from datetime import datetime
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from backend.models.comment import Comment
from backend.models.post import Post
from backend.models.author import Author


async def list_comments(
    db: AsyncSession,
    post_id: int | None = None,
    subreddit_id: int | None = None,
    author: str | None = None,
    sort_by: str = "created_utc",
    sort_order: str = "desc",
    since: datetime | None = None,
    until: datetime | None = None,
    page: int = 1,
    per_page: int = 25,
) -> tuple[list[dict], int]:
    base = select(Comment, Author.username).outerjoin(Author).join(Post)

    filters = []
    if post_id:
        filters.append(Comment.post_id == post_id)
    if subreddit_id:
        filters.append(Post.subreddit_id == subreddit_id)
    if author:
        filters.append(Author.username == author)
    if since:
        filters.append(Comment.created_utc >= since)
    if until:
        filters.append(Comment.created_utc <= until)

    if filters:
        base = base.where(*filters)

    count_stmt = select(func.count()).select_from(base.subquery())
    total = (await db.execute(count_stmt)).scalar() or 0

    sort_col = getattr(Comment, sort_by, Comment.created_utc)
    if sort_order == "asc":
        base = base.order_by(sort_col.asc())
    else:
        base = base.order_by(sort_col.desc())

    base = base.offset((page - 1) * per_page).limit(per_page)

    result = await db.execute(base)
    comments = []
    for comment, author_name in result.all():
        data = {c.name: getattr(comment, c.name) for c in comment.__table__.columns}
        data["author_name"] = author_name
        comments.append(data)

    return comments, total