import gc
import uuid
from pathlib import Path
from typing import Any, Dict, List, Optional, Tuple

import gradio as gr
import torch
from diffusers import ShapEPipeline
from PIL import Image

MODEL_ID = "openai/shap-e"

pipe = None
DEVICE = "cuda" if torch.cuda.is_available() else "cpu"
DTYPE = torch.float16 if DEVICE == "cuda" else torch.float32

ROOT_DIR = Path(__file__).resolve().parent
DATA_DIR = ROOT_DIR / "data"
ASSETS_DIR = DATA_DIR / "assets"
ASSETS_DIR.mkdir(parents=True, exist_ok=True)

EXAMPLES = [
    "A cute stylized robot with a round head",
    "A fantasy treasure chest with gold trim",
    "A small dragon figurine, toy-like, colorful",
    "A low-poly medieval house",
    "A ceramic teapot shaped like an owl",
    "A cartoon submarine with tiny windows",
]


def get_pipeline():
    global pipe

    if pipe is None:
        kwargs = {"torch_dtype": DTYPE}
        if DEVICE == "cuda":
            kwargs["variant"] = "fp16"

        pipe = ShapEPipeline.from_pretrained(MODEL_ID, **kwargs)
        pipe = pipe.to(DEVICE)

    return pipe


def make_white_background_transparent(frame: Image.Image, threshold: int = 245) -> Image.Image:
    """
    Делает почти-белый фон прозрачным.
    Если R, G и B все >= threshold, пиксель считаем фоном.
    """
    img = frame.convert("RGBA")
    data = img.getdata()

    new_data = []
    for r, g, b, a in data:
        if r >= threshold and g >= threshold and b >= threshold:
            new_data.append((255, 255, 255, 0))
        else:
            new_data.append((r, g, b, a))

    img.putdata(new_data)
    return img


def crop_to_nontransparent_content(img: Image.Image, padding: int = 8) -> Image.Image:
    """
    Обрезает лишние прозрачные поля вокруг объекта.
    """
    alpha = img.getchannel("A")
    bbox = alpha.getbbox()
    if bbox is None:
        return img

    left, top, right, bottom = bbox
    left = max(0, left - padding)
    top = max(0, top - padding)
    right = min(img.width, right + padding)
    bottom = min(img.height, bottom + padding)

    return img.crop((left, top, right, bottom))


def save_frames_to_files(frames, prompt: str) -> List[str]:
    asset_id = f"asset_{uuid.uuid4().hex[:8]}"
    asset_dir = ASSETS_DIR / asset_id
    asset_dir.mkdir(parents=True, exist_ok=True)

    frame_paths = []
    for i, frame in enumerate(frames):
        img = frame.convert("RGBA")
        img = make_white_background_transparent(img, threshold=245)
        img = crop_to_nontransparent_content(img, padding=8)

        frame_path = asset_dir / f"view_{i:03d}.png"
        img.save(frame_path)
        frame_paths.append(str(frame_path))

    return frame_paths


def make_asset(prompt: str, frame_paths: List[str]) -> Dict[str, Any]:
    return {
        "prompt": prompt,
        "frame_paths": frame_paths,
        "selected_index": 0,
    }


def gallery_items_from_assets(saved_assets: List[Dict[str, Any]]) -> List[Tuple[str, str]]:
    items = []
    for i, asset in enumerate(saved_assets):
        frame_paths = asset.get("frame_paths", [])
        if not frame_paths:
            continue

        idx = int(asset.get("selected_index", 0))
        idx = max(0, min(idx, len(frame_paths) - 1))
        caption = f"{i + 1}. {asset.get('prompt', '')}"
        items.append((frame_paths[idx], caption))
    return items


def current_view_from_selected(
    saved_assets: List[Dict[str, Any]],
    selected_asset_index: Optional[int],
):
    if selected_asset_index is None:
        return None, "No asset selected.", gr.update(interactive=False), gr.update(interactive=False)

    if selected_asset_index < 0 or selected_asset_index >= len(saved_assets):
        return None, "No asset selected.", gr.update(interactive=False), gr.update(interactive=False)

    asset = saved_assets[selected_asset_index]
    frame_paths = asset.get("frame_paths", [])
    if not frame_paths:
        return None, "No asset selected.", gr.update(interactive=False), gr.update(interactive=False)

    idx = int(asset.get("selected_index", 0))
    idx = max(0, min(idx, len(frame_paths) - 1))
    label = f"Asset {selected_asset_index + 1} · View {idx + 1} / {len(frame_paths)}"
    return frame_paths[idx], label, gr.update(interactive=True), gr.update(interactive=True)


def selected_view_path(
    saved_assets: List[Dict[str, Any]],
    selected_asset_index: Optional[int],
):
    if selected_asset_index is None:
        return None

    if selected_asset_index < 0 or selected_asset_index >= len(saved_assets):
        return None

    asset = saved_assets[selected_asset_index]
    frame_paths = asset.get("frame_paths", [])
    if not frame_paths:
        return None

    idx = int(asset.get("selected_index", 0))
    idx = max(0, min(idx, len(frame_paths) - 1))
    return frame_paths[idx]


def generate_and_add_asset(
    prompt: str,
    steps: int,
    guidance_scale: float,
    frame_size: int,
    seed: int,
    saved_assets: List[Dict[str, Any]],
):
    prompt = (prompt or "").strip()
    if not prompt:
        raise gr.Error("Prompt is empty.")

    saved_assets = saved_assets or []

    pipeline = get_pipeline()
    generator = torch.Generator(device=DEVICE).manual_seed(int(seed))

    result = pipeline(
        prompt,
        guidance_scale=float(guidance_scale),
        num_inference_steps=int(steps),
        frame_size=int(frame_size),
        generator=generator,
    )

    frames = result.images[0]
    frame_paths = save_frames_to_files(frames, prompt)

    new_asset = make_asset(prompt, frame_paths)
    saved_assets = saved_assets + [new_asset]
    selected_asset_index = len(saved_assets) - 1

    gallery_items = gallery_items_from_assets(saved_assets)
    current_view, view_text, prev_btn, next_btn = current_view_from_selected(
        saved_assets, selected_asset_index
    )

    gc.collect()
    if DEVICE == "cuda":
        torch.cuda.empty_cache()

    return saved_assets, selected_asset_index, gallery_items, current_view, view_text, prev_btn, next_btn


def select_asset(
    saved_assets: List[Dict[str, Any]],
    evt: gr.SelectData,
):
    if not saved_assets:
        return None, [], None, "No asset selected.", gr.update(interactive=False), gr.update(interactive=False)

    if evt is None or evt.index is None:
        return None, gallery_items_from_assets(saved_assets), None, "No asset selected.", gr.update(interactive=False), gr.update(interactive=False)

    idx = evt.index
    if isinstance(idx, (list, tuple)):
        idx = idx[0]
    idx = int(idx)

    current_view, view_text, prev_btn, next_btn = current_view_from_selected(saved_assets, idx)
    gallery_items = gallery_items_from_assets(saved_assets)

    return idx, gallery_items, current_view, view_text, prev_btn, next_btn


def prev_view(
    saved_assets: List[Dict[str, Any]],
    selected_asset_index: Optional[int],
):
    if selected_asset_index is None:
        raise gr.Error("Select an asset in the gallery first.")

    if selected_asset_index < 0 or selected_asset_index >= len(saved_assets):
        raise gr.Error("Select an asset in the gallery first.")

    asset = saved_assets[selected_asset_index]
    frame_paths = asset.get("frame_paths", [])
    if not frame_paths:
        raise gr.Error("Selected asset has no frames.")

    idx = int(asset.get("selected_index", 0))
    idx = (idx - 1) % len(frame_paths)
    asset["selected_index"] = idx

    gallery_items = gallery_items_from_assets(saved_assets)
    current_view, view_text, prev_btn, next_btn = current_view_from_selected(
        saved_assets, selected_asset_index
    )
    return saved_assets, gallery_items, current_view, view_text, prev_btn, next_btn


def next_view(
    saved_assets: List[Dict[str, Any]],
    selected_asset_index: Optional[int],
):
    if selected_asset_index is None:
        raise gr.Error("Select an asset in the gallery first.")

    if selected_asset_index < 0 or selected_asset_index >= len(saved_assets):
        raise gr.Error("Select an asset in the gallery first.")

    asset = saved_assets[selected_asset_index]
    frame_paths = asset.get("frame_paths", [])
    if not frame_paths:
        raise gr.Error("Selected asset has no frames.")

    idx = int(asset.get("selected_index", 0))
    idx = (idx + 1) % len(frame_paths)
    asset["selected_index"] = idx

    gallery_items = gallery_items_from_assets(saved_assets)
    current_view, view_text, prev_btn, next_btn = current_view_from_selected(
        saved_assets, selected_asset_index
    )
    return saved_assets, gallery_items, current_view, view_text, prev_btn, next_btn


def clear_saved_assets():
    return [], None, [], None, "No asset selected.", gr.update(interactive=False), gr.update(interactive=False)


def set_prompt(value: str):
    return value