from datetime import datetime
import uuid

from sqlalchemy import JSON, Column, DateTime, Float, Integer, String, Text
from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import declarative_base

from app.config import get_settings

settings = get_settings()

Base = declarative_base()

# 延迟创建 engine/session，在首次使用时再实例化
_engine = None
_async_session = None


def _get_engine():
    global _engine
    if _engine is None:
        _engine = create_async_engine(
            settings.database_url,
            echo=settings.backend_env == "development",
            pool_pre_ping=True,
        )
    return _engine


def _get_session():
    global _async_session
    if _async_session is None:
        _async_session = async_sessionmaker(_get_engine(), class_=AsyncSession, expire_on_commit=False)
    return _async_session


# async_session 是 async_sessionmaker 实例，调用它返回 AsyncSession
async_session = _get_session()


async def init_db():
    """创建所有表（首次启动时调用）。"""
    async with _get_engine().begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
    # 自动迁移：为已有表补齐新字段
    await _migrate_tables()


async def _migrate_tables():
    """补齐表新增字段（兼容已有数据库）。"""
    from sqlalchemy import text
    from sqlalchemy.exc import ProgrammingError, OperationalError
    alter_stmts = [
        # deploy_tasks 补齐字段
        "ALTER TABLE deploy_tasks ADD COLUMN deploy_mode VARCHAR(16) DEFAULT 'export'",
        "ALTER TABLE deploy_tasks ADD COLUMN endpoint_url VARCHAR(256)",
        "ALTER TABLE deploy_tasks ADD COLUMN port INTEGER",
        "ALTER TABLE deploy_tasks ADD COLUMN pid VARCHAR(32)",
        "ALTER TABLE deploy_tasks ADD COLUMN user_id VARCHAR(36)",
    ]
    async with _get_engine().begin() as conn:
        for stmt in alter_stmts:
            try:
                await conn.execute(text(stmt))
            except (ProgrammingError, OperationalError):
                pass


class TrainingJobModel(Base):
    __tablename__ = "training_jobs"

    id = Column(String(36), primary_key=True)
    model_id = Column(String(256), nullable=False)
    model_type = Column(String(32), nullable=False)
    dataset_id = Column(String(36), nullable=False)
    peft_method = Column(String(32), nullable=False)
    task_type = Column(String(32), default="sft")
    dataset_template = Column(String(32), default="alpaca")

    status = Column(String(32), default="pending")
    progress = Column(Float, default=0.0)
    current_epoch = Column(Integer, default=0)
    current_step = Column(Integer, default=0)
    total_steps = Column(Integer, default=0)
    loss = Column(Float, nullable=True)
    learning_rate = Column(Float, nullable=True)

    epochs = Column(Integer, default=3)
    batch_size = Column(Integer, default=4)
    gradient_accumulation = Column(Integer, default=4)
    max_seq_length = Column(Integer, default=2048)
    warmup_ratio = Column(Float, default=0.05)
    save_strategy = Column(String(32), default="epoch")
    eval_strategy = Column(String(32), default="epoch")
    eval_steps = Column(Integer, default=100)

    lora_r = Column(Integer, default=16)
    lora_alpha = Column(Integer, default=32)
    lora_dropout = Column(Float, default=0.05)
    lora_target_modules = Column(String(256), default="all-linear")
    qlora_bits = Column(Integer, default=4)

    # PPO
    ppo_epochs = Column(Integer, default=4)
    vf_coef = Column(Float, default=0.1)
    kl_coef = Column(Float, default=0.2)
    response_length = Column(Integer, default=512)
    reward_model_path = Column(String(512), nullable=True)
    reward_type = Column(String(32), default="heuristic")

    created_at = Column(DateTime, default=datetime.utcnow)
    started_at = Column(DateTime, nullable=True)
    finished_at = Column(DateTime, nullable=True)
    error_message = Column(Text, nullable=True)
    adapter_path = Column(String(512), nullable=True)


class DatasetRecord(Base):
    __tablename__ = "datasets"

    id = Column(String(36), primary_key=True)
    name = Column(String(256), nullable=False)
    format = Column(String(16), nullable=False)
    record_count = Column(Integer, default=0)
    file_path = Column(String(512), nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)


class ModelCache(Base):
    __tablename__ = "model_cache"

    id = Column(String(256), primary_key=True)
    name = Column(String(256), nullable=False)
    model_type = Column(String(32), nullable=False)
    path = Column(String(512), nullable=True)
    is_downloaded = Column(Integer, default=0)
    context_length = Column(Integer, nullable=True)
    supported_peft_methods = Column(String(256), default="")
    created_at = Column(DateTime, default=datetime.utcnow)


class EvalResultModel(Base):
    __tablename__ = "eval_results"

    id = Column(String(36), primary_key=True)
    job_id = Column(String(36), nullable=False)
    status = Column(String(32), default="pending")  # pending|running|completed|failed
    metrics = Column(Text, default="{}")
    progress = Column(Float, default=0.0)
    error = Column(Text, nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)


class DeployTaskModel(Base):
    __tablename__ = "deploy_tasks"

    id = Column(String(36), primary_key=True)
    job_id = Column(String(36), nullable=False)
    user_id = Column(String(36), nullable=True)               # 部署任务所属用户
    status = Column(String(32), default="pending")
    deploy_mode = Column(String(16), default="export")  # export | serve
    output_path = Column(String(512), nullable=True)
    endpoint_url = Column(String(256), nullable=True)  # serve 模式下的 base_url
    port = Column(Integer, nullable=True)               # serve 模式分配的端口
    pid = Column(String(32), nullable=True)             # serve 模式远程进程 PID
    error = Column(Text, nullable=True)
    progress = Column(Float, default=0.0)
    finished_at = Column(DateTime, nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)


class ModelDownloadTask(Base):
    __tablename__ = "model_download_tasks"

    id = Column(String(36), primary_key=True)
    model_id = Column(String(256), nullable=False)
    use_modelscope = Column(Integer, default=0)
    status = Column(String(32), default="pending")  # pending|downloading|completed|failed
    path = Column(String(512), nullable=True)
    error = Column(Text, nullable=True)
    progress = Column(Float, default=0.0)
    created_at = Column(DateTime, default=datetime.utcnow)
    finished_at = Column(DateTime, nullable=True)


class DatasetDownloadTask(Base):
    __tablename__ = "dataset_download_tasks"

    id = Column(String(36), primary_key=True)
    dataset_id = Column(String(256), nullable=False)
    use_modelscope = Column(Integer, default=0)
    status = Column(String(32), default="pending")  # pending|downloading|completed|failed
    path = Column(String(512), nullable=True)
    error = Column(Text, nullable=True)
    record_count = Column(Integer, default=0)
    created_at = Column(DateTime, default=datetime.utcnow)
    finished_at = Column(DateTime, nullable=True)


class UserModel(Base):
    __tablename__ = "users"

    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    username = Column(String(128), unique=True, nullable=False, index=True)
    email = Column(String(256), nullable=True)
    real_name = Column(String(128), nullable=True)
    avatar_url = Column(String(512), nullable=True)
    company = Column(String(128), nullable=True)
    department = Column(String(128), nullable=True)
    position = Column(String(128), nullable=True)
    roles = Column(JSON, default=list)
    is_active = Column(Integer, default=1, nullable=False)
    is_superuser = Column(Integer, default=0, nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)


class RefreshTokenModel(Base):
    __tablename__ = "refresh_tokens"

    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    user_id = Column(String(36), nullable=False, index=True)
    token = Column(String(512), unique=True, nullable=False, index=True)
    expires_at = Column(DateTime, nullable=False)
    revoked = Column(Integer, default=0, nullable=False)
    created_at = Column(DateTime, default=datetime.utcnow)


class ApiKeyModel(Base):
    __tablename__ = "api_keys"

    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    user_id = Column(String(36), nullable=False, index=True)
    key = Column(String(128), unique=True, nullable=False, index=True)  # sk-xxx
    name = Column(String(128), nullable=False, default="default")
    status = Column(String(16), default="active")  # active | revoked
    last_used_at = Column(DateTime, nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)


async def get_db() -> AsyncSession:
    async with async_session() as session:
        yield session