import streamlit as st
from PIL import Image
import io

def compress_image(input_image, output_format, quality=85):
    """
    Compress an image and return the compressed image.

    Parameters:
    - input_image (PIL.Image.Image): The input image.
    - output_format (str): The format of the output image ('JPEG', 'JPG', 'PNG', or 'WEBP').
    - quality (int, optional): The quality of the output image (1-100). Default is 85.

    Returns:
    - bytes: The compressed image in bytes.
    """
    img_byte_arr = io.BytesIO()
    if output_format.upper() in ['JPEG', 'JPG']:
        input_image.save(img_byte_arr, format='JPEG', quality=quality)
    elif output_format.upper() == 'PNG':
        input_image.save(img_byte_arr, format='PNG', compress_level=int((100-quality)/10))
    elif output_format.upper() == 'WEBP':
        input_image.save(img_byte_arr, format='WEBP', quality=quality)
    img_byte_arr = img_byte_arr.getvalue()
    return img_byte_arr

def main():
    st.title("Image Compression App")

    uploaded_file = st.sidebar.file_uploader("Upload an image", type=["jpg", "jpeg", "png", "webp"])

    if uploaded_file is not None:
        try:
            # Display the uploaded image
            image = Image.open(uploaded_file)
            st.sidebar.image(image, caption="Uploaded Image", use_column_width=True)
            
            # Get the size of the uploaded file
            uploaded_file.seek(0, io.SEEK_END)
            original_size = uploaded_file.tell()
            uploaded_file.seek(0, io.SEEK_SET)
            st.sidebar.write(f"Original size: {original_size / 1024:.2f} KB")

            # Determine the default format based on the original file
            original_format = image.format if image and image.format else 'JPEG'
            if original_format.upper() not in ['JPEG', 'JPG', 'PNG', 'WEBP']:
                original_format = 'JPEG'
            output_format = st.sidebar.selectbox("Select output format", ['JPEG', 'JPG', 'PNG', 'WEBP'], index=['JPEG', 'JPG', 'PNG', 'WEBP'].index(original_format.upper()))

            # Convert image to RGB if it has an alpha channel and the output format is JPEG, JPG, or WEBP
            if image and image.mode in ("RGBA", "P") and output_format.upper() in ['JPEG', 'JPG', 'WEBP']:
                image = image.convert("RGB")

            quality = st.sidebar.slider("Select compression quality", 1, 100, 85)

            # Display estimated size of compressed image
            compressed_image_bytes = compress_image(image, output_format, quality)
            compressed_size = len(compressed_image_bytes)
            st.sidebar.write(f"Estimated compressed size: {compressed_size / 1024:.2f} KB")

            if st.button("Compress Image"):
                st.image(compressed_image_bytes, caption="Compressed Image", use_column_width=True)
                
                # Determine file extension for download
                file_extension = output_format.lower()
                st.download_button(
                    label=f"Download Compressed Image.{file_extension.upper()}",
                    data=compressed_image_bytes,
                    file_name=f"compressed_image.{file_extension}",
                    mime=f"image/{file_extension}"
                )
        except Exception as e:
            st.error(f"An error occurred: {e}")

if __name__ == "__main__":
    main()