"""Persist caller-authored templates with frozen local research evidence."""

import math

from sqlalchemy import select

from ..models import BacktestItem, BacktestResult, ResearchAsset
from ..research.assets import Assets
from ..research.workspace_contracts import AssetWrite
from .queries import item_summary


async def create_template(db, args, principal, *, asset_id=None):
    """Save a new asset or revision inside the caller's account-locked, idempotent transaction.

    Args contain the external model's TemplateSpec and local source item IDs.
    Return the versioned asset and theoretical combination count. Raise
    ResearchError for name conflicts or missing/incomplete research evidence.
    Stored evidence proves provenance, not profitability or platform eligibility;
    schema validation does not validate every expanded FASTEXPR combination.
    Optional asset_id selects a version update guarded by args.expected_version;
    a stale version raises HTTP 409 and cannot overwrite a historical revision.
    """
    from .service import ResearchError

    existing = await db.scalar(select(ResearchAsset).where(
        ResearchAsset.kind == "template", ResearchAsset.name == args.template.name,
        ResearchAsset.id != asset_id if asset_id else True,
    ).order_by(ResearchAsset.id).limit(1))
    if existing:
        raise ResearchError("TEMPLATE_NAME_CONFLICT", "模板名称已存在，请使用新名称；此工具不覆盖已有模板",
                            affected_items=[{"template_id": existing.id, "version": existing.version}])
    previous = await Assets(db).get(asset_id, expected_kind="template") if asset_id else None
    rows = (await db.execute(select(BacktestItem, BacktestResult).outerjoin(
        BacktestResult, BacktestResult.item_id == BacktestItem.id,
    ).where(BacktestItem.id.in_(args.source_item_ids)))).all()
    found = {item.id: (item, result) for item, result in rows}
    missing = [item_id for item_id in args.source_item_ids if item_id not in found]
    if missing:
        raise ResearchError("NOT_FOUND", "部分来源回测候选不存在", affected_items=missing)
    incomplete = [item.id for item, result in rows if (
        item.platform_status != "completed" or item.collection_status != "complete"
        or item.persistence_status != "saved" or not result or not result.complete
    )]
    if incomplete:
        raise ResearchError("SOURCE_NOT_READY", "来源候选须完成回测、结果采集和持久化，请先读取 get_backtest_results",
                            affected_items=sorted(incomplete))
    provenance = {
        "source": {"kind": "mcp", "reference": args.reference},
        "hypothesis": args.hypothesis,
        "mcp_token_id": principal.token_id,
        "admin_id": principal.admin_id,
        "source_items": [item_summary(*found[item_id]) for item_id in args.source_item_ids],
    }
    if previous:
        provenance["parent_template"] = {"id": asset_id, "version": args.expected_version}
    asset = await Assets(db).save(AssetWrite(
        kind="template", content=args.template.model_dump(mode="json"),
        version=args.expected_version if asset_id else None,
    ), asset_id=asset_id, provenance=provenance)
    return {
        **asset, "template_id": asset["id"],
        "combination_count": (str(math.prod(len(v.values) for v in args.template.variables.values()))
                              if all(v.values for v in args.template.variables.values()) else None),
        "validation": {"structure": "valid", "source_evidence": "recorded" if args.source_item_ids else "not_provided",
                       "expanded_candidates": "not_validated", "platform_semantics": "unknown"},
        "next_step": "选择数据准备和回测参数，用 expand_research_template 生成候选集合；核对候选后按已获授权范围调用 start_template_backtest。也可在模板工坊完成。",
    }