from __future__ import annotations

import math
import os
import random
import time
import uuid
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Iterable

# ZeroGPU must patch Torch/CUDA before Torch or Diffusers is imported.
import spaces
import torch
from diffusers import EulerDiscreteScheduler, StableDiffusionPipeline

MODEL_IDS = ("Manojb/stable-diffusion-2-1-base",)
DEFAULT_MODEL_ID = MODEL_IDS[0]
MAX_SEED = 2_147_483_647
ZERO_GPU_SIZE = "large"
MIN_GPU_DURATION_SECONDS = 10
MAX_GPU_DURATION_SECONDS = 300
OUTPUT_MAX_AGE_SECONDS = 12 * 60 * 60
OUTPUT_MAX_FILES = 64
OUTPUT_DIR = Path(__file__).resolve().parent / ".runtime" / "outputs"


@dataclass(frozen=True)
class RuntimeInfo:
    mode: str
    device: str
    dtype: torch.dtype
    cuda_available: bool
    gpu_name: str | None
    model_loaded: bool

    @property
    def is_zerogpu(self) -> bool:
        return self.mode == "zerogpu"

    @property
    def is_assigned_gpu(self) -> bool:
        return self.mode == "assigned_gpu"

    @property
    def is_gpu(self) -> bool:
        return self.is_zerogpu or self.is_assigned_gpu


def _detect_runtime() -> RuntimeInfo:
    is_zerogpu = bool(os.getenv("SPACES_ZERO_GPU"))
    cuda_available = bool(torch.cuda.is_available())

    if is_zerogpu:
        mode = "zerogpu"
        device = "cuda"
        dtype = torch.float16
    elif cuda_available:
        mode = "assigned_gpu"
        device = "cuda"
        dtype = torch.float16
    else:
        mode = "cpu"
        device = "cpu"
        dtype = torch.float32

    gpu_name: str | None = None
    if cuda_available and not is_zerogpu:
        try:
            gpu_name = torch.cuda.get_device_name(torch.cuda.current_device())
        except Exception:
            gpu_name = "CUDA device"
    elif is_zerogpu:
        gpu_name = f"ZeroGPU {ZERO_GPU_SIZE}"

    return RuntimeInfo(
        mode=mode,
        device=device,
        dtype=dtype,
        cuda_available=cuda_available,
        gpu_name=gpu_name,
        model_loaded=False,
    )


RUNTIME = _detect_runtime()


def _load_pipelines() -> dict[str, StableDiffusionPipeline]:
    pipelines: dict[str, StableDiffusionPipeline] = {}
    for model_id in MODEL_IDS:
        scheduler = EulerDiscreteScheduler.from_pretrained(
            model_id,
            subfolder="scheduler",
        )
        pipeline = StableDiffusionPipeline.from_pretrained(
            model_id,
            scheduler=scheduler,
            torch_dtype=RUNTIME.dtype,
            use_safetensors=True,
        )
        pipeline.to(RUNTIME.device)
        pipeline.set_progress_bar_config(disable=False)
        pipelines[model_id] = pipeline
    return pipelines


if RUNTIME.is_gpu:
    torch.set_float32_matmul_precision("high")

PIPELINES = _load_pipelines()
RUNTIME = RuntimeInfo(
    mode=RUNTIME.mode,
    device=RUNTIME.device,
    dtype=RUNTIME.dtype,
    cuda_available=RUNTIME.cuda_available,
    gpu_name=RUNTIME.gpu_name,
    model_loaded=bool(PIPELINES),
)


def startup_summary() -> str:
    summary = {
        "runtime": RUNTIME.mode,
        "device": RUNTIME.device,
        "dtype": str(RUNTIME.dtype).replace("torch.", ""),
        "gpu": RUNTIME.gpu_name,
        "model_loaded": RUNTIME.model_loaded,
        "models": list(MODEL_IDS),
    }
    return f"SD21 runtime: {summary}"


print(startup_summary(), flush=True)


def runtime_banner_markdown() -> str:
    if RUNTIME.is_zerogpu:
        return (
            "**Runtime: ZeroGPU** — the model is preloaded on CUDA emulation and each generation "
            f"requests ZeroGPU `{ZERO_GPU_SIZE}` with a workload-based duration."
        )
    if RUNTIME.is_assigned_gpu:
        gpu_name = RUNTIME.gpu_name or "CUDA GPU"
        return (
            f"**Runtime: assigned GPU** — `{gpu_name}` detected. The pipeline stays resident on "
            "CUDA and does not request ZeroGPU quota."
        )
    return (
        "**Runtime: CPU** — the pipeline is loaded in `float32` and generation is available, "
        "but inference can be very slow."
    )


def require_pipeline(model_id: str) -> StableDiffusionPipeline:
    pipeline = PIPELINES.get(model_id)
    if pipeline is None:
        raise RuntimeError(f"Pipeline not found: {model_id}")
    return pipeline


def random_seed() -> int:
    return random.SystemRandom().randint(0, MAX_SEED)


def estimate_gpu_duration(
    *,
    width: int,
    height: int,
    steps: int,
    samples: int,
) -> int:
    """Initial conservative ZeroGPU declaration, calibrated from the prior 10s baseline.

    The declaration scales with pixel area, denoising steps, and sequential samples. It is a
    maximum allocation request, not a prediction of billed wall time on assigned GPU hardware.
    """
    width = max(64, int(width))
    height = max(64, int(height))
    steps = max(1, int(steps))
    samples = max(1, int(samples))
    normalized_work = steps * samples * ((width * height) / (512 * 512))
    seconds = math.ceil(8.0 + 0.08 * normalized_work)
    return max(MIN_GPU_DURATION_SECONDS, min(MAX_GPU_DURATION_SECONDS, seconds))


def estimate_basic_duration(
    prompt: str,
    negative: str,
    scale: float,
    model_id: str = DEFAULT_MODEL_ID,
    images: Any = None,
    *_args: Any,
    **_kwargs: Any,
) -> int:
    del prompt, negative, scale, model_id, images
    return estimate_gpu_duration(width=512, height=512, steps=50, samples=1)


def estimate_advanced_duration(
    prompt: str,
    negative: str,
    scale: float,
    width: int,
    height: int,
    steps: int,
    seed: int,
    samples: int,
    model_id: str = DEFAULT_MODEL_ID,
    images: Any = None,
    *_args: Any,
    **_kwargs: Any,
) -> int:
    del prompt, negative, scale, seed, model_id, images
    return estimate_gpu_duration(
        width=width,
        height=height,
        steps=steps,
        samples=samples,
    )


def _gallery_path(item: Any) -> str | None:
    if item is None:
        return None
    if isinstance(item, (str, Path)):
        return str(item)
    if isinstance(item, dict):
        if item.get("path"):
            return str(item["path"])
        image = item.get("image")
        if isinstance(image, dict) and image.get("path"):
            return str(image["path"])
        if getattr(image, "path", None):
            return str(image.path)
        return None
    if getattr(item, "path", None):
        return str(item.path)
    image = getattr(item, "image", None)
    if getattr(image, "path", None):
        return str(image.path)
    if isinstance(item, (tuple, list)) and item:
        return _gallery_path(item[0])
    return None


def _gallery_caption(item: Any) -> str | None:
    if isinstance(item, dict):
        caption = item.get("caption")
        return str(caption) if caption is not None else None
    caption = getattr(item, "caption", None)
    if caption is not None:
        return str(caption)
    if isinstance(item, (tuple, list)) and len(item) > 1 and item[1] is not None:
        return str(item[1])
    return None


def normalize_gallery_items(items: Any) -> list[Any]:
    normalized: list[Any] = []
    for item in items or []:
        path = _gallery_path(item)
        if path is None:
            continue
        caption = _gallery_caption(item)
        normalized.append((path, caption) if caption else path)
    return normalized


def cleanup_outputs() -> None:
    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
    now = time.time()
    files = sorted(
        (path for path in OUTPUT_DIR.glob("*.jpg") if path.is_file()),
        key=lambda path: path.stat().st_mtime,
        reverse=True,
    )
    for index, path in enumerate(files):
        too_old = now - path.stat().st_mtime > OUTPUT_MAX_AGE_SECONDS
        over_limit = index >= OUTPUT_MAX_FILES
        if too_old or over_limit:
            try:
                path.unlink()
            except OSError:
                pass


def save_image(image: Any, seed: int) -> str:
    cleanup_outputs()
    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
    path = OUTPUT_DIR / f"sd21_{seed}_{uuid.uuid4().hex}.jpg"
    image.save(path, format="JPEG", quality=95)
    return str(path)


cleanup_outputs()