"""Collection operations own validation; callers own transactions and authorization."""

from uuid import uuid4

from fastapi import HTTPException
from sqlalchemy import delete, func, or_, select
from sqlalchemy.orm import aliased

from ..catalog.contracts import EntryOutput, Scope
from ..catalog.research_metadata import upstream
from ..catalog.service import Catalog
from ..catalog.sync import identifier, label, normalize
from ..models import (
    CatalogBatch,
    CatalogDataset,
    CatalogEntry,
    CatalogScope,
    DataPreparation,
    PreparationField,
    ResearchInputSnapshot,
    now,
)
from ..research.serialization import encode_snapshot
from .contracts import FieldFilters


def page(items, total, limit, offset, **extra):
    return dict(
        items=items, total=total, limit=limit, offset=offset, has_more=offset + len(items) < total, **extra
    )


def contains(value):
    return "%" + value.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_") + "%"


class Preparations:
    def __init__(self, db, client=None):
        self.db, self.client = db, client

    async def fields(self, filters):
        scope = await self.db.get(CatalogScope, filters.key())
        owner = aliased(CatalogEntry)
        query = (
            select(
                CatalogEntry,
                CatalogBatch.dataset_id,
                owner.name.label("dataset_name"),
                owner.category,
                owner.subcategory,
            )
            .join(CatalogBatch, CatalogEntry.batch_id == CatalogBatch.id)
            .join(
                CatalogDataset,
                (CatalogDataset.field_version == CatalogBatch.id)
                & (CatalogDataset.scope_key == filters.key()),
            )
            .outerjoin(
                owner,
                (owner.id == CatalogBatch.dataset_id)
                & (owner.batch_id == (scope.catalog_version if scope else None)),
            )
            .where(CatalogBatch.complete.is_(True))
        )
        if filters.q:
            query = query.where(
                or_(
                    *[
                        column.ilike(contains(filters.q), escape="\\")
                        for column in (
                            CatalogEntry.id,
                            CatalogEntry.name,
                            CatalogEntry.description,
                            CatalogBatch.dataset_id,
                            owner.name,
                        )
                    ]
                )
            )
        for key in ("dataset_id", "field_type", "category", "subcategory"):
            value = getattr(filters, key)
            column = (
                CatalogBatch.dataset_id
                if key == "dataset_id"
                else func.coalesce(getattr(CatalogEntry, key), getattr(owner, key))
                if key in ("category", "subcategory")
                else getattr(CatalogEntry, key)
            )
            if value:
                query = query.where(column == value)
        for key in ("coverage", "user_count", "alpha_count"):
            low, high = getattr(filters, key + "_min"), getattr(filters, key + "_max")
            if low is not None:
                query = query.where(getattr(CatalogEntry, key) >= low)
            if high is not None:
                query = query.where(getattr(CatalogEntry, key) <= high)
        if filters.synced_from:
            query = query.where(CatalogEntry.synced_at >= filters.synced_from)
        if filters.synced_to:
            query = query.where(CatalogEntry.synced_at <= filters.synced_to)
        total = await self.db.scalar(select(func.count()).select_from(query.subquery()))
        column = (
            CatalogBatch.dataset_id if filters.sort == "dataset_id" else getattr(CatalogEntry, filters.sort)
        )
        query = query.order_by(
            (column.desc() if filters.direction == "desc" else column.asc()).nulls_last(),
            CatalogBatch.dataset_id,
            CatalogEntry.id,
        )
        rows = (await self.db.execute(query.limit(filters.limit).offset(filters.offset))).all()
        items = [
            {
                **self.local_field(row, dataset_id, name, filters),
                "category": row.category or category,
                "subcategory": row.subcategory or subcategory,
            }
            for row, dataset_id, name, category, subcategory in rows
        ]
        return page(items, total, filters.limit, filters.offset)

    @staticmethod
    def local_field(row, dataset_id, name, scope):
        return encode_snapshot(
            dict(
                **EntryOutput.model_validate(row, from_attributes=True).model_dump(
                    exclude={"scope", "dataset_id", "collection_version"}
                ),
                field_id=row.id,
                dataset_id=dataset_id,
                dataset_name=name or dataset_id,
                collection_version=row.batch_id,
                scope=scope.model_dump(include=set(Scope.model_fields)),
                source="local",
                fetched_at=row.synced_at,
            )
        )

    async def online_fields(self, filters):
        if self.client is None:
            raise HTTPException(409, "请先连接 WorldQuant")
        params = dict(
            instrumentType=filters.instrument_type,
            region=filters.region,
            universe=filters.universe,
            delay=filters.delay,
            limit=filters.limit,
            offset=filters.offset,
        )
        for key, remote in (("q", "search"), ("dataset_id", "dataset.id"), ("field_type", "type")):
            value = getattr(filters, key)
            if value:
                params[remote] = value
        for key, remote in (
            ("coverage", "coverage"),
            ("user_count", "userCount"),
            ("alpha_count", "alphaCount"),
        ):
            for suffix, op in (("min", ">"), ("max", "<")):
                value = getattr(filters, key + "_" + suffix)
                if value is not None:
                    params[remote + op] = value
        raw = await upstream(self.client.get("/data-fields", params))
        rows = raw.get("results")
        if not isinstance(rows, list):
            raise HTTPException(502, "平台字段列表格式无法识别")
        items = []
        for row in rows:
            if not isinstance(row, dict):
                raise HTTPException(502, "平台字段记录格式无法识别")
            dataset = row.get("dataset")
            owner = dataset.get("id") if isinstance(dataset, dict) else dataset
            try:
                owner = identifier(owner)
                data = normalize(row, owner)
            except Exception as exc:
                from ..worldquant import WqError

                if isinstance(exc, WqError):
                    raise HTTPException(502, str(exc)) from None
                raise
            if filters.dataset_id and owner != filters.dataset_id:
                raise HTTPException(502, "平台返回其他数据集字段")
            for remote_key, key in (
                ("instrumentType", "instrument_type"),
                ("instrument_type", "instrument_type"),
                ("region", "region"),
                ("universe", "universe"),
                ("delay", "delay"),
            ):
                if remote_key in row and row[remote_key] != getattr(filters, key):
                    raise HTTPException(502, "平台字段范围与查询不一致")
            items.append(
                encode_snapshot(
                    dict(
                        **data,
                        field_id=data["id"],
                        dataset_id=owner,
                        dataset_name=label(dataset) or owner,
                        source="worldquant",
                        collection_version=None,
                        scope=filters.model_dump(include=set(Scope.model_fields)),
                        fetched_at=now(),
                        synced_at=None,
                    )
                )
            )
        count = raw.get("count")
        known_total = type(count) is int and count >= 0
        more = (
            bool(raw["next"])
            if "next" in raw
            else (filters.offset + len(items) < count if known_total else len(items) == filters.limit)
        )
        result = page(
            items,
            count if known_total else filters.offset + len(items) + int(more),
            filters.limit,
            filters.offset,
        )
        result.update(has_more=more, total_known=known_total)
        return result

    async def resolve_fields(self, scope, refs):
        """Resolve trusted source records before any collection member is written."""
        if any(ref.scope.key() != scope.key() for ref in refs):
            raise HTTPException(422, "不能跨区域、Top、Delay 或品种添加字段")
        result = {}
        for ref in refs:
            if ref.source == "local":
                dataset = await Catalog(self.db).dataset(scope, ref.dataset_id, lock=True)
                if not dataset.field_version or dataset.field_version != ref.collection_version:
                    raise HTTPException(409, "字段来源已更新，请重新查询后添加")
                entry = await self.db.get(CatalogEntry, (dataset.field_version, ref.field_id))
                if not entry:
                    raise HTTPException(422, "字段不属于指定数据集")
                scope_row = await self.db.get(CatalogScope, scope.key())
                owner = await self.db.get(CatalogEntry, (scope_row.catalog_version, ref.dataset_id))
                field = self.local_field(entry, ref.dataset_id, owner.name if owner else None, scope)
            else:
                offset, seen, field = 0, set(), None
                while True:
                    response = await self.online_fields(
                        FieldFilters(
                            **scope.model_dump(),
                            q=ref.field_id,
                            dataset_id=ref.dataset_id,
                            limit=100,
                            offset=offset,
                        )
                    )
                    field = next((item for item in response["items"] if item["id"] == ref.field_id), None)
                    if field or not response["has_more"]:
                        break
                    ids = {item["id"] for item in response["items"]}
                    if not ids - seen:
                        raise HTTPException(502, "平台字段分页未前进")
                    seen.update(ids)
                    offset += len(response["items"])
                if not field:
                    raise HTTPException(422, "在线字段已不可用，请重新查询")
            if field["id"] in result and result[field["id"]]["dataset_id"] != field["dataset_id"]:
                raise HTTPException(422, "同名字段的数据集归属冲突")
            result[field["id"]] = field
        return list(result.values())

    async def get(self, preparation_id, version=None, lock=False):
        query = select(DataPreparation).where(DataPreparation.id == preparation_id)
        row = await self.db.scalar(query.with_for_update() if lock else query)
        if not row:
            raise HTTPException(404, "数据准备集合不存在")
        if version is not None and row.version != version:
            raise HTTPException(409, "集合已修改，请重新读取或选择；当前草稿已保留")
        return row

    async def output(self, row):
        count, datasets = (
            await self.db.execute(
                select(func.count(), func.count(func.distinct(PreparationField.dataset_id))).where(
                    PreparationField.preparation_id == row.id
                )
            )
        ).one()
        return encode_snapshot(
            dict(
                id=row.id,
                name=row.name,
                note=row.note,
                scope=row.scope,
                version=row.version,
                field_count=count,
                dataset_count=datasets,
                created_at=row.created_at,
                updated_at=row.updated_at,
            )
        )

    async def list(self, q="", scope_key=None, limit=25, offset=0):
        query = select(DataPreparation)
        if scope_key:
            query = query.where(DataPreparation.scope_key == scope_key)
        if q:
            query = query.where(
                or_(
                    DataPreparation.name.ilike(contains(q), escape="\\"),
                    DataPreparation.note.ilike(contains(q), escape="\\"),
                )
            )
        total = await self.db.scalar(select(func.count()).select_from(query.subquery()))
        rows = await self.db.scalars(
            query.order_by(DataPreparation.updated_at.desc(), DataPreparation.id).limit(limit).offset(offset)
        )
        return page([await self.output(row) for row in rows], total, limit, offset)

    async def members(self, preparation_id, q="", dataset_id=None, limit=25, offset=0):
        await self.get(preparation_id)
        query = select(PreparationField).where(PreparationField.preparation_id == preparation_id)
        if dataset_id:
            query = query.where(PreparationField.dataset_id == dataset_id)
        if q:
            query = query.where(
                or_(
                    PreparationField.field_id.ilike(contains(q), escape="\\"),
                    PreparationField.content["name"].as_string().ilike(contains(q), escape="\\"),
                    PreparationField.content["description"].as_string().ilike(contains(q), escape="\\"),
                )
            )
        total = await self.db.scalar(select(func.count()).select_from(query.subquery()))
        rows = await self.db.scalars(
            query.order_by(PreparationField.dataset_id, PreparationField.field_id).limit(limit).offset(offset)
        )
        return page([row.content for row in rows], total, limit, offset)

    async def create(self, name, note, scope, fields):
        row = DataPreparation(
            id=str(uuid4()), name=name, note=note, scope=scope.model_dump(), scope_key=scope.key()
        )
        self.db.add(row)
        await self.db.flush()
        await self.add(row, fields)
        return await self.output(row)

    async def add(self, row, fields):
        for field in fields:
            existing = await self.db.get(PreparationField, (row.id, field["id"]))
            if existing:
                if existing.dataset_id != field["dataset_id"]:
                    raise HTTPException(422, "同名字段的数据集归属冲突")
                continue
            self.db.add(
                PreparationField(
                    preparation_id=row.id, field_id=field["id"], dataset_id=field["dataset_id"], content=field
                )
            )
        await self.db.flush()

    async def copy_dataset(self, body):
        dataset = await Catalog(self.db).dataset(body.scope, body.dataset_id, lock=True)
        if not dataset.field_version or dataset.field_version != body.collection_version:
            raise HTTPException(409, "数据集尚未完整同步或版本已更新")
        batch = await self.db.get(CatalogBatch, dataset.field_version)
        if not batch.complete:
            raise HTTPException(409, "数据集尚未完整同步")
        source = await Catalog(self.db).detail(body.scope, body.dataset_id)
        rows = await self.db.scalars(
            select(CatalogEntry)
            .where(CatalogEntry.batch_id == dataset.field_version)
            .order_by(CatalogEntry.id)
        )
        fields = [self.local_field(row, body.dataset_id, source["name"], body.scope) for row in rows]
        return await self.create(
            f"{source['name'] or body.dataset_id} · {now():%Y%m%d-%H%M%S-%f}", "", body.scope, fields
        )

    async def remove(self, refs):
        rows = [await self.get(ref.id, ref.version, lock=True) for ref in sorted(refs, key=lambda r: r.id)]
        for row in rows:
            await self.db.execute(delete(PreparationField).where(PreparationField.preparation_id == row.id))
            await self.db.delete(row)
        return {"deleted": len(rows)}

    async def freeze(self, refs):
        """Lock collection versions and capture source-independent research snapshots atomically."""
        snapshots = []
        for ref in sorted(refs, key=lambda r: r.id):
            row = await self.get(ref.id, ref.version, lock=True)
            existing = await self.db.scalar(
                select(ResearchInputSnapshot).where(
                    ResearchInputSnapshot.preparation_id == row.id,
                    ResearchInputSnapshot.preparation_version == row.version,
                )
            )
            if existing:
                snapshots.append(await self.snapshot(existing.id))
                continue
            fields = [
                r.content
                for r in await self.db.scalars(
                    select(PreparationField)
                    .where(PreparationField.preparation_id == row.id)
                    .order_by(PreparationField.field_id)
                )
            ]
            if not fields:
                raise HTTPException(422, "空集合不能用于研究")
            fixed = ResearchInputSnapshot(
                id=str(uuid4()),
                preparation_id=row.id,
                preparation_version=row.version,
                content=dict(
                    name=row.name,
                    scope=row.scope,
                    fields=fields,
                    field_ids=[f["id"] for f in fields],
                    field_types={f["id"]: f["field_type"] for f in fields},
                    dataset_ids=sorted({f["dataset_id"] for f in fields}),
                ),
            )
            self.db.add(fixed)
            await self.db.flush()
            snapshots.append(await self.snapshot(fixed.id))
        return snapshots

    async def snapshot(self, snapshot_id):
        row = await self.db.get(ResearchInputSnapshot, snapshot_id)
        if not row:
            raise HTTPException(404, "研究输入快照不存在")
        return encode_snapshot(
            dict(
                **row.content,
                id=row.id,
                preparation_id=row.preparation_id,
                preparation_version=row.preparation_version,
                created_at=row.created_at,
            )
        )

    async def bind(self, body):
        refs = getattr(body, "preparation_refs", [])
        if refs:
            fixed = await self.freeze(refs)
            body.input_ids = list(dict.fromkeys([*body.input_ids, *[r["id"] for r in fixed]]))
            body.preparation_refs = []
        if not body.input_ids:
            raise HTTPException(422, "请选择非空的数据准备集合")
        limit = next(
            m.max_length for m in type(body).model_fields["input_ids"].metadata if hasattr(m, "max_length")
        )
        if len(body.input_ids) > limit:
            raise HTTPException(422, f"最多可选择 {limit} 个研究输入")
        return body