import os
from pathlib import Path
from urllib.parse import quote_plus

from dotenv import load_dotenv
from sqlalchemy import create_engine

_env_dir = Path(__file__).resolve().parent
load_dotenv(_env_dir / ".env.local", override=False)   # 本地开发优先
load_dotenv(_env_dir / ".env", override=False)          # 兜底（Docker/线上）
from sqlalchemy.orm import sessionmaker, declarative_base

# 可选：整串 URL（优先级最高），例如 postgresql+psycopg2://user:pass@host:5432/dbname
_database_url = os.environ.get("DATABASE_URL", "").strip()

if _database_url:
    SQLALCHEMY_DATABASE_URL = _database_url
else:
    PG_HOST = os.environ.get("PG_HOST", "localhost")
    PG_PORT = os.environ.get("PG_PORT", "5432")
    PG_USER = os.environ.get("PG_USER", "postgres")
    PG_PASSWORD = os.environ.get("PG_PASSWORD", "postgres")
    PG_DB = os.environ.get("PG_DB", "vector_match")
    _pw = quote_plus(PG_PASSWORD)
    SQLALCHEMY_DATABASE_URL = (
        f"postgresql+psycopg2://{PG_USER}:{_pw}@{PG_HOST}:{PG_PORT}/{PG_DB}"
    )

PG_SCHEMA = os.environ.get("PG_SCHEMA", "vector_match")

engine = create_engine(
    SQLALCHEMY_DATABASE_URL,
    pool_pre_ping=True,
    pool_size=20,
    pool_recycle=180,
    pool_timeout=60,
    max_overflow=10,
)

# 每次连接自动切换到 vector_match schema
from sqlalchemy import event

@event.listens_for(engine, "connect")
def _set_search_path(dbapi_conn, connection_record):
    cursor = dbapi_conn.cursor()
    cursor.execute(f"SET search_path TO {PG_SCHEMA}, public")
    cursor.close()

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

DATA_DIR = os.path.join(os.path.dirname(__file__), "data")
os.makedirs(DATA_DIR, exist_ok=True)

_SCHEMA_TABLES = (
    "vector_match_task",
    "vector_dataset",
    "vector_data_row",
    "vector_embedding",
    "match_result",
)


def get_db():
    db = SessionLocal()
    try:
        yield db
    except Exception:
        db.rollback()
        raise
    finally:
        db.close()


def _table_sql_name(table: str) -> str:
    if engine.dialect.name == "postgresql":
        return f'"{PG_SCHEMA}"."{table}"'
    return table


def _column_names_conn(conn, table: str) -> set:
    """
    与当前连接共用同一事务，避免在持有 ALTER 锁的事务内再用 inspect(engine) 开新连接查目录，
    否则 PostgreSQL 上会自锁（会话 A 持锁等 B 查元数据，B 等 A 释放锁）。
    """
    from sqlalchemy import inspect

    insp = inspect(conn)
    schema = PG_SCHEMA if engine.dialect.name == "postgresql" else None
    return {c["name"] for c in insp.get_columns(table, schema=schema)}


def _ensure_is_archived_column():
    """旧库无 is_archived 时补列。"""
    from sqlalchemy import inspect, text

    insp = inspect(engine)
    schema = PG_SCHEMA if engine.dialect.name == "postgresql" else None
    try:
        cols = insp.get_columns("vector_match_task", schema=schema)
    except Exception:
        return
    if any(c["name"] == "is_archived" for c in cols):
        return
    ft = _table_sql_name("vector_match_task")
    ddl = (
        f"ALTER TABLE {ft} ADD COLUMN is_archived INTEGER NOT NULL DEFAULT 0"
        if engine.dialect.name == "postgresql"
        else "ALTER TABLE vector_match_task ADD COLUMN is_archived INTEGER NOT NULL DEFAULT 0"
    )
    with engine.begin() as conn:
        conn.execute(text(ddl))


def _ensure_time_is_delete_columns():
    """
    统一：created_at→created_time；任务表 updated_at→updated_time；
    各表补 is_delete；is_deleted→is_delete；遗留 deleted_at 迁移后删除。
    """
    from sqlalchemy import text

    ft_task = _table_sql_name("vector_match_task")

    with engine.begin() as conn:
        cols = _column_names_conn(conn, "vector_match_task")
        if "created_at" in cols and "created_time" not in cols:
            conn.execute(text(f"ALTER TABLE {ft_task} RENAME COLUMN created_at TO created_time"))
        if "updated_at" in cols and "updated_time" not in cols:
            conn.execute(text(f"ALTER TABLE {ft_task} RENAME COLUMN updated_at TO updated_time"))
        if "is_deleted" in cols and "is_delete" not in cols:
            conn.execute(text(f"ALTER TABLE {ft_task} RENAME COLUMN is_deleted TO is_delete"))
        cols = _column_names_conn(conn, "vector_match_task")
        if "deleted_at" in cols:
            if "is_delete" not in cols:
                conn.execute(
                    text(f"ALTER TABLE {ft_task} ADD COLUMN is_delete INTEGER NOT NULL DEFAULT 0")
                )
            conn.execute(text(f"UPDATE {ft_task} SET is_delete = 1 WHERE deleted_at IS NOT NULL"))
            conn.execute(text(f"ALTER TABLE {ft_task} DROP COLUMN deleted_at"))

    for table in _SCHEMA_TABLES:
        ft = _table_sql_name(table)
        with engine.begin() as conn:
            cols = _column_names_conn(conn, table)
            if "created_at" in cols and "created_time" not in cols:
                conn.execute(text(f"ALTER TABLE {ft} RENAME COLUMN created_at TO created_time"))
            cols = _column_names_conn(conn, table)
            if "is_delete" not in cols:
                conn.execute(
                    text(f"ALTER TABLE {ft} ADD COLUMN is_delete INTEGER NOT NULL DEFAULT 0")
                )
            cols = _column_names_conn(conn, table)
            if "updated_time" not in cols:
                conn.execute(text(f"ALTER TABLE {ft} ADD COLUMN updated_time TIMESTAMP NULL"))
                if "created_time" in cols:
                    conn.execute(
                        text(
                            f"UPDATE {ft} SET updated_time = created_time "
                            f"WHERE updated_time IS NULL"
                        )
                    )


def init_db():
    from models import Base as ModelBase  # noqa: F401
    from sqlalchemy import text
    with engine.connect() as conn:
        conn.execute(text(f"CREATE SCHEMA IF NOT EXISTS {PG_SCHEMA}"))
        conn.commit()
    ModelBase.metadata.create_all(bind=engine)
    _ensure_is_archived_column()
    _ensure_time_is_delete_columns()