import { Injectable, InternalServerErrorException } from '@nestjs/common';
import { OracleDBService } from 'src/db/db.service';
import { AuthLoginDTO } from './auth.dto';
import * as oracledb from 'oracledb';
import { ConfigService } from '@nestjs/config';
import axios, { AxiosRequestConfig, AxiosResponse } from 'axios';
import { Request } from 'express';
import * as jwkToPem from "jwk-to-pem"
import * as jwt from "jsonwebtoken"
import { UnauthorizedException } from 'src/exceptions/unauthorized.exception';
import { ConflictException } from 'src/exceptions/conflict.exception';
import { BadRequestException } from 'src/exceptions/badRequest.exception';

interface DecodedToken {
  email: string;
  [key: string]: any;
}

interface IntrospectResult {
  active: boolean;
}

@Injectable()
export class AuthService {
  private keyCache: Record<string, string> = {};

  private readonly KEYCLOAK_URL: string;
  private readonly KEYCLOAK_REALM: string;
  private readonly KEYCLOAK_BASE_URL: string;
  private readonly JWKS_URL: string;
  private readonly TOKENS_INTROSPECT_URL: string;
  private readonly CLIENT_ID: string;
  private readonly CLIENT_SECRET: string;
  private readonly TOKEN_URL: string;
  private readonly USERS_URL: string;

  constructor(
    private readonly oracleDBService: OracleDBService,
    private readonly configService: ConfigService,
  ) {
    const KEYCLOAK_URL = this.configService.get<string>('KEYCLOAK_URL');
    if (!KEYCLOAK_URL) throw new Error('Environment variable KEYCLOAK_URL is not set');
    this.KEYCLOAK_URL = KEYCLOAK_URL;

    const KEYCLOAK_REALM = this.configService.get<string>('KEYCLOAK_REALM');
    if (!KEYCLOAK_REALM) throw new Error('Environment variable KEYCLOAK_REALM is not set');
    this.KEYCLOAK_REALM = KEYCLOAK_REALM;

    const CLIENT_ID = this.configService.get<string>('CLIENT_ID');
    if (!CLIENT_ID) throw new Error('Environment variable KEYCLOAK CLIENT_ID is not set');
    this.CLIENT_ID = CLIENT_ID;

    const CLIENT_SECRET = this.configService.get<string>('CLIENT_SECRET');
    if (!CLIENT_SECRET) throw new Error('Environment variable KEYCLOAK CLIENT_SECRET is not set');
    this.CLIENT_SECRET = CLIENT_SECRET;

    this.KEYCLOAK_BASE_URL = `${this.KEYCLOAK_URL}/realms/${this.KEYCLOAK_REALM}/protocol/openid-connect`;

    this.JWKS_URL = `${this.KEYCLOAK_BASE_URL}/certs`

    this.TOKENS_INTROSPECT_URL = `${this.KEYCLOAK_BASE_URL}/token/introspect`

    this.TOKEN_URL = `${this.KEYCLOAK_BASE_URL}/token`

    this.USERS_URL = `${this.KEYCLOAK_URL}/admin/realms/${this.KEYCLOAK_REALM}/users`;
  }

  async login(body: AuthLoginDTO) {
    let connection;
    let rows = [];
    try {
      connection = await this.oracleDBService.getConnection();
      if (!connection) {
        throw new Error('No DB Connected');
      }

      const result = await connection.execute(
        `BEGIN
                    USERLOGIN_PKG.ValidateUser(:P_EMAILADDR,:P_PASSWORD,:p_login_cursor);
                END;`,
        {
          P_EMAILADDR: {
            val: body.P_EMAILADDR,
            type: oracledb.DB_TYPE_NVARCHAR,
          },
          P_PASSWORD: {
            val: body.P_PASSWORD,
            type: oracledb.DB_TYPE_NVARCHAR,
          },
          p_login_cursor: {
            type: oracledb.CURSOR,
            dir: oracledb.BIND_OUT,
          },
        },
        {
          outFormat: oracledb.OUT_FORMAT_OBJECT,
        },
      );

      if (result.outBinds && result.outBinds.p_login_cursor) {
        const cursor = result.outBinds.p_login_cursor;
        let rowsBatch;

        do {
          rowsBatch = await cursor.getRows(100);
          rows = rows.concat(rowsBatch);
        } while (rowsBatch.length > 0);

        await cursor.close();
      } else {
        throw new BadRequestException('Error executing request try after some time!');
      }

      if (rows[0]['ERRORMESG']) {
        throw new BadRequestException('Invalid username or password!');
      }
      return { msg: 'Logged in successfully' };
    } catch (err) {
      throw new BadRequestException('Invalid username or password');
    }
    finally {
      if (connection) {
        try {
          await connection.close();
        } catch (closeErr) {
          console.error('Failed to close connection:', closeErr);
        }
      }
    }
  }

  private async getPublicKey(kid: string): Promise<string> {
    try {
      // Check if the key is already cached
      if (this.keyCache[kid]) return this.keyCache[kid];

      // Fetch the JWKS (JSON Web Key Set)
      const { data } = await axios.get(this.JWKS_URL);

      // Validate the response shape
      if (!data?.keys || !Array.isArray(data.keys)) {
        console.log("Invalid JWKS response");
        throw new UnauthorizedException('Authentication failed');
      }

      // Find the key with the matching kid
      const key = data.keys.find((k) => k.kid === kid);
      if (!key) {
        console.log("Authentication failed: Key not found");
        throw new UnauthorizedException('Authentication failed');
      }

      // Convert JWK to PEM format and cache it
      const pem = jwkToPem(key);
      this.keyCache[kid] = pem;

      return pem;
    } catch (error) {
      if (error instanceof UnauthorizedException) {
        throw error; // Let UnauthorizedException bubble up as-is
      }
      // Optionally log error details for debugging
      console.error('Failed to retrieve or process JWKS:', error);
      // Wrap other errors as InternalServerException
      console.log('Failed to retrieve public key');
      throw new InternalServerErrorException();
    }
  }

  async introspectTokenX(token: string): Promise<any> {
    let det: any = await jwt.decode(token);

    const { email } = det;

    console.log("email : ", email);

    let uid = await this.getUserIdByEmail(email);

    console.log("uid : ", uid);

    const USERINFO_URL = `${this.KEYCLOAK_URL}/admin/realms/${this.KEYCLOAK_REALM}/users/${uid}/sessions`;

    const admintoken = await this.getAdminAccessToken();

    try {
      console.log("url : ", USERINFO_URL);

      const response = await axios.get(USERINFO_URL, {
        headers: {
          Authorization: `Bearer ${admintoken}`
        }
      });

      console.log("active session data : ", response.data);

      console.log("from AuthService decodeToken .......................... end");

      if (response.data.length > 0) return { active: true };
      else return { active: false }

    } catch (error) {
      console.log("Error in introspectToken : ", error.message);
      throw new InternalServerErrorException()
    }
  }

  async introspectToken(token: string, publicKey: string): Promise<IntrospectResult> {
    try {
      // Securely verify the token
      const decoded = jwt.verify(token, publicKey, { algorithms: ['RS256'], }) as DecodedToken;

      const { email } = decoded;

      if (!email) throw new UnauthorizedException('Token does not contain an email.');

      // const uid = await this.getUserIdByEmail(email);

      // if (!uid) throw new UnauthorizedException('No user ID found for email.');

      // const userInfoUrl = `${this.KEYCLOAK_URL}/admin/realms/${this.KEYCLOAK_REALM}/users/${uid}/sessions`;

      // const adminToken = await this.getAdminAccessToken();

      // const response = await axios.get(userInfoUrl, {
      //   headers: {
      //     Authorization: `Bearer ${adminToken}`,
      //   },
      // });

      const sessionData = await this.getUserSession(email);

      return { active: Array.isArray(sessionData) && sessionData.length > 0 };

    } catch (error: any) {
      console.log("Error in introspectToken:", error.message || error);

      if (error instanceof UnauthorizedException || error instanceof jwt.TokenExpiredError || error instanceof jwt.JsonWebTokenError || error instanceof jwt.NotBeforeError) {
        throw new UnauthorizedException('Authentication failed');
      }

      throw new InternalServerErrorException('Failed to introspect token');
    }
  }

  async getUserSession(email) {
    try {
      const uid = await this.getUserIdByEmail(email);

      if (!uid) throw new UnauthorizedException('No user ID found for email.');

      const userInfoUrl = `${this.KEYCLOAK_URL}/admin/realms/${this.KEYCLOAK_REALM}/users/${uid}/sessions`;

      const adminToken = await this.getAdminAccessToken();

      const response = await axios.get(userInfoUrl, {
        headers: {
          Authorization: `Bearer ${adminToken}`,
        },
      });

      const sessionData = response.data;

      return sessionData

    } catch (error) {
      if (error instanceof UnauthorizedException) throw error
      console.log("Error while getting User session.....");
      throw new InternalServerErrorException()
    }
  }

  async decodeToken(token: string): Promise<any> {
    const decodedHeader = jwt.decode(token, { complete: true });

    if (!decodedHeader || typeof decodedHeader !== 'object') {
      throw new UnauthorizedException("Authentication failed")
    }

    const kid: any = decodedHeader.header.kid;

    const publicKey = await this.getPublicKey(kid);

    const introspection = await this.introspectToken(token, publicKey);

    if (!introspection.active) {
      console.log("Introspect failed for token");
      throw new UnauthorizedException("Authentication Failed")
    }

    const verified = jwt.verify(token, publicKey, { algorithms: ['RS256'] });

    return verified;
  }

  async loginUser(username: string, password: string, req: Request): Promise<any> {

    const access_token = req.cookies?.access_token;
    const refresh_token = req.cookies?.refresh_token;

    const params = new URLSearchParams();
    params.append('grant_type', 'password');
    params.append('client_id', this.CLIENT_ID);
    params.append('client_secret', this.CLIENT_SECRET);
    params.append('username', username);
    params.append('password', password);
    // params.append('scope', 'openid');

    try {
      const userSession = await this.getUserSession(username)

      if (access_token && refresh_token && userSession.length > 0) {
        let tokens = await this.getTokenFromRefreshToken(refresh_token);
        const decodedHeader = jwt.decode(access_token, { complete: true });

        if (!decodedHeader || typeof decodedHeader !== 'object') {
          throw new UnauthorizedException("Authentication failed")
        }

        const kid: any = decodedHeader.header.kid;

        const publicKey = await this.getPublicKey(kid);

        const decoded = jwt.verify(access_token, publicKey, { algorithms: ['RS256'] });

        const email = (decoded && typeof decoded === 'object') ? (decoded as any).email : undefined;
        return { ...tokens, email }
      }

      const response = await axios.post(this.TOKEN_URL, params, {
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      });

      let k = { ...response.data, email: username };

      return k;
    } catch (error) {
      console.log("error while logging : ", error.message);

      throw new BadRequestException('Invalid username or password');
    }
  }

  async getUserIdByEmailX(email: string) {

    let url = `${this.USERS_URL}?email=${email}`;

    let adminAccessToken = await this.getAdminAccessToken();

    console.log("admin access_token for getting uid : ", adminAccessToken);
    console.log("url for uid : ", url);

    const options: AxiosRequestConfig = {
      method: 'GET',
      url,
      headers: {
        Authorization: `Bearer ${adminAccessToken}`,
        "Content-Type": "application/json"
      }
    };

    try {
      const { data } = await axios.request(options);
      return data[0]?.id;
    } catch (error) {
      // console.error(error);
      console.log("from getUserIdByEmail : ", error.message);
    }
  }

  async getUserIdByEmail(email: string): Promise<string> {
    try {
      const adminAccessToken = await this.getAdminAccessToken();
      const url = `${this.USERS_URL}?email=${encodeURIComponent(email)}`;
      const options: AxiosRequestConfig = {
        method: 'GET',
        url,
        headers: {
          Authorization: `Bearer ${adminAccessToken}`,
          'Content-Type': 'application/json',
        },
      };

      const response = await axios.request(options);

      if (response.status !== 200 || !Array.isArray(response.data)) {
        console.log("failed to retrieve user-id....");
        throw new UnauthorizedException("Authentication failed")
      }

      const user = response.data[0];
      if (user?.id) {
        return user.id
      } else {
        throw new UnauthorizedException("Authentication failed")
      }

    } catch (error) {
      console.log("Error in getUserIdByEmail ...........");
      if (error instanceof UnauthorizedException) {
        throw error
      }

      throw new InternalServerErrorException();
    }
  }

  async forgotPassword() {

    const validatePasswordURLSearchParams = new URLSearchParams({
      grant_type: 'password',
      client_id: `${this.CLIENT_ID}`,
      client_secret: `${this.CLIENT_SECRET}`,
      username: `${'a@gmail.com'}`,
      password: `${'A1!bcdef'}`,
    });

    let userID = await this.getUserIdByEmail("");

    let resetPasswordURL = `${this.USERS_URL}/${userID}/reset-password`;

    let adminAccessToken = await this.getAdminAccessToken();

    const options1: AxiosRequestConfig = {
      method: 'PUT',
      url: resetPasswordURL,
      headers: {
        Authorization: `Bearer ${adminAccessToken}`
      },
      data: {
        type: 'password',
        value: 'A1!bcdef',
        temporary: false,
      }
    };

    const options2: AxiosRequestConfig = {
      method: 'POST',
      url: this.TOKEN_URL,
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
      },
      data: validatePasswordURLSearchParams
    };

    try {
      const { data } = await axios.request(options2);
      return { statusCode: 200, message: 'password reset successfull' }
    } catch (error) {
      // console.error(error);
      console.log(error.message);

      throw new InternalServerErrorException()

    }
  }

  async getAdminAccessToken() {
    try {
      const adminParams = new URLSearchParams({
        grant_type: 'client_credentials',
        client_id: this.CLIENT_ID,
        client_secret: this.CLIENT_SECRET,
      });

      const { data } = await axios.post(this.TOKEN_URL, adminParams, {
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
        timeout: 6000, // optional: add a timeout to avoid hanging requests
      });

      if (!data.access_token) {
        console.log("failed to retrieve admin access token.....");
        throw new UnauthorizedException("Authentication failed")
      }

      return data.access_token;

    } catch (error) {
      if (error instanceof UnauthorizedException) throw error
      console.log("Error in getAdminAccessToken");
      throw new InternalServerErrorException();
    }
  }

  async registerUser(body: AuthLoginDTO, req: Request) {
    let det = await req['user'];
    if (det?.email !== body.P_EMAILADDR) {
      throw new BadRequestException();
    }
    const userPayload = {
      username: body.P_EMAILADDR,
      // firstName:"A",
      // lastName:"B",
      email: body.P_EMAILADDR,
      emailVerified: true,
      enabled: true,
      credentials: [
        {
          type: 'password',
          value: body.P_PASSWORD,
          temporary: false,
        },
      ],
    };

    console.log(userPayload);

    const adminAccessToken = await this.getAdminAccessToken();

    try {
      const response = await axios.post(this.USERS_URL, userPayload, {
        headers: {
          Authorization: `Bearer ${adminAccessToken}`,
          'Content-Type': 'application/json',
        },
      });

      if (response.status === 201) {

        const uid = await this.getUserIdByEmail(body.P_EMAILADDR);

        const res = await this.assignRoleToUser(uid, "ca");

        console.log(res);

        return { message: 'User created successfully' };
      }

    } catch (error) {
      // handle errors like user exists, validation errors, etc.
      console.log(error.message);

      if (error.message === "Request failed with status code 409") {
        throw new ConflictException("User already exist");
      }

      throw new InternalServerErrorException('Failed to create user');
    }
  }

  async logoutUser(refreshToken: string): Promise<any> {
    const url = `${this.KEYCLOAK_BASE_URL}/logout`;

    const params = new URLSearchParams();
    params.append('client_id', this.CLIENT_ID);
    params.append('client_secret', this.CLIENT_SECRET);
    params.append('refresh_token', refreshToken);

    try {
      const response = await axios.post(url, params, {
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      });
      return { statusCode: 200, message: 'Logged-Out successfully' };
    } catch (error) {
      throw new InternalServerErrorException('Logout failed');
    }
  }

  async getClientUUID(): Promise<string> {
    try {
      const token = await this.getAdminAccessToken();

      const realm = this.KEYCLOAK_REALM;
      const clientId = this.CLIENT_ID;
      const keycloakUrl = this.KEYCLOAK_URL;

      const response = await axios.get(
        `${keycloakUrl}/admin/realms/${realm}/clients?clientId=${encodeURIComponent(clientId)}`,
        {
          headers: {
            Authorization: `Bearer ${token}`,
          },
          validateStatus: () => true, // manually handle status codes
        }
      );

      if (response.status !== 200) {
        throw new Error(`Failed to fetch client list. Status: ${response.status}. Message: ${JSON.stringify(response.data)}`);
      }

      const clients = response.data;

      if (!Array.isArray(clients) || clients.length === 0) {
        throw new Error(`Client with ID '${clientId}' not found in realm '${realm}'.`);
      }

      const clientUUID = clients[0].id;

      if (!clientUUID) {
        throw new Error(`Client UUID is missing in the response for clientId '${clientId}'.`);
      }

      return clientUUID;
    } catch (error) {
      console.error('❌ Error in getClientUUID:', error.message || error);
      throw error; // rethrow for upstream handling
    }
  }

  async getClientRole(roleName: string): Promise<any> {
    const token = await this.getAdminAccessToken();

    const clientUUID = await this.getClientUUID();

    try {
      const response = await axios.get(
        `${this.KEYCLOAK_URL}/admin/realms/${this.KEYCLOAK_REALM}/clients/${clientUUID}/roles/${roleName}`,
        {
          headers: {
            Authorization: `Bearer ${token}`,
          },
        },
      );

      return response.data;
    } catch (error) {
      console.error(`Error getting client role '${roleName}'`);
      console.error(error.response?.data || error.message);
      throw new InternalServerErrorException(`Could not find client role '${roleName}'`);
    }
  }

  async assignRoleToUser(userId: string, roleName: string): Promise<any> {
    try {
      const token = await this.getAdminAccessToken();

      const clientId = await this.getClientUUID();

      const role = await this.getClientRole(roleName);

      const url = `${this.KEYCLOAK_URL}/admin/realms/${this.KEYCLOAK_REALM}/users/${userId}/role-mappings/clients/${clientId}`;

      const response = await axios.post(
        url,
        [role],
        {
          headers: {
            Authorization: `Bearer ${token}`,
          },
          validateStatus: () => true, // To manually check status if needed
        }
      );

      if (response.status >= 200 && response.status < 300) {
        console.log(`✅ Role "${roleName}" successfully assigned to user ${userId}.`);

        return { message: "Successfully assigned to user" }
      } else {
        throw new Error(`❌ Failed to assign role. Status: ${response.status}. Data: ${JSON.stringify(response.data)}`);
      }
    } catch (error) {
      console.error(`🔥 Error assigning role "${roleName}" to user ${userId}:`, error.message || error);
      throw error; // Rethrow to allow upstream handling
    }
  }

  async getTokenFromRefreshToken(req: Request) {

    const refreshToken = req.cookies['refresh_token'];

    if (!refreshToken) {

      console.log("refesh token not present");

      throw new UnauthorizedException('Authentication failed');

    }

    const params = new URLSearchParams();
    params.append('grant_type', 'refresh_token');
    params.append('client_id', this.CLIENT_ID);
    params.append('client_secret', this.CLIENT_SECRET);
    params.append('refresh_token', refreshToken);

    // console.log("url for refresh is : ", `${this.KEYCLOAK_URL}/auth/realms/${this.KEYCLOAK_REALM}/protocol/openid-connect/token`);

    try {
      const response = await axios.post(this.TOKEN_URL, params, {
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      });

      return response.data;
    } catch (error) {
      if (axios.isAxiosError(error) && error.response) {
        console.error('🔴 Axios error:', {
          status: error.response.status,
          data: error.response.data,
        });
      } else {
        console.error('🔴 Unexpected error:', error.message);
      }
      console.log("Error while refreshing tokens : ", error.message);
      throw new UnauthorizedException('Authentication failed');
    }
  }
}