from sqlalchemy import create_engine, inspect, text, String, Integer, Text, Boolean, Float, DateTime, Date
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
import os

from app.config import DATABASE_PATH, DATABASE_URL

# 确保 data 目录存在
os.makedirs(os.path.dirname(DATABASE_PATH) if os.path.dirname(DATABASE_PATH) else ".", exist_ok=True)

# 创建引擎
engine = create_engine(
    DATABASE_URL,
    connect_args={"check_same_thread": False}
)

# 创建会话工厂
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# 创建基类
Base = declarative_base()


def get_db():
    """获取数据库会话"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


# SQLAlchemy 类型到 SQLite 类型名的映射
_TYPE_MAP = {
    String: "VARCHAR",
    Integer: "INTEGER",
    Text: "TEXT",
    Boolean: "BOOLEAN",
    Float: "REAL",
    DateTime: "DATETIME",
    Date: "DATE",
}


def _col_type_str(col_type) -> str:
    """将 SQLAlchemy 列类型转为 SQLite 类型字符串"""
    if col_type.__class__ in _TYPE_MAP:
        base = _TYPE_MAP[col_type.__class__]
    else:
        base = str(col_type).split("(")[0].strip()

    length = getattr(col_type, "length", None)
    if length:
        return f"{base}({length})"
    return base


def init_db():
    """初始化数据库表，自动补充新增的列"""
    # 导入所有模型，确保 Base.metadata 包含全部表定义
    from app.models import (  # noqa: F401
        task, category, tag, user_settings, habit, anniversary, account,
    )
    Base.metadata.create_all(bind=engine)

    # 通用自动迁移：对比 ORM 模型与实际表结构，补充缺失的列（SQLite 兼容）
    inspector = inspect(engine)
    table_names = set(inspector.get_table_names())

    with engine.begin() as conn:
        for table_cls in Base.metadata.sorted_tables:
            table_name = table_cls.name
            if table_name not in table_names:
                continue

            existing_cols = {c["name"] for c in inspector.get_columns(table_name)}

            for col in table_cls.columns:
                if col.name in existing_cols:
                    continue
                # 跳过无服务端默认值且不可为空的列（容易出错）
                if col.nullable is False and col.server_default is None and col.default is None:
                    continue

                sqlite_type = _col_type_str(col.type)

                ddl = f"ALTER TABLE {table_name} ADD COLUMN {col.name} {sqlite_type}"

                # 为可空列或已有默认值的列附加 DEFAULT
                if col.server_default is not None:
                    ddl += f" DEFAULT {col.server_default.arg}"
                elif col.default is not None and col.nullable:
                    default_val = col.default.arg
                    if isinstance(default_val, str):
                        ddl += f" DEFAULT '{default_val}'"
                    elif isinstance(default_val, bool):
                        ddl += f" DEFAULT {1 if default_val else 0}"
                    else:
                        ddl += f" DEFAULT {default_val}"

                conn.execute(text(ddl))