"""Drop the role from figure titles; the badge and the link already say it.

Titles read "Stem figure — Occult Fracture". The role is already visible from
where the figure sits on the question, and the link itself is the
`question_media` row, not the words in the title. What is useful in a bank of
440 is the subject, so that is all the title should be.

The id stays the identifier it always was, and no link is touched.

    docker compose exec backend python -m scripts.retitle_figures
    docker compose exec backend python -m scripts.retitle_figures --apply
"""
import re
import sys

from sqlalchemy import text as sa_text

from app.database import SessionLocal
from app.models.media import MediaAsset

PREFIX = re.compile(r"^(stem|explanation) figure\s*—\s*", re.I)


def main():
    apply_changes = "--apply" in sys.argv
    db = SessionLocal()
    try:
        # Where a figure has no subject of its own, the question's category is
        # the best name available; the filename is not a name at all.
        subjects = {}
        for media_id, name in db.execute(sa_text("""
            SELECT qm.media_id, c.name
            FROM question_media qm
            JOIN questions q ON q.id = qm.question_id
            LEFT JOIN question_categories c ON c.id = q.question_category_id
        """)).fetchall():
            if name and media_id not in subjects:
                subjects[media_id] = name

        # A detached figure has no link to take a subject from, but its caption
        # records which question it came off. That is still the best name.
        detached = {}
        for asset in db.query(MediaAsset).all():
            match = re.search(r"question #(\d+)", asset.caption or "")
            if match and asset.id not in subjects:
                detached[asset.id] = int(match.group(1))
        if detached:
            names = dict(db.execute(sa_text("""
                SELECT q.id, c.name FROM questions q
                LEFT JOIN question_categories c ON c.id = q.question_category_id
                WHERE q.id = ANY(:ids)
            """), {"ids": list(detached.values())}).fetchall())
            for media_id, question_id in detached.items():
                if names.get(question_id):
                    subjects[media_id] = names[question_id]

        changed = []
        for asset in db.query(MediaAsset).all():
            title = asset.title or ""
            if PREFIX.search(title):
                new = PREFIX.sub("", title).strip()
            elif re.match(r"^page_\d+_img", title):
                new = subjects.get(asset.id) or title
            else:
                continue
            if new and new != title:
                changed.append((asset, title, new))

        print(f"  titles to change: {len(changed)}")
        for _asset, old, new in changed[:6]:
            print(f"    {old:<44} -> {new}")
        if not apply_changes:
            print("\n  Re-run with --apply.")
            return 0

        for asset, _old, new in changed:
            asset.title = new[:300]
        db.flush()

        # A legend is what a reader sees in an explanation, so twelve figures all
        # called "Pediatric Surgery" is twelve legends that say nothing. Only the
        # repeats are numbered; a subject used once stays clean.
        from collections import defaultdict

        by_title = defaultdict(list)
        for asset in db.query(MediaAsset).order_by(MediaAsset.id).all():
            by_title[asset.title].append(asset)
        questions = dict(db.execute(sa_text(
            "SELECT media_id, MIN(question_id) FROM question_media GROUP BY media_id")).fetchall())
        numbered = 0
        for title, assets in by_title.items():
            if len(assets) < 2:
                continue
            for asset in assets:
                question_id = questions.get(asset.id)
                asset.title = (f"{title} · Q{question_id}" if question_id
                               else f"{title} · #{asset.id}")[:300]
                numbered += 1
        db.commit()
        print(f"  disambiguated: {numbered} repeated subjects")
        print(f"\n  retitled: {len(changed)}  (no link changed; the id is the link)")
    finally:
        db.close()
    return 0


if __name__ == "__main__":
    sys.exit(main())