import torch
import gradio as gr
from diffusers import (
    StableDiffusionPipeline,
    StableDiffusionInstructPix2PixPipeline,
    StableVideoDiffusionPipeline,
    WanPipeline,
)
from diffusers.utils import export_to_video, load_image

# Detect device & dtype
device = "cuda" if torch.cuda.is_available() else "cpu"
dtype = torch.float16 if device == "cuda" else torch.float32

# Factory to load & offload a pipeline
def make_pipe(cls, model_id, **kwargs):
    pipe = cls.from_pretrained(model_id, torch_dtype=dtype, **kwargs)
    # Enables CPU offload of model parts not in use
    pipe.enable_model_cpu_offload()
    return pipe

# Hold pipelines in globals but don’t load yet  
TXT2IMG_PIPE = None
IMG2IMG_PIPE = None
TXT2VID_PIPE = None
IMG2VID_PIPE = None

def generate_image_from_text(prompt):
    global TXT2IMG_PIPE
    if TXT2IMG_PIPE is None:
        TXT2IMG_PIPE = make_pipe(
            StableDiffusionPipeline, 
            "stabilityai/stable-diffusion-2-1-base"
        ).to(device)
    return TXT2IMG_PIPE(prompt, num_inference_steps=20).images[0]

def generate_image_from_image_and_prompt(image, prompt):
    global IMG2IMG_PIPE
    if IMG2IMG_PIPE is None:
        IMG2IMG_PIPE = make_pipe(
            StableDiffusionInstructPix2PixPipeline,
            "timbrooks/instruct-pix2pix"
        ).to(device)
    out = IMG2IMG_PIPE(prompt=prompt, image=image, num_inference_steps=8)
    return out.images[0]

def generate_video_from_text(prompt):
    global TXT2VID_PIPE
    if TXT2VID_PIPE is None:
        TXT2VID_PIPE = make_pipe(
            WanPipeline,
            "Wan-AI/Wan2.1-T2V-1.3B-Diffusers"
        ).to(device)
    frames = TXT2VID_PIPE(prompt=prompt, num_frames=12).frames[0]
    return export_to_video(frames, "wan_video.mp4", fps=8)

def generate_video_from_image(image):
    global IMG2VID_PIPE
    if IMG2VID_PIPE is None:
        IMG2VID_PIPE = make_pipe(
            StableVideoDiffusionPipeline,
            "stabilityai/stable-video-diffusion-img2vid-xt",
            variant="fp16" if dtype==torch.float16 else None
        ).to(device)
    image = load_image(image).resize((512, 288))
    frames = IMG2VID_PIPE(image, num_inference_steps=16).frames[0]
    return export_to_video(frames, "svd_video.mp4", fps=8)

with gr.Blocks() as demo:
    gr.Markdown("# 🧠 Lightweight Any‑to‑Any AI Playground")

    with gr.Tab("Text → Image"):
        inp = gr.Textbox(label="Prompt")
        out = gr.Image()
        gr.Button("Generate").click(generate_image_from_text, inp, out)

    with gr.Tab("Image → Image"):
        img = gr.Image(label="Input Image")
        prm = gr.Textbox(label="Edit Prompt")
        out2 = gr.Image()
        gr.Button("Generate").click(generate_image_from_image_and_prompt, [img, prm], out2)

    with gr.Tab("Text → Video"):
        inp2 = gr.Textbox(label="Prompt")
        out_vid = gr.Video()
        gr.Button("Generate").click(generate_video_from_text, inp2, out_vid)

    with gr.Tab("Image → Video"):
        img2 = gr.Image(label="Input Image")
        out_vid2 = gr.Video()
        gr.Button("Animate").click(generate_video_from_image, img2, out_vid2)

demo.launch()