from __future__ import annotations

import hashlib
import logging
from datetime import UTC, datetime

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.db.models import CrawlRun, Publication, ScholarProfile, ScholarPublication
from app.services.doi.normalize import first_doi_from_texts
from app.services.ingestion.fingerprints import (
    build_publication_fingerprint,
    build_publication_url,
    canonical_title_for_dedup,
    normalize_title,
)
from app.services.publication_identifiers import application as identifier_service
from app.services.runs.events import run_events
from app.services.scholar.parser import PublicationCandidate

logger = logging.getLogger(__name__)


def validate_publication_candidate(candidate: PublicationCandidate) -> None:
    if not candidate.title.strip():
        raise RuntimeError("Publication candidate is missing title.")
    if candidate.citation_count is not None and int(candidate.citation_count) < 0:
        raise RuntimeError("Publication candidate has negative citation_count.")


async def find_publication_by_cluster(
    db_session: AsyncSession,
    *,
    cluster_id: str | None,
) -> Publication | None:
    if not cluster_id:
        return None
    result = await db_session.execute(select(Publication).where(Publication.cluster_id == cluster_id))
    return result.scalar_one_or_none()


async def find_publication_by_fingerprint(
    db_session: AsyncSession,
    *,
    fingerprint: str,
) -> Publication | None:
    result = await db_session.execute(select(Publication).where(Publication.fingerprint_sha256 == fingerprint))
    return result.scalar_one_or_none()


def select_existing_publication(
    *,
    cluster_publication: Publication | None,
    fingerprint_publication: Publication | None,
) -> Publication | None:
    if cluster_publication is not None:
        return cluster_publication
    return fingerprint_publication


def compute_canonical_title_hash(title: str) -> str:
    canonical = canonical_title_for_dedup(title)
    return hashlib.sha256(canonical.encode("utf-8")).hexdigest()


async def find_publication_by_canonical_title_hash(
    db_session: AsyncSession,
    *,
    canonical_title_hash: str,
) -> Publication | None:
    result = await db_session.execute(
        select(Publication).where(Publication.canonical_title_hash == canonical_title_hash)
    )
    return result.scalar_one_or_none()


async def create_publication(
    db_session: AsyncSession,
    *,
    candidate: PublicationCandidate,
    fingerprint: str,
) -> Publication:
    publication = Publication(
        cluster_id=candidate.cluster_id,
        fingerprint_sha256=fingerprint,
        title_raw=candidate.title,
        title_normalized=normalize_title(candidate.title),
        canonical_title_hash=compute_canonical_title_hash(candidate.title),
        year=candidate.year,
        citation_count=int(candidate.citation_count or 0),
        author_text=candidate.authors_text,
        venue_text=candidate.venue_text,
        pub_url=build_publication_url(candidate.title_url),
        pdf_url=None,
    )
    db_session.add(publication)
    await db_session.flush()
    return publication


def update_existing_publication(
    *,
    publication: Publication,
    candidate: PublicationCandidate,
) -> None:
    if candidate.cluster_id and publication.cluster_id is None:
        publication.cluster_id = candidate.cluster_id
    publication.title_raw = candidate.title
    publication.title_normalized = normalize_title(candidate.title)
    if candidate.year is not None:
        publication.year = candidate.year
    if candidate.citation_count is not None:
        publication.citation_count = int(candidate.citation_count)
    if candidate.authors_text:
        publication.author_text = candidate.authors_text
    if candidate.venue_text:
        publication.venue_text = candidate.venue_text
    if candidate.title_url:
        publication.pub_url = build_publication_url(candidate.title_url)
    first_doi_from_texts(candidate.title_url, candidate.venue_text, candidate.title)


async def resolve_publication(
    db_session: AsyncSession,
    candidate: PublicationCandidate,
) -> Publication:
    validate_publication_candidate(candidate)
    fingerprint = build_publication_fingerprint(candidate)
    cluster_publication = await find_publication_by_cluster(
        db_session,
        cluster_id=candidate.cluster_id,
    )
    fingerprint_publication = await find_publication_by_fingerprint(
        db_session,
        fingerprint=fingerprint,
    )
    publication = select_existing_publication(
        cluster_publication=cluster_publication,
        fingerprint_publication=fingerprint_publication,
    )
    if publication is None:
        canonical_hash = compute_canonical_title_hash(candidate.title)
        publication = await find_publication_by_canonical_title_hash(
            db_session,
            canonical_title_hash=canonical_hash,
        )
    if publication is None:
        created = await create_publication(
            db_session,
            candidate=candidate,
            fingerprint=fingerprint,
        )
        await identifier_service.sync_identifiers_for_publication_fields(
            db_session,
            publication=created,
        )
        return created
    update_existing_publication(
        publication=publication,
        candidate=candidate,
    )
    await identifier_service.sync_identifiers_for_publication_fields(
        db_session,
        publication=publication,
    )
    return publication


async def upsert_profile_publications(
    db_session: AsyncSession,
    *,
    run: CrawlRun,
    scholar: ScholarProfile,
    publications: list[PublicationCandidate],
) -> int:
    seen_publication_ids: set[int] = set()
    discovered_count = 0

    for candidate in publications:
        publication = await resolve_publication(db_session, candidate)
        if publication.id in seen_publication_ids:
            continue
        seen_publication_ids.add(publication.id)

        link_result = await db_session.execute(
            select(ScholarPublication).where(
                ScholarPublication.scholar_profile_id == scholar.id,
                ScholarPublication.publication_id == publication.id,
            )
        )
        link = link_result.scalar_one_or_none()
        if link is not None:
            continue

        link = ScholarPublication(
            scholar_profile_id=scholar.id,
            publication_id=publication.id,
            is_read=False,
            first_seen_run_id=run.id,
        )
        db_session.add(link)
        discovered_count += 1

        await commit_discovered_publication(
            db_session,
            run=run,
            scholar=scholar,
            publication=publication,
        )

    if not scholar.baseline_completed:
        scholar.baseline_completed = True

    return discovered_count


async def commit_discovered_publication(
    db_session: AsyncSession,
    *,
    run: CrawlRun,
    scholar: ScholarProfile,
    publication: Publication,
) -> None:
    run.new_pub_count = int(run.new_pub_count or 0) + 1
    await db_session.commit()
    await run_events.publish(
        run_id=run.id,
        event_type="publication_discovered",
        data={
            "publication_id": publication.id,
            "title": publication.title_raw,
            "pub_url": publication.pub_url,
            "scholar_profile_id": scholar.id,
            "scholar_label": scholar.display_name or scholar.scholar_id,
            "first_seen_at": datetime.now(UTC).isoformat(),
            "new_publication_count": int(run.new_pub_count or 0),
        },
    )