"""迁移状态诊断：比对库实际结构、`alembic_version` 记录与迁移链 head，给出对齐建议。

方案 A 把 39 张基线表补进 Alembic 链首（`20260909_baseline_schema`）后，存在三类库：

1. **空库**：直接 `alembic upgrade head` 全量建库；
2. **由 Alembic 迁移建起的库**（如本地 `jr`）：`alembic_version` 已位于新链上，
   直接 `upgrade head` 即可，Alembic 不会重跑祖先迁移；
3. **由 DBA 脚本手工建库、`alembic_version` 为空**的库：直接 `upgrade head` 会尝试重建
   已存在的表而失败，**必须先 `alembic stamp <与当前结构相符的版本>`**。

本脚本只读诊断，不执行任何 DDL，也不代替人工执行 stamp。它按"结构特征"由新到旧推断
库实际所处的版本，从而给出可执行的建议命令。

用法：
    python tools/migration_state_check.py
"""

from __future__ import annotations

import sys
from pathlib import Path

from sqlalchemy import create_engine, text
from sqlalchemy.engine import Connection

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT))

from alembic.config import Config  # noqa: E402
from alembic.script import ScriptDirectory  # noqa: E402

from app.core.config import get_settings  # noqa: E402

# 由新到旧排列：每个版本引入一个可探测的结构特征。
FEATURES: list[tuple[str, str, str]] = [
    (
        "20260909_memory_active_key",
        "memory_unit.active_memory_key 生成列",
        """SELECT COUNT(*) FROM information_schema.COLUMNS
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'memory_unit'
             AND COLUMN_NAME = 'active_memory_key'""",
    ),
    (
        "20260909_constraint_fix",
        "fin_market_price 联合唯一键",
        """SELECT COUNT(*) FROM information_schema.STATISTICS
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'fin_market_price'
             AND INDEX_NAME = 'uk_fin_market_price_product_id_trade_date'""",
    ),
    (
        "20260909_api_receipt",
        "api_request_receipt 表",
        """SELECT COUNT(*) FROM information_schema.TABLES
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'api_request_receipt'""",
    ),
    (
        "20260909_session",
        "svc_conversation_session 表",
        """SELECT COUNT(*) FROM information_schema.TABLES
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'svc_conversation_session'""",
    ),
    (
        "20260909_outbox_delivery",
        "outbox_delivery 表",
        """SELECT COUNT(*) FROM information_schema.TABLES
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'outbox_delivery'""",
    ),
    (
        "20260909_agent_platform_v31",
        "agent_run 表",
        """SELECT COUNT(*) FROM information_schema.TABLES
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'agent_run'""",
    ),
    (
        "20260909_baseline_schema",
        "sys_user 表",
        """SELECT COUNT(*) FROM information_schema.TABLES
           WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'sys_user'""",
    ),
]


def satisfied(connection: Connection, statement: str) -> bool:
    return bool(connection.execute(text(statement)).scalar())


def infer_revision(connection: Connection) -> tuple[str | None, str | None]:
    """按结构特征推断库所处版本，返回 (revision, 命中的特征描述)。"""
    for revision, description, statement in FEATURES:
        if satisfied(connection, statement):
            return revision, description
    return None, None


def main() -> int:
    config = Config(str(ROOT / "alembic.ini"))
    heads = sorted(ScriptDirectory.from_config(config).get_heads())
    engine = create_engine(get_settings().mysql_dsn.replace("mysql+asyncmy", "mysql+pymysql"))
    with engine.connect() as connection:
        # 空库连 alembic_version 表都还没有，必须先探测再查询，否则报 1146。
        has_version_table = bool(
            connection.execute(
                text(
                    "SELECT COUNT(*) FROM information_schema.TABLES "
                    "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'alembic_version'"
                )
            ).scalar()
        )
        recorded = (
            connection.execute(text("SELECT version_num FROM alembic_version")).scalars().all()
            if has_version_table
            else []
        )
        tables = connection.execute(
            text(
                "SELECT COUNT(*) FROM information_schema.TABLES "
                "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME <> 'alembic_version'"
            )
        ).scalar()
        inferred, feature = infer_revision(connection)
    engine.dispose()

    print(f"迁移链 head      : {', '.join(heads) or '(none)'}")
    print(f"alembic_version : {', '.join(recorded) if recorded else '(空，未记录任何版本)'}")
    print(f"业务表数量       : {tables}")
    print(f"结构推断版本     : {inferred or '无法匹配已知版本'}"
          + (f"（命中特征：{feature}）" if feature else ""))
    print()

    if not recorded and not tables:
        print("判定：空库。")
        print("建议：alembic upgrade head")
        return 0

    if not recorded and tables:
        if inferred is None:
            print("判定：库中有表但无版本记录，且结构不符合任何已知版本。")
            print("建议：人工核对库结构后再决定 stamp 目标；不要直接 upgrade（会重建已有表而失败）。")
            return 1
        print("判定：库由脚本或人工建起，没有 Alembic 版本记录。")
        print("直接 upgrade 会尝试重建已存在的表并失败，必须先对齐版本记录：")
        print(f"建议：alembic stamp {inferred}")
        print("      alembic upgrade head")
        return 0

    if set(recorded) == set(heads):
        print("判定：版本记录已位于 head，无需升级。")
        print("建议：alembic current 复核；结构差异用 tools/audit_constraints.py 检查。")
        return 0

    print("判定：版本记录不在 head。")
    print("建议：alembic current    # 确认当前版本")
    print("      alembic upgrade head")
    if inferred is not None and inferred not in recorded:
        print(f"注意：结构特征显示库可能已处于 {inferred}，但版本记录为 {', '.join(recorded)}；")
        print("      若二者不符，请先核对结构再决定是否 stamp，不要盲目 upgrade。")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())