import logging
from datetime import datetime, timezone

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

from app.models.api.api_generation_task import ApiGenerationTask
from app.models.api.api_key import ApiKey

logger = logging.getLogger("videogen")


async def check_quota(key: ApiKey) -> bool:
    """检查 API Key 配额是否充足。

    Returns:
        True = 配额充足或无限额, False = 已超限。
    """
    if key.quota_limit is None:
        return True
    return key.quota_used < key.quota_limit


async def get_active_video_tasks_count(api_key_id: str, db: AsyncSession) -> int:
    """统计 API Key 当前活跃的视频任务数。

    活跃 = status IN ('pending', 'generating', 'processing') AND gen_type='video'
    """
    result = await db.execute(
        select(func.count(ApiGenerationTask.id)).where(
            ApiGenerationTask.api_key_id == api_key_id,
            ApiGenerationTask.gen_type == "video",
            ApiGenerationTask.status.in_(["pending", "generating", "processing"]),
            ApiGenerationTask.deleted_at.is_(None),
        )
    )
    return result.scalar_one() or 0


async def can_start_video_task(key: ApiKey, db: AsyncSession) -> bool:
    """检查是否可以立即启动新的视频任务。

    Returns:
        True = 可以立即启动, False = 需要排队。
    """
    if key.max_concurrent_video_tasks is None:
        return True  # 无限制
    current = await get_active_video_tasks_count(key.id, db)
    return current < key.max_concurrent_video_tasks


async def get_queued_video_tasks(key: ApiKey, db: AsyncSession, limit: int = 10) -> list[ApiGenerationTask]:
    """获取排队的视频任务列表（按创建时间排序）。"""
    result = await db.execute(
        select(ApiGenerationTask).where(
            ApiGenerationTask.api_key_id == key.id,
            ApiGenerationTask.gen_type == "video",
            ApiGenerationTask.status == "queued",
            ApiGenerationTask.deleted_at.is_(None),
        ).order_by(ApiGenerationTask.created_at.asc()).limit(limit)
    )
    return list(result.scalars().all())


async def increment_quota(db: AsyncSession, key: ApiKey, credits_cost: float) -> None:
    """原子性增加配额使用量。"""
    key.quota_used = round((key.quota_used or 0.0) + credits_cost, 2)
    await db.flush()