from __future__ import annotations

from datetime import UTC, datetime, timedelta
import re

from app.auth import (
    authenticate_user,
    create_access_token,
    generate_refresh_token,
    get_password_hash,
    get_token_by_refresh_token,
    store_token,
)
from app.config import settings
from app.database import DailyChallengeStats, User
from app.database.statistics import UserStatistics
from app.dependencies import get_db
from app.log import logger
from app.models.oauth import (
    OAuthErrorResponse,
    RegistrationRequestErrors,
    TokenResponse,
    UserRegistrationErrors,
)
from app.models.score import GameMode

from fastapi import APIRouter, Depends, Form
from fastapi.responses import JSONResponse
from sqlalchemy import text
from sqlmodel import select
from sqlmodel.ext.asyncio.session import AsyncSession


def create_oauth_error_response(
    error: str, description: str, hint: str, status_code: int = 400
):
    """创建标准的 OAuth 错误响应"""
    error_data = OAuthErrorResponse(
        error=error, error_description=description, hint=hint, message=description
    )
    return JSONResponse(status_code=status_code, content=error_data.model_dump())


def validate_username(username: str) -> list[str]:
    """验证用户名"""
    errors = []

    if not username:
        errors.append("Username is required")
        return errors

    if len(username) < 3:
        errors.append("Username must be at least 3 characters long")

    if len(username) > 15:
        errors.append("Username must be at most 15 characters long")

    # 检查用户名格式（只允许字母、数字、下划线、连字符）
    if not re.match(r"^[a-zA-Z0-9_-]+$", username):
        errors.append(
            "Username can only contain letters, numbers, underscores, and hyphens"
        )

    # 检查是否以数字开头
    if username[0].isdigit():
        errors.append("Username cannot start with a number")

    return errors


def validate_email(email: str) -> list[str]:
    """验证邮箱"""
    errors = []

    if not email:
        errors.append("Email is required")
        return errors

    # 基本的邮箱格式验证
    email_pattern = r"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$"
    if not re.match(email_pattern, email):
        errors.append("Please enter a valid email address")

    return errors


def validate_password(password: str) -> list[str]:
    """验证密码"""
    errors = []

    if not password:
        errors.append("Password is required")
        return errors

    if len(password) < 8:
        errors.append("Password must be at least 8 characters long")

    return errors


router = APIRouter(tags=["osu! OAuth 认证"])


@router.post("/users")
async def register_user(
    user_username: str = Form(..., alias="user[username]"),
    user_email: str = Form(..., alias="user[user_email]"),
    user_password: str = Form(..., alias="user[password]"),
    db: AsyncSession = Depends(get_db),
):
    """用户注册接口 - 匹配 osu! 客户端的注册请求"""

    username_errors = validate_username(user_username)
    email_errors = validate_email(user_email)
    password_errors = validate_password(user_password)

    result = await db.exec(select(User).where(User.username == user_username))
    existing_user = result.first()
    if existing_user:
        username_errors.append("Username is already taken")

    result = await db.exec(select(User).where(User.email == user_email))
    existing_email = result.first()
    if existing_email:
        email_errors.append("Email is already taken")

    if username_errors or email_errors or password_errors:
        errors = RegistrationRequestErrors(
            user=UserRegistrationErrors(
                username=username_errors,
                user_email=email_errors,
                password=password_errors,
            )
        )

        return JSONResponse(
            status_code=422, content={"form_error": errors.model_dump()}
        )

    try:
        # 创建新用户
        # 确保 AUTO_INCREMENT 值从3开始（ID=1是BanchoBot，ID=2预留给ppy）
        result = await db.execute(  # pyright: ignore[reportDeprecated]
            text(
                "SELECT AUTO_INCREMENT FROM information_schema.TABLES "
                "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'lazer_users'"
            )
        )
        next_id = result.one()[0]
        if next_id <= 2:
            await db.execute(text("ALTER TABLE lazer_users AUTO_INCREMENT = 3"))
            await db.commit()

        new_user = User(
            username=user_username,
            email=user_email,
            pw_bcrypt=get_password_hash(user_password),
            priv=1,  # 普通用户权限
            country_code="CN",  # 默认国家
            join_date=datetime.now(UTC),
            last_visit=datetime.now(UTC),
        )
        db.add(new_user)
        await db.commit()
        await db.refresh(new_user)
        assert new_user.id is not None, "New user ID should not be None"
        for i in GameMode:
            statistics = UserStatistics(mode=i, user_id=new_user.id)
            db.add(statistics)
        daily_challenge_user_stats = DailyChallengeStats(user_id=new_user.id)
        db.add(daily_challenge_user_stats)
        await db.commit()
    except Exception:
        await db.rollback()
        # 打印详细错误信息用于调试
        logger.exception(f"Registration error for user {user_username}")

        # 返回通用错误
        errors = RegistrationRequestErrors(
            message="An error occurred while creating your account. Please try again."
        )

        return JSONResponse(
            status_code=500, content={"form_error": errors.model_dump()}
        )


@router.post("/oauth/token", response_model=TokenResponse)
async def oauth_token(
    grant_type: str = Form(...),
    client_id: str = Form(...),
    client_secret: str = Form(...),
    scope: str = Form("*"),
    username: str | None = Form(None),
    password: str | None = Form(None),
    refresh_token: str | None = Form(None),
    db: AsyncSession = Depends(get_db),
):
    """OAuth 令牌端点"""
    # 验证客户端凭据
    if (
        client_id != settings.OSU_CLIENT_ID
        or client_secret != settings.OSU_CLIENT_SECRET
    ):
        return create_oauth_error_response(
            error="invalid_client",
            description=(
                "Client authentication failed (e.g., unknown client, "
                "no client authentication included, "
                "or unsupported authentication method)."
            ),
            hint="Invalid client credentials",
            status_code=401,
        )

    if grant_type == "password":
        # 密码授权流程
        if not username or not password:
            return create_oauth_error_response(
                error="invalid_request",
                description=(
                    "The request is missing a required parameter, includes an "
                    "invalid parameter value, "
                    "includes a parameter more than once, or is otherwise malformed."
                ),
                hint="Username and password required",
            )

        # 验证用户
        user = await authenticate_user(db, username, password)
        if not user:
            return create_oauth_error_response(
                error="invalid_grant",
                description=(
                    "The provided authorization grant (e.g., authorization code, "
                    "resource owner credentials) "
                    "or refresh token is invalid, expired, revoked, "
                    "does not match the redirection URI used in "
                    "the authorization request, or was issued to another client."
                ),
                hint="Incorrect sign in",
            )

        # 生成令牌
        access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
        access_token = create_access_token(
            data={"sub": str(user.id)}, expires_delta=access_token_expires
        )
        refresh_token_str = generate_refresh_token()

        # 存储令牌
        assert user.id
        await store_token(
            db,
            user.id,
            access_token,
            refresh_token_str,
            settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60,
        )

        return TokenResponse(
            access_token=access_token,
            token_type="Bearer",
            expires_in=settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60,
            refresh_token=refresh_token_str,
            scope=scope,
        )

    elif grant_type == "refresh_token":
        # 刷新令牌流程
        if not refresh_token:
            return create_oauth_error_response(
                error="invalid_request",
                description=(
                    "The request is missing a required parameter, "
                    "includes an invalid parameter value, "
                    "includes a parameter more than once, or is otherwise malformed."
                ),
                hint="Refresh token required",
            )

        # 验证刷新令牌
        token_record = await get_token_by_refresh_token(db, refresh_token)
        if not token_record:
            return create_oauth_error_response(
                error="invalid_grant",
                description=(
                    "The provided authorization grant (e.g., authorization code, "
                    "resource owner credentials) or refresh token is "
                    "invalid, expired, revoked, "
                    "does not match the redirection URI used "
                    "in the authorization request, or was issued to another client."
                ),
                hint="Invalid refresh token",
            )

        # 生成新的访问令牌
        access_token_expires = timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
        access_token = create_access_token(
            data={"sub": str(token_record.user_id)}, expires_delta=access_token_expires
        )
        new_refresh_token = generate_refresh_token()

        # 更新令牌
        await store_token(
            db,
            token_record.user_id,
            access_token,
            new_refresh_token,
            settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60,
        )

        return TokenResponse(
            access_token=access_token,
            token_type="Bearer",
            expires_in=settings.ACCESS_TOKEN_EXPIRE_MINUTES * 60,
            refresh_token=new_refresh_token,
            scope=scope,
        )

    else:
        return create_oauth_error_response(
            error="unsupported_grant_type",
            description=(
                "The authorization grant type is not supported "
                "by the authorization server."
            ),
            hint="Unsupported grant type",
        )