"""Spec dispatch: run one or many fetch specs, never raising for a single failure."""

from __future__ import annotations

from typing import Any, Callable

from web_fetcher.adapters import eurostat, http
from web_fetcher.core import Fetched, FetchError, Observation, fetch_bytes

ADAPTERS: dict[str, Callable[[dict[str, Any], Callable[[str], Fetched]], list[Observation]]] = {
    "eurostat": eurostat.fetch,
    "http_json": http.fetch_json,
    "http_csv": http.fetch_csv,
    "xlsx_wide": http.fetch_xlsx_wide,
}


def run_spec(spec: dict[str, Any], get: Callable[[str], Fetched] | None = None,
             cache_dir: str | None = None, replay_dir: str | None = None) -> list[Observation]:
    """Run one spec. Adapter errors become an `error` observation, not an exception.

    A value is never returned without a source: an `ok` observation whose
    adapter could not name one (the spec lacks `source`) becomes an `error`.
    """
    sid = spec.get("id", "?")
    kind = spec.get("adapter")
    if kind == "manual":
        return [Observation(spec_id=sid, status="not_found", source=spec.get("source"),
                            note="manual: no machine-readable source; collect at review")]
    adapter = ADAPTERS.get(kind or "")
    if adapter is None:
        return [Observation(spec_id=sid, status="error", note=f"unknown adapter {kind!r}")]
    getter = get or (lambda url: fetch_bytes(url, cache_dir=cache_dir, replay_dir=replay_dir))
    try:
        return [_require_source(o) for o in adapter(spec, getter)]
    except FetchError as exc:
        return [Observation(spec_id=sid, status="error", note=str(exc)[:300])]
    except (KeyError, ValueError, TypeError) as exc:
        return [Observation(spec_id=sid, status="error", note=f"parse error: {exc!s}"[:300])]


def _require_source(obs: Observation) -> Observation:
    if obs.status == "ok" and not obs.source:
        return Observation(spec_id=obs.spec_id, status="error", url=obs.url, retrieved_at=obs.retrieved_at,
                           payload_sha256=obs.payload_sha256,
                           note="spec has no 'source'; values are never returned without one")
    return obs


def run_specs(specs: list[dict[str, Any]], **kw: Any) -> list[Observation]:
    out: list[Observation] = []
    for spec in specs:
        out.extend(run_spec(spec, **kw))
    return out