map/load-app.js

import show_error from './show-error.mjs';
import * as marked from './marked.js';

console.clear();

window.marked = marked;

class MarkdownElement extends HTMLElement {
  constructor() {
    super();
  }

  connectedCallback() {
    const shadowRoot = this.attachShadow({mode:'open'});

    const markdown_changed = () => {
      const html = marked.parse(this.textContent);
      shadowRoot.innerHTML = html;
      for(let a of shadowRoot.querySelectorAll('a')) {
        a.setAttribute('target','_blank');
      }
    }
    const observer = new MutationObserver(markdown_changed);
    observer.observe(this, {characterData: true, subtree: true});
    markdown_changed();
  }
}
customElements.define('mark-down', MarkdownElement);

class LeafletElement extends HTMLElement {
  constructor() {
    super();
  }

  addStylesheet(url) {
    const linkElem = document.createElement("link");
    linkElem.setAttribute("rel", "stylesheet");
    linkElem.setAttribute("href", url);
    this.shadowRoot.append(linkElem);
  }

  connectedCallback() {
    const shadowRoot = this.attachShadow({mode:'open'});

    this.addStylesheet("https://unpkg.com/leaflet@1.9.4/dist/leaflet.css");
    this.addStylesheet('map.css');

    const div = this.div = document.createElement('div');
    div.style.height = '100%';
    shadowRoot.append(div);
    const map = this.map = L.map(div);

    this.markers = [];

    this.update_view();
    this.update_markers();

    L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
      maxZoom: 19,
      attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>'
    }).addTo(map);    

    map.on('move', () => {
      const {lat,lng} = map.getCenter();
    })

    map.on('click', e => {
      const ce = new CustomEvent('mapclick', {detail: {latlng: e.latlng}});
      this.dispatchEvent(ce);
    })

    map.on('move', e => {
      this.dispatchEvent(new CustomEvent('mapmove'));
    })

  }
  static get observedAttributes() { return ['lat', 'lon', 'markers'] };

  update_view() {
    const centre = this.getAttribute('centre') == 'true';
    const home = ['lat','lon'].map(a => parseFloat(this.getAttribute(a)) || 0);

    if(centre) {
      this.map.setView(home, this.map.getZoom() || 13);
    }
  }

  update_markers() {
    this.markers.forEach(m => {
      m.marker.remove();
    })

    const data = JSON.parse(this.getAttribute('markers'));
    this.markers = data.map(({id,pos,icon}) => {
      const marker = L.marker(
        pos, 
        {
          icon: L.divIcon({html: `<span id="${id}">${icon}</span>`}),
          iconSize: [20,20]
        }
      );
      marker.addTo(this.map);

      marker.on('click', e => {
        this.dispatchEvent(new CustomEvent('markerclick', {detail: {id}}));
      })
      
      return {pos, marker};
    });

  }

  attributeChangedCallback(name, oldValue, newValue) {
  if(!this.map) {
    return;
  }
    switch(name) {
      case 'lat':
      case 'lon':
      case 'centre':
        this.update_view();
        break;
      case 'markers':
        this.update_markers();
        break;
    }
  }

  set html(value) {
    this.shadowRoot.innerHTML = value;
  }
}
customElements.define('leaflet-map', LeafletElement);

let opfs = await navigator.storage.getDirectory();

async function init_app() {
    const compilation_error = await show_error;
    if(compilation_error) {
        return;
    }

    let markers = [];

    try {
      markers = await (await fetch('data/markers.json')).json();

    } catch(e) {
      try {
        const fh = await opfs.getFileHandle('markers.json');
        const f = await fh.getFile();
        markers = JSON.parse(await f.text())
      } catch(e) {
      }
    
    }


    const emoji = await (await fetch('emoji_metadata.json')).json();
    
    const app = Elm.App.init({node: document.body, flags: {emoji, markers}});
    
    const params = new URLSearchParams(location.search);

    navigator.geolocation.watchPosition(
      (r) => { 
        app.ports.receive_position.send(r.coords);
      },
      (e) => console.error(e),
      {enableHighAccuracy: true}
    );

    const send_value_handlers = {
      save: async ({markers}) => {
        const f = await opfs.getFileHandle('markers.json', {create:true});
        const w = await f.createWritable();
        await w.write(JSON.stringify(markers));
        await w.close();

        const fd = new FormData();
        fd.set('content', JSON.stringify(markers));
        fetch('cgi-bin/save_data.py', {
          method: 'POST',
          body: fd
        })
      }
    }

    app.ports.send_value.subscribe(msg => {
      send_value_handlers[msg.type](msg);
    });
}

init_app();