import {
	BadRequestException,
	forwardRef,
	Inject,
	Injectable,
	Logger,
	UnauthorizedException,
} from "@nestjs/common";
import { ConfigService } from "@nestjs/config";
import { authenticator } from "otplib";
import { toDataURL } from "qrcode";
import { HashingService } from "../crypto/services/hashing.service";
import { JwtService } from "../crypto/services/jwt.service";
import { SessionsService } from "../sessions/sessions.service";
import { UsersService } from "../users/users.service";
import { LoginDto } from "./dto/login.dto";
import { RegisterDto } from "./dto/register.dto";

@Injectable()
export class AuthService {
	private readonly logger = new Logger(AuthService.name);

	constructor(
		@Inject(forwardRef(() => UsersService))
		private readonly usersService: UsersService,
		private readonly hashingService: HashingService,
		private readonly jwtService: JwtService,
		private readonly sessionsService: SessionsService,
		private readonly configService: ConfigService,
	) {}

	async generateTwoFactorSecret(userId: string) {
		this.logger.log(`Generating 2FA secret for user ${userId}`);
		const user = await this.usersService.findOne(userId);
		if (!user) throw new UnauthorizedException();

		const secret = authenticator.generateSecret();
		const otpauthUrl = authenticator.keyuri(
			user.username,
			this.configService.get("DOMAIN_NAME") || "Memegoat",
			secret,
		);

		await this.usersService.setTwoFactorSecret(userId, secret);

		const qrCodeDataUrl = await toDataURL(otpauthUrl);
		return {
			secret,
			qrCodeDataUrl,
		};
	}

	async enableTwoFactor(userId: string, token: string) {
		this.logger.log(`Enabling 2FA for user ${userId}`);
		const secret = await this.usersService.getTwoFactorSecret(userId);
		if (!secret) {
			throw new BadRequestException("2FA not initiated");
		}

		const isValid = authenticator.verify({ token, secret });
		if (!isValid) {
			throw new BadRequestException("Invalid 2FA token");
		}

		await this.usersService.toggleTwoFactor(userId, true);
		return { message: "2FA enabled successfully" };
	}

	async disableTwoFactor(userId: string, token: string) {
		this.logger.log(`Disabling 2FA for user ${userId}`);
		const secret = await this.usersService.getTwoFactorSecret(userId);
		if (!secret) {
			throw new BadRequestException("2FA not enabled");
		}

		const isValid = authenticator.verify({ token, secret });
		if (!isValid) {
			throw new BadRequestException("Invalid 2FA token");
		}

		await this.usersService.toggleTwoFactor(userId, false);
		return { message: "2FA disabled successfully" };
	}

	async register(dto: RegisterDto) {
		this.logger.log(`Registering new user: ${dto.username}`);
		const { username, email, password } = dto;

		const passwordHash = await this.hashingService.hashPassword(password);
		const emailHash = await this.hashingService.hashEmail(email);

		const user = await this.usersService.create({
			username,
			email,
			passwordHash,
			emailHash,
		});

		return {
			message: "User registered successfully",
			userId: user.uuid,
		};
	}

	async login(dto: LoginDto, userAgent?: string, ip?: string) {
		this.logger.log(`Login attempt for email: ${dto.email}`);
		const { email, password } = dto;

		const emailHash = await this.hashingService.hashEmail(email);
		const user = await this.usersService.findByEmailHash(emailHash);

		if (!user) {
			this.logger.warn(`Login failed: user not found for email hash`);
			throw new UnauthorizedException("Invalid credentials");
		}

		const isPasswordValid = await this.hashingService.verifyPassword(
			password,
			user.passwordHash,
		);

		if (!isPasswordValid) {
			this.logger.warn(`Login failed: invalid password for user ${user.uuid}`);
			throw new UnauthorizedException("Invalid credentials");
		}

		if (user.isTwoFactorEnabled) {
			this.logger.log(`2FA required for user ${user.uuid}`);
			return {
				message: "2FA required",
				requires2FA: true,
				userId: user.uuid,
			};
		}

		const accessToken = await this.jwtService.generateJwt({
			sub: user.uuid,
			username: user.username,
		});

		const session = await this.sessionsService.createSession(
			user.uuid,
			userAgent,
			ip,
		);

		this.logger.log(`User ${user.uuid} logged in successfully`);
		return {
			message: "User logged in successfully",
			access_token: accessToken,
			refresh_token: session.refreshToken,
		};
	}

	async verifyTwoFactorLogin(
		userId: string,
		token: string,
		userAgent?: string,
		ip?: string,
	) {
		this.logger.log(`2FA verification attempt for user ${userId}`);
		const user = await this.usersService.findOneWithPrivateData(userId);
		if (!user || !user.isTwoFactorEnabled) {
			throw new UnauthorizedException();
		}

		const secret = await this.usersService.getTwoFactorSecret(userId);
		if (!secret) throw new UnauthorizedException();

		const isValid = authenticator.verify({ token, secret });
		if (!isValid) {
			this.logger.warn(
				`2FA verification failed for user ${userId}: invalid token`,
			);
			throw new UnauthorizedException("Invalid 2FA token");
		}

		const accessToken = await this.jwtService.generateJwt({
			sub: user.uuid,
			username: user.username,
		});

		const session = await this.sessionsService.createSession(
			user.uuid,
			userAgent,
			ip,
		);

		this.logger.log(`User ${userId} logged in successfully via 2FA`);
		return {
			message: "User logged in successfully (2FA)",
			access_token: accessToken,
			refresh_token: session.refreshToken,
		};
	}

	async refresh(refreshToken: string) {
		const session = await this.sessionsService.refreshSession(refreshToken);
		const user = await this.usersService.findOne(session.userId);

		if (!user) {
			throw new UnauthorizedException("User not found");
		}

		const accessToken = await this.jwtService.generateJwt({
			sub: user.uuid,
			username: user.username,
		});

		return {
			access_token: accessToken,
			refresh_token: session.refreshToken,
		};
	}

	async logout() {
		return { message: "User logged out" };
	}
}