# # core/image_generator.py
# import os
# import torch
# from diffusers import StableDiffusionXLPipeline
# from huggingface_hub import hf_hub_download
# from pathlib import Path
# from typing import List
# from io import BytesIO
# import base64
# from PIL import Image

# # Set cache and model directories early
# HF_CACHE_DIR = Path("/tmp/hf_cache")
# HF_CACHE_DIR.mkdir(parents=True, exist_ok=True)
# os.chmod(HF_CACHE_DIR, 0o777)

# os.environ["HF_HOME"] = str(HF_CACHE_DIR)
# os.environ["TRANSFORMERS_CACHE"] = str(HF_CACHE_DIR)
# os.environ["XDG_CACHE_HOME"] = str(HF_CACHE_DIR)
# os.environ["HF_DATASETS_CACHE"] = str(HF_CACHE_DIR)
# os.environ["HF_MODULES_CACHE"] = str(HF_CACHE_DIR)

# MODEL_DIR = Path("/tmp/models/realvisxl_v4")
# MODEL_DIR.mkdir(parents=True, exist_ok=True)
# os.chmod(MODEL_DIR, 0o777)


# # ---------------- MODEL CONFIG ----------------
# MODEL_REPO = "SG161222/RealVisXL_V4.0"
# MODEL_FILENAME = "realvisxlV40_v40LightningBakedvae.safetensors"
# MODEL_DIR = Path("/tmp/models/realvisxl_v4")
# os.makedirs(MODEL_DIR, exist_ok=True)

# # ---------------- MODEL DOWNLOAD ----------------
# def download_model() -> Path:
#     """
#     Downloads RealVisXL V4.0 model if not present.
#     Returns the local model path.
#     """
#     model_path = MODEL_DIR / MODEL_FILENAME
#     if not model_path.exists():
#         print("[ImageGen] Downloading RealVisXL V4.0 model...")
#         model_path = hf_hub_download(
#             repo_id=MODEL_REPO,
#             filename=MODEL_FILENAME,
#             local_dir=str(MODEL_DIR),
#             cache_dir=str(HF_CACHE_DIR),  # ensure writable cache is used
#             force_download=False,
#         )
#         print(f"[ImageGen] Model downloaded to: {model_path}")
#     else:
#         print("[ImageGen] Model already exists. Skipping download.")
#     return model_path

# # ---------------- PIPELINE LOAD ----------------
# def load_pipeline() -> StableDiffusionXLPipeline:
#     """
#     Loads the RealVisXL V4.0 model for image generation.
#     """
#     model_path = download_model()
#     print("[ImageGen] Loading model into pipeline...")
#     pipe = StableDiffusionXLPipeline.from_single_file(
#         str(model_path),
#         torch_dtype=torch.float16 if torch.cuda.is_available() else torch.float32,
#     )
#     if torch.cuda.is_available():
#         pipe.to("cuda")
#     print("[ImageGen] Model ready.")
#     return pipe

# # ---------------- GLOBAL PIPELINE CACHE ----------------
# pipe: StableDiffusionXLPipeline | None = None

# # ---------------- UTILITY: PIL TO BASE64 ----------------
# def pil_to_base64(img: Image.Image) -> str:
#     """
#     Converts a PIL image to a base64 string for frontend display.
#     """
#     buffered = BytesIO()
#     img.save(buffered, format="PNG")
#     img_bytes = buffered.getvalue()
#     img_b64 = base64.b64encode(img_bytes).decode("utf-8")
#     return f"data:image/png;base64,{img_b64}"

# # ---------------- IMAGE GENERATION ----------------
# def generate_images(prompt: str, seed: int = None, num_images: int = 3) -> List[str]:
#     """
#     Generates high-quality images using RealVisXL V4.0.
#     Supports deterministic generation using a seed.
    
#     Args:
#         prompt (str): Text prompt for image generation.
#         seed (int, optional): Seed for deterministic generation.
#         num_images (int): Number of images to generate.
        
#     Returns:
#         List[str]: List of base64-encoded images.
#     """
#     global pipe
#     if pipe is None:
#         pipe = load_pipeline()

#     print(f"[ImageGen] Generating {num_images} image(s) for prompt: '{prompt}' with seed={seed}")
#     images: List[str] = []

#     for i in range(num_images):
#         generator = None
#         if seed is not None:
#             device = "cuda" if torch.cuda.is_available() else "cpu"
#             generator = torch.Generator(device).manual_seed(seed + i)

#         result = pipe(prompt, num_inference_steps=30, generator=generator).images[0]
#         images.append(pil_to_base64(result))

#     print(f"[ImageGen] Generated {len(images)} images successfully.")
#     return images


# core/image_generator.py
import os
import torch
from diffusers import StableDiffusionXLPipeline
from huggingface_hub import hf_hub_download
from pathlib import Path
from typing import List
from io import BytesIO
import base64
from PIL import Image

# ---------------- CACHE & MODEL DIRECTORIES ----------------
HF_CACHE_DIR = Path("/tmp/hf_cache")
MODEL_DIR = Path("/tmp/models/realvisxl_v4")

# Create directories safely (no chmod)
for d in [HF_CACHE_DIR, MODEL_DIR]:
    d.mkdir(parents=True, exist_ok=True)

# Apply environment variables BEFORE any Hugging Face usage
os.environ.update({
    "HF_HOME": str(HF_CACHE_DIR),
    "TRANSFORMERS_CACHE": str(HF_CACHE_DIR),
    "XDG_CACHE_HOME": str(HF_CACHE_DIR),
    "HF_DATASETS_CACHE": str(HF_CACHE_DIR),
    "HF_MODULES_CACHE": str(HF_CACHE_DIR),
})

# ---------------- MODEL CONFIG ----------------
MODEL_REPO = "SG161222/RealVisXL_V4.0"
MODEL_FILENAME = "realvisxlV40_v40LightningBakedvae.safetensors"

# ---------------- MODEL DOWNLOAD ----------------
def download_model() -> Path:
    """
    Downloads RealVisXL V4.0 model if not present.
    Returns local path.
    """
    model_path = MODEL_DIR / MODEL_FILENAME
    if not model_path.exists():
        print("[ImageGen] Downloading RealVisXL V4.0 model...")
        model_path = Path(
            hf_hub_download(
                repo_id=MODEL_REPO,
                filename=MODEL_FILENAME,
                cache_dir=str(HF_CACHE_DIR),
                force_download=False,
                resume_download=True,  # safer if download interrupted
            )
        )
        print(f"[ImageGen] Model downloaded to: {model_path}")
    else:
        print("[ImageGen] Model already exists. Skipping download.")
    return model_path

# ---------------- PIPELINE LOAD ----------------
def load_pipeline() -> StableDiffusionXLPipeline:
    """
    Loads the RealVisXL V4.0 model for image generation.
    """
    model_path = download_model()
    print("[ImageGen] Loading model into pipeline...")

    pipe = StableDiffusionXLPipeline.from_single_file(
        str(model_path),
        torch_dtype=torch.float16 if torch.cuda.is_available() else torch.float32,
    )

    if torch.cuda.is_available():
        pipe.to("cuda")
    else:
        pipe.to("cpu")

    # Optional: skip safety checker to save memory/performance
    pipe.safety_checker = None  
    # Enable attention slicing for memory-efficient CPU usage
    pipe.enable_attention_slicing()  

    print("[ImageGen] Model ready.")
    return pipe

# ---------------- GLOBAL PIPELINE CACHE ----------------
pipe: StableDiffusionXLPipeline | None = None

# ---------------- UTILITY: PIL → BASE64 ----------------
def pil_to_base64(img: Image.Image) -> str:
    """
    Converts PIL image to base64 string for frontend.
    """
    buffered = BytesIO()
    img.save(buffered, format="PNG")
    return f"data:image/png;base64,{base64.b64encode(buffered.getvalue()).decode()}"

# ---------------- IMAGE GENERATION ----------------
def generate_images(prompt: str, seed: int | None = None, num_images: int = 3) -> List[str]:
    """
    Generates high-quality images using RealVisXL V4.0.
    Returns a list of base64-encoded PNGs.
    """
    global pipe
    if pipe is None:
        pipe = load_pipeline()

    print(f"[ImageGen] Generating {num_images} image(s) for prompt: '{prompt}' seed={seed}")
    images: List[str] = []

    for i in range(num_images):
        generator = None
        if seed is not None:
            device = "cuda" if torch.cuda.is_available() else "cpu"
            generator = torch.Generator(device).manual_seed(seed + i)

        try:
            result = pipe(prompt, num_inference_steps=30, generator=generator).images[0]
            images.append(pil_to_base64(result))
        except Exception as e:
            print(f"[ImageGen] ⚠️ Generation failed on image {i}: {e}")
            continue

    print(f"[ImageGen] Generated {len(images)} image(s) successfully.")
    return images