"""Routing and probe logic for provider selection."""

from __future__ import annotations

from concurrent.futures import ThreadPoolExecutor
from dataclasses import dataclass
from typing import Any, cast
from collections.abc import Mapping
import urllib.parse

from ..config import build_user_agent
from ..extraction.html.landing import fetch_landing_html
from ..http import HttpTransport, RequestFailure
from ..metadata.types import ProviderMetadata
from ..provider_catalog import (
    official_provider_names,
    provider_metadata_probe_short_circuit,
    provider_supports_metadata_api_probe,
)
from ..providers.base import ProviderFailure
from ..reason_codes import ERROR, NO_ACCESS, NO_RESULT, NOT_CONFIGURED, NOT_SUPPORTED, RATE_LIMITED
from ..providers.protocols import MetadataProvider
from ..runtime import RUNTIME_UNSET, RuntimeContext, resolve_runtime_context
from ..tracing import route_marker
from ..publisher_identity import (
    infer_provider_from_doi,
    infer_provider_from_publisher,
    infer_provider_from_url,
    normalize_doi,
    ordered_provider_candidates,
)
from ..utils import choose_public_landing_page_url, extend_unique, normalize_text, safe_text
from .resolution import resolve_paper
from .session_cache import (
    CROSSREF_METADATA_KEY,
    LANDING_PDF_PROBE_KEY,
    PROVIDER_PROBE_KEY,
    RESOLVED_QUERY_KEY,
    cached_call,
    get_cached,
)
from .types import FetchStrategy, HasFulltextProbeResult, PaperFetchFailure, RouteProbeResult

OFFICIAL_PROVIDER_NAMES = official_provider_names()


@dataclass(frozen=True)
class LandingPageCitationPdfProbeResult:
    has_citation_pdf_url: bool
    title: str | None
    citation_pdf_urls: list[str]


def provider_allowed(provider_name: str | None, strategy: FetchStrategy) -> bool:
    normalized = strategy.normalized_preferred_providers()
    if normalized is None:
        return True
    if provider_name is None:
        return False
    return normalize_text(provider_name).lower() in normalized


def crossref_allowed_as_source(strategy: FetchStrategy) -> bool:
    return provider_allowed("crossref", strategy)


def route_signal_markers(*, landing_urls: list[str | None] | None = None, publishers: list[str | None] | None = None, doi: str | None = None) -> list[str]:
    markers: list[str] = []
    for url in landing_urls or []:
        provider = infer_provider_from_url(url)
        if provider:
            extend_unique(markers, [route_marker(f"signal_domain_{provider}")])
    for publisher in publishers or []:
        provider = infer_provider_from_publisher(publisher)
        if provider:
            extend_unique(markers, [route_marker(f"signal_publisher_{provider}")])
    provider = infer_provider_from_doi(doi)
    if provider:
        extend_unique(markers, [route_marker(f"signal_doi_{provider}")])
    return markers


def build_official_provider_candidates(resolved, *, routing_metadata: Mapping[str, Any] | None, strategy: FetchStrategy) -> list[tuple[str, str]]:
    candidates = ordered_provider_candidates(
        landing_urls=[resolved.landing_url, safe_text((routing_metadata or {}).get("landing_page_url"))],
        publishers=[safe_text((routing_metadata or {}).get("publisher"))],
        doi=resolved.doi,
    )
    return [
        (provider, signal)
        for provider, signal in candidates
        if provider in OFFICIAL_PROVIDER_NAMES and provider_allowed(provider, strategy)
    ]


def classify_probe_state(failure: ProviderFailure) -> str:
    if failure.code == NO_RESULT:
        return "negative"
    return "unknown"


def _is_unknown_has_fulltext_probe_failure(error: ProviderFailure) -> bool:
    return error.code in {NO_ACCESS, RATE_LIMITED, NOT_CONFIGURED, NOT_SUPPORTED, ERROR}


def _probe_warning(prefix: str, message: str) -> str:
    normalized_message = normalize_text(message)
    if not normalized_message:
        return prefix
    return f"{prefix}: {normalized_message}"


def _landing_page_citation_pdf_probe(
    landing_url: str,
    *,
    transport: HttpTransport,
    env: Mapping[str, str],
) -> LandingPageCitationPdfProbeResult:
    landing_fetch = fetch_landing_html(
        landing_url,
        transport=transport,
        headers={
            "Accept": "text/html,application/xhtml+xml",
            "User-Agent": build_user_agent(env),
        },
        max_redirects=0,
        retry_on_transient=True,
    )
    html_metadata = landing_fetch.metadata
    raw_meta = html_metadata.get("raw_meta") or {}
    citation_pdf_values = raw_meta.get("citation_pdf_url") if isinstance(raw_meta, Mapping) else None
    citation_pdf_urls = [
        urllib.parse.urljoin(landing_fetch.final_url, normalized)
        for normalized in [normalize_text(item) for item in (citation_pdf_values or [])]
        if normalized
    ]
    return LandingPageCitationPdfProbeResult(
        has_citation_pdf_url=bool(citation_pdf_urls),
        title=normalize_text(html_metadata.get("title")),
        citation_pdf_urls=list(dict.fromkeys(citation_pdf_urls)),
    )


def resolve_query_with_session_cache(
    query: str,
    *,
    resolver,
    transport: HttpTransport,
    env: Mapping[str, str],
    context: RuntimeContext,
):
    return cached_call(RESOLVED_QUERY_KEY, (normalize_text(query) or str(query),), context, lambda: resolver(query, transport=transport, env=env))


def fetch_crossref_metadata_with_session_cache(doi: str | None, crossref_client: object, *, context: RuntimeContext | None = None) -> ProviderMetadata | None:
    if not doi or not isinstance(crossref_client, MetadataProvider):
        return None
    normalized_doi = normalize_doi(doi) or doi
    def fetch_metadata() -> ProviderMetadata:
        return cast(ProviderMetadata, dict(crossref_client.fetch_metadata({"doi": normalized_doi})))
    return cached_call(CROSSREF_METADATA_KEY, (normalized_doi,), context, fetch_metadata) if context is not None else fetch_metadata()


def fetch_provider_metadata_probe_with_session_cache(
    provider_name: str,
    doi: str | None,
    *,
    clients: Mapping[str, object],
    context: RuntimeContext | None = None,
) -> ProviderMetadata | None:
    if not doi:
        return None
    client = clients.get(provider_name)
    if not isinstance(client, MetadataProvider):
        return None
    normalized_doi = normalize_doi(doi) or doi
    def fetch_metadata() -> ProviderMetadata | None:
        return cast(ProviderMetadata, dict(metadata)) if (metadata := client.fetch_metadata({"doi": normalized_doi})) else None
    return cached_call(PROVIDER_PROBE_KEY, (normalize_text(provider_name).lower(), normalized_doi), context, fetch_metadata) if context is not None else fetch_metadata()


def landing_page_citation_pdf_probe_with_session_cache(
    landing_url: str,
    *,
    transport: HttpTransport,
    env: Mapping[str, str],
    context: RuntimeContext | None = None,
) -> LandingPageCitationPdfProbeResult:
    def fetch_probe() -> LandingPageCitationPdfProbeResult:
        return _landing_page_citation_pdf_probe(landing_url, transport=transport, env=env)
    return cached_call(LANDING_PDF_PROBE_KEY, (normalize_text(landing_url) or landing_url,), context, fetch_probe) if context is not None else fetch_probe()


def get_cached_landing_page_citation_pdf_probe(
    landing_url: str | None,
    *,
    context: RuntimeContext | None,
) -> LandingPageCitationPdfProbeResult | None:
    if context is None or not landing_url:
        return None
    return cast(
        LandingPageCitationPdfProbeResult | None,
        get_cached(LANDING_PDF_PROBE_KEY, (normalize_text(landing_url) or landing_url,), context),
    )


def probe_official_provider(
    provider_name: str,
    *,
    doi: str,
    clients: Mapping[str, object],
    context: RuntimeContext | None = None,
) -> RouteProbeResult:
    if not provider_supports_metadata_api_probe(provider_name):
        return RouteProbeResult(provider=provider_name, state="unknown")
    short_circuit = provider_metadata_probe_short_circuit(provider_name)
    if short_circuit is not None:
        try:
            metadata = short_circuit(doi)
        except ProviderFailure as exc:
            return RouteProbeResult(provider=provider_name, state=classify_probe_state(exc))
        if metadata:
            return RouteProbeResult(provider=provider_name, state="positive", metadata=cast(ProviderMetadata, dict(metadata)))
        return RouteProbeResult(provider=provider_name, state="negative")
    if not isinstance(clients.get(provider_name), MetadataProvider):
        return RouteProbeResult(provider=provider_name, state="unknown")
    try:
        probe_metadata = fetch_provider_metadata_probe_with_session_cache(
            provider_name,
            doi,
            clients=clients,
            context=context,
        )
    except ProviderFailure as exc:
        return RouteProbeResult(provider=provider_name, state=classify_probe_state(exc))
    if probe_metadata:
        return RouteProbeResult(
            provider=provider_name,
            state="positive",
            metadata=cast(ProviderMetadata, dict(probe_metadata)),
        )
    return RouteProbeResult(provider=provider_name, state="negative")


def metadata_api_probe_provider_names(resolved, *, routing_metadata: Mapping[str, Any] | None, strategy: FetchStrategy) -> list[str]:
    return [
        provider_name
        for provider_name, _signal in build_official_provider_candidates(resolved, routing_metadata=routing_metadata, strategy=strategy)
        if provider_supports_metadata_api_probe(provider_name)
    ]


def select_route_probe(probes: list[RouteProbeResult]) -> RouteProbeResult | None:
    for state in ("positive", "unknown", "negative"):
        for probe in probes:
            if probe.state == state:
                return probe
    return None


def probe_has_fulltext(
    query: str,
    *,
    transport: HttpTransport | None | object = RUNTIME_UNSET,
    env: Mapping[str, str] | None | object = RUNTIME_UNSET,
    clients: Mapping[str, object] | None | object = RUNTIME_UNSET,
    context: RuntimeContext | None = None,
    resolve_paper_fn=None,
) -> HasFulltextProbeResult:
    runtime = resolve_runtime_context(context, env=env, transport=transport, clients=clients)
    assert runtime.env is not None
    assert runtime.transport is not None
    active_env = runtime.env
    active_transport = runtime.transport
    client_registry = dict(runtime.get_clients())
    resolver = resolve_paper_fn or resolve_paper
    resolved = resolve_query_with_session_cache(query, resolver=resolver, transport=active_transport, env=active_env, context=runtime)
    if resolved.candidates and not resolved.doi:
        raise PaperFetchFailure("ambiguous", "Query resolution is ambiguous; choose one of the DOI candidates.", candidates=resolved.candidates)

    warnings: list[str] = []
    evidence: list[str] = []
    title = normalize_text(resolved.title)
    doi = normalize_doi(safe_text(resolved.doi)) or None
    crossref_metadata: ProviderMetadata | None = None
    crossref_client = client_registry.get("crossref")

    strategy = FetchStrategy()
    initial_metadata_probe_providers = metadata_api_probe_provider_names(resolved, routing_metadata=None, strategy=strategy) if doi else []

    def fetch_crossref_metadata() -> ProviderMetadata | None:
        return fetch_crossref_metadata_with_session_cache(doi, crossref_client, context=runtime)

    def fetch_provider_probe_metadata(provider_name: str) -> ProviderMetadata | None:
        return fetch_provider_metadata_probe_with_session_cache(provider_name, doi, clients=client_registry, context=runtime)

    def fetch_landing_probe(landing_url: str) -> LandingPageCitationPdfProbeResult:
        return landing_page_citation_pdf_probe_with_session_cache(landing_url, transport=active_transport, env=active_env, context=runtime)

    landing_probe_by_url: dict[str, LandingPageCitationPdfProbeResult] = {}
    landing_probe_errors: dict[str, RequestFailure] = {}
    provider_probe_metadata: dict[str, ProviderMetadata] = {}
    provider_probe_errors: dict[str, ProviderFailure] = {}
    metadata_probe_provider_order: list[str] = list(initial_metadata_probe_providers)
    crossref_error: ProviderFailure | None = None
    initial_landing_url = choose_public_landing_page_url(resolved.landing_url)

    with ThreadPoolExecutor(max_workers=max(1, 2 + len(initial_metadata_probe_providers))) as executor:
        crossref_future = executor.submit(fetch_crossref_metadata) if doi and isinstance(crossref_client, MetadataProvider) else None
        provider_probe_futures = {
            provider_name: executor.submit(fetch_provider_probe_metadata, provider_name)
            for provider_name in initial_metadata_probe_providers
        }
        landing_future = executor.submit(fetch_landing_probe, initial_landing_url) if initial_landing_url else None

        if crossref_future is not None:
            try:
                crossref_metadata = crossref_future.result()
            except ProviderFailure as exc:
                crossref_error = exc
        for provider_name, future in provider_probe_futures.items():
            try:
                metadata = future.result()
                if metadata:
                    provider_probe_metadata[provider_name] = metadata
            except ProviderFailure as exc:
                provider_probe_errors[provider_name] = exc
        if landing_future is not None and initial_landing_url:
            try:
                landing_probe_by_url[initial_landing_url] = landing_future.result()
            except RequestFailure as exc:
                landing_probe_errors[initial_landing_url] = exc

    if crossref_metadata:
        title = normalize_text(crossref_metadata.get("title")) or title
        if crossref_metadata.get("license_urls"):
            extend_unique(evidence, ["crossref_license"])
        if crossref_metadata.get("fulltext_links"):
            extend_unique(evidence, ["crossref_fulltext_link"])
    elif crossref_error is not None and _is_unknown_has_fulltext_probe_failure(crossref_error):
        extend_unique(warnings, [_probe_warning("Crossref metadata probe unavailable", crossref_error.message)])

    if doi:
        for provider_name in metadata_api_probe_provider_names(resolved, routing_metadata=crossref_metadata, strategy=strategy):
            if provider_name not in metadata_probe_provider_order:
                metadata_probe_provider_order.append(provider_name)
            if provider_name in provider_probe_metadata or provider_name in provider_probe_errors:
                continue
            try:
                metadata = fetch_provider_probe_metadata(provider_name)
                if metadata:
                    provider_probe_metadata[provider_name] = metadata
            except ProviderFailure as exc:
                provider_probe_errors[provider_name] = exc

    for provider_name in metadata_probe_provider_order:
        metadata = provider_probe_metadata.get(provider_name)
        if metadata:
            extend_unique(evidence, [f"provider_probe:{provider_name}"])
            title = normalize_text(metadata.get("title")) or title
            continue
        error = provider_probe_errors.get(provider_name)
        if error is not None and _is_unknown_has_fulltext_probe_failure(error):
            extend_unique(warnings, [_probe_warning(f"{provider_name} metadata probe unavailable", error.message)])

    landing_url = choose_public_landing_page_url(resolved.landing_url, (crossref_metadata or {}).get("landing_page_url"))
    if landing_url:
        if landing_url not in landing_probe_by_url and landing_url not in landing_probe_errors:
            try:
                landing_probe_by_url[landing_url] = fetch_landing_probe(landing_url)
            except RequestFailure as exc:
                landing_probe_errors[landing_url] = exc
        if landing_url in landing_probe_by_url:
            landing_probe = landing_probe_by_url[landing_url]
            if landing_probe.has_citation_pdf_url:
                extend_unique(evidence, ["landing_page_citation_pdf_url"])
            title = landing_probe.title or title
        elif landing_url in landing_probe_errors:
            extend_unique(warnings, [_probe_warning("Landing-page metadata probe unavailable", str(landing_probe_errors[landing_url]))])

    state = "likely_yes" if evidence else "unknown"
    return HasFulltextProbeResult(query=resolved.query, doi=doi, title=title, state=state, evidence=evidence, warnings=warnings)
