import { existsSync } from 'node:fs';
import { access, constants, mkdir, readFile, unlink, writeFile } from 'node:fs/promises';
import path from 'node:path';
import yaml from 'yaml';
import { ImmichApi } from './api.service';

class LoginError extends Error {
  constructor(message: string) {
    super(message);

    this.name = this.constructor.name;

    Error.captureStackTrace(this, this.constructor);
  }
}

export class SessionService {
  private get authPath() {
    return path.join(this.configDirectory, '/auth.yml');
  }

  constructor(private configDirectory: string) {}

  async connect(): Promise<ImmichApi> {
    let instanceUrl = process.env.IMMICH_INSTANCE_URL;
    let apiKey = process.env.IMMICH_API_KEY;

    if (!instanceUrl || !apiKey) {
      await access(this.authPath, constants.F_OK).catch((error) => {
        if (error.code === 'ENOENT') {
          throw new LoginError('No auth file exist. Please login first');
        }
      });

      const data: string = await readFile(this.authPath, 'utf8');
      const parsedConfig = yaml.parse(data);

      instanceUrl = parsedConfig.instanceUrl;
      apiKey = parsedConfig.apiKey;

      if (!instanceUrl) {
        throw new LoginError(`Instance URL missing in auth config file ${this.authPath}`);
      }

      if (!apiKey) {
        throw new LoginError(`API key missing in auth config file ${this.authPath}`);
      }
    }

    instanceUrl = await this.resolveApiEndpoint(instanceUrl);

    const api = new ImmichApi(instanceUrl, apiKey);

    const pingResponse = await api.pingServer().catch((error) => {
      throw new Error(`Failed to connect to server ${instanceUrl}: ${error.message}`, error);
    });

    if (pingResponse.res !== 'pong') {
      throw new Error(`Could not parse response. Is Immich listening on ${instanceUrl}?`);
    }

    return api;
  }

  async login(instanceUrl: string, apiKey: string): Promise<ImmichApi> {
    console.log(`Logging in to ${instanceUrl}`);

    instanceUrl = await this.resolveApiEndpoint(instanceUrl);

    const api = new ImmichApi(instanceUrl, apiKey);

    // Check if server and api key are valid
    const userInfo = await api.getMyUserInfo().catch((error) => {
      throw new LoginError(`Failed to connect to server ${instanceUrl}: ${error.message}`);
    });

    console.log(`Logged in as ${userInfo.email}`);

    if (!existsSync(this.configDirectory)) {
      // Create config folder if it doesn't exist
      const created = await mkdir(this.configDirectory, { recursive: true });
      if (!created) {
        throw new Error(`Failed to create config folder ${this.configDirectory}`);
      }
    }

    await writeFile(this.authPath, yaml.stringify({ instanceUrl, apiKey }), { mode: 0o600 });

    console.log(`Wrote auth info to ${this.authPath}`);

    return api;
  }

  async logout(): Promise<void> {
    console.log('Logging out...');

    if (existsSync(this.authPath)) {
      await unlink(this.authPath);
      console.log('Removed auth file ' + this.authPath);
    }

    console.log('Successfully logged out');
  }

  private async resolveApiEndpoint(instanceUrl: string): Promise<string> {
    const wellKnownUrl = new URL('.well-known/immich', instanceUrl);
    try {
      const wellKnown = await fetch(wellKnownUrl).then((response) => response.json());
      const endpoint = new URL(wellKnown.api.endpoint, instanceUrl).toString();
      if (endpoint !== instanceUrl) {
        console.debug(`Discovered API at ${endpoint}`);
      }
      return endpoint;
    } catch {
      return instanceUrl;
    }
  }
}