import { SecretsManagerClient, GetSecretValueCommand } from '@aws-sdk/client-secrets-manager';

const secretsClient = new SecretsManagerClient({});

interface SlackCredentials {
  botToken: string;
  signingSecret: string;
}

let cachedCredentials: SlackCredentials | undefined;

async function getSlackCredentials(): Promise<SlackCredentials> {
  if (!cachedCredentials) {
    const res = await secretsClient.send(
      new GetSecretValueCommand({ SecretId: process.env.SLACK_SECRET_ARN! }),
    );
    cachedCredentials = JSON.parse(res.SecretString!) as SlackCredentials;
  }
  return cachedCredentials;
}

interface AppHomeEvent {
  userId: string;
}

export const handler = async (event: AppHomeEvent): Promise<void> => {
  const credentials = await getSlackCredentials();

  const blocks = [
    {
      type: 'header',
      text: { type: 'plain_text', text: "Hi, I'm Alex!", emoji: true },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: "I'm Sea Haven's internal AI assistant. Here's what I can help you with:",
      },
    },
    { type: 'divider' },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*Vendor Lookup*\nFind existing vendors in QuickBooks or discover new ones nearby.\n_Try: "Find me a plumber near ABE2"_',
      },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*Work Order Status*\nLook up any work order by its WO number.\n_Try: "What\'s the status of WO 10046966057?"_',
      },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*Purchase Order Details*\nLook up PO status, line items, and shipping info.\n_Try: "Show me PO 2D-20023475"_',
      },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*Payment & Invoice Status*\nCheck if a vendor has been paid or if an invoice is scheduled.\n_Try: "Has invoice 12345 been paid?" or "What payments went to Acme?"_',
      },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*Site Lookups*\nFind the address and details for any Amazon facility by site code.\n_Try: "Where is DFW6?" or "List all sites in Texas"_',
      },
    },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*Company Policies & SOPs*\nAnswer questions about the employee handbook, SA8000 compliance, and SOPs.\n_Try: "What\'s our PTO policy?"_',
      },
    },
    { type: 'divider' },
    {
      type: 'section',
      text: {
        type: 'mrkdwn',
        text: '*How to reach me:*\n• Send me a DM right here\n• @mention me in any channel I\'m in',
      },
    },
    {
      type: 'context',
      elements: [
        {
          type: 'mrkdwn',
          text: "I only know about data in our systems. If I can't answer something, I'll let you know — and my team reviews those gaps regularly to keep improving.",
        },
      ],
    },
  ];

  const res = await fetch('https://slack.com/api/views.publish', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${credentials.botToken}`,
    },
    body: JSON.stringify({
      user_id: event.userId,
      view: { type: 'home', blocks },
    }),
  });

  if (!res.ok) {
    throw new Error(`Slack views.publish HTTP error: ${res.status}`);
  }

  const data = (await res.json()) as { ok: boolean; error?: string };
  if (!data.ok) {
    throw new Error(`Slack views.publish API error: ${data.error}`);
  }
};