"""Bounded graph traversal with explicit continuation, retaining every result source."""

from fastapi import HTTPException
from sqlalchemy import or_, select

from ..models import Alpha, BacktestResult, BacktestRun, ResearchExperiment, ResearchParent
from .experiments import Experiments
from .provenance import alpha_sources, saved_sources


async def lineage(db, alpha_id=None, experiment_id=None, limit=25, offset=0):
    if bool(alpha_id) == bool(experiment_id):
        raise HTTPException(422, "指定 Alpha 或实验之一")
    sources = None
    frontier = set()
    truncated = False
    if alpha_id:
        if not await db.get(Alpha, alpha_id):
            raise HTTPException(404, "Alpha 尚未同步")
        sources = await alpha_sources(db, alpha_id, limit, offset)
        source_ids = list(
            await db.scalars(
                saved_sources()
                .with_only_columns(BacktestRun.source["research_id"].as_string())
                .where(BacktestResult.alpha_id == alpha_id)
                .distinct()
                .limit(101)
            )
        )
        children = list(
            await db.scalars(
                select(ResearchParent.child_id)
                .where(ResearchParent.parent_kind == "alpha", ResearchParent.parent_id == alpha_id)
                .order_by(ResearchParent.child_id)
                .limit(101)
            )
        )
        frontier = set(source_ids + children) - {None}
        truncated = len(frontier) > 100
    else:
        await Experiments(db).get(experiment_id)
        frontier.add(experiment_id)
    found, edges = {}, {}
    for _ in range(8):
        wanted = sorted(frontier - set(found))
        if not wanted:
            break
        remaining = 100 - len(found)
        if len(wanted) > remaining:
            truncated = True
        wanted = wanted[:remaining]
        if not wanted:
            break
        rows = list(await db.scalars(select(ResearchExperiment).where(ResearchExperiment.id.in_(wanted))))
        for row in rows:
            found[row.id] = await Experiments(db).get(row.id)
        produced = list(
            await db.scalars(
                saved_sources()
                .with_only_columns(BacktestResult.alpha_id)
                .where(BacktestRun.source["research_id"].as_string().in_(wanted))
                .distinct()
                .limit(1001)
            )
        )
        truncated |= len(produced) > 1000
        parent_alphas = {p["id"] for row in rows for p in row.parents if p["kind"] == "alpha"}
        related_sources = list(
            await db.scalars(
                saved_sources()
                .with_only_columns(BacktestRun.source["research_id"].as_string())
                .where(BacktestResult.alpha_id.in_(parent_alphas | set(produced[:1000])))
                .distinct()
                .limit(101)
            )
        )
        truncated |= len(related_sources) > 100
        relations = list(
            await db.scalars(
                select(ResearchParent)
                .where(
                    or_(
                        ResearchParent.child_id.in_(wanted),
                        (ResearchParent.parent_kind == "alpha")
                        & ResearchParent.parent_id.in_(produced[:1000]),
                        (ResearchParent.parent_kind == "experiment") & ResearchParent.parent_id.in_(wanted),
                    )
                )
                .order_by(ResearchParent.child_id, ResearchParent.parent_kind, ResearchParent.parent_id)
                .limit(1001)
            )
        )
        truncated |= len(relations) > 1000
        frontier = set(related_sources[:100]) - {None}
        for edge in relations[:1000]:
            edges[(edge.child_id, edge.parent_kind, edge.parent_id)] = {
                "child_id": edge.child_id,
                "parent_kind": edge.parent_kind,
                "parent_id": edge.parent_id,
            }
            frontier.add(edge.child_id)
            if edge.parent_kind == "experiment":
                frontier.add(edge.parent_id)
    unresolved = sorted(frontier - set(found))
    return {
        "items": list(found.values()),
        "edges": list(edges.values()),
        "sources": sources,
        "truncated": truncated or bool(unresolved),
        "unresolved_experiment_ids": unresolved,
        "limit": 100,
        "max_depth": 8,
    }