const gql = require('graphql-tag');
const crypto = require('crypto');
const fetch = require('node-fetch');

const environment = 'demo.ownzones.com';

// this is the API endpoint where the GraphQL interface is exposed
const endpoint = 'graphql-gateway.external.demo.oz.nico.ownzones.com/graphql';

/**
 * generating the api keys:
 *  - in Connect console go to your username (top right corner) > "Edit Account"
 *  - click New Api Key
 *  - click SAVE and copy your keys in the variables below
 * note: this is the first and the LAST time when you'll see your secret key; if somehow you will lose it, you need to generate another pair of keys
 */
const orgSlug = 'ownzones-demo';
const publicKey = '<your key>';
const secretKey = '<your secret>';

/**
 * A helper function to create a file locator structure from a file path.
 */
function makeS3Locator(bucket, path) {
  return {
    type: 'S3FileLocator',
    bucket,
    key: path,
    url: `s3://${bucket}/${path}`,  
  };
}

/**
 * Generic method to send a GraphQL request to the Connect API.
 */
async function request(query, variables) {
  // generate the request signature
  const body = JSON.stringify([{ query, variables }]);
  const payload = {
    url: endpoint,
    body,
    organization_slug: orgSlug,
  };

  const hmac = crypto.createHmac('sha256', secretKey);
  hmac.write(JSON.stringify(payload));
  hmac.end();

  const signature = hmac.read().toString('hex');

  // send the request, including the signature
  const response = await fetch(`https://${endpoint}`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-Organization-Slug': orgSlug,
      'oz-key-id': publicKey,
      'oz-signature': signature
    },
    body: JSON.stringify([{
      query,
      variables,
    }]),
  });

  if (response.status !== 200) {
    const body = await response.text();
    throw new Error(body);
  } else {
    const body = await response.json();
    const gqlResponse = body[0];

    if (gqlResponse.errors) {
      throw new Error(gqlResponse.errors[0].message);
    }
    
    return gqlResponse.data;
  }
};

/**
 * Obtains the ID of a file by performing a search in the Connect inventory.
 */
async function findMediaItem(filename) {
  const query = gql`
    query FindMediaItemByFilename($filename: String!) {
      files(search: $filename) {
        edges {
          node {
            id
            assetId
            filename
            ingestWorkflow {
              id
              status
            }
          }
        }
      }
    }
  `;

  const data = await request(query, { filename });

  if (data.files.edges.length === 0) {
    throw new Error('File not found');
  }

  return data.files.edges[0].node;
}

/**
 * Obtains information about a background Connect workflow.
 */
async function checkWorkflow(id) {
  const query = gql`
    query CheckWorkflow($id: ID!) {
      workflow(id: $id) {
        id
        status
        progress
        tasks {
          id
          type
          status
          error {
            message
          }
        }
      }
    }
  `;

  const response = await request(query, { id });

  return response.workflow;
}

module.exports = {
  environment,
  endpoint,
  orgSlug,
  makeS3Locator,
  request,
  findMediaItem,
  checkWorkflow,
};