"""Job / Experiment 的 SQLAlchemy 实现（Phase 4）。"""

from __future__ import annotations

from sqlalchemy import Select, func, select
from sqlalchemy.orm import Session

from app.domain.entities.research import ExperimentRecord, ExperimentSummary, JobRecord
from app.infrastructure.persistence.sqlalchemy.models.jobs import ExperimentModel, JobModel


def _job_to_model(job: JobRecord) -> JobModel:
    return JobModel(**job.model_dump())


class SqlAlchemyJobRepository:
    def __init__(self, session: Session) -> None:
        self._session = session

    def create(self, job: JobRecord) -> JobRecord:
        self._session.add(_job_to_model(job))
        self._session.flush()
        return job

    def get(self, job_id: str) -> JobRecord | None:
        row = self._session.get(JobModel, job_id)
        return JobRecord.model_validate(row, from_attributes=True) if row else None

    def update(self, job: JobRecord) -> None:
        row = self._session.get(JobModel, job.id)
        if row is None:
            raise KeyError(f"job {job.id} 不存在")
        for k, v in job.model_dump().items():
            setattr(row, k, v)

    def list_recent(self, kind: str | None = None, limit: int = 20) -> list[JobRecord]:
        stmt = select(JobModel).order_by(JobModel.created_at.desc()).limit(limit)
        if kind:
            stmt = stmt.where(JobModel.kind == kind)
        return [
            JobRecord.model_validate(r, from_attributes=True)
            for r in self._session.scalars(stmt).all()
        ]

    def list_by_status(self, status: str, limit: int = 100) -> list[JobRecord]:
        rows = self._session.scalars(
            select(JobModel)
            .where(JobModel.status == status)
            .order_by(JobModel.created_at)
            .limit(limit)
        ).all()
        return [JobRecord.model_validate(r, from_attributes=True) for r in rows]


class SqlAlchemyExperimentRepository:
    """Experiment 归档仓储。

    `list_filtered` 刻意**不加载 `result_json`**（MEDIUMTEXT，完整存档后单条数 MB），
    只 SELECT 元数据列 + SQL 侧算出的字符长度，避免列表接口把上百 MB 拉进内存。
    """

    def __init__(self, session: Session) -> None:
        self._session = session

    def save(self, experiment: ExperimentRecord) -> ExperimentRecord:
        self._session.add(ExperimentModel(**experiment.model_dump()))
        self._session.flush()
        return experiment

    def upsert(self, experiment: ExperimentRecord) -> ExperimentRecord:
        """按 id 插入或覆盖（`merge` 语义）：重建归档时保持原 id 不变。"""
        self._session.merge(ExperimentModel(**experiment.model_dump()))
        self._session.flush()
        return experiment

    def get(self, experiment_id: str) -> ExperimentRecord | None:
        row = self._session.get(ExperimentModel, experiment_id)
        return ExperimentRecord.model_validate(row, from_attributes=True) if row else None

    def list_recent(self, limit: int = 50) -> list[ExperimentRecord]:
        rows = self._session.scalars(
            select(ExperimentModel).order_by(ExperimentModel.created_at.desc()).limit(limit)
        ).all()
        return [ExperimentRecord.model_validate(r, from_attributes=True) for r in rows]

    # -- 列表 / 过滤（SQL 层完成过滤+分页，参数绑定，不做字符串拼接）-------------

    @staticmethod
    def _escape_like(value: str) -> str:
        """转义 LIKE 元字符：用户输入里的 % / _ / \\ 不应被当成通配符。"""
        return value.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")

    def _filter_conditions(self, *, kind: str | None, q: str | None):
        """kind 精确匹配 + q 大小写不敏感模糊匹配（id / spec_json=因子名 / summary_text）。"""
        conditions = []
        if kind:
            conditions.append(ExperimentModel.kind == kind)
        if q:
            pattern = f"%{self._escape_like(q.lower())}%"
            conditions.append(
                func.lower(ExperimentModel.id).like(pattern, escape="\\")
                | func.lower(ExperimentModel.spec_json).like(pattern, escape="\\")
                | func.lower(func.coalesce(ExperimentModel.summary_text, "")).like(
                    pattern, escape="\\"
                )
            )
        return conditions

    def _summary_stmt(self, conditions) -> Select:
        return select(
            ExperimentModel.id,
            ExperimentModel.kind,
            ExperimentModel.spec_json,
            ExperimentModel.summary_text,
            ExperimentModel.code_version,
            ExperimentModel.data_version,
            ExperimentModel.job_id,
            ExperimentModel.created_at,
            self._char_length().label("result_bytes"),
        ).where(*conditions)

    def _char_length(self):
        """归档 JSON 的**字符数**（不取大字段本身）。

        MySQL 的 `LENGTH()` 返回字节数，字符数要用 `CHAR_LENGTH()`；SQLite 只有
        `length()`（对 TEXT 返回字符数）。按方言选择，避免中文归档在两个库上口径
        不一致。
        """
        if self._session.get_bind().dialect.name == "sqlite":
            return func.length(ExperimentModel.result_json)
        return func.char_length(ExperimentModel.result_json)

    def list_filtered(
        self,
        *,
        kind: str | None = None,
        q: str | None = None,
        limit: int = 200,
        offset: int = 0,
    ) -> list[ExperimentSummary]:
        stmt = (
            self._summary_stmt(self._filter_conditions(kind=kind, q=q))
            # created_at 在 MySQL datetime(0) 下只有秒精度，同秒创建的归档必须有
            # 稳定的次级排序键，否则分页会重复/漏项
            .order_by(ExperimentModel.created_at.desc(), ExperimentModel.id.desc())
            .limit(max(limit, 0))
            .offset(max(offset, 0))
        )
        return [
            ExperimentSummary(
                id=row.id,
                kind=row.kind,
                spec_json=row.spec_json,
                summary_text=row.summary_text,
                code_version=row.code_version,
                data_version=row.data_version,
                job_id=row.job_id,
                created_at=row.created_at,
                result_bytes=int(row.result_bytes or 0),
            )
            for row in self._session.execute(stmt).all()
        ]

    def count_filtered(self, *, kind: str | None = None, q: str | None = None) -> int:
        stmt = (
            select(func.count())
            .select_from(ExperimentModel)
            .where(*self._filter_conditions(kind=kind, q=q))
        )
        return int(self._session.execute(stmt).scalar() or 0)

    def delete(self, experiment_id: str) -> bool:
        """删除归档本身；返回 False 表示不存在。不触碰 job 表。"""
        row = self._session.get(ExperimentModel, experiment_id)
        if row is None:
            return False
        self._session.delete(row)
        self._session.flush()
        return True