"""
app/services/fission_service.py — 第11环裂变 扇出 service

1爆款 → N套完整笔记包。每套=一个独立 GenerationTask(回填 source_fission_id),
复用主管道 run_generation_pipeline 生成文案+配图。
🔴 占位档位规则见 fission_prompt.py,真实措辞待北哥定义(倩倩姐2026-06-16先打通)。
"""
import json
import logging

from sqlalchemy.orm import Session

from app.core.response import raise_business
from app.middleware.workspace_guard import CurrentUser
from app.models.fission import FissionTask
from app.models.task import GenerationTask
from app.services.ai_engine.fission_prompt import valid_level
from app.services.task_service import _check_user_has_key, enqueue_generation

logger = logging.getLogger(__name__)

MAX_FANOUT = 5  # 每用户并发上限5(红线),裂变扇出数受同等约束


def create_fission(
    db: Session, current_user: CurrentUser,
    source_task_id: int, reference_level: str, fanout_count: int,
) -> tuple[int, list[int]]:
    """
    从一个源任务裂变出 N 套子任务。
    返回 (fission_id, [子task_id,...])。
    """
    _check_user_has_key(db, current_user.user_id, current_user.workspace_id)

    level = valid_level(reference_level)
    n = max(1, min(fanout_count or 3, MAX_FANOUT))

    # 读源任务(取产品+主题+已选文案作为爆款源)
    src = db.query(GenerationTask).filter(
        GenerationTask.id == source_task_id,
        GenerationTask.workspace_id == current_user.workspace_id,
    ).first()
    if not src:
        raise_business("裂变源任务不存在")

    source_note = {"title": src.theme or "", "content": _extract_source_copy(db, src)}

    # 建 fission_task 记录
    ft = FissionTask(
        workspace_id=current_user.workspace_id,
        source_note=json.dumps(source_note, ensure_ascii=False),
        reference_level=level, fanout_count=n, status="generating",
    )
    db.add(ft); db.commit(); db.refresh(ft)

    # 扇出 N 个子任务(回填 source_fission_id),复用主管道
    task_ids: list[int] = []
    for _ in range(n):
        sub = GenerationTask(
            workspace_id=current_user.workspace_id,
            product_id=src.product_id, operator_id=current_user.user_id,
            theme=src.theme, text_count=src.text_count, image_count=src.image_count,
            track="ai", need_product_image=src.need_product_image,
            status="pending", source_fission_id=ft.id,
        )
        db.add(sub); db.commit(); db.refresh(sub)
        enqueue_generation(sub.id)
        task_ids.append(sub.id)

    logger.info("fission created id=%s level=%s fanout=%s tasks=%s",
                ft.id, level, n, task_ids)
    return ft.id, task_ids


def _extract_source_copy(db: Session, src: GenerationTask) -> str:
    """取源任务已选/最高分文案当爆款正文;无则用主题兜底。"""
    from app.models.task import TextCandidate
    c = (db.query(TextCandidate)
         .filter(TextCandidate.task_id == src.id)
         .order_by(TextCandidate.is_selected.desc(), TextCandidate.id.asc())
         .first())
    if c and c.content:
        return c.content
    return src.theme or ""