"""Maintenance-queue Celery tasks.

Currently holds the blocklist cleanup task that retroactively removes
blocklisted tag names from the library. The earlier sync_character_fandoms
task was removed on 2026-04-21 as part of the bare-name refactor.
"""
import logging

from celery import shared_task
from sqlalchemy import text

from app import db
from app.models import Tag

log = logging.getLogger(__name__)


@shared_task(
    name='app.tasks.maintenance.sync_character_fandoms_to_images',
    soft_time_limit=300,
    time_limit=600,
)
def sync_character_fandoms_to_images() -> dict:
    """For every character tag with a non-null fandom_id, ensure the fandom
    tag is attached to every image that has the character attached.

    Backfills the gap left by migration j26042101 — the migration set
    tag.fandom_id from the old '(Fandom)' suffix but did not retroactively
    add fandom rows to image_tags. Set operations made AFTER the migration
    via /api/tag/<id>/set-fandom do this inline, so running this task once
    (or whenever the user suspects drift) is sufficient.

    Additive only — never removes fandom attachments. Idempotent via
    ON CONFLICT DO NOTHING.

    Returns a summary with per-character counts so the result is
    introspectable.
    """
    chars = (
        Tag.query
        .filter_by(kind='character')
        .filter(Tag.fandom_id.isnot(None))
        .all()
    )
    total_links_added = 0
    characters_processed = 0
    failures = 0
    for char in chars:
        try:
            result = db.session.execute(
                text("""
                    INSERT INTO image_tags (image_id, tag_id)
                    SELECT it.image_id, :fandom_id
                    FROM image_tags it
                    WHERE it.tag_id = :char_id
                    ON CONFLICT DO NOTHING
                """),
                {'char_id': char.id, 'fandom_id': char.fandom_id},
            )
            total_links_added += result.rowcount or 0
            db.session.commit()
            characters_processed += 1
        except Exception as e:
            db.session.rollback()
            failures += 1
            log.warning(
                "sync_character_fandoms_to_images: char tag %s (%s) failed: %s",
                char.id, char.name, e,
            )
    log.info(
        "sync_character_fandoms_to_images: processed %d characters, added %d links, %d failures",
        characters_processed, total_links_added, failures,
    )
    return {
        'characters_scanned': len(chars),
        'characters_processed': characters_processed,
        'links_added': total_links_added,
        'characters_failed': failures,
    }


@shared_task(
    name='app.tasks.maintenance.sweep_blocklisted_tag_from_images',
    soft_time_limit=60,
    time_limit=120,
)
def sweep_blocklisted_tag_from_images(name: str) -> dict:
    """Remove a blocklisted tag name from every image that has it attached,
    then delete the Tag row itself.

    Scope is limited to kind='user' tags — that's the kind WD14's general
    category gets materialized as when accepted, which is the vast majority
    of blocklist hits. Character / fandom / artist / series / post / archive
    tags sharing the same name are left alone: those are deliberate, curated
    entities, and removing them silently because of a blocklist text match
    would be destructive.

    Returns a summary dict so the Celery result is introspectable.
    """
    tag = Tag.query.filter_by(kind='user', name=name).first()
    if tag is None:
        log.info("sweep_blocklisted_tag_from_images: no kind='user' tag named %r; nothing to do", name)
        return {'name': name, 'tag_found': False, 'image_tags_deleted': 0, 'tag_deleted': False}

    result = db.session.execute(
        text("DELETE FROM image_tags WHERE tag_id = :tid"),
        {'tid': tag.id},
    )
    rowcount = result.rowcount or 0
    db.session.delete(tag)
    db.session.commit()

    log.info(
        "sweep_blocklisted_tag_from_images: removed %r (tag_id=%d) from %d images",
        name, tag.id, rowcount,
    )
    return {
        'name': name,
        'tag_found': True,
        'image_tags_deleted': rowcount,
        'tag_deleted': True,
    }