from __future__ import annotations

import sys
from dataclasses import dataclass
from pathlib import Path
from typing import Literal

from huggingface_hub import HfApi, hf_hub_download
from huggingface_hub.utils import enable_progress_bars
from tqdm.auto import tqdm as auto_tqdm

GGUF_SORT_FIELD = Literal[
    "created_at",
    "downloads",
    "last_modified",
    "likes",
    "trending_score",
]


@dataclass(frozen=True, slots=True)
class GGUFRepository:
    repo_id: str
    downloads: int | None = None
    likes: int | None = None
    gated: str | bool | None = None


@dataclass(frozen=True, slots=True)
class GGUFFileEntry:
    repo_id: str
    filename: str
    size_bytes: int | None = None
    blob_id: str | None = None

    @property
    def name(self) -> str:
        return Path(self.filename).name


@dataclass(frozen=True, slots=True)
class GGUFDownloadStatus:
    repo_id: str
    filename: str
    revision: str | None = None
    commit_hash: str | None = None
    size_bytes: int | None = None
    is_cached: bool | None = None
    will_download: bool | None = None


class _StdoutTqdm(auto_tqdm):
    def __init__(self, *args, **kwargs):
        kwargs.setdefault("file", sys.stdout)
        kwargs.setdefault("disable", False)
        kwargs.setdefault("dynamic_ncols", True)
        kwargs.setdefault("leave", True)
        super().__init__(*args, **kwargs)


def _format_size(size_bytes: int | None) -> str:
    if size_bytes is None:
        return "unknown size"

    size = float(size_bytes)
    for unit in ("B", "KiB", "MiB", "GiB", "TiB"):
        if size < 1024.0 or unit == "TiB":
            if unit == "B":
                return f"{int(size)} {unit}"
            return f"{size:.1f} {unit}"
        size /= 1024.0

    return f"{size_bytes} B"


def _build_api(token: str | None = None) -> HfApi:
    return HfApi(token=token)


def search_gguf_repositories(
    query: str | None = None,
    *,
    author: str | None = None,
    limit: int = 20,
    sort: GGUF_SORT_FIELD = "downloads",
    token: str | None = None,
) -> list[GGUFRepository]:
    """
    Search Hugging Face model repos tagged as GGUF.
    """
    api = _build_api(token)
    models = api.list_models(
        filter="gguf",
        search=query or None,
        author=author,
        sort=sort,
        limit=limit,
        expand=["downloads", "likes", "gated"],
    )

    return [
        GGUFRepository(
            repo_id=model.id,
            downloads=getattr(model, "downloads", None),
            likes=getattr(model, "likes", None),
            gated=getattr(model, "gated", None),
        )
        for model in models
    ]


def list_repo_gguf_files(
    repo_id: str,
    *,
    revision: str | None = None,
    token: str | None = None,
) -> list[GGUFFileEntry]:
    """
    List GGUF files available inside a specific Hugging Face model repo.
    """
    api = _build_api(token)
    model_info = api.model_info(repo_id=repo_id, revision=revision, files_metadata=True)
    siblings = getattr(model_info, "siblings", None) or ()

    gguf_files = [
        GGUFFileEntry(
            repo_id=repo_id,
            filename=sibling.rfilename,
            size_bytes=getattr(sibling, "size", None),
            blob_id=getattr(sibling, "blob_id", None),
        )
        for sibling in siblings
        if sibling.rfilename.lower().endswith(".gguf")
    ]
    gguf_files.sort(key=lambda entry: entry.filename.lower())
    return gguf_files


def get_gguf_file_status(
    repo_id: str,
    filename: str,
    *,
    revision: str | None = None,
    cache_dir: str | Path | None = None,
    local_dir: str | Path | None = None,
    token: str | None = None,
) -> GGUFDownloadStatus:
    """
    Ask the Hub whether a GGUF file is already cached and whether it would download.
    """
    dry_run_info = hf_hub_download(
        repo_id=repo_id,
        filename=filename,
        revision=revision,
        cache_dir=cache_dir,
        local_dir=local_dir,
        token=token,
        dry_run=True,
    )

    size_bytes = getattr(dry_run_info, "file_size", None)
    if size_bytes is None:
        size_bytes = getattr(dry_run_info, "size", None)

    return GGUFDownloadStatus(
        repo_id=repo_id,
        filename=filename,
        revision=revision,
        commit_hash=getattr(dry_run_info, "commit_hash", None),
        size_bytes=size_bytes,
        is_cached=getattr(dry_run_info, "is_cached", None),
        will_download=getattr(dry_run_info, "will_download", None),
    )


def ensure_gguf_downloaded(
    repo_id: str,
    filename: str,
    *,
    revision: str | None = None,
    cache_dir: str | Path | None = None,
    local_dir: str | Path | None = None,
    token: str | None = None,
    force_download: bool = False,
    local_files_only: bool = False,
) -> Path:
    """
    Download a GGUF file if needed and return the local filesystem path.

    With no local_dir provided, the returned path points into the Hugging Face cache.
    """
    target = f"{repo_id}/{filename}"

    if local_files_only:
        print(f"Looking for cached GGUF: {target}")
    else:
        status = get_gguf_file_status(
            repo_id=repo_id,
            filename=filename,
            revision=revision,
            cache_dir=cache_dir,
            local_dir=local_dir,
            token=token,
        )

        if force_download:
            print(f"Re-downloading GGUF: {target} ({_format_size(status.size_bytes)})")
        elif status.is_cached and not status.will_download:
            print(f"Using cached GGUF: {target}")
        elif status.will_download:
            print(f"Downloading GGUF: {target} ({_format_size(status.size_bytes)})")
        else:
            print(f"Resolving GGUF: {target}")

        enable_progress_bars()

    resolved_path = hf_hub_download(
        repo_id=repo_id,
        filename=filename,
        revision=revision,
        cache_dir=cache_dir,
        local_dir=local_dir,
        token=token,
        force_download=force_download,
        local_files_only=local_files_only,
        tqdm_class=_StdoutTqdm,
    )
    local_path = Path(resolved_path)
    print(f"GGUF ready: {local_path}")
    return local_path


__all__ = [
    "GGUFDownloadStatus",
    "GGUFFileEntry",
    "GGUFRepository",
    "GGUF_SORT_FIELD",
    "ensure_gguf_downloaded",
    "get_gguf_file_status",
    "list_repo_gguf_files",
    "search_gguf_repositories",
]