import logging

from datetime import datetime

from fastapi import APIRouter, Depends, HTTPException, Query, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from models.database import get_db
from models.models import User
from .account_limits import (
    UNLIMITED_ACCOUNTS,
    count_user_account_breakdown,
    normalize_max_accounts,
)
from .account_quota import default_stop_worker, sync_user_account_quota
from .dependencies import get_current_user, require_user_manager
from .email_service import (
    build_password_reset_link,
    build_verification_link,
    send_password_reset_email,
    send_verification_email,
)
from .email_verification import create_verification_token, mask_email, verify_email_token
from .password_reset import create_password_reset_token, verify_password_reset_token
from .jwt_utils import create_access_token
from .passwords import hash_password, verify_password
from .roles import ALL_ROLES, ROLE_LABELS, ROLE_OPERATOR, ensure_role, is_admin
from .schemas import (
    LoginRequest,
    MessageResponse,
    ForgotPasswordRequest,
    ForgotPasswordResponse,
    RegisterRequest,
    RegisterResponse,
    ResendVerificationRequest,
    ResetPasswordRequest,
    RolesResponse,
    RoleInfo,
    TokenResponse,
    UserCreate,
    UserResponse,
    UserUpdate,
    VerifyEmailRequest,
)
from .system_settings import SystemSettingsData, load_settings

logger = logging.getLogger("auth.router")

router = APIRouter(prefix="/api/auth", tags=["auth"])


async def _build_user_response(db: AsyncSession, user: User, with_count: bool = False) -> UserResponse:
    payload = UserResponse.model_validate(user)
    if with_count:
        breakdown = await count_user_account_breakdown(db, user.id)
        payload.account_count = breakdown["total"]
        payload.active_account_count = breakdown["active"]
        payload.disabled_account_count = breakdown["disabled"]
    return payload


async def _ensure_email_available(
    db: AsyncSession,
    email: str | None,
    exclude_user_id: int | None = None,
) -> str | None:
    value = (str(email).strip().lower() if email else "") or None
    if not value:
        return None
    stmt = select(User).where(User.email == value)
    if exclude_user_id:
        stmt = stmt.where(User.id != exclude_user_id)
    exists = await db.execute(stmt)
    if exists.scalar_one_or_none():
        raise HTTPException(status_code=400, detail="邮箱已被其他用户使用")
    return value


def _apply_email_verified(user: User, verified: bool | None) -> None:
    if verified is None:
        return
    user.email_verified = verified
    if verified:
        if not user.email_verified_at:
            user.email_verified_at = datetime.utcnow()
    else:
        user.email_verified_at = None


def _email_not_verified_detail(user: User) -> dict:
    return {
        "code": "email_not_verified",
        "message": "邮箱尚未验证，请先完成邮箱验证后再登录",
        "email": mask_email(user.email or ""),
    }


def _email_not_bound_detail() -> dict:
    return {
        "code": "email_not_bound",
        "message": "该账号未绑定邮箱，请联系管理员绑定邮箱后再登录",
    }


def _require_email_access(user: User, settings: SystemSettingsData) -> None:
    if is_admin(user.role):
        return
    if settings.email_binding_required and not user.email:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=_email_not_bound_detail(),
        )
    if not settings.email_verification_required:
        return
    if user.email_verified:
        return
    if user.email:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=_email_not_verified_detail(user),
        )


async def _issue_token(user: User) -> TokenResponse:
    token = create_access_token(str(user.id), {"role": user.role, "username": user.username})
    return TokenResponse(access_token=token)


async def _send_user_verification(
    db: AsyncSession,
    user: User,
    settings: SystemSettingsData,
) -> tuple[bool, str | None]:
    if not user.email:
        raise HTTPException(status_code=400, detail="该账号未绑定邮箱")
    token = await create_verification_token(
        db, user, expire_hours=settings.email_verify_token_hours
    )
    await db.commit()
    link = build_verification_link(token, settings)
    if not settings.smtp_configured():
        logger.warning(
            "SMTP 未配置，验证链接: user=%s email=%s link=%s",
            user.username,
            user.email,
            link,
        )
        dev_url = link if settings.debug_show_verify_link else None
        return False, dev_url
    try:
        await send_verification_email(user.email, user.username, token, settings)
        return True, None
    except Exception as exc:
        logger.exception("Send verification email failed for user=%s", user.username)
        dev_url = link if settings.debug_show_verify_link else None
        if dev_url:
            return False, dev_url
        raise HTTPException(status_code=400, detail=f"邮件发送失败：{exc}") from exc


@router.post("/login", response_model=TokenResponse)
async def login(body: LoginRequest, db: AsyncSession = Depends(get_db)):
    settings = await load_settings(db)
    result = await db.execute(select(User).where(User.username == body.username.strip()))
    user = result.scalar_one_or_none()
    if not user or not verify_password(body.password, user.password_hash):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="用户名或密码错误")
    if not user.is_active:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="账号已禁用")
    _require_email_access(user, settings)
    return await _issue_token(user)


@router.post("/register", response_model=RegisterResponse)
async def register(body: RegisterRequest, db: AsyncSession = Depends(get_db)):
    settings = await load_settings(db)
    if not settings.registration_enabled:
        raise HTTPException(status_code=403, detail="当前未开放用户注册")

    username = body.username.strip()
    email = str(body.email).strip().lower()

    exists = await db.execute(select(User).where(User.username == username))
    if exists.scalar_one_or_none():
        raise HTTPException(status_code=400, detail="用户名已存在")

    exists = await db.execute(select(User).where(User.email == email))
    if exists.scalar_one_or_none():
        raise HTTPException(status_code=400, detail="邮箱已被注册")

    verification_required = settings.email_verification_required

    user = User(
        username=username,
        email=email,
        password_hash=hash_password(body.password),
        display_name=body.display_name or username,
        role=ROLE_OPERATOR,
        is_active=True,
        email_verified=not verification_required,
        email_verified_at=datetime.utcnow() if not verification_required else None,
        max_accounts=max(0, int(settings.default_register_max_accounts or 3)),
    )
    db.add(user)
    await db.flush()

    if not verification_required:
        await db.commit()
        await db.refresh(user)
        return RegisterResponse(
            message="注册成功，可直接登录",
            email=mask_email(user.email),
            verification_sent=False,
            verification_required=False,
        )

    verification_sent, dev_url = await _send_user_verification(db, user, settings)
    await db.refresh(user)
    message = "注册成功，验证邮件已发送，请查收并完成验证后再登录"
    if not verification_sent:
        message = (
            "注册成功。验证邮件未能发出，请使用下方链接或联系管理员检查 SMTP 配置"
            if dev_url
            else "注册成功。邮件服务未配置或发送失败，请联系管理员"
        )

    return RegisterResponse(
        message=message,
        email=mask_email(user.email),
        verification_sent=verification_sent,
        verification_required=True,
        dev_verify_url=dev_url,
    )


@router.post("/verify-email", response_model=MessageResponse)
async def verify_email(body: VerifyEmailRequest, db: AsyncSession = Depends(get_db)):
    user = await verify_email_token(db, body.token.strip())
    if not user:
        raise HTTPException(status_code=400, detail="验证链接无效或已过期")
    await db.commit()
    return MessageResponse(message="邮箱验证成功，现在可以登录了")


@router.get("/verify-email", response_model=MessageResponse)
async def verify_email_get(token: str = Query(..., min_length=8), db: AsyncSession = Depends(get_db)):
    user = await verify_email_token(db, token.strip())
    if not user:
        raise HTTPException(status_code=400, detail="验证链接无效或已过期")
    await db.commit()
    return MessageResponse(message="邮箱验证成功，现在可以登录了")


@router.post("/forgot-password", response_model=ForgotPasswordResponse)
async def forgot_password(body: ForgotPasswordRequest, db: AsyncSession = Depends(get_db)):
    settings = await load_settings(db)
    if not settings.smtp_configured():
        raise HTTPException(
            status_code=400,
            detail="邮件服务未配置，请联系管理员重置密码",
        )

    email = str(body.email).strip().lower() if body.email else None
    username = body.username.strip() if body.username else None
    if not email and not username:
        raise HTTPException(status_code=400, detail="请提供邮箱或用户名")

    user = None
    if email:
        result = await db.execute(select(User).where(User.email == email))
        user = result.scalar_one_or_none()
    if not user and username:
        result = await db.execute(select(User).where(User.username == username))
        user = result.scalar_one_or_none()

    generic = ForgotPasswordResponse(
        message="若账号存在且已绑定邮箱，重置邮件将发送到注册邮箱",
        email=mask_email(user.email if user and user.email else (email or "")),
        reset_sent=True,
    )

    if not user or not user.email or not user.is_active:
        return generic

    token = await create_password_reset_token(
        db, user, expire_hours=settings.email_verify_token_hours
    )
    await db.commit()
    link = build_password_reset_link(token, settings)
    try:
        await send_password_reset_email(user.email, user.username, token, settings)
    except Exception as exc:
        logger.exception("Send password reset email failed for user=%s", user.username)
        dev_url = link if settings.debug_show_verify_link else None
        if dev_url:
            return ForgotPasswordResponse(
                message="邮件发送失败，请使用下方开发重置链接",
                email=mask_email(user.email),
                reset_sent=False,
                dev_reset_url=dev_url,
            )
        raise HTTPException(status_code=400, detail=f"邮件发送失败：{exc}") from exc
    return ForgotPasswordResponse(
        message="重置邮件已发送，请查收并按邮件说明设置新密码",
        email=mask_email(user.email),
        reset_sent=True,
        dev_reset_url=None,
    )


@router.post("/reset-password", response_model=MessageResponse)
async def reset_password(body: ResetPasswordRequest, db: AsyncSession = Depends(get_db)):
    user = await verify_password_reset_token(db, body.token.strip())
    if not user:
        raise HTTPException(status_code=400, detail="重置链接无效或已过期")
    if not user.is_active:
        raise HTTPException(status_code=400, detail="账号已禁用，请联系管理员")
    user.password_hash = hash_password(body.password)
    await db.commit()
    return MessageResponse(message="密码已重置，请使用新密码登录")


@router.post("/resend-verification", response_model=RegisterResponse)
async def resend_verification(body: ResendVerificationRequest, db: AsyncSession = Depends(get_db)):
    settings = await load_settings(db)
    if not settings.email_verification_required:
        raise HTTPException(status_code=400, detail="当前系统未开启邮箱验证")
    email = str(body.email).strip().lower() if body.email else None
    username = body.username.strip() if body.username else None
    if not email and not username:
        raise HTTPException(status_code=400, detail="请提供邮箱或用户名")

    user = None
    if email:
        result = await db.execute(select(User).where(User.email == email))
        user = result.scalar_one_or_none()
    if not user and username:
        result = await db.execute(select(User).where(User.username == username))
        user = result.scalar_one_or_none()

    if not user:
        return RegisterResponse(
            message="若账号存在且未验证，验证邮件将发送到注册邮箱",
            email=mask_email(email or ""),
            verification_sent=True,
            verification_required=True,
        )

    if user.email_verified:
        raise HTTPException(status_code=400, detail="该账号邮箱已验证，可直接登录")

    verification_sent, dev_url = await _send_user_verification(db, user, settings)
    message = (
        "验证邮件已重新发送，请查收"
        if verification_sent
        else "邮件未能发出，请使用下方验证链接或联系管理员检查 SMTP 配置"
    )
    return RegisterResponse(
        message=message,
        email=mask_email(user.email or ""),
        verification_sent=verification_sent,
        verification_required=True,
        dev_verify_url=dev_url,
    )


@router.get("/me", response_model=UserResponse)
async def get_me(user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
    return await _build_user_response(db, user, with_count=True)


@router.get("/roles", response_model=RolesResponse)
async def list_roles(_: User = Depends(get_current_user)):
    return RolesResponse(
        roles=[RoleInfo(value=r, label=ROLE_LABELS.get(r, r)) for r in ALL_ROLES]
    )


users_router = APIRouter(prefix="/api/users", tags=["users"])


@users_router.get("", response_model=list[UserResponse])
async def list_users(
    db: AsyncSession = Depends(get_db),
    _: User = Depends(require_user_manager),
):
    result = await db.execute(select(User).order_by(User.id.asc()))
    users = result.scalars().all()
    responses = []
    for user in users:
        responses.append(await _build_user_response(db, user, with_count=True))
    return responses


@users_router.post("", response_model=UserResponse)
async def create_user(
    body: UserCreate,
    db: AsyncSession = Depends(get_db),
    _: User = Depends(require_user_manager),
):
    settings = await load_settings(db)
    exists = await db.execute(select(User).where(User.username == body.username))
    if exists.scalar_one_or_none():
        raise HTTPException(status_code=400, detail="用户名已存在")
    try:
        role = ensure_role(body.role)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))
    email = await _ensure_email_available(db, str(body.email) if body.email else None)
    if settings.email_binding_required and not is_admin(role) and not email:
        raise HTTPException(status_code=400, detail="系统已开启「登录必须绑定邮箱」，请填写邮箱")
    if email:
        email_verified = body.email_verified
    else:
        email_verified = not settings.email_binding_required
    user = User(
        username=body.username.strip(),
        password_hash=hash_password(body.password),
        display_name=body.display_name or body.username,
        role=role,
        is_active=True,
        email=email,
        email_verified=email_verified,
        email_verified_at=datetime.utcnow() if email and email_verified else None,
        max_accounts=normalize_max_accounts(body.max_accounts, role),
    )
    db.add(user)
    await db.commit()
    await db.refresh(user)
    return await _build_user_response(db, user, with_count=True)


@users_router.put("/{user_id}", response_model=UserResponse)
async def update_user(
    user_id: int,
    body: UserUpdate,
    db: AsyncSession = Depends(get_db),
    current: User = Depends(require_user_manager),
):
    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(status_code=404, detail="用户不存在")
    settings = await load_settings(db)
    if user.id == current.id and body.is_active is False:
        raise HTTPException(status_code=400, detail="不能禁用当前登录账号")
    if body.display_name is not None:
        user.display_name = body.display_name
    if body.role is not None:
        prev_role = user.role
        try:
            user.role = ensure_role(body.role)
        except ValueError as e:
            raise HTTPException(status_code=400, detail=str(e))
        if is_admin(user.role):
            user.max_accounts = UNLIMITED_ACCOUNTS
            await sync_user_account_quota(db, user, stop_worker=default_stop_worker)
        elif is_admin(prev_role) and not is_admin(user.role):
            settings = await load_settings(db)
            user.max_accounts = max(0, int(settings.default_register_max_accounts or 3))
            await sync_user_account_quota(db, user, stop_worker=default_stop_worker)
    if body.is_active is not None:
        user.is_active = body.is_active
    if body.password:
        user.password_hash = hash_password(body.password)

    updates = body.model_dump(exclude_unset=True)
    if "max_accounts" in updates and not is_admin(user.role):
        user.max_accounts = normalize_max_accounts(updates["max_accounts"], user.role)
        await sync_user_account_quota(db, user, stop_worker=default_stop_worker)
    if "email" in updates:
        raw_email = updates.get("email")
        user.email = await _ensure_email_available(
            db,
            str(raw_email) if raw_email else None,
            exclude_user_id=user.id,
        )
        if not user.email:
            user.email_verified = not (
                settings.email_binding_required and not is_admin(user.role)
            )
            user.email_verified_at = None
    if "email_verified" in updates:
        if not user.email:
            raise HTTPException(status_code=400, detail="未绑定邮箱时无法设置验证状态")
        _apply_email_verified(user, updates["email_verified"])

    if settings.email_binding_required and not is_admin(user.role) and not user.email:
        raise HTTPException(status_code=400, detail="系统已开启「登录必须绑定邮箱」，该用户需绑定邮箱")

    await db.commit()
    await db.refresh(user)
    return await _build_user_response(db, user, with_count=True)


@users_router.delete("/{user_id}")
async def delete_user(
    user_id: int,
    db: AsyncSession = Depends(get_db),
    current: User = Depends(require_user_manager),
):
    if user_id == current.id:
        raise HTTPException(status_code=400, detail="不能删除当前登录账号")
    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(status_code=404, detail="用户不存在")
    await db.delete(user)
    await db.commit()
    return {"message": "用户已删除"}