app/main.py

from fastapi import FastAPI, File, UploadFile, HTTPException, Header
from fastapi.responses import FileResponse
from huggingface_hub import hf_hub_download
from firebase_admin import credentials, initialize_app, app_check
import uuid
import os
from PIL import Image
import torch
import io
from torchvision import transforms

app = FastAPI(title="Text-Guided Image Colorization API")

# -------------------------------------------------
# 🔐 Firebase App Check Initialization
# -------------------------------------------------
cred = credentials.Certificate("firebase-key.json")  # Your service account key
initialize_app(cred)

UPLOAD_DIR = "uploads"
RESULTS_DIR = "results"
os.makedirs(UPLOAD_DIR, exist_ok=True)
os.makedirs(RESULTS_DIR, exist_ok=True)

# -------------------------------------------------
# 🧠 Load ColorizeNet Model
# -------------------------------------------------
MODEL_REPO = "Hammad712/GAN-Colorization-Model"
MODEL_FILENAME = "generator.pt"
model_path = hf_hub_download(repo_id=MODEL_REPO, filename=MODEL_FILENAME)
state_dict = torch.load(model_path, map_location="cpu")

# (Example model structure – replace with your actual ColorizeNet)
# from your_model import ColorizeNet
# model = ColorizeNet()
# model.load_state_dict(state_dict)
# model.eval()

# Dummy colorization function
def colorize_image(img: Image.Image):
    transform = transforms.ToTensor()
    tensor = transform(img.convert("L")).unsqueeze(0)
    tensor = tensor.repeat(1, 3, 1, 1)
    output_img = transforms.ToPILImage()(tensor.squeeze())
    return output_img

# -------------------------------------------------
# 🩺 1. Health Check
# -------------------------------------------------
@app.get("/health")
def health_check():
    return {"status": "healthy", "model_loaded": True}

# -------------------------------------------------
# ✅ Firebase App Check Token Validation
# -------------------------------------------------
def verify_app_check_token(token: str):
    # In production, verify token with Firebase REST API or Admin SDK.
    if not token or len(token) < 20:
        raise HTTPException(status_code=401, detail="Missing or invalid Firebase App Check token")
    return True

# -------------------------------------------------
# 📤 2. Upload Image
# -------------------------------------------------
@app.post("/upload")
async def upload_image(
    file: UploadFile = File(...),
    x_firebase_appcheck: str = Header(None)
):
    verify_app_check_token(x_firebase_appcheck)

    if not file.content_type.startswith("image/"):
        raise HTTPException(status_code=400, detail="Invalid file type")

    image_id = str(uuid.uuid4())
    filename = f"{image_id}.jpg"
    path = os.path.join(UPLOAD_DIR, filename)

    with open(path, "wb") as f:
        f.write(await file.read())

    return {
        "success": True,
        "image_id": image_id,
        "image_url": f"https://logicgoinfotechspaces-text-guided-image-colorization.hf.space/uploads/{filename}",
        "filename": filename
    }

# -------------------------------------------------
# 🎨 3. Colorize Image
# -------------------------------------------------
@app.post("/colorize")
async def colorize(
    file: UploadFile = File(...),
    x_firebase_appcheck: str = Header(None)
):
    verify_app_check_token(x_firebase_appcheck)

    if not file.content_type.startswith("image/"):
        raise HTTPException(status_code=400, detail="Invalid file type")

    img = Image.open(io.BytesIO(await file.read()))
    output_img = colorize_image(img)

    result_id = str(uuid.uuid4())
    filename = f"{result_id}.jpg"
    path = os.path.join(RESULTS_DIR, filename)
    output_img.save(path)

    base_url = "https://logicgoinfotechspaces-text-guided-image-colorization.hf.space"
    return {
        "success": True,
        "result_id": result_id,
        "download_url": f"{base_url}/results/{filename}",
        "api_download_url": f"{base_url}/download/{result_id}",
        "filename": filename
    }

# -------------------------------------------------
# ⬇️ 4. Download Processed Image
# -------------------------------------------------
@app.get("/download/{file_id}")
def download_result(file_id: str, x_firebase_appcheck: str = Header(None)):
    verify_app_check_token(x_firebase_appcheck)
    path = os.path.join(RESULTS_DIR, f"{file_id}.jpg")
    if not os.path.exists(path):
        raise HTTPException(status_code=404, detail="File not found")
    return FileResponse(path, media_type="image/jpeg")

# -------------------------------------------------
# 🌈 5. Get Result (Public URL)
# -------------------------------------------------
@app.get("/results/{filename}")
def get_result(filename: str):
    path = os.path.join(RESULTS_DIR, filename)
    if not os.path.exists(path):
        raise HTTPException(status_code=404, detail="File not found")
    return FileResponse(path, media_type="image/jpeg")

# -------------------------------------------------
# 🖼️ 6. Get Uploaded Image (Public URL)
# -------------------------------------------------
@app.get("/uploads/{filename}")
def get_upload(filename: str):
    path = os.path.join(UPLOAD_DIR, filename)
    if not os.path.exists(path):
        raise HTTPException(status_code=404, detail="File not found")
    return FileResponse(path, media_type="image/jpeg")