---")
    with st.expander("🛠️ Installation & Usage"):
        st.code("""
# 1. Install required libraries
pip install streamlit Pillow PyMuPDF

# 2. Save the code files (app.py, pdf_processor.py, ui_components.py)
#    in the same directory.

# 3. Run the Streamlit application
streamlit run app.py
        """, language="bash")