main.py

from fastapi import FastAPI, Form, Request
from fastapi.responses import HTMLResponse, RedirectResponse
from fastapi.templating import Jinja2Templates
from utility import load_image, interpolate_batch, interpolate_single
from io import BytesIO
from PIL import Image
import base64
import numpy as np

app = FastAPI()

# Setup Jinja2 templates
templates = Jinja2Templates(directory="templates")


def convert_frames_to_base64(frames):
    """Converts numpy image arrays to base64 strings for displaying in HTML."""
    base64_frames = []
    for frame in frames:
        img = Image.fromarray((frame * 255).astype(np.uint8))
        buffered = BytesIO()
        img.save(buffered, format="PNG")
        base64_str = base64.b64encode(buffered.getvalue()).decode("utf-8")
        base64_frames.append(base64_str)
    return base64_frames


@app.get("/", response_class=HTMLResponse)
async def index(request: Request):
    return templates.TemplateResponse("index.html", {"request": request})


@app.post("/", response_class=HTMLResponse)
async def generate_frames(request: Request, img1_url: str = Form(...), img2_url: str = Form(...)):
    if not img1_url or not img2_url:
        return RedirectResponse(url="/", status_code=303)

    frames = interpolate_single(img1_url, img2_url)
    if frames is not None:
        base64_frames = convert_frames_to_base64(frames)
        return templates.TemplateResponse("result.html", {"request": request, "frames": base64_frames})
    else:
        return HTMLResponse("Error processing images.", status_code=500)