'use strict';
const visit = require('unist-util-visit-parents');
const u = require('unist-builder');
const dedent = require('dedent');
const fromEntries = require('object.fromentries');

const parseParams = (paramString = '') => {
  const params = fromEntries(new URLSearchParams(paramString));

  if (!params.platform) {
    params.platform = 'web';
  }

  return params;
};

const processNode = (node, parent) => {
  return new Promise(async (resolve, reject) => {
    try {
      const params = parseParams(node.meta);

      // Gather necessary Params
      const name = params.name ? decodeURIComponent(params.name) : 'Example';
      const description = params.description
        ? decodeURIComponent(params.description)
        : 'Example usage';
      const sampleCode = node.value;
      const encodedSampleCode = encodeURIComponent(sampleCode);
      const dependencies = params.dependencies || '';
      const platform = params.platform || 'web';
      const supportedPlatforms = params.supportedPlatforms || 'ios,android,web';
      const theme = params.theme || 'light';
      const preview = params.preview || 'true';
      const loading = params.loading || 'lazy';

      // Generate Node for SnackPlayer
      // See https://github.com/expo/snack/blob/main/docs/embedding-snacks.md
      const snackPlayerDiv = u('html', {
        value: dedent`
          <div
            class="snack-player"
            data-snack-name="${name}"
            data-snack-description="${description}"
            data-snack-code="${encodedSampleCode}"
            data-snack-dependencies="${dependencies}"
            data-snack-platform="${platform}"
            data-snack-supported-platforms="${supportedPlatforms}"
            data-snack-theme="${theme}"
            data-snack-preview="${preview}"
            data-snack-loading="${loading}"
          ></div>
          `,
      });

      // Replace code block with SnackPlayer Node
      const index = parent[0].children.indexOf(node);
      parent[0].children.splice(index, 1, snackPlayerDiv);
    } catch (e) {
      return reject(e);
    }
    resolve();
  });
};

const SnackPlayer = () => {
  return tree =>
    new Promise(async (resolve, reject) => {
      const nodesToProcess = [];
      // Parse all CodeBlocks
      visit(tree, 'code', (node, parent) => {
        // Add SnackPlayer CodeBlocks to processing queue
        if (node.lang == 'SnackPlayer') {
          nodesToProcess.push(processNode(node, parent));
        }
      });

      // Wait for all promises to be resolved
      Promise.all(nodesToProcess).then(resolve()).catch(reject());
    });
};

module.exports = SnackPlayer;