"""The drawing lookup the job talks to: M-Files through MFilesKit, or the fixture files (fake.py).

One M-Files `Vault` per worker process (each sign-in can use a licence), kept in the dict the scheduler passes
(`JobContext.shared`) or, when there is none, in this module's own cache keyed by MFILES_URL. A new
`DrawingLookup` per run, because its result cache lives on the instance.

Read-only. Nothing here writes to M-Files.
"""

from __future__ import annotations

import logging
import os
import threading
from dataclasses import dataclass
from pathlib import Path
from typing import TYPE_CHECKING, Any, Protocol

if TYPE_CHECKING:
    from mfileskit.drawings import DrawingStatus
    from mfileskit.vault import Vault

    from ..settings import Settings

log = logging.getLogger(__name__)

VAULT_KEY = "mfiles_vault"
NOTE_MAX = 500


class DrawingFetchError(LookupError):
    """A download did not work. The message is safe to log (no credentials)."""


@dataclass(slots=True)
class Found:
    """What M-Files has for one drawing number: the subset the decision needs, plus identity for change detection."""

    dwg: str
    ok: bool = True
    rev: int | None = None
    name: str | None = None
    obj_id: int | None = None
    obj_version: int | None = None
    file_id: int | None = None
    file_version: int | None = None
    file_size: int | None = None
    base: str | None = None
    draft_rev: int | None = None
    draft_where: str = ""
    in_drafting: bool = False
    note: str = ""

    @property
    def identity(self) -> tuple[int | None, int | None, int | None, int | None]:
        return (self.obj_id, self.obj_version, self.file_id, self.file_version)


def failed(dwg: str, note: str) -> Found:
    return Found(dwg=dwg, ok=False, note=note[:NOTE_MAX])


class Lookup(Protocol):
    def status(self, dwg: str) -> Found: ...

    def download(self, found: Found, dest: Path) -> int:
        """Write the released PDF to `dest`; bytes written. Raises DrawingFetchError (a LookupError)."""
        ...

    def describe(self) -> str: ...


def from_status(st: DrawingStatus) -> Found:
    """MFilesKit's DrawingStatus -> Found."""
    ov, fi = st.obj_ver, st.file
    return Found(
        dwg=st.drawing,
        ok=bool(st.ok),
        rev=st.rev,
        name=st.name,
        obj_id=ov.id if ov is not None else None,
        obj_version=ov.version if ov is not None else None,
        file_id=fi.id if fi is not None else None,
        file_version=fi.version if fi is not None else None,
        file_size=fi.size if fi is not None else None,
        base=st.base,
        draft_rev=st.draft_rev,
        draft_where=st.draft_where or "",
        in_drafting=bool(st.in_drafting),
        note=(st.note or "")[:NOTE_MAX],
    )


class MFilesLookup:
    """M-Files through `mfileskit.drawings.DrawingLookup`. Read-only."""

    def __init__(self, vault: Vault) -> None:
        from mfileskit.drawings import DrawingLookup

        self.vault = vault
        self._lookup = DrawingLookup(vault)  # reads the vault schema; raises MFilesError when the vault is down
        self._seen: dict[str, DrawingStatus] = {}

    def status(self, dwg: str) -> Found:
        from mfileskit.errors import MFilesError

        dwg = (dwg or "").strip()
        try:
            st = self._lookup.status(dwg)
        except MFilesError as e:  # status() catches these itself; this is a second net
            return failed(dwg, f"M-Files lookup failed: {e}")
        self._seen[dwg] = st
        return from_status(st)

    def download(self, found: Found, dest: Path) -> int:
        from mfileskit.errors import MFilesError

        st = self._seen.get(found.dwg)
        if st is None or st.obj_ver is None or st.file is None:
            raise DrawingFetchError(f"{found.dwg}: no released file to download")
        try:
            return int(self._lookup.download(st, dest))
        except MFilesError as e:
            raise DrawingFetchError(f"{found.dwg}: download failed: {e}"[:NOTE_MAX]) from None

    def describe(self) -> str:
        url = getattr(getattr(self.vault, "settings", None), "url", "") or ""
        return f"M-Files {url}".strip()


# ---------------------------------------------------------------- one vault per process

_LOCK = threading.Lock()
_CACHE: dict[str, Any] = {}


def _cache_for(cache: dict[str, Any] | None) -> tuple[dict[str, Any], str]:
    if cache is not None:
        return cache, VAULT_KEY
    return _CACHE, f"{VAULT_KEY}:{os.environ.get('MFILES_URL', '')}"


def vault_for(settings: Settings, cache: dict[str, Any] | None = None) -> Vault:
    """The process's Vault, made once with `Vault.from_env()` (MFILES_* from the environment; the entrypoint
    exports MFILES_PASSWORD from its secret file) and signed in."""
    from mfileskit.vault import Vault

    store, key = _cache_for(cache)
    with _LOCK:
        vault = store.get(key)
        if vault is None:
            vault = Vault.from_env().connect()
            store[key] = vault
        return vault


def forget_vault(cache: dict[str, Any] | None = None) -> None:
    """Drop (and close) the cached Vault, so the next run signs in again."""
    store, key = _cache_for(cache)
    with _LOCK:
        vault = store.pop(key, None)
    if vault is not None:
        try:
            vault.close()
        except Exception as e:  # closing a broken connection may fail; nothing to do
            log.info("closing the M-Files vault failed: %s", type(e).__name__)


def make(settings: Settings, cache: dict[str, Any] | None = None) -> Lookup:
    """The lookup for one run. `drawing_source = fixture` reads `fixture_dir`; otherwise M-Files.

    Raises when M-Files cannot be opened (the job then records a degraded run). A failed open drops the cached
    Vault so the next run tries a fresh sign-in.
    """
    if getattr(settings, "drawing_source", "mfiles") == "fixture":
        from .fake import FixtureLookup

        return FixtureLookup(Path(settings.fixture_dir))
    try:
        return MFilesLookup(vault_for(settings, cache))
    except Exception:
        forget_vault(cache)
        raise