import {
  ConflictException,
  Injectable,
  ForbiddenException,
  UnauthorizedException,
} from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import * as bcrypt from 'bcryptjs';
import * as jwt from 'jsonwebtoken';
import { User } from '../entities/user.entity';
import { GuildNode } from '../entities/guild-node.entity';
import { GuildUser } from '../entities/guild-user.entity';
import { RegisterDto } from './dto.register.dto';
import { LoginDto } from './dto.login.dto';
import { AuditService } from '../audit/audit.service';
import { parseDurationToSeconds } from './token.util';

function signAccessToken(userId: string, email: string): string {
  const secret = process.env.JWT_ACCESS_SECRET as string;
  const expiresIn = parseDurationToSeconds(process.env.JWT_ACCESS_EXPIRES_IN ?? '15m', 900);
  return jwt.sign({ sub: userId, email }, secret, { expiresIn });
}

function signRefreshToken(userId: string, email: string): string {
  const secret = process.env.JWT_REFRESH_SECRET as string;
  const expiresIn = parseDurationToSeconds(process.env.JWT_REFRESH_EXPIRES_IN ?? '30d', 2592000);
  return jwt.sign({ sub: userId, email, typ: 'refresh' }, secret, { expiresIn });
}

function signGuildAccessToken(userId: string, email: string, guildNodeId: string): string {
  const secret = process.env.JWT_ACCESS_SECRET as string;
  const expiresIn = parseDurationToSeconds(process.env.JWT_ACCESS_EXPIRES_IN ?? '15m', 900);
  return jwt.sign({ sub: userId, email, gid: guildNodeId, typ: 'guild_access' }, secret, { expiresIn });
}

@Injectable()
export class AuthService {
  constructor(
    @InjectRepository(User)
    private readonly userRepo: Repository<User>,
    @InjectRepository(GuildNode)
    private readonly guildNodeRepo: Repository<GuildNode>,
    @InjectRepository(GuildUser)
    private readonly guildUserRepo: Repository<GuildUser>,
    private readonly audit: AuditService,
  ) {}

  private async getUserGuildsAndTokens(userId: string, email: string) {
    let memberships = await this.guildUserRepo.find({
      where: { userId, status: 'active' },
    });

    if (!memberships.length) {
      const activeNodes = await this.guildNodeRepo.find({ where: { status: 'active' } });
      if (activeNodes.length) {
        await this.guildUserRepo.save(
          activeNodes.map((n) =>
            this.guildUserRepo.create({
              userId,
              guildNodeId: n.nodeId,
              status: 'active',
            }),
          ),
        );
        memberships = await this.guildUserRepo.find({ where: { userId, status: 'active' } });
      }
    }

    const nodeIds = memberships.map((x) => x.guildNodeId);
    if (!nodeIds.length) {
      return { guilds: [], guildAccessTokens: [] as Array<{ guildNodeId: string; token: string; tokenType: string }> };
    }

    const nodes = await this.guildNodeRepo
      .createQueryBuilder('n')
      .where('n.nodeId IN (:...nodeIds)', { nodeIds })
      .andWhere('n.status = :status', { status: 'active' })
      .getMany();

    const guilds = nodes.map((n) => ({
      nodeId: n.nodeId,
      name: n.name,
      endpoint: n.endpoint,
      status: n.status,
    }));

    const guildAccessTokens = guilds.map((g) => ({
      guildNodeId: g.nodeId,
      token: signGuildAccessToken(userId, email, g.nodeId),
      tokenType: 'Bearer',
    }));

    return { guilds, guildAccessTokens };
  }

  async register(input: RegisterDto) {
    const exists = await this.userRepo.findOne({ where: { email: input.email } });
    if (exists) {
      throw new ConflictException('email already exists');
    }

    const passwordHash = await bcrypt.hash(input.password, 10);
    const user = this.userRepo.create({
      email: input.email,
      passwordHash,
      refreshTokenHash: null,
    });
    const saved = await this.userRepo.save(user);

    await this.audit.write({
      action: 'auth.register',
      actorId: saved.id,
      targetType: 'user',
      targetId: saved.id,
      detail: JSON.stringify({ email: saved.email }),
    });

    return {
      id: saved.id,
      email: saved.email,
      createdAt: saved.createdAt,
    };
  }

  async login(input: LoginDto) {
    const user = await this.userRepo.findOne({ where: { email: input.email } });
    if (!user) throw new UnauthorizedException('invalid credentials');

    const ok = await bcrypt.compare(input.password, user.passwordHash);
    if (!ok) throw new UnauthorizedException('invalid credentials');

    const accessToken = signAccessToken(user.id, user.email);
    const refreshToken = signRefreshToken(user.id, user.email);
    user.refreshTokenHash = await bcrypt.hash(refreshToken, 10);
    await this.userRepo.save(user);

    await this.audit.write({
      action: 'auth.login',
      actorId: user.id,
      targetType: 'user',
      targetId: user.id,
      detail: JSON.stringify({ email: user.email }),
    });

    const { guilds, guildAccessTokens } = await this.getUserGuildsAndTokens(user.id, user.email);

    return {
      accessToken,
      refreshToken,
      tokenType: 'Bearer',
      user: {
        id: user.id,
        email: user.email,
      },
      guilds,
      guildAccessTokens,
    };
  }

  async listMyGuilds(accessToken: string) {
    const payload = this.verifyCenterAccessToken(accessToken);
    const userId = String(payload.sub ?? '');
    const email = String(payload.email ?? '');
    return this.getUserGuildsAndTokens(userId, email);
  }

  verifyCenterAccessToken(accessToken: string): jwt.JwtPayload {
    try {
      const payload = jwt.verify(accessToken, process.env.JWT_ACCESS_SECRET as string) as jwt.JwtPayload;
      if (!payload?.sub) throw new Error('invalid');
      return payload;
    } catch {
      throw new UnauthorizedException('invalid access token');
    }
  }

  async introspectGuildToken(token: string, guildNodeId: string, sharedSecret?: string) {
    const expectedSecret = process.env.CENTER_SHARED_SECRET as string;
    if (!sharedSecret || sharedSecret !== expectedSecret) {
      throw new ForbiddenException('invalid shared secret');
    }

    let payload: jwt.JwtPayload;
    try {
      payload = jwt.verify(token, process.env.JWT_ACCESS_SECRET as string) as jwt.JwtPayload;
    } catch {
      return { active: false };
    }

    const userId = String(payload.sub ?? '');
    const tokenGuildNodeId = String(payload.gid ?? '');
    if (!userId || tokenGuildNodeId !== guildNodeId || payload.typ !== 'guild_access') {
      return { active: false };
    }

    const membership = await this.guildUserRepo.findOne({
      where: { userId, guildNodeId, status: 'active' },
    });
    if (!membership) return { active: false };

    return {
      active: true,
      user: {
        id: userId,
        email: String(payload.email ?? ''),
      },
      guildNodeId,
    };
  }

  async refresh(refreshToken: string) {
    let payload: jwt.JwtPayload;
    try {
      payload = jwt.verify(refreshToken, process.env.JWT_REFRESH_SECRET as string) as jwt.JwtPayload;
    } catch {
      throw new UnauthorizedException('invalid refresh token');
    }

    const userId = String(payload.sub ?? '');
    const user = await this.userRepo.findOne({ where: { id: userId } });
    if (!user || !user.refreshTokenHash) {
      throw new UnauthorizedException('invalid refresh token');
    }

    const tokenOk = await bcrypt.compare(refreshToken, user.refreshTokenHash);
    if (!tokenOk) throw new UnauthorizedException('invalid refresh token');

    const newAccessToken = signAccessToken(user.id, user.email);
    const newRefreshToken = signRefreshToken(user.id, user.email);
    user.refreshTokenHash = await bcrypt.hash(newRefreshToken, 10);
    await this.userRepo.save(user);

    await this.audit.write({
      action: 'auth.refresh',
      actorId: user.id,
      targetType: 'user',
      targetId: user.id,
      detail: null,
    });

    return {
      accessToken: newAccessToken,
      refreshToken: newRefreshToken,
      tokenType: 'Bearer',
    };
  }

  async logout(refreshToken: string) {
    let payload: jwt.JwtPayload;
    try {
      payload = jwt.verify(refreshToken, process.env.JWT_REFRESH_SECRET as string) as jwt.JwtPayload;
    } catch {
      return { status: 'ok' };
    }

    const userId = String(payload.sub ?? '');
    if (!userId) return { status: 'ok' };

    const user = await this.userRepo.findOne({ where: { id: userId } });
    if (!user) return { status: 'ok' };

    user.refreshTokenHash = null;
    await this.userRepo.save(user);
    await this.audit.write({
      action: 'auth.logout',
      actorId: user.id,
      targetType: 'user',
      targetId: user.id,
      detail: null,
    });
    return { status: 'ok' };
  }
}