app.py

import gradio as gr
import fal_client
import os
from typing import Optional, List
from huggingface_hub import whoami

# It is recommended to create this as a Secret on your Hugging Face Space
# For example: FAL_KEY = "fal_key_..."
FAL_KEY = os.getenv("FAL_KEY", "")

# Set the key for the fal_client
if FAL_KEY:
    fal_client.api_key = FAL_KEY

def get_fal_key():
    """Checks for the FAL_KEY and raises a Gradio error if it's not set."""
    if not FAL_KEY:
        raise gr.Error("FAL_KEY is not set. Please add it to your Hugging Face Space secrets.")

def verify_pro_status(token: Optional[gr.OAuthToken]) -> bool:
    """Verifies if the user is a Hugging Face PRO user using their token."""
    if not token:
        return False
    try:
        user_info = whoami(token=token.token)
        return user_info.get("isPro", False)
    except Exception as e:
        print(f"Could not verify user's PRO status: {e}")
        return False

# --- Backend Generation Functions ---

def run_single_image_logic(prompt: str, image: Optional[str] = None) -> str:
    """Handles text-to-image or single image-to-image and returns a single URL string."""
    get_fal_key()
    if image:
        image_url = fal_client.upload_file(image)
        result = fal_client.run(
            "fal-ai/nano-banana/edit",
            arguments={"prompt": prompt, "image_url": image_url},
        )
    else:
        result = fal_client.run(
            "fal-ai/nano-banana", arguments={"prompt": prompt}
        )
    return result["images"][0]["url"]

def run_multi_image_logic(prompt: str, images: List[str]) -> str:
    """
    Handles multi-image editing and returns the URL of the LAST generated image.
    """
    get_fal_key()
    if not images:
        raise gr.Error("Please upload at least one image in the 'Multiple Images' tab.")

    last_image_url = ""
    for image_path in images:
        image_url = fal_client.upload_file(image_path)
        result = fal_client.run(
            "fal-ai/nano-banana/edit",
            arguments={"prompt": prompt, "image_url": image_url},
        )
        last_image_url = result["images"][0]["url"]
    return last_image_url

# --- Gradio App UI ---
with gr.Blocks(theme=gr.themes.Soft()) as demo:
    gr.Markdown("# Nano Banana Image Generation")
    gr.Markdown("Generate or edit images with FAL. **Sign in with Hugging Face to begin.**")

    login_button = gr.LoginButton()
    pro_message = gr.Markdown(visible=False)
    main_interface = gr.Column(visible=False)

    with main_interface:
        gr.Markdown("## Welcome, PRO User!")
        with gr.Row():
            # LEFT COLUMN: Inputs
            with gr.Column(scale=1):
                prompt_input = gr.Textbox(
                    label="Prompt",
                    placeholder="A delicious looking pizza"
                )
                active_tab_state = gr.State(value="single")
                with gr.Tabs() as tabs:
                    with gr.TabItem("Single Image", id="single") as single_tab:
                        image_input = gr.Image(
                            type="filepath",
                            label="Input Image (Optional for text-to-image)"
                        )
                    with gr.TabItem("Multiple Images", id="multiple") as multi_tab:
                        gallery_input = gr.Gallery(
                            label="Input Images", file_types=["image"]
                        )
                generate_button = gr.Button("Generate", variant="primary")

            # RIGHT COLUMN: Outputs
            with gr.Column(scale=1):
                output_image = gr.Image(label="Output")
                use_image_button = gr.Button("♻️ Use this Image for Next Edit")

    # --- Event Handlers ---

    def unified_generator(
        prompt: str,
        single_image: Optional[str],
        multi_images: Optional[List[str]],
        active_tab: str,
        oauth_token: Optional[gr.OAuthToken] = None,
    ) -> str:
        if not verify_pro_status(oauth_token):
            raise gr.Error("Access Denied. This service is for PRO users only.")
        if active_tab == "multiple" and multi_images:
            return run_multi_image_logic(prompt, multi_images)
        else:
            return run_single_image_logic(prompt, single_image)

    single_tab.select(lambda: "single", None, active_tab_state)
    multi_tab.select(lambda: "multiple", None, active_tab_state)

    generate_button.click(
        unified_generator,
        inputs=[prompt_input, image_input, gallery_input, active_tab_state],
        outputs=[output_image],
    )

    # Corrected handler for the continuous editing loop.
    # It takes the output image and directly returns it to be used as the input.
    use_image_button.click(
        lambda img: img, # A simple function that returns its input
        inputs=[output_image],
        outputs=[image_input]
    )

    # --- Access Control Logic ---
    def control_access(
        profile: Optional[gr.OAuthProfile] = None,
        oauth_token: Optional[gr.OAuthToken] = None
    ):
        if not profile:
            return gr.update(visible=False), gr.update(visible=False)
        if verify_pro_status(oauth_token):
            return gr.update(visible=True), gr.update(visible=False)
        else:
            message = (
                "## ✨ Exclusive Access for PRO Users\n\n"
                "Thank you for your interest! This feature is available exclusively for our Hugging Face **PRO** members.\n\n"
                "To unlock this and many other benefits, please consider upgrading your account.\n\n"
                "### [**Become a PRO Member Today!**](https://huggingface.co/pro)"
            )
            return gr.update(visible=False), gr.update(visible=True, value=message)

    demo.load(control_access, inputs=None, outputs=[main_interface, pro_message])

if __name__ == "__main__":
    demo.launch()