import { AWSLogEvent, AWSLogsData, AWSEvent } from './AWSLogEvent';
import * as zlib from 'zlib';
import * as https from 'https';

export const handler = async (event: AWSEvent) => {

  if (!process.env.WebhookURL) {
    throw new Error("WebhookURL is not defined in environment variables");
  }
  const webhookURL = new URL(process.env.WebhookURL);

  console.log('Loading function');
  if (!event.awslogs || !event.awslogs.data) {
    console.error('Invalid event format:', JSON.stringify(event));
    throw new Error('Invalid event format');
  }

  try {
    const compressedData = Buffer.from(event.awslogs.data, 'base64');
    const decodedData = zlib.gunzipSync(compressedData).toString('utf-8');
    const payload: AWSLogsData = JSON.parse(decodedData);
    const logGroup = payload.logGroup;
    const logStream = payload.logStream;
    const region = process.env.AWS_REGION;
    const logStreamURL = `https://console.aws.amazon.com/cloudwatch/home?region=${region}#logsV2:log-groups/log-group/${encodeURIComponent(logGroup)}/log-events/${encodeURIComponent(logStream)}`;

    const promises = payload.logEvents.map((logEvent: AWSLogEvent) => {
      const timestamp = new Date(logEvent.timestamp);
      timestamp.setHours(timestamp.getHours() + 9); // Adjust for time zone
      const logEventMessage = logEvent.message.slice(0, 1500) + ' ...';

      const webhookPayload = {
        text:
          `
${timestamp.toISOString()}
LogGroup: ${logGroup}
<${logStreamURL}|Message>:
\`\`\`${logEventMessage}\`\`\`
          `
      };

      const httpRequestOptions = {
        hostname: webhookURL.hostname,
        path: webhookURL.pathname,
        method: 'POST',
        headers: {
          'Content-Type': 'application/json'
        }
      };

      return new Promise((resolve, reject) => {
        const req = https.request(httpRequestOptions, (res) => {
          if (res.statusCode === 200) {
            console.log('Notification sent to webhook successfully');
            resolve(`Successfully processed log event.`);
          } else {
            reject(new Error(`Failed to send notification with status code: ${res.statusCode}`));
          }
        });

        req.on('error', (error) => {
          console.error('Error sending notification to webhook: ', error);
          reject(error);
        });

        req.write(JSON.stringify(webhookPayload));
        req.end();
      });
    });

    await Promise.all(promises);

    return `Successfully processed ${payload.logEvents.length} records.`;
  } catch (error) {
    console.error('Error processing log event: ', error);
    throw error;
  }
};

export interface AWSLogEvent {
  id: string;
  timestamp: number;
  message: string;
}

export interface AWSLogsData {
  logGroup: string;
  logStream: string;
  logEvents: AWSLogEvent[];
}

export interface AWSEvent {
  awslogs: {
    data: string;
  };
}