"""
认证相关API
"""
from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from sqlalchemy.orm import Session
from pydantic import BaseModel, field_validator
import re
import secrets
import logging
from app.core.database import get_db
from app.core.security import verify_password, get_password_hash, create_access_token
from app.models.user import User
from datetime import datetime, timedelta
from app.core.config import settings
from app.core.exceptions import ConflictError, UnauthorizedError, NotFoundError
from app.core.redis_client import get_redis_client

logger = logging.getLogger(__name__)

router = APIRouter(
    prefix="/api/v1/auth",
    tags=["auth"],
    responses={
        401: {"description": "未授权"},
        400: {"description": "请求参数错误"},
        500: {"description": "服务器内部错误"}
    }
)

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")
oauth2_scheme_optional = OAuth2PasswordBearer(
    tokenUrl="/api/v1/auth/login", auto_error=False
)


class UserCreate(BaseModel):
    """用户创建模型"""
    username: str
    email: str
    password: str

    @field_validator("email")
    @classmethod
    def email_format(cls, v: str) -> str:
        if not v or not re.match(r"^[^@]+@[^@]+\.[^@]+$", v):
            raise ValueError("邮箱格式无效")
        return v.lower()


class UserResponse(BaseModel):
    """用户响应模型"""
    id: str
    username: str
    email: str
    role: str

    class Config:
        from_attributes = True


class MeResponse(BaseModel):
    """当前用户完整信息（含工作区列表）"""
    id: str
    username: str
    email: str
    role: str
    workspaces: list = []
    current_workspace_id: str | None = None


class Token(BaseModel):
    """令牌响应模型"""
    access_token: str
    token_type: str = "bearer"


@router.post("/register", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def register(user_data: UserCreate, db: Session = Depends(get_db)):
    """用户注册"""
    # 检查用户名是否已存在
    if db.query(User).filter(User.username == user_data.username).first():
        raise ConflictError("用户名已存在")
    
    # 检查邮箱是否已存在
    if db.query(User).filter(User.email == user_data.email).first():
        raise ConflictError("邮箱已存在")
    
    # 创建新用户
    hashed_password = get_password_hash(user_data.password)
    user = User(
        username=user_data.username,
        email=user_data.email,
        password_hash=hashed_password
    )
    db.add(user)
    db.commit()
    db.refresh(user)
    
    return user


def _get_user_default_workspace_id(db: Session, user: User) -> str | None:
    """获取用户的默认工作区 ID。优先使用默认工作区，其次第一个 membership。"""
    from app.models.workspace import Workspace, WorkspaceMembership

    # 优先使用系统默认工作区
    default_ws = db.query(Workspace).filter(Workspace.is_default == 1, Workspace.status == "active").first()
    if default_ws:
        membership = (
            db.query(WorkspaceMembership)
            .filter(
                WorkspaceMembership.workspace_id == default_ws.id,
                WorkspaceMembership.user_id == user.id,
            )
            .first()
        )
        if membership:
            return default_ws.id

    # 没有默认工作区，使用第一个 membership
    first_membership = (
        db.query(WorkspaceMembership)
        .filter(WorkspaceMembership.user_id == user.id)
        .first()
    )
    if first_membership:
        return first_membership.workspace_id

    return None


@router.post("/login", response_model=Token)
async def login(
    form_data: OAuth2PasswordRequestForm = Depends(),
    db: Session = Depends(get_db),
    client_type: str = "web"
):
    """用户登录。client_type=android/ios 时签发 7 天 token，web 默认 30 分钟。"""
    user = db.query(User).filter(User.username == form_data.username).first()

    if not user or not verify_password(form_data.password, user.password_hash):
        logger.warning(f"登录失败: 用户名 {form_data.username}")
        raise UnauthorizedError("用户名或密码错误")

    from datetime import timedelta

    if client_type in ("android", "ios"):
        expires = timedelta(minutes=settings.JWT_MOBILE_TOKEN_EXPIRE_MINUTES)
    else:
        expires = timedelta(minutes=settings.JWT_ACCESS_TOKEN_EXPIRE_MINUTES)

    ws_id = _get_user_default_workspace_id(db, user)

    access_token = create_access_token(
        data={"sub": user.id, "username": user.username, "ws": ws_id or ""},
        expires_delta=expires,
    )

    return {"access_token": access_token, "token_type": "bearer"}


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db)
) -> User:
    """FastAPI 依赖 — 从 JWT 提取当前用户，返回 User 模型。"""
    from app.core.security import decode_access_token

    payload = decode_access_token(token)
    if payload is None:
        raise UnauthorizedError("无效的访问令牌")

    user_id = payload.get("sub")
    if user_id is None:
        raise UnauthorizedError("无效的访问令牌")

    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise NotFoundError("用户", user_id)

    return user


@router.get("/me", response_model=MeResponse)
async def get_me(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db)
):
    """获取当前用户信息（含工作区列表）。"""
    from app.core.security import decode_access_token
    from app.services.workspace_service import get_user_workspaces

    payload = decode_access_token(token)
    if payload is None:
        raise UnauthorizedError("无效的访问令牌")

    user_id = payload.get("sub")
    if user_id is None:
        raise UnauthorizedError("无效的访问令牌")

    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise NotFoundError("用户", user_id)

    workspaces = get_user_workspaces(db, user)
    current_ws_id = payload.get("ws", "")

    return {
        "id": user.id,
        "username": user.username,
        "email": user.email,
        "role": user.role,
        "workspaces": workspaces,
        "current_workspace_id": current_ws_id if current_ws_id else None,
    }


@router.post("/switch-workspace/{workspace_id}")
async def switch_workspace(
    workspace_id: str,
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db),
):
    """切换当前工作区，重新签发 JWT（包含新的 ws 字段）。"""
    from app.core.security import decode_access_token
    from app.services.workspace_service import check_workspace_access

    payload = decode_access_token(token)
    if payload is None:
        raise UnauthorizedError("无效的访问令牌")

    user_id = payload.get("sub")
    if user_id is None:
        raise UnauthorizedError("无效的访问令牌")

    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise NotFoundError("用户", user_id)

    if not check_workspace_access(db, user, workspace_id):
        raise HTTPException(status_code=403, detail="无权访问此工作区")

    from datetime import timedelta

    expires = timedelta(minutes=settings.JWT_ACCESS_TOKEN_EXPIRE_MINUTES)
    new_token = create_access_token(
        data={"sub": user.id, "username": user.username, "ws": workspace_id},
        expires_delta=expires,
    )

    return {"access_token": new_token, "token_type": "bearer", "workspace_id": workspace_id}


# ─── 密码重置 ───────────────────────────────────────────────

RESET_CODE_TTL_SEC = 600  # 验证码 10 分钟有效
RESET_RATE_LIMIT_SEC = 60  # 同一邮箱 60 秒内只能发一次


class ForgotPasswordRequest(BaseModel):
    email: str

    @field_validator("email")
    @classmethod
    def email_format(cls, v: str) -> str:
        if not v or not re.match(r"^[^@]+@[^@]+\.[^@]+$", v):
            raise ValueError("邮箱格式无效")
        return v.lower()


class ResetPasswordRequest(BaseModel):
    email: str
    code: str
    new_password: str

    @field_validator("email")
    @classmethod
    def email_format(cls, v: str) -> str:
        if not v or not re.match(r"^[^@]+@[^@]+\.[^@]+$", v):
            raise ValueError("邮箱格式无效")
        return v.lower()

    @field_validator("new_password")
    @classmethod
    def password_length(cls, v: str) -> str:
        if len(v) < 6:
            raise ValueError("密码不少于 6 个字符")
        if len(v) > 32:
            raise ValueError("密码不超过 32 个字符")
        return v


async def _send_reset_email(email: str, code: str) -> bool:
    """发送密码重置邮件。SMTP 不可用时记日志。"""
    try:
        import aiosmtplib
        from email.mime.text import MIMEText
        from email.mime.multipart import MIMEMultipart

        smtp_host = getattr(settings, 'SMTP_HOST', '') or 'smtp.qq.com'
        smtp_port = int(getattr(settings, 'SMTP_PORT', 0) or 587)
        smtp_user = getattr(settings, 'SMTP_USER', '') or ''
        smtp_password = getattr(settings, 'SMTP_PASSWORD', '') or ''

        if not smtp_user or not smtp_password:
            logger.warning("SMTP 未配置，无法发送邮件。重置码: %s", code)
            return False

        msg = MIMEMultipart()
        msg['From'] = smtp_user
        msg['To'] = email
        msg['Subject'] = '天工智能体 - 密码重置验证码'
        msg.attach(MIMEText(
            f'您的密码重置验证码是：<b>{code}</b><br><br>'
            f'验证码 10 分钟内有效。如非本人操作请忽略此邮件。',
            'html', 'utf-8'
        ))

        await aiosmtplib.send(
            msg, hostname=smtp_host, port=smtp_port,
            username=smtp_user, password=smtp_password,
            use_tls=smtp_port == 587,
        )
        logger.info("密码重置邮件已发送至 %s", email)
        return True
    except Exception as e:
        logger.warning("邮件发送失败: %s，重置码: %s", e, code)
        return False


@router.post("/forgot-password")
async def forgot_password(body: ForgotPasswordRequest, db: Session = Depends(get_db)):
    """发送密码重置验证码。"""
    user = db.query(User).filter(User.email == body.email).first()
    if not user:
        # 不泄露邮箱是否注册，统一返回成功
        return {"message": "如果邮箱已注册，验证码已发送"}

    redis = get_redis_client()

    # 频率限制
    rate_key = f"pwd_reset_rate:{body.email}"
    if redis:
        if redis.exists(rate_key):
            ttl = redis.ttl(rate_key)
            raise HTTPException(
                status_code=429,
                detail=f"操作过于频繁，请 {ttl} 秒后重试"
            )

    code = secrets.randbelow(900000) + 100000  # 6 位数字
    code_str = str(code)

    # 存储到 Redis
    code_key = f"pwd_reset_code:{body.email}"
    if redis:
        redis.setex(code_key, RESET_CODE_TTL_SEC, code_str)
        redis.setex(rate_key, RESET_RATE_LIMIT_SEC, "1")
    else:
        # 无 Redis 时用内存存储（重启失效）
        if not hasattr(forgot_password, '_memory_store'):
            forgot_password._memory_store = {}
            forgot_password._memory_rate = {}
        forgot_password._memory_store[body.email] = {
            "code": code_str,
            "expires_at": datetime.utcnow() + timedelta(seconds=RESET_CODE_TTL_SEC),
        }
        forgot_password._memory_rate[body.email] = \
            datetime.utcnow() + timedelta(seconds=RESET_RATE_LIMIT_SEC)

    # 尝试发送邮件
    sent = await _send_reset_email(body.email, code_str)

    if not sent:
        # SMTP 未配置时记录验证码并返回（开发/测试环境）
        logger.info("开发模式：%s 的密码重置验证码为 %s", body.email, code_str)
        return {
            "message": "验证码已生成",
            "dev_code": code_str,
        }

    return {"message": "验证码已发送至邮箱"}


@router.post("/reset-password")
async def reset_password(body: ResetPasswordRequest, db: Session = Depends(get_db)):
    """使用验证码重置密码。"""
    user = db.query(User).filter(User.email == body.email).first()
    if not user:
        raise HTTPException(status_code=400, detail="邮箱未注册")

    redis = get_redis_client()
    code_key = f"pwd_reset_code:{body.email}"
    stored_code = None

    if redis:
        stored_code = redis.get(code_key)
    elif hasattr(forgot_password, '_memory_store'):
        entry = forgot_password._memory_store.get(body.email, {})
        if entry and entry.get("expires_at", datetime.min) > datetime.utcnow():
            stored_code = entry.get("code")

    if not stored_code:
        raise HTTPException(status_code=400, detail="验证码已过期或未请求")

    if stored_code != body.code.strip():
        raise HTTPException(status_code=400, detail="验证码错误")

    # 更新密码
    user.password_hash = get_password_hash(body.new_password)
    db.commit()

    # 清除验证码
    if redis:
        redis.delete(code_key)
    elif hasattr(forgot_password, '_memory_store'):
        forgot_password._memory_store.pop(body.email, None)

    logger.info("用户 %s 密码重置成功", user.username)
    return {"message": "密码重置成功，请使用新密码登录"}


async def get_optional_user(
    token: str | None = Depends(oauth2_scheme_optional),
    db: Session = Depends(get_db)
) -> User | None:
    """获取当前用户（可选登录）。未提供 token 或 token 无效时返回 None。"""
    if not token:
        return None
    from app.core.security import decode_access_token

    payload = decode_access_token(token)
    if payload is None:
        return None

    user_id = payload.get("sub")
    if user_id is None:
        return None

    user = db.query(User).filter(User.id == user_id).first()
    return user