"""What the TUI knows about the server's books beyond the files: title, author, read status
and which books exist at all (so a book can be listed before it is downloaded). Set only by
`sync`; the reader's position is progress.py.
"""

from __future__ import annotations

import json
import os
from pathlib import Path

from . import paths

_DATA_DIR = paths.data_dir()
_META_FILE = _DATA_DIR / "library.json"


def _load_all() -> dict[str, dict]:
    try:
        data = json.loads(_META_FILE.read_text())
    except (OSError, ValueError):
        return {}
    return data if isinstance(data, dict) else {}


def _save_all(data: dict[str, dict]) -> None:
    _DATA_DIR.mkdir(parents=True, exist_ok=True)
    tmp = _META_FILE.with_suffix(".tmp")
    tmp.write_text(json.dumps(data, indent=1))
    os.replace(tmp, _META_FILE)


def is_read(book_key: str) -> bool:
    entry = _load_all().get(book_key)
    return bool(entry and entry.get("is_read"))


def get(book_key: str) -> dict | None:
    return _load_all().get(book_key)


def get_extra(name: str, default=None):
    """A setting kept beside the books (stored under '_<name>'): the folder order, the sort."""
    entry = _load_all().get("_" + name)
    return entry["value"] if isinstance(entry, dict) and "value" in entry else default


def set_extra(name: str, value) -> None:
    data = _load_all()
    data["_" + name] = {"value": value}
    _save_all(data)


def set_local_pages(book_key: str, pages: int) -> None:
    """A book's length worked out from the file here (the server's meta may not have it)."""
    data = _load_all()
    entry = data.setdefault("_pages", {"value": {}})
    entry.setdefault("value", {})[book_key] = int(pages)
    _save_all(data)


def local_pages() -> dict[str, int]:
    return dict(get_extra("pages", {}) or {})


def remote_entries() -> dict[str, dict]:
    """Every server book: key -> {server_id, title, author, is_read, uploaded_at}."""
    return {k: v for k, v in _load_all().items() if isinstance(v, dict) and v.get("server_id") is not None}


def set_remote(entries: dict[str, dict]) -> None:
    """Replace the server books with `entries` (a book deleted on the server drops out)."""
    data = {k: v for k, v in _load_all().items() if not (isinstance(v, dict) and v.get("server_id") is not None)}
    data.update(entries)
    _save_all(data)